View Full Version : HUFF DUFF and the Battle of the Atlantic

The Sailor
14-02-2008, 07:34
High frequency direction finder is usually known by its acronym HF/DF, pronounced Huff-Duff. This has become the common name for this type of radio direction finder, and was coined during World War II.

The idea of using two or more radio receivers to find the bearings of a radio transmitter and with the use of simple triangulation find the approximate position of the transmitter had been known and used since the invention of wireless communication. The general principle is to rotate a directional aerial and note where the signal is strongest. With simple aerial design the signal will be strongest when pointing directly towards and directly away from the source, so two bearings from different positions are usually taken, and the intersection plotted. More modern aerials employ uni-directional techniques.

Battle of the Atlantic

Along with ASDIC (sonar), Ultra code breaking (COMINT) and radar, "Huff-Duff" was a valuable part of the Allies' armoury in detecting German U-boats and commerce raiders during the Battle of the Atlantic.

The Royal Navy designed a particularly sophisticated apparatus that could take bearings on the high frequency radio transmitters employed by the German Kriegsmarine in World War II. There were severe technical problems of engineering effective high frequency direction finding systems for operation on ships, mainly due to the effects of the superstructure on the wavefront of arriving radio signals. However, these problems were overcome under the technical leadership of the Polish engineer Waclaw Struszynski, working at the Admiralty Signal Establishment.

A key feature of the British "Huff-Duff" was the use of an oscilloscope display and fixed aerial which could instantaneously reveal the direction of the transmission, without the time taken in conventional direction finding to rotate the aerial—U-boat transmissions were deliberately kept short, and it was wrongly assumed by the U-boat captains that this would avoid detection of the sender's direction.

Another feature was the use of continuously motor-driven tuning, to scan the likely frequencies to pick up and sound an automatic alarm when any transmissions were detected.

In 1942 the allies began to install Huff-Duff on convoy escort ships, enabling them to get much more accurate triangulation fixes on U-boats transmitting from over the horizon, beyond the range of radar. This allowed hunter-killer ships and aircraft to be dispatched at high speed in the direction of the U-boat, which could be illuminated by radar if still on the surface and by ASDIC if it had dived. It was the operation of these technologies in combination which eventually turned the tide against the U-boats.

28-11-2009, 20:42
From Belfast site:-

http://images.google.co.uk/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/a/a7/HMS_Belfast_-_Huff_Duff.jpg&imgrefurl=http://commons.wikimedia.org/wiki/File:HMS_Belfast_-_Huff_Duff.jpg&usg=__9GWz78fz0jp_jZ1R0-SqGLaV01Q=&h=2674&w=2320&sz=2990&hl=en&start=3&um=1&itbs=1&tbnid=JjNHjDUo9RCghM:&tbnh=150&tbnw=130&prev=/images%3Fq%3DHUFF%2BDUFF%26hl%3Den%26sa%3DX%26um%3 D1

Little h

28-11-2009, 20:51
Some excellent explanations in the scheme of things:-


Little h

18-10-2012, 23:26
HF/DF An Allied Weapon against German U-Boats 1939-1945

Radio communication influenced WW II much more than was realised by the early post war
historians and by the general public. For example, after 1974 ULTRA became common
knowledge yet, even today, some aspects still remain secret. Likewise, though HF/DF
(huff-duff) was known about, the understanding of its technology remains limited. It is quite
likely that this is due to the strict secrecy practised by the British authorities. It even happened
that, in the 1960's, after Derek Wellman offered BBC TV a play concerning his experience as
a wartime huff-duff operator, a call came advising him that "this subject is not of interest to
the British people"!!
The aim of this paper is to explain, briefly, some aspects of HF/DF so as to create a greater
understanding of its technology and the circumstances surrounding its use. After all, it could
be associated either directly or indirectly with the sinking of an estimated 24 % of all U-Boats
lost during WW II.
© Arthur O. Bauer Diemen, The Netherlands Stgcdv&t@xs4all.nl 27 December 2004

HF/DF an Allied weapon against German U-boats 1939 - 1945

During the First World War the German U-boats played an important role. The main aim of
the U-boat High Command was to cut off the Allied life line. The fact that the United States
gave up their initial relatively neutral stance and joined the Allies has to be ascribed above all
to the so-called unrestricted U-boat war fought by the Germans.
As one knows, the British were able (very cleverly) to persuade the USA to come into the war
before the end of 1917. Though this is not the place to examine in detail how this came about!
The First World War showed how vulnerable the supply lines between the USA and Great
Britain are. In the Second World War there too was a moment when the shipping losses
became unbearable and the cancellation of convoys across the Atlantic was a distinct
possibility as the shipyards could no longer make good the losses of tonnage. Building a ship
just takes longer than its torpedoing.
The course of history is rarely determined by one factor or cause alone and that was naturally
no different in the two world wars. Nonetheless, individual events or circumstances
sometimes exercise a great influence on the way things work out.

Some aspects of "Direction Finding", a well known technology
Famous names appear when we look back into the historical sequence of inventions which
lead to the design of modern direction finding apparatus. In my opinion, one of the most
important was the invention, by E. Bellini and A. Tosi, in 1907 of the radiogoniometer,
which became known as Bellini - Tosi or the so-called B-T goniometer. After about 1915, i.e.
after the sensitivity of receivers became more adequate, B-T became very popular and has
been widely used since. (Keen, p. 156 - 201, et al.)

Figure 1: The goniometer principle of Bellini-Tosi

It can easily be understood from this line drawing that two wire loop aerials are fed onto two
field coils. These coils are mounted so as to be at right angles. It is known that the induced
magnetic field lines do not then (theoretically) affect each other.
Their real invention was to introduce a search coil, which acts as a magnetic flux pick-up
device. It is evident that when a particular E.M. (Electro Magnetic) wave induces an electrical
current in one or both loops this subsequently results in an electrical current in the goniometer
circuit. It can be understood that this produces a magnetic flux pattern which is due to the
arriving E.M. wave. With shore based DF antennas the search coil zero setting was usually
related to the direction of an antenna loop which picked up the maximum field strength from a
specified source or direction. Shore based antennas were (are), quite often lined up North-
South and East-West. For ship board antennas relationship tended to refer to Fore - Aft and
Port - Starboard.
It can be proved that only the magnetic field component H of an E.M. wave can induce an
antenna loop current when its perimeter is < 3 λ (wave length). Sense antennas commonly
function on the electrical or E field component of E.M. waves.

As we know each antenna loop in fig. 1 is delivering its appropriate current onto its connected
field coil, hence the magnetic field distribution is equivalent to that of the induced loop
currents. Although I am not going to prove it here, we can easily explain this principle by
assuming that an incident E.M. wave reaches the antenna system under an angle of 45 degrees
parallel to the horizontal plane, and this subsequently results in equal currents in both loop
circuits. If we bring the cylindrical axis of the search coil parallel to that of one of the field
coils, only half of the induced antenna power can be picked up by it. Only when the
cylindrical axis of the search coil is brought into line with the arriving E.M. wave (hence in
our assumption the bearing angle P = 45°) can the optimal power transfer occur. What
happens if we rotate the search coil through 180°? Again a flux (signal) maximum will be
picked up. Hence it is impossible, by means of such B-T goniometer only, to determine from
which direction the arriving E.M. wave is approaching, is it from 45° or 225°? Therefore a
sense antenna has to be incorporated and its signal will create, by vector summation, a
cardioid radiation pattern (which I do not intend to discuss further).
We will look briefly at the origin of B-T vector summation.

............................(article continues)

For this explanation we will ignore the coupling deviations (errors) of this goniometer type,
because these are of a systematical order and do not influence the fundamentals of DF by
means of a B-T goniometer.
The HF/DF type FH 3 utilised the manually controlled B-T goniometer in conjunction with
the Navy type B 21 B receiver. This latter system proved to be the backbone of huff-duff
against the U-boat threat, on board most escort vessels. For instance, even during the zenith
of the Battle of the Atlantic (during the early days of May 1943) of seven escorting convoy
ships of ONS 5 only HMS Duncan was equipped with a FH 4. (ADM 237/113, and Bauer, p.
150) Not until the second half of 1944 did the FH 3 apparatus became surpassed by its famous
successor the FH 4, which will be introduced hereafter.
Watson-Watt and Herd designed for the Radio Research Board in 1926 their twin channel
receiver, which was originally designed to detect the direction of thunderstorms and
consequently was not required to be, for this purpose, very sensitive. This type of direction
finder became well known as: - Watson-Watt, or Twin Path C.R.D.F., receiver system.
It is fairly clear that the twin channel indicator in figure 3 has some similarity with Bellini-
Tosi's invention. The field coils are replaced by the X and Y deflection plates of a CRT. The
indication of the E.M. wave direction (bearing) now appeared automatically, when
appropriate deflection voltage were induced between the appropriate deflection plates. In
some way we can understand that according to Keen (p. 159) this apparatus was described as
an "Electrostatic Radiogoniometer".
The major advantage of this invention is its instant bearing indication, without any man made
delay. In other words, the search coil was "quasi replaced" by an electronic beam which
painted a Lissajous figure on the indicator screen of a CRT, and whose amplitude was
proportional to the resulting vector pointer after summation of the two field components. Only
when an E.M. wave is exactly in line with one loop, and thus causes only one deflection to be
fed with electrical energy, no vector summation occurs. Therefore one sees only a straight
vertical- or horizontal-line on the CRT.

.........................(article continues)

For this explanation we will ignore the coupling deviations (errors) of this goniometer type,
because these are of a systematical order and do not influence the fundamentals of DF by
means of a B-T goniometer.
The HF/DF type FH 3 utilised the manually controlled B-T goniometer in conjunction with
the Navy type B 21 B receiver. This latter system proved to be the backbone of huff-duff
against the U-boat threat, on board most escort vessels. For instance, even during the zenith
of the Battle of the Atlantic (during the early days of May 1943) of seven escorting convoy
ships of ONS 5 only HMS Duncan was equipped with a FH 4. (ADM 237/113, and Bauer, p.
150) Not until the second half of 1944 did the FH 3 apparatus became surpassed by its famous
successor the FH 4, which will be introduced hereafter.
Watson-Watt and Herd designed for the Radio Research Board in 1926 their twin channel
receiver, which was originally designed to detect the direction of thunderstorms and
consequently was not required to be, for this purpose, very sensitive. This type of direction
finder became well known as: - Watson-Watt, or Twin Path C.R.D.F., receiver system.
It is fairly clear that the twin channel indicator in figure 3 has some similarity with Bellini-
Tosi's invention. The field coils are replaced by the X and Y deflection plates of a CRT. The
indication of the E.M. wave direction (bearing) now appeared automatically, when
appropriate deflection voltage were induced between the appropriate deflection plates. In
some way we can understand that according to Keen (p. 159) this apparatus was described as
an "Electrostatic Radiogoniometer".
The major advantage of this invention is its instant bearing indication, without any man made
delay. In other words, the search coil was "quasi replaced" by an electronic beam which
painted a Lissajous figure on the indicator screen of a CRT, and whose amplitude was
proportional to the resulting vector pointer after summation of the two field components. Only
when an E.M. wave is exactly in line with one loop, and thus causes only one deflection to be
fed with electrical energy, no vector summation occurs. Therefore one sees only a straight
vertical- or horizontal-line on the CRT.

............................................(artic le continues)

HF/DF designed in Britain
We shall not discuss the background history of HF/DF, as this has been described by several
others e.g.: P.G. Redgment, and in the US, by Kathleen Broome Williams, et al.
DF on shortwave was already well known and widely used by shore DF stations before WW
II. The main problem is to overcome the distinct shortcomings of antenna loops (aerials),
which caused more or less severe bearing deviations (errors) especially on board ships. The
best antenna system for DF on shortwave proved to be the well known Adcock antenna,
although this antenna type has some disadvantages when it is used for DF of ground waves.
Adcock antennas need a very strictly controlled linear antenna site (plain and flat instrata
with uniform conductivity), which can hardly be obtained on board ships due to
discontinuities which are caused by the superstructure of ships. Due to this hampering antenna
behaviour the opinio communis was that accurate DF on shortwave could never be made fully
operational on board ships of any kind.
One of the main DF problems which is faced on board ships is caused by the more or less
erratic behaviour of fields re-radiated originated by the superstructure of ships, for instance,
by ship masts - the bridge and pipes - (which proved to be excellent re-radiators when these
are excited by E.M. waves in respect to n A 3 λ) etc.. The relatively high Q-factor of these reradiators
can often cause an equal or even higher signal input at the front-end of a DF receiver
than that which is induced, in the antenna system, by the arriving E.M. wave! As we have
seen before, this could cause severe bearing errors which could reach 20° or more. This
phenomenon was well known in those days, but the question arose as to how could this be
countered and/or controlled? It soon proved that a DF antenna positioned (mounted) at the top
of the tallest mast in the ship was the most favourable site. [IEE Proceeding, p. 798]
In my opinion it was the Polish engineer Struszynski - working at ASE - who was the "pater
intellectualis" of a team which solved this problem.
Both the PS and FA loop can clearly be noticed, in figure 5 on the next page, on top of the
central chamber. Struszynski designed, among other things, the particular coupling
transformers which linked the symmetrical coaxial antenna cables either on to the B-T
goniometer of the FH 3 or on to the front-end of the FH 4 receiver. These RF transformers
have a very low stray field effect and are electrostatically shielded so as to prevent capacitive
coupling (stray pick-up) between the primary and secondary windings. It is evident that these
transformers were matched to the terminating impedance of the antenna circuits. Each set of
transformers had individually to be matched for equal electrical parameters. Separating the
direct antenna loop currents from the front-end of the receiver, as well as the careful
symmetrical wiring of the coaxial cable circuit, enhanced the common mode rejection of the
system up to about 100 dB at 1 MHz. It can be seen that energy induced in a symmetrical
coaxial cable by a stray field will be picked up by both conductors at the same time thus
cancelling out any effects at the secondary circuit of the transformer. (IEE p.825) Even the
radio hut and all its entering cables had to be electrically shielded and filtered so as to prevent
any stray fields from being picked up by the receiver itself.

Figure 5: The FH 4 antenna circuit

The coaxial cables (so-called: twin-core feeder cables) used in these DF systems had to
be all from the same production lot (same cable reel) and their mutual difference in cable
length had to be kept within a maximum of 1 inch, so as to prevent unacceptable phase errors!
As we have noticed, the re-radiation field of the resonating antenna mast could be of severe
proportions and such fields would be picked-up by the sense aerial too! Struszynski's team
again solved this problem by balancing - for RF - the sense aerial circuit against the mounting
mast by means of an adjustable electronic bridge circuit. (Redgment, p. 239)
"The antenna"
The RN sailors called this antenna the "birdcage", though how it worked electrically was kept
a secret for many years. This secrecy was aided by it's very complex construction.

Figure 6: The FH 4 antenna in detail

The previous line drawing shows its well known antenna profile. Even with explanation this
figure is not easy to understand and gives no immediate clue as to how smart the design was.

Figure 7: The PS loop

The line drawing above shows the broadside view of the PS antenna loop and the edge-on
view of the FA loop.

Figure 8: The sense antenna

Shown here is the sense aerial on top of the central chamber (see fig. 6), the aerial is facing
upwards. Downwards we see the counterpoise, which provides an artificial ground. To extend
the counterpoise the rods are folded upwards as well. I am not sure whether they also serve
the additional purpose of screening off the re-radiated fields which are arriving from lower

Figure 9: The reinforcement rods

It is evident that the previously shown extended counterpoise could not be kept structurally
stable. Therefore, reinforcement rods were introduced to stiffen this complex antenna
construction. For stable and precise operation this was a real must, certainly when one realises
the nature of the environmental conditions in which it had to perform!

Watson-Watt type DF receiver
The early design of the "twin-channel" receiver type R.L.135 and R.L.66A had already been
done by the Plessy Co. Ltd. in 1940; though it took quite some time before the first
operational FH 4 apparatus became available for the RN in 1943. The early type used a set of
5 interchangeable coil boxes, which were stored in a (hanging) box to the left and right of the
receiver and which covered a frequency range between 1- 25 MHz. Its successor FH 4 Mark
IV was equipped with switched coils which covered 4 frequencies ranges between 1 - 24
MHz. (manual FH 4, chapter 2, p. 8, Bauer, p. 101 - 109, 133 -139).

Figure 10: Blockdiagram of the FH 4 receiver

This blockdiagram explains the principle of the twin-channel HF/DF type FH 4. As we
will see hereafter, the FA and PS channels were "carbon copies" to ensure that signal delay
for both channels was kept (theoretically) equal. Only one local oscillator needed to be
utilised, whose signal was fed to both mixers simultaneously.

Figure 11: Principle diagram of the FH 4 receiver

Shown here is the basic circuit diagram of the FH 4, which we will discuss briefly. Let us first
focus on the main FA and PS receiver channels. The two loops are linked via the transformers
T2 (designed by Struszynski) on to the input bandfilter at the front-end of the receiver,
followed by the RF amplifier stage V1 to the mixer (Frequency Changer) valve V2 . The
common local oscillator (F.C. oscillator) is generated by valve V3 and fed simultaneously to
the mixers V2. After passing three IF stages V4 - V6 both signals are fed to the CRT deflection
plates. The bearing display is similar to that shown in figure 3.
We have seen, already, that a B-T goniometer itself always indicates a bearing which could be
at + or - 180°. This ambiguity can be solved by the introduction of a third (sense) signal
which phase-quadrature is relative - positive or negative - with respect to the fields induced in
the antenna loop.

It is obvious that it had to be amplified equally as both loop signals, and that any time delay
deviation of the signal phase had to be prevented. Inevitably, a third equal receiver channel
had to be incorporated in the receiver to accommodate the sense signal. But this could hardly
be managed in the available room left in the receiver. In my opinion a smart, though "poor
man's", solution was chosen to overcome this limitation.

Figure 12: Blockdiagram of the FH 4, used in sense mode

The sense signal was fed to one of the receiver channels after the accompanying loop signal
was disconnected. At the same time the accompanying IF output which is connected with the
deflection plates of the CRT is disconnected from it and these plates are now electrically
connected to ground. The IF signal is then fed, via the sense limiter, to the Wehnelt cylinder,
so as to control the beam current of the CRT in such a manner that, without signal, its beam
current was cut-off (blocking) and only when a sufficient signal was received could a trace be
observed on the CRT screen.

Let us look, on the next page, at the principle involved (disregard phase difference between
the signals).
1. the FA loop and its radiation pattern in respect to an arriving E.M. wave.
2. the typical circular radiation pattern of a sense aerial
3. the CRT; its Y deflection system is fed by the accompanying output of the IF strip and
the X deflection plates are connected to ground.
4- 5. the upper sinusoid is representing the output of the IF strip. The lower sinusoid is re
ceived by the sense channel and fed in an appropriate manner onto the Wehnelt cylinder.
The time span which coincides with the positive half cycle (0° - 180°) of the sense signal is
used to de-block the Wehnelt cylinder of the CRT. (often called "control grid", which is, in
technical means, not correctly)

..................................(article continues)

Let us refer back to figure 11 and concentrate first on the test oscillator section.
In the centre of it we notice that the mixer valve V9 has a multiple function. The triode section
is used as a BFO generator, whose signal is fed onto the detector stage so as to interfere in a
regular manner with the IF signal. A certain amount of energy is picked up from the local
oscillator valve V3 via C2, which is then followed by a separator stage V8 and fed onto the
mixer section of valve V9. Let us assume that the test signal is activated by the appropriate
settings of switch 7. The BFO signal is then disconnected from the IF stage and fed - via IF
rejection filters - onto V10 which amplifies and probably also separates the test loop circuit
from this mixer stage. If the BFO setting is adjusted correctly the test oscillator frequency will
always be exactly identical to that to which the receiver is tuned.
A third signal is generated in the test oscillator unit. This RF signal was used to ensure that
the receiver channels could be adjusted properly for their mutual amplification factor as well
as for mutual signal phase.
To carry out this alignment, the first step was to switch on the so-called comparator mode (S2 -
S3 ). Both receiver channels were thus connected onto the same signal source. When
amplification and signal phase were matched properly, a straight line was observed between
45° and 225°, which is in Navy terms equal to 45° and 135°. When, for instance, the phase
tuning is incorrect an ellipsoid is shown with all its implications as we have already discussed.
After this foregoing alignment (set up) the test loop was switched on. (S2 and S3 are opened

Figure14: Test loop of the FH 4 antenna

Shown is here the test loop, which is mounted in the central axis of the DF antenna. Generally
speaking, if we see somewhere a "Birdcage" antenna without a test loop it is certainly in used
with a FH 3 installation. Only when a test loop is utilised is the receiver concerned an FH 4
apparatus. I do not know if its successor the FH 5 used such a test facility as well because,
today, this information is still kept classified (some ships are still equipped with this
The main function of such a test loop is to check the mutual (amplification and) signal phase
of the two RF stages of the receiver which can be controlled by trimmer CT1 (fig. 11) on the
front panel (whilst, of course, watching the display on the CRT).
Up until now, we still don't exactly know what made this equipment so outstanding because,
if we neglect its antenna circuit, all the rest was certainly common knowledge for the
Germans also in those days. Watson-Watt type direction finders had been in wide use since
the end of the 1920s.

Radiation patterns of the FH3/4 antenna
As we have already noticed, the superstructures of ships can cause all sorts of bearing
deviations. We will discuss this phenomenon for some sample frequencies, though it has to be
noticed that a frequency change of, for example, only 10 kHz can cause radiation patterns to
be changed in an erratic manner. Due to this phenomenon, interpolation between curves is not
possible and a calibration curve is needed for every frequency that is likely to be used in the
operation of the installation. (IEE, p. 810)

How then can acceptable bearings be achieved within deviation limits of between 3 to 5
Many deviations are of a systematic nature and are widely dependant upon the superstructure
of a ship. But systematic deviations lend themselves to be compensated for by means of a
calibration curve and this proved to be the solution to this problem! The Germans call this
technique "Funkbeschickung" and its technology was already widely used in the 1930s for
medium and long wave DF systems.
For each possible frequency a calibration chart had to be prepared, which would hardly be
managed when we realise that German U-boats on the northern (western) hemisphere used
frequencies in the range 3.7 - 15 MHz. Thus, a frequency band of . 11 MHz had to be
covered. If we further assume that a calibration had to be made for every 20 kHz then more
than 500 curves (theoretically) had to be prepared for each ship equipped with HF/DF! It has
to be realised too, that the so-called "Penang" boats (also called "monsoon boats"), sailing to
the Far East, were communicating on frequencies up to 24 MHz.

A calibration procedure was carried out as follows:-
Each ship had to be anchored on a buoy such that a calibration vessel could circle it with
constant radius and which sent bearing signals at a distance of approximately one mile from
all directions and, at the same time, all vessels had to be far enough from shore to avoid any
DF aberrations resulting from land effects.
At every 5° of azimuth - "blurring" percentage, bearing deviations and the quality of sense
indication had to be logged. The bearing accuracy was visually checked by optical means.
Consequently, this vessel had to stop for each calibration step 71 times for one circle. Thus, if
we assume that such a calibration vessel had to sail 500 times around the ship under
calibration the task would seem impossible and could hardly be managed, in my opinion. (500
x 71 = 35500 steps!)
But, it was the Germans themselves who made what seems to be impossible nevertheless
become possible!
According to PRO document ADM 220/69 dated 3 July 1943 - which considered a list (for
the calibration officers concerned) of the frequencies for which the HF/DF systems had to be
calibrated for the Atlantic and Arctic areas - only 44 frequencies which were expected to be
utilised! Though, we always have to consider that such details only exposure a certain
momentum. (For more details see Bauer, p. 16 - 20)
True bearings by means of the FH 4 and its correction curves.

Figure 16: FH 4 bearing error compenstation, by means of correction curves

Shown here are the main attributes which had to be used to assure more or less accurate
bearings by means of HF/DF.
For each frequency separate bearing curves had to be prepared for Port (Red side) and for
Starboard (Green side) of a ship.
Let us assume that an arriving E.M. wave induces an antenna current and a bearing trace
becomes visible on the screen of a CRT. The operator had (after preceding tuning
procedures) to rotate a perspex disc which covers the bearing display (CRT) so as to bring the
cursor hair line along this trace (which cursor also acts as a bearing memory). We will take, as
our example, values of 30° and 150° (respectively) for the green and red curves (these
equate to readings of 340° and 160° for the coincident gyro compass readings). The operator's
next immediate step was to select the correct "sense" direction.
Following this, he had to refer to the calibration curves and he finds that for the Green side
curve a bearing deviation correction of - 6 degrees is needed and for the Red side curve a
deviation correction of - 5 degrees was required. Hence, dependant on the sense setting, the
expected bearing is at: 30° - 6° = 24° or at 150° - 5° = 145°. The blurring curves were mainly
used for regular calibration purposes.

An interesting aspect is that, although severe bearing deviations occur, the average
systematical accuracy still remains within reasonable limits. This phenomenon is well known
in statistics and is due to the fact that not all variable deviations are possessed of the same
sign, so that not all parameters are varying into the same direction.
On this occasion we have not discussed the nature of the U-boat communications and related
technical topics. The contents of this paper are essentially a condensation of the five year
research work covered, and published, in my book:-
"Funkpeilung als alliierte Waffe gegen deutsche U-boote 1939 - 1939"
For those who would like to study the subject of HF/DF - I strongly recommend two superb
books: Wireless Direction Finding by Keen and Funkpeiltechnik by Grabau and Pfaff. (see ref.)

In history major technological breakthroughs hardly ever originate due to one circumstance or
factor only, but almost always result from a sequence of developments which finally leads to
what became known as "the particular solution". Prime examples are, for instance, the
development of the atomic bomb, or centimetre radar. HF/DF is, in this respect, no exception.
In retrospective let us first look at some technical aspects of "huff-duff".
We have noticed that HF/DF had not been invented in Britain, it was a step by step scientific
process which started in the early days of this century. Bellini -Tosi's goniometer proved to be
of fundamental significance and it became widely used for all sorts of direction finding
We have not discussed the French - American developments which were mainly based upon
Busignies work done in Paris in the late 1920s and 1930s, and which were brought to the US
on behalf of ITT in late 1940. Kathleen Broome Williams' book contains much detailed
information concerning this historical aspect (though, unfortunately, in technical respect here
knowledge is too meagre!). Even these HF/DF apparatuses used the B-T principle, although
with a spinning search coil. (Keen, p.877-880) It is interesting to note that according to
Williams' book, Busignies, also designed a rotating single loop DF apparatus. (also Wireless
World, p. 414 - 416)

The main problem hampering accurate DF on ships is due to the re-radiated electro
magnetic fields which are caused by the superstructure. Re-radiated signals can hardly be
avoided under these circumstances. It was Struszynski who solved this major handicap by the
introduction of a totally new antenna design, which became known as the "birdcage" antenna.
We have noticed how the segments of this antenna were constructed and fit together. Not
exactly obvious however is Struszynski's most significant invention: - the RF balancing
circuit which - for radio frequencies - separates the top of the mounting ship mast from the
sense antenna circuit (which is an inextricable part of the "Birdcage" antenna). Although the
Americans claim that they had designed (developed?), during WW II, their own HF/DF
antenna. However, I do not know if the Americans have utilised a Struszynski like "RF bridge
circuit" to isolate the sense aerial from the ship mast. Though, in my opinion, the US HF/DF
antenna design looks less stiff ("a nice weather artefact"). (KBW p. 46 and Henney/Markus p.
We have also seen the disadvantages of Watson-Watt's direction finder design and, we have
learned about its implications as well. I suppose that this was a choice made by the Royal
Navy in the expectation that this type of HF/DF apparatus was the most likely to come into
service quickly. Certainly for shore direction finding installations, the AH 6 (which is the
shore version of the FH 4) had a great advantage over any chopped or rotating DF
(goniometer) apparatus due to the lack of any forced synchronous modulation which could
always interfere with the contents of an intercepted wireless signal.
I have met Dutch post war FH 4 operators and they told me that this apparatus was rather "unfriendly"
to maintain, especially for those who had to align it. It utilised more than 41 tuning
facilities, whose alignment had to be checked on a regular basis! According to the manual a
set-up alignment could only be carried out after a warming-up period of six hours! Taking all
this into consideration then, it is after all, nearly a miracle that this apparatus worked so well
and did such a great job!
The introduction of calibration charts made correction of bearing errors of a systematic nature
possible. We have seen that - due to the unpredictable nature of re-radiated E.M. fields caused
by the superstructure of ships - a separate calibration chart had to be prepared for each
frequency to be operated. This amounted to a possible provision for more than 500 available
frequencies which might have had to be utilised for each ship. Under these circumstances
shipborne HF/DF - as were used by the Allies - could never, tactically, have worked at all! All
shipborne direction finders allowed for monitoring of only one frequency at the time, in those
days. To slightly overcome this great disadvantage, the RN utilised a second communication
receiver (Navy B 28 B . CR 100) which, at the same time, was tuned onto a different
frequency which was expected to be used by the U-boat control as well. (Each HF/DF antenna
could be linked - thus wired - onto one receiver only!) Each audio signal was connected onto
one earphone section, so as to make monitoring of two different wireless signals at the same
time possible. This mode was called: split phone operation.
It must be said that we were quite lucky that the U-boat wireless signals were nearly always
tuned zero beat onto frequencies which were controlled by shore stations and these call signs
were quite well known. Hence, huff-duff operators only had to monitor a limited number of frequencies.

Although we have not discussed this subject, we have to regard that for certain
operations the Germans used so-called "off frequencies" which could operate randomly (from
the Allied point of view) - for special services - between plus and minus 300 kHz from a
particular centre frequency. Williams shows by an wartime document (p. 201) that, for
example, such frequencies had to be watched by a total number of ten monitoring operators at
the same time!

From an historical point of view, I think it is fair to conclude that: -
The role of allied HF/DF is generally undervalued. That this is no merely marginal
phenomenon becomes clear when we notice that presumably a quarter (although some sources
count this figure to be at a much lower rate) of all U-boat losses can statistically be associated
with HF/DF operations during WW II. It is therefore no exaggeration to call radio direction
finding a most significant weapon in the war against the U-boats and it undoubtedly
influenced Allied warfare to a not inconsiderable extent.
Also, that its success owed quite a lot to wrong assessments made by the wireless
organisation of the "Kriegsmarine", which kept on utilising zero beat operation for
their standard U-boat wireless communications!

I have to thank all who made it finally possible to complete the work of my book, which list
contains more than 60 names. But I have to mention those who made it possible for me to
start working on this task: Karel Hagemans, Pat Hawker, Heinz Lissok, Ralph Erskine, Klaus
Herold, Hans Richter.
I also have to thank for the friendly support of: IEE, Franksch' Verlag, and of course many
other individuals and institutions as well.
Without the indispensable support of Richard Walker this paper hardly would have been
ADM ... refs are stored at PRO, Kew Garden.
Bauer A.O., Funkpeilung als alliierte Waffe gegen deutsche U-Boote 1939 - 1945. Delivered
by, Liebich Funk GmbH, D - 47486 Rheinberg, Germany, 1997.
Grabau & Pfaff, Funkpeiltechnik, Grundlage - Verfahren und Anwendungen, Franckh'sche
Verlagshandlung Stuttgart, 1989.
Henney K. and Markus J., Huff Duff, Scientific American, April 1946
IEE Proceedings, Journal Institution Electrical Engineering, Part IIIA, 94, (1947) based on
Proceedings of the Radiocommunication Convention March/April 1947.
Keen, Wireless Direction Finding, Published for "Wireless World", by Iliffe & Sons, Ltd.
London, 1947, Fourth edition.
Redgment P.G.: High-Frequency Direction Finding, edited by Kingsley, Applications of
Radar and other Electronic Systems in the Royal Navy in World War II, Basingstoke 1995.
Williams, Kathleen Broome, Secret Weapon, U.S. High-Frequency Direction Finding in the
Battle of the Atlantic. Naval Institute Press, Annapolis, Maryland, 1996, USA.
Wireless World, Volume XLIV, January 5 th - June 29 th, 1939
PDF source here (http://aobauer.home.xs4all.nl/HFDF1998.pdf)

My comment;
The reason for including the excerpts above is to highlight the fact that not only was this equipment used in the period identified in the heading, it continued to be used for a number of decades thereafter. Indeed, it was used during those later years, together and oft times in conjunction with, early examples of shipborne SHF/DF equipment.

The use to which the equipment was put is only partially described in the above article, as is usually the case in most articles/reports that one reads. The element that is frequently neglected is what is done with the information that the shipborne operator(s) obtained. Because of course there would be no such thing as triangulation if the operator simply passed his findings to the ops room or bridge - one bearing hardly a fix makes;).

That is where the HF/DF operators would come into the equation; getting the information which had to be communicated with extreme urgency, to a controlling unit whom together with the associated information from other ships, would use all the bearings to ascertain the position of the target, whereupon decisions could/would be made relating to what should be done about it.

Little h

19-10-2012, 17:49
On November 19, 1942, Admiral Noble was replaced as Commander-in-Chief of Western Approaches Command by Admiral Sir Max Horton.
Horton used the growing number of escorts becoming available to organize "support groups", to reinforce convoys that came under attack. Unlike the regular escort groups, support groups were not directly responsible for the safety of any particular convoy.
This gave them much greater tactical flexibility, allowing them to detach ships to hunt submarines spotted by reconnaissance or picked up by HF/DF.

Where regular escorts would have to break off and stay with their convoy, the support group ships could keep hunting a U-boat for many hours. One tactic introduced by Captain John Walker was the "hold-down", where a group of ships would patrol over a submerged U-boat until its air ran out and it was forced to the surface. This might require two or three days.


19-10-2012, 20:31
Building an Intercept Station During World/War II
Joseph Horn

From the late fall of 1942 to the summer of 1943.
eleven sailors and I were shipped from Noroton Heights
Radio School, Connecticut, to German Morse school at
Cheltenham, Maryland, then, to Oppelachia:A.irfield in
Florida and on to Bahia. Brazil. Among the twelve ofus
shipped to Bahia were~ land Gene Sheck,
who are still employed y NSA. How we were selected IS
still a mystery because at that time the selectionsystem for
assigning personnel leaving Noroton Heights Radio
School was not very scientific. Typically, it was: those
A-F, standby for submarine duty, all those G-K, standby
for cruiser duty, all those L-S, standby for destroyer.duty,
all those T-Z, standby for amphibious duty. With that
kind of selection process, I have to wonder, still,how they
arrived at calling .. Sheck, I I .." to be
assigned to USN Station at Cheltenham, Maryland. At
that time I was very disappointed about the assignment
because 1) I didn't know what was entailed, and 2) I had
joined the Navy to go to sea and fight. Whether or not
the assignment was proper, I have lived to tell about it.

We were sent to Brazil to build an intercept and OF
station at Salinas de Margarita-literally, to cut it out of
the jungle. Salinas was to be the southern leg of a three
station, intercept-and-HF/DF net with control at Recife,
Brazil, and the northern station at Belem on the Amazon
River. Salinas, about 25 miles by water from the city of
Bahia, was located on a peninsula covered with such
dense jungle that it was usually considered an island.
Our targets were German submarines operating in the
mid. and southern Atlantic, Allied ships and aircraft in
distress, and Argentine Navy and enemy covert activities
in South America and Africa. The covert communications
were intercepted by a Coast Guard unit which was
stationed at Recife with our Navy. I never did find out
what happened after we were able to locate a covert
transmitter but did observe that they were not heard
shortly thereafter. The German submarines were not
difficult to identify since they usually sent a message
called a "B-barred," which began with "dahh dit dit
dit dahhh." This sound made the cold chills run-I can
still hear it occasionally. The DF equipment (DAB) was
a far cry from that of today. It was about 15 feet long,
mounted on a pivot with antennas at each end. The
operator manually twisted the machine back and forth
as many times as be could during the 20 or so seconds
that a suspected enemy submarine transmitted. getting
as many crosses as he could on the scope in order to
estimate the direction. One had to be in fairly good physical
condition to be able to twist the equipment back
and forth rapidly enough to get a bearing. The DAB
at Bahia had a practice of twisting off at the bottom of
the pedestal. which was another reason one had tobe in
fairly good physical condition.

Communications were not very rapid in those days.
Our only electrical communications were by manual
Morse. We communicated by Morse within the OF net
for tip-off and reporting. Recife communicated with
Washington for administrative and operational traffic
and acted as rday point between. Washington and
Ascension Island. Once when I was operating the Recife
Washington circuit and could not raise Washington to
receive high precedence traffic, Navy control at Guam
came up on my.frequency, received my messages and
relayed them to Washington. (I do not think HF wave
propagation predictions would have come up with that
one.) Operating communications circuits was less
demanding than operating an intercept position-you
could always ask for a repeat if something were missed
when communicating. Also, when communicating. you
could ask the operator at the other end to slow down, to
improve sending or, in a dire situation, to put another
operator on the set.

In contrast to today's highly formatted procedures for
intercepting manual Morse-with-----------------

------------------------ our main
objective was to copy every dit and dah that the target
sent. The format was incidental. In fact, we objected even
when told that the date should be typed on the upper
right hand corner of the page. A lot more is expected of
today's intercept operators: now the operator is expected
to copy the target, do running traffic analysis and then tag
everything for computer processing.

The receivers we used were rather simple in design.
One did not have to turn the BFO to change the pitch of
a signal; you could just put your hand on the chasis. If
someone walked too close to your receiver, the pitch
changed. Simplicity in the design of the receivers was a
blessing in disguise because of the severe lack of spare
parts. An essential part of maintenance training was
learning how to repair a burned-out tube with a shot of
high voltage. It worked, sometimes.
For DF tip-off and reporting we used a tracking code,
for administrative and operational traffic, one-time pads.
Pencils with erasers were an important part of the
inventory: we used them to push the paper strips back and
forth on the board when enciphering traffic. This slow,
tedious method of encipherrnent had its drawbacks but, in
retrospect, it served as a great managerial tool in keeping
electrical communications to a minimum. One cannot but
wonder what the reduction in our current electrical
communications would be if the only available
encipherment systems used manually manipulated paper ,
key strips.

The German Navy operators sounded like machines.
Towards the end of the war, however, there was a
noticeable deterioration in the quality of their
communications. On the other end of the spectrum, the
Italians and Argentinians competed for qualifying as the
poorest communicators.

There were five of us that first went to Salinas de
Margarita to build the station, with others arriving later
to make a total crew of 21 Americans: 1 Officer in
Charge, 2 machinist mates, 1 medic, 2 cooks, 1 Chief, 2
First Class. and 12 Radiomen. It seems that the Officer in
Charge was selected because he could speak Portugese
rather than for his managerial abilities. We hired
laborers and skilled craftsmen from the local population
of about 700 people. Until the barracks, power station
and galley had been built, we lived on a small cabin
cruiser that had brought us from Bahia. Captain Harper,
USN, was the Captain of our boat for a while.

The villagers had no electricity and no method of
refrigeration. The natives were quite interested in our
electric lights but did not like the sensation of cold
produced by ice cubes. In this area the temperature, even
in the wintertime, never went below 55-60 degrees and
since these people had never experienced the feeling of
cold, handling an ice cube, even briefly, caused them
acute pain. Our buildings at Salinas had no provision for
heat and the only hot water was in the galley.
The people of Salinas appeared to be gentle and to be
happy with their lot. Their main occupations were
fishing, pearl diving and working on salt beds. The
religion was a mixture of Voodooism and Catholicism. It
was customary to see a person in pagan dress on a
Catholic holy day. There were no native doctors or
dentists on Salinas. We did have a medic on the station
but some natives refused treatment through fear. Malaria
was as common as a cold in America. Some-of the natives
were very skilled craftsmen in woodworking although
their tools were quite primitive.

Logistics was a major problem at Salinas. I can recall
that the only meat we had for three weeks was turkey.
Even the ingenuity of an excellent Italian-American cook
cannot make turkey tolerable three times a day for three
weeks. Broadway Rhythm with Lena Horne was our only
movie for a seven-week period. You would be amazed at
the improvisations that take place under these conditions.
Did you ever see an entire movie backwards? By the end
of the seven weeks, all the parts had been memorized by
the sailors, including Lena Horne's, and one innovation
was to turn the volume down and have the sailors take the
speaking and singing parts.

Because of the lack of spare partS, the three vehicles (a
weapons carrier, a jeep and a motor scooter), were often
inoperative. Partly due to inoperative vehicles and partly
due to the lack of recreation, horses became a part of the
station complement. Most of the sailors, at one time or
another, owned a horse, except for a seaman guard who
had a donkey. I bought a beautiful quarter horse and a
very ornate saddle for the total price of $75.00. Horse
racing and rides through the jungle became enjoyable
pastimes. When I had to go to the transmitter shack to
change frequencies, it was usually by horseback. If the
fuel shortage continues, this kind of experience in
travelling may prove useful.

....................was sent to Bahia in 1948 to help the
Brazilian Navy take over the station. The transfer to
the Brazilians was accomplished in 1949 and the entire
net turned over to them by 1950.

Mr. Horn retired recently from NSA after spend.
ing most of his career io collection activities.

(b) (3)-P.L. 86-36
(My comment - all of the above line has been overscored/cancelled)
source nsa.gov (http://www.nsa.gov/public_info/_files/cryptologic_spectrum/buidling_intercept_stn.pdf)

Little h

19-10-2012, 21:23
Destroyer Escort Historical Museum
USS Slater DE766 Albany New York

Destroyer Escort Weapons and Technology

Destroyer escorts mounted the latest and most up-to-date anti-submarine weapons and detection gear available during World War II, including depth charges, hedgehogs, air and surface search radar, sonar, and a high frequency radio direction finder known as HF/DF. Destroyer escorts also carried a sophisticated control station for this technology known as the combat information center. The ships mounted hedgehog ahead-thrown depth charges and conventional depth charges for attacking submerged boats, as well as large and small caliber deck guns. All of these technologies are preserved intact aboard the SLATER today.

Radar transmitted microwave beams in a straight line through the air. When these beams struck an object, reflected energy returned to and was captured by the radar antennas. The effective range of search radars was extended by placing the surface and air antennas high on top of the ship's mast. Targets could be detected by radar long before visual sightings were made. This reflected information was displayed on radar scopes as the contact's bearing and range. Radarmen plotted this information and, with a series of plots over time, could determine the contact's course and speed.

Radar was one of the most important innovations of World War II. Sets mounted onboard ships early in World War II could barely detect a large ship and had very little chance of finding the small conning tower of a submarine. However, radar technology evolved rapidly during the war and improved sets were installed on ships frequently. By the time the SLATER was commissioned in 1944, its radar sets could detect airplanes almost ninety miles away and a U-boat's periscope at two miles away. The radar sets currently mounted onboard the ship, an SA air search set and SL surface search set, are the same types carried by the SLATER during World War II.1

Sonar was a destroyer escort's only means of detecting a submerged submarine. A sound wave was transmitted through the water. An object in the water caused an echo to return. The operator used the time the echo took to return to estimate the distance to a potential target. Sonar technology improved dramatically during the course of World War II, but it was still markedly inferior to sonar equipment in use today. The sonar set carried onboard the USS SLATER, designated QGB, was similar to a searchlight beam in that it scanned only a small area at one time, and that it had to be constantly shifted manually to scan the whole area ahead of a ship.2

Upon the SLATER's return from Greece, the sonar room had been gutted and a postwar SQS-4 sonar stack was in place in the lower sound room. This sonar set has been restored to working condition by SLATER volunteers. In addition, a World War II QGB set from the USS LOESER DE680, identical to that carried by the SLATER, was donated to the museum in 2006. This set was installed in its original location in the SLATER's upper sound room on the flying bridge. Other sonar equipment, including a bulkhead mounted attack plotter and tactical range recorder, are installed in their original positions in the sound room.

One of the most important technological developments of World War II resulted in the HF/DF detection gear. HF/DF stood for high frequency direction finder, but was most commonly known as Huff Duff. This detection gear was installed on Allied escort ships and found at land based listening stations during WWII. Huff Duff was developed to intercept Nazi U-boat transmissions. Nazi strategy called for U-boats to keep in constant radio contact with U-boat headquarters in France. They radioed convoy contact and weather reports and received their operating instructions.

By intercepting these transmissions, the Allies were able to determine the direction, or line of position of the U-boat relative to the receiving ship or land installation. If two or more allied ships or land facilities in different locations intercepted the same transmission, it was possible to triangulate the U-boat's position. Convoys could thus be rerouted to avoid the submarines. Allied hunter killer groups, many of them including destroyer escorts, could then locate and attack the U-boat wolf packs. (A wolf pack refers to a group of German subs traveling and operating together, thus increasing their ability to cause damage to a convoy). HF/DF intercepts were responsible for nearly one quarter of all U-boat losses during World War II.

The actual Huff Duff equipment consisted of a tall radio antenna carried aft of the stack. The radio receiver and scope were located at the operator's station in a compartment in the aft deckhouse on destroyer escorts. Although the SLATER itself never carried a HF/DF set, the equipment currently on display in the ship is the last Huff Duff set known to exist. Given the significance of HF/DF to the Allied victory in World War II, the set is displayed onboard the SLATER in the location that it would have been mounted on other destroyer escorts. 3

The efforts of the radar, sonar and HF/DF operators on destroyer escorts were coordinated by a station known as the Combat Information Center or CIC. This was an area abaft the bridge and under the flying bridge that housed the radar equipment, plotting tables, internal and external communications gear, and various other status and plotting boards. CIC received, evaluated and plotted on a universal drafting machine all information from sonar, radar, bridge, lookouts, radio, semaphore flags or signal lights, and anything else pertinent. It then fed data and recommendations to the captain on the flying bridge to assist him in his decisions.

In addition to tracking air and sea contacts and reporting their course and speed, CIC also assisted in station keeping, fire control, shore bombardment, navigation and search and rescue. The CIC was the nerve center and eyes of the ship whenever the ship was underway by night, day, fog, rain, snow or clear skies. The value of the Combat Information Center in the destruction of enemy submarines was considerable.

Once a destroyer escort detected a submarine, it could attack with hedgehogs and depth charges. The hedgehog projector was designed to fire twenty-four projectiles at a submarine ahead of a destroyer escort while the ship still had sonar contact with the target. World War II sonar scanned only ahead, so contact was always lost when an attacking ship got over the submarine in order to drop depth charges. The hedgehog projector solved this problem. Hedgehog projectiles were loaded on a launcher consisting of cylindrical bars called spigots, attached to cradles, which swung about a fore and aft axis by means of a roll correction gear assembly mounted on a gun train indicator pedestal. The movement was limited, but it allowed the spigots to train enough to compensate for roll of the ship and to aid in leading the target. The spigots are so positioned that, when fired, the charges described an elliptical pattern of about 140 by 120 feet. Hedgehog projectiles carried a contact fuze, meaning a direct hit on the submarine was required. Nevertheless, even the small charge carried in the projectile head was lethal.4

Destroyers also carried large number of depth charges to counter submarines. There were two depth charge racks on the stern and four depth charge projectors on each side of the ship to fire depth charges outward. The depth charge, with its 300 to 600 pounds of TNT, was the traditional antisubmarine weapon. However, a depth charge barrage required a high degree of accuracy, particularly against double-hulled German U-boats. The "water hammer" effect of a 300 pound depth charge required an explosion within thirty yards of the submarine hull for damage and ten yards for a kill. The 600 pound depth charge's lethal area was considerably enlarged. During the war, the Navy introduced a new type of charge with a "teardrop" shape and tail fins, like aerial bombs, to make them sink faster. Depth charges were detonated by hydrostatic pressure, with depth set before firing. Later models also had magnetic impulse detonators which would fire when in proximity to a submarine. Japanese submarines, lacking the hull strength and depth tolerance of their German counterparts, were more vulnerable to destruction by this weapon. 5

Finally, destroyer escorts carried many guns. As noted above, destroyer escorts carried either 3"/50 main guns or 5"/38 guns. The USS SLATER, being a CANNON class, mounted three 3"/50 guns. The 3"/50 caliber dual purpose guns were mounted inside circular gun shields. The later destroyer escort classes had two 5"/38 caliber dual purpose destroyer type guns in enclosed movable gun mounts. Both types could be fired individually or by director fire control. The 3" guns were frequently criticized as lacking in penetration power against double-hulled U-boats. The 5" type was far more effective.

In addition to the above weapons, a destroyer escort had a secondary battery of about eight 20mm machine guns and one quadruple 1.1" or one twin 40mm machine gun. Although designed primarily for anti-aircraft defense, these guns were quite often effective antipersonnel weapons. They could quickly sweep an enemy gun crew off the deck of a submarine or keep men pinned down inside the conning tower of a damaged submarine on the surface. The advent of kamikazes in the Pacific induced a hurried and massive addition of 40mm, 20mm, 50 caliber and even 30 caliber machine guns. The SLATER represents this late war modification. It mounts three twin 40mm gun mounts and nine twin 20mm machine gun mounts.6

Destroyer Escorts in the Atlantic

The Battle of the Atlantic was the longest battle of World War II. It began immediately upon the British declaration of war against Germany in September 1939 and ended with Germany's surrender to the Allies in May 1945. During those six years, thousands of ships were sunk and tens of thousands of men were killed in the Atlantic Ocean. The battle pitted Allied merchant and supply ships, along with their escorts, against German submarines, aircraft, and surface raiders. British Prime Minister Winston Churchill said of the Battle of the Atlantic, "everything elsewhere on land, sea and air, depended ultimately on the outcome of this battle." The outcome of the Battle of the Atlantic depended on the destroyer escort.

The outbreak of World War II caught both the British and German navies by surprise. Germany had less than fifty U-boats available in 1939, but the British had few escorts with which to counter them. The Nazis immediately began a program of unrestricted submarine warfare against British shipping, a strategy that came very near to starving England out of World War II. Although the British Navy began convoying ships as soon as the war started, its lack of escorts cost these convoys dearly. As more and more German submarines entered the battle, British shipping losses increased at an alarming rate.

Churchill appealed to President Franklin Roosevelt for aid. Although the United States was neutral, Roosevelt agreed to provide the British Navy with fifty obsolete four piper destroyers in exchange for the use of British bases in the Caribbean. The United States also began neutrality patrols, ostensibly to protect neutral shipping rights in the western Atlantic but also to give American naval commanders vital experience should the United States enter the war. The United States also agreed to build escort vessels for the British under the Lend Lease Program. It was this program, combined with America's experimentation with the World War I Eagle Boats, which ultimately led to the development of the destroyer escort.

The Japanese attack on Pearl Harbor on 7 December 1941 brought the United States openly into the war. Germany's declaration of war against the United States also greatly expanded the Battle of the Atlantic. German submarines, which had been operating out of western France since its capitulation in June 1940, had the range to reach the East Coast as well as the Gulf of Mexico. America's sudden entry into the war left it completely unprepared to face the U-boat menace. In the first months of 1942 alone, German submarines sank hundreds of Allied ships, mostly along the eastern United States.

The United States Navy soon adopted the British convoy system, but it lacked enough ships to escort the hundreds of ships sailing across the Atlantic to supply England. By this time, the Navy had approved the destroyer escort design, but it would be nearly a year before the first destroyer escort joined the fleet. American industry was still transitioning from a peacetime to a wartime footing, so there not enough war materials necessary to build all of the warships and landing craft needed to fight a war in two oceans. Until the destroyer escorts were available in force, the US Navy was forced to rely on stopgap escort vessels, including the four pipers and sub chasers. Despite the mammoth efforts of these inadequate ships, 1942 proved to be the worst year of the war for the Allies in terms of ships lost in the Atlantic. Between January and December 1942, German U-boats and aircraft sank over 1,000 Allied ships both in the Atlantic and off the East Coast of the United States. 1

Finally, in January 1943, the first destroyer escorts entered the Battle of the Atlantic. American industrial capacity had caught up with demand and would soon exceed all expectations. By the end of the year, sixteen American shipyards were launching seventeen destroyer escorts per month. These new ships immediately began the dangerous task of escorting Allied merchant ships across the U-boat infested Atlantic. Destroyer escorts became even more deadly adversaries to the U-boats as improved electronic equipment, such as radar and HF/DF, became available. In addition, the construction of small escort carriers allowed the Navy to form hunter killer groups. These groups, consisting of one escort carrier supported by several destroyer escorts, were not tethered to a convoy, but could roam the Atlantic ferreting out U-boats and destroying them.

The tide of the Battle of the Atlantic turned irrevocably against the Nazis in May 1943. That was the first month that more U-boats were sunk than Allied merchant vessels. From May 1943 until the end of the war two years later, German submarines were unable to duplicate their successes of the first three years of the war. Destroyer escorts were an instrumental part of the Allied victory in the Atlantic. Their range and seaworthiness allowed them to escort convoys back and forth across the Atlantic despite fierce North Atlantic storms. Their radar, sonar and HF/DF equipment allowed them to detect U-boats, surfaced or submerged, by day or by night and in any weather conditions. Their speed, maneuverability and firepower made them lethal foes once a U-boat had been found. Finally, their overwhelming numbers due to their rapid construction made it virtually impossible for the submarines to hide.2

Destroyer escorts also carried out several important feats during the Battle of the Atlantic. Perhaps the most important of these feats was the capture of the German submarine U-505.3 The submarine was captured on 4 June 1944 by a hunter killer group composed of the escort carrier USS GUADALCANAL CVE60 and the destroyer escorts USS PILLSBURY DE133, USS POPE DE134, USS FLAHERTY DE135, USS CHATELAIN DE149, and USS JENKS DE665. The destroyer escorts attacked the submerged U-boat and forced her to surface. Boarding parties from the destroyer escorts then rushed over to the submarine while its crew abandoned ship. The American sailors stopped the submarine from sinking and then towed it back to Bermuda.

The capture of the U-505 was one of the greatest intelligence coups of World War II. It gave the Allies a working Enigma code machine; a device which generated codes that the Allies had been only marginally successful at cracking. It also produced a complete set of the code books to go along with the machine. Most importantly, the U-505 gave the Allies the current settings for the Enigma machine in use by the U-boat fleet, which allowed the Allies to begin cracking German codes with great success. These finds allowed Allied cryptographers to intercept, decode and read German radio transmissions almost as quickly as the Germans themselves. The U-505 was an intelligence bonanza in other ways as well. It gave the Allies an opportunity to test the capabilities of their German foes, which in turn led to improved tactics to counter the U-boats.4

The USS SLATER also had a small part to play in the U-505 incident. Among the many discoveries on the submarine was a new type of acoustic torpedo. These deadly weapons locked onto the propeller noise of Allied ships and caused massive damage when they struck. The acoustic torpedo was taken from the U-505 and loaded onto the SLATER, which was in Bermuda at the time completing training exercises. The SLATER rushed the torpedo back to the United States for analysis, which resulted in an improved countermeasure to the acoustic torpedo known as the Foxer gear. This improved countermeasure saved many lives in the war's remaining months. The U-505 and the torpedo delivered by the SLATER are currently on display at the Museum of Science and Industry in Chicago, Illinois.

Germany's surrender in May 1945 ended the longest continuous battle of the war. Between 1939 and 1945, more than 2,700 Allied merchant ships were lost to enemy activity, with over 1,000 being lost to German U-boats alone. Over 130,000 Allied sailors lost their lives in the battle. Although these losses were severe, they would have been much worse without destroyer escorts. Once these ships entered the battle in 1943, U-boat successes dropped dramatically. By the time the SLATER joined the battle in 1944, convoy losses to U-boats had been almost eliminated. The SLATER escorted 176 merchant ships across the Atlantic without loss during World War II.5

As severe as the Allied losses were, they were much worse for the U-boat force. Of 1,100 German submarines produced during the war, nearly 800 were lost to Allied action. 28,000 of 40,000 U-boat sailors were killed in the Battle of Atlantic. Statistically, the job of a German submarine sailor was the deadliest of the entire war. Destroyer escorts were responsible for many of these U-boat losses. They were instrumental to the Allied success in Europe during World War II.6

.................................(article continues)

1 Davis, Destroyer Escorts of World War II, 5; Elliot, Allied Escort Ships, 523-4.
2 For an in-depth evaluation of World War II sonar technology, see Hackmann, Willem, Seek and Strike: Sonar, Anti-Submarine Warfare and the Royal Navy, 1914-1954, London: Her Majesty's Stationery Office, 1984.
3 Andrews, Tempest, 2, 20; Elliot, Allied Escort Ships, 525-6.
4 Elliot, Allied Escort Ships, 530-1; Campbell, John, Naval Weapons of World War II, Annapolis: United States Naval Institute Press, 1985, 91-2.
5 Ibid., 88-90; Friedman, Norman, US Naval Weapons, London: Conway Maritime Press, 1983, 122-24.
6 Roscoe, Destroyer Operations, 15-18; Friedman, Naval Weapons, 64-7, 72-3, 76-81.

Help restore the USS SLATER by donating.
Destroyer Escort Historical Museum
(518) 431-1943 · Broadway and Quay · Albany, NY 12202
Open to Visitors: April-November, Wednesday-Sunday, 10AM-4PM

Source; USS Slater.org (http://www.ussslater.org/history/dehistory/history_atlanticbattle.html) where the full 4 page article can be read

Little h

19-10-2012, 23:59
Here are the WWII recollections of a former member of the Branch to which I later belonged - Tel(S)


My personal history in the Royal Navy

I was called up into His Majesty's Royal Navy on 8th March 1943 and
reported to HMS Royal Arthur (Butlins Holiday Camp) Skegness for
kitting out and basic training which lasted seven weeks, then it was
up to Dundee for 18 weeks to train as a Telegraphist (Wireless
Operator) after which it was over to the West Coast of Scotland at
Ayr another Butlins camp HMS Scotia where a further 10 weeks were
spent, final exams were taken and I passed out as an Ordinary

The next port of call was to my Naval depot HMS Drake at Plymouth
and after a short stay was sent to Eastbourne for a period of 3
weeks to train as a High Frequency Direction Finding operator
(HF/DF) more universally known in the Navy as Huff Duff.

Again I passed out and was promoted to Telegraphist Special
Operator (Tel(s)) it was now the second week of December 1943 Back
again to HMS Drake to await a draft to a ship, and early in the new
year of 1944 I along with two colleagues who had trained with me
took the long journey from Plymouth to Belfast where we reported to
the base ship HMS Caroline a First World War Cruiser to await the
arrival of HMS Cooke a Captain Class Frigate, part of the 3rd
Escort Group.

The 3rd Escort Group based at Belfast spent many patrols in the
Atlantic in support of Convoys, then when D Day came the Group were
involved in the English Channel where on the 9th Day after D Day we
lost HMS Blackwood 20 miles NNE of Cap de la Hague torpedoed by

We worked in the English Channel up to early September, then it was
a three week trip across the Atlantic and back escorting convoys,
after which it was a Russian Convoy and on the return journey we had
to return to Russia with a fast convoy and did not get back to
Belfast until 16th November 1944.

Irish Sea patrols came next for a shortish period due to the U-Boats
penetrating our Western seaboard. Our final travels took us once
again into the English Channel where we patrolled until the war

It was back to HMS Drake after HMS Cooke paid off at Hull to await
my next draft which was to Malta where I was shore based at a small
interception wireless station And after twelve months on Malta I
finally was sent home for demobilization. My final date of
discharge from the Royal Navy was 21st September 1946

I wish to acknowledge the considerable amount of help I have
received from fellow members of the Captain Class Frigate
Association, with details of operations and their personal
photographs many of which are shown on this web site, one person I
must pick out for the really vast amount of information he has
provided me with is the late Donald Collingwood who unfortunately
Crossed the Bar early in August.

I also wish to thank Gupmundur Helgason for allowing me to use up to
date information as displayed on his web site Uboat.net which
records all the U-boats sunk during World War II.

Roy B. Tynan
(Summer 2003)
Copyright Roy Tynan MMIII
source here (http://gopherproxy.meulie.net/sdf.org/0/users/happy/ccf/granddad.txt)

Little h

21-10-2012, 00:13
The following selected excerpts are taken from J. Proc's NAVAL RADIO OPERATIONS DURING WORLD WAR II a site which provides quality information and to which I make frequently reference for many of my posts.

In these excerpts there are explanations of D/F equipment in use, the Operators using same and the procedure for reporting intercepted transmissions.


Medium and low frequency radio signals have very long wavelengths so there is little hope of building efficient, highly directional shipboard DF antennas at these frequencies. However, at relatively short distances, even an small antenna will work because enough signal will be present for detection. Most warships of the inter-war period were fitted with direction finders whose antennas consisted of a pair of crossed loops. They were generally described as navigational in nature, but they could have been conceived as a means of detecting enemy transmitters just beyond the horizon.High frequency direction finding (HF/DF) is also known by the sobriquet Huff Duff and was a relatively new development at the outbreak of hostilities. Production was slow and experience in correct operating techniques had to be gained step by painful step. By the end of 1942, HF/DF was accepted as an essential part of the equipment that vessels had to carry. Later in the war, convoy rescue ships and some merchant ships were fitted with HF/DF sets. In retrospect, Huff Duff played an extremely important part in the Battle of the Atlantic along with ASDIC and Radar.
From the beginning of World War II, a shore based Huff Duff organization was in existence. The network of stations in the British Isles gradually grew to include shore stations in Africa, Iceland, Greenland, Bermuda and North America. In Canada, there were stations located at Cap d'Espoir, Gaspe; Coverdale, New Brunswick; Harbour Grace, Gander Newfoundland, Fort Chimo, Quebec and Hartlen Point, Nova Scotia. There was also a very active station in Winter Harbour, Maine. Cross bearings could be taken by means of all these stations and fixes were plotted by special tracking centres. Escorts would then be alerted and the courses of convoys altered, if necessary. Alternately, aircraft or hunter- killer groups could be dispatched to the area of a Huff Duff fix.

In the summer of 1942, three British HF/DF sets were given to the U.S. Naval Research Laboratory for study and evaluation. By the fall of that year, sets were being installed in American ships because the Americans succeeded in developing an improved version of the British FH4 and called their set the DAQ.In Canada, in September of 1942, the Canadian Naval Staff approved in principle, the fitting of the HF/DF set Type FH3 in each Canadian destroyer of an escort group. However, the Canadian destroyer Restigouche had her Huff Duff set fitted earlier when she was undergoing repairs in Glasgow Scotland during the period December 1941 to March of 1942. The captain, Lt. Cdr. D.W. Piers, acting on his own initiative and against headquarters policy, convinced a British officer to fit the FH3 set. Fittings in other ships occurred during the winter or 1942/43 with the installation of the model FH4 Huff Duff. When FH4's were not available, FH3's were installed in their place.

The problem of retrofitting a Huff Duff cabin into Canadian ships was solved in various ways. In the destroyer Restigouche, it was built on the upper deck amidships directly aft of the 3 inch gun platform while the HF/DF mast and antenna was fitted to the forward end of the after superstructure. On Tribal Class destroyers, the Huff Duff cabin was generally fitted under the lattice mast and over the crew's galley, however, on Huron and HAIDA the cabin was mounted aft. In Frigates, such as Montreal and Wentworth, the cabin was located under the port wing of the bridge and resembled a boy's square club house.

Security was paramount but inconsistent in these fittings. Official photographs of the ships would have the sparsely ribbed, bird cage antenna censored from the top of the mast, whereas standard Supply Demands would have the shipment marked with the notation "for installation in the HF/DF cabin". Initially, each Huff Duff equipped ship was required to carry three additional Wireless Telegraphy (W/T) operators and Canadian ratings for the Huff Duff branch had to come from the fleet.
............................(article continues)

Telegraphists drafted for the special Huff Duff course had to obtain a copy accuracy rate of 85% at eighteen words per minute in tests carried out by the Signal Training Centres. Special training consisted of a course in enemy W/T procedure, enemy W/T organization and a operations/maintenance course on the HF/DF equipment. A Leading Telegraphist Special Operator was distinguishable from a Leading Tel General Service by the absence of stars from the W/T badge, and having only a pair of wings divided by a lighting flash. Later in the war, as the size of the fleet increased, there was a proportional requirement for shore based operators. Wrens were enlisted to augment the shore staff.

In the early part of the war, the limitations of the HF/DF system precluded accurate position finding of U-boats in the Atlantic. The gradual addition of more shore stations and the installation and improvement of Huff Duff eventually produced a system that was amazingly accurate. Naval Service Headquarters in Ottawa promptly received all U-boat bearings taken by the British. Ottawa was able to obtain fixes of enemy units in the area east of 30 degrees West with equal efficiency and in approximately the same time as was done in the Plotting Centre at the Admiralty. The positions obtained by Huff Duff were then broadcast to the escorts at sea.

Occasionally, small problems arose. For example, during late 1943, the comparison of HF/DF bearing reports taken at sea with those of shore stations showed a constant reversal of sense (reciprocal bearing) when receiving U-boat transmissions on 4000 kc. Ships exhibiting this problem were HMS Hotspur, Dundee, Berry, and HMCS Ottawa. The discovery of this problem led to the requirement for frequent calibration of HF/DF equipment. When steaming close to shore, the D/F came in handy in fog or when the "old man" was off course.

From time to time, Huff Duff required calibration. This involved taking simultaneous visual and radio bearings of a distant transmitting station on relative bearings around the compass at intervals not exceeding 5 degrees. To accomplish this, a ship would generally be anchored in open water and simultaneous visual and radio observations would be made on a transmitting station. This station was located on a small auxiliary vessel chugging slowly around the ship. Conversely, the calibration could also be accomplished with the ship being swung relative to a fixed radio station. For HF/DF calibration, special auxiliary vessels were available on both the East and West coasts of Canada. Two of these were HMCS Seretha II at St. John's, Newfoundland and HMCS Merry Chase on the west coast. There were many different wireless exercises carried out during patrols. One such exercise took place with an aircraft. First, the aircraft was located using DF and the bearing was then passed on to the aircraft using W/T. Then the aircraft would home in on the ship. The usual routine was for the aircraft to transmit its call sign along with five second dashes on 375 kc. The ship would take the bearing. The bearing and the time was passed to the aircraft on 3925 kc.
..........................(article continues)

The greater need for special operators was in the Atlantic theatre. Here, an operator would listen on an assigned frequency made known by the Admiralty. These frequencies were listed in numbered sets called a Series. Two examples of these frequencies were 10525 and 12215 kc. The regular and constant relay of information on convoy position, course and speed back to German shore authorities on HF formed the basis of wolf pack operations. Once a member of the pack sighted the convoy, it was usually tasked as a 'contact keeper' until the pack was drawn in. This shadower made brief radio transmissions at regular intervals followed by a short MF homing beacon transmission. The MF homing beacon was the only direct communications permitted between the U-boats thus allowing the other members of the wolf pack to locate the convoy. As each U-boat gained contact with the convoy, it too made an HF report and continued to do so periodically until the battle was over.
On hearing a U-boat transmission, the intercepting operator would press a foot pedal which activated a microphone. He would then shout a coded warning to other Huff Duff equipped ships to tune the intercepted frequency. After the other escorts and the convoy rescue ships obtained bearings, the results would be passed to the Senior Officer (SO) of the escort group and a fix was obtained. If it was a 15 to 20 mile ground wave bearing, the Senior Officer would send an escort chasing down the bearing. The SO would also have a message transmitted notifying shore authorities of the U-boat's bearing or position.

Ashore, operators would listen and search on Marconi CSR5 receivers. When a U-boat's transmission was picked up, the operator on watch would immediately warn another operator at a remote site where the actual work of taking another bearing would be performed. All Huff Duff operators knew how to recognize German transmissions and there was no dearth of signals. In the absence of HF/DF, the RCN also attempted to use the U-boat's own MF homing beacon which could be received on the commercial MF/DF set that was fitted on many Canadian ships. Unfortunately, the MF signal diffused rapidly and while it was sufficient to draw U-boats into the general area of a convoy, it was not sharp enough to permit an Escort to locate a small and elusive U-boat.

The initial first sighting report by a U-boat invariably commenced with a recognizable symbol, namely, the B-Bar followed by four letter cypher groups. The following is an example of a first sighting report :

For transmitting homing signals, U-boats used different frequencies according to the time of day. Two popular frequencies were 384 and 437 kc. The signals were usually made at 15 and 45 minutes past each hour and would commence with a series of V's. Here is an example of a message:

When German headquarters needed to communicate with U-boats, they repeated all broadcasts at one half to one hour intervals in case the transmissions were garbled. There was no need for the U- boat to signal receipt of a message. To the advantage of the Allies, the Germans's liberal use of radio made it possible for the British Admiralty in London to realistically make hour-to-hour tactical decisions then transmit those decisions to commanders at sea. This information could be used to prevent the assembly of a U- boat formation or in the worst case, reduce the number of U-boats to be dealt with when the attack finally came.
.................................(article continues)

Order CCNO 526 defined how D/F reports from H.M.C. ships should be sent:

D/F reports of all signals, both H/F and M/F, believed to be transmitted by enemy units (particularly U-boats), are to be forwarded by all H.M.C. Ships and by H.M. Ships operating under orders of R.C.N., in duplicate, to Captain (D) of their base for information and for onward transmission to the Officer-in-Charge, Operational Intelligence Centre, Naval Service Headquarters. In the case of group operations one collated report for the group as a whole is to be rendered by the Senior Officer. These reports are to contain the following information:--

(a) Dates on which watches commenced and ceased.
(b) Frequencies or series guarded on all receivers.
(c) Details of all enemy unit transmissions intercepted as follows:--
(i) Date and time of intercept at end of transmission, G.M.T.
(ii) Frequency in kilocycles.
(iii) Ship's position.
(iv) True bearing (and reciprocal when unsensed).
(v) Class of bearing.
(vi) "Ground wave", "Sky wave" or "Uncertain".
(vii) Strength of signal.
(viii) Remarks, to include as much of the preamble and text as could be read.

2. With regard to (c), (viii), above, it will not normally be possible to read the text of H/F messages from the unit transmission due to the over-riding importance of obtaining a bearing and sense. These details however, can usually be read from the Shore Station's acknowledgement. It should always be possible to read the text of U-boat M/F homing transmissions in addition to obtaining a bearing and sense, as the messages are repeated once or twice at each transmission.

3. In the case of operations by a group of ships the names of all ships fitted with H/F D/F should be included. Where duties comprise convoy escort the names of the rescue ship and any fitted merchant ships in the convoy should be given.

4. Remarks on enemy W/T procedure, particularly if they indicate changes in procedure, frequencies, etc., as compared with current publications and instructions, should be included.

5. Remarks on the tactical aspect of bearings of intercepted enemy transmissions should be included in the Report of Proceedings of the Senior Officer (in the case of convoy operations the Senior Officer of Escorts).

In addition, order CCNO 560 defines the content of intercept reports sent by HMC Ships when copying enemy transmissions. An excerpt is provided here:

Any H.M.C. ships may be ordered to report by signal, the interception and/or the bearing of any W/T transmission suspected of being of enemy origin. In such cases it is essential that the following information be included:--
(a) The frequency of the transmission.
(b) The time (G.M.T.) at which the transmission was heard, i.e. the end of the first transmission, not the end of the repeat back by a shore W/T station.
(c) If possible, the preamble and first or last two groups of the message. In the case of those messages prefixed "BB" or "WW", the first group and as much of the rest of the text as could be read, should be sent.
NOTE.-- Any report made to shore authorities which includes a bearing or bearings, whether made as the result of a request from shore authorities or independently of such a request, must include the position of the intercepting ship or ships.
..................................(article continues throught to the end)
-----------------------------------------------------------------------------------------------------------------------------------------------------source http://jproc.ca/rrp/nro_ww2.html

Little h

Brian Wentzell
21-10-2012, 14:21
Harry: If one only had enough time to read Jerry Proc's entire online book! It is filled with interesting historical info.

21-10-2012, 15:02
Harry: If one only had enough time to read Jerry Proc's entire online book! It is filled with interesting historical info.


Indeed so, much praise should go to Jerry for his online works.

In fact, it is my intention that excerpts from yet another of his pages will appear shortly on the thread, as evidence of the part played by the Women's Royal Canadian Naval Service (WRCNS) in the activity to which the thread relates.

Little h

21-10-2012, 20:29
Destroyer Escort Historical Museum
USS Slater DE766 Albany New York - (continued)

Further to post #7 paragraph 8 (copied immediately below for convenience):-
The actual Huff Duff equipment consisted of a tall radio antenna carried aft of the stack. The radio receiver and scope were located at the operator's station in a compartment in the aft deckhouse on destroyer escorts. Although the SLATER itself never carried a HF/DF set, the equipment currently on display in the ship is the last Huff Duff set known to exist. Given the significance of HF/DF to the Allied victory in World War II, the set is displayed onboard the SLATER in the location that it would have been mounted on other destroyer escorts. 3

Since posting the above excerpt I have discovered the following PDF article on the internet, some of the contents of which is apparently at odds with the details included above, see:-

HD/FD(sic) the HUFF DUFF
By: Frank McClatchie
Former RT1/C, USS NEAL A. SCOTT DE-769

.....................................(article continues)

The invention of the HUFF DUFF high frequency direction finder process in England and further development by the Naval Research Laboratories early in WWII enabled much faster detection of transmitter direction than had ever been done before. Basically the new HUFF DUFF radio direction finder was "instantaneous" and a transmitter direction could be determined with the transmission of a single dot of code from the Submarine.

Fortunately the Germans did not catch onto this new process right away, and we were able to manufacture a number of HUFF DUFF receivers and install them in many shore locations as well as in quite a few ship-board locations including the USS SLATER the ship I served on during WWII. This enabled the allies to get "Cross Bearings" on many Submarines before they could finish their radio transmission.
.......................................(article continues through to the end)

PDF source here (http://www.fmsystems-inc.com/manuals/HUFFDUFFart.pdf)

So one is left wondering if the HF/DF equipment was indeed installed in the Slater during WWII and subsequently removed, thereafter and upon decommissioning an example of the equipment was obtained and re-installed as described in the earlier excerpt. Hmmm a curious situation.

The latest PDF article carried a image of the installation in the Slater, which is posted as an attachment below.

Little h

21-10-2012, 22:48
Below please find excerpts regarding the WWII HF/DF activities of HMCS COVERDALE, which have been taken from one of the articles in Jerry Proc's excellent online articles, see:-


Developed by: Jerry Proc
Last updated: September 28/12


Coverdale, a tender to Stadacona, was established as a Special Wireless Station (HF/DF) on Nov 23, 1942. It was situated across the Petitcodiac River, slightly south of Moncton, New Brunswick. Construction was completed in the January-February 1944 period and commencement of operations began when WRENS started arriving in numbers.The name Coverdale came from a village in the immediate vicinity and was named after Myles Coverdale, who produced the first complete printed translation of the Bible in English in 1535. Because this site was located over a tremendous bog, it was selected for HF/DF operations because it provided a very good ground plane for radio frequency signals and the abundance of water provided a good source of domestic water.


The requirement to build Coverdale was part of the RCN’s General Extension of DF Facilities 1942-3 program. Other stations in this program were to be built at Gloucester, Ont.; London, Ont.; Cap D’espoir, PQ; Lacombe, Alberta; Westlock, Alberta; Medicine Hat, Alberta; Churchill, Manitoba; Albro Lake, N.S. and Gordon Head , BC. The cost of this expansion was budgeted at $770,415.

The Coverdale site was selected after an extensive survey by the Director of Signals Division, RCN. It was to be located in the town of Gunningville, Albert County, New Brunswick. On Nov 23, 1942, the Coverdale ‘DF’ and ‘Y’ site was given financial approval by the Treasury board thus establishing the base. The approval was granted based on the requirements provided in file NS1074-6-2 dated Aug 31, 1942 5. In one document, Coverdale is also referred to as a ‘Z’ site.

Planning for the site started much earlier than the establishment date as attested by the July 7, 1942 date written on some of the site planning blueprints.

By Aug 31, 1942 the facilities required for Coverdale were generally defined as follows:

Main Operational Building; Subsidiary Operational Building Barracks; three car garage with living quarters above it for male personnel.
Estimated cost : $180,000
- A 10 kilowatt electrical feed from Moncton Gas and Electric.
- Two parcels of land. Parcel A was to be 800 by 1300 feet, Parcel B was to be 600 by 600 feet.
Both parcels to be fenced in by a wood fence.
- Wooden antenna masts: Five 90 ft., four 60 ft., two 25 ft., and six 15 ft. securely guyed and provided with pole steps and with blocks for halyards.
- A gasoline powered standby (emergency) motor-generator with an automatic switchover panel.

In order for Coverdale to act as the control station for the east coast DF network, the following were needed :
- A private tone channel for the Cap d’Espoir Quebec D/F station.
- A Teletype circuit to NSHQ, Ottawa.
- A private telephone line on the Moncton exchange for administrative purposes.
- Two lines for the use of personnel (preferably pay phones). All of the lines had to be brought into the station through underground cable from the main road.
- Grounding system for the site similar to the one being planned for Gloucester

The equipment and furnishings for the base was expected to initially cost $61,000. There was no specific mention of radio equipment.

The initial personnel will consist of three male officers , four W.R.C.N.S. officers, three male ratings and 140 WRCNS ratings.
.............................(article continues)

During WWII, the major activity at the station was taking D/F bearings on German U-boats and assisting with search and rescue operations for aircraft in distress. In the book No Day Long Enough, page 179, RDF Chapter, F.D.Green says "The first installation near Moncton, NB, detected a U-boat and set in motion a successful attack resulting in its destruction".
............................(article continues with details of later use in the 1950's and 1960's)

............ The number of of stations in the Net remained constant well into the 1950's and 1960's until more modern HF/DF technology and cost cutting measures caused a reduction in their numbers.
........................(article continues)

............ When Coverdale closed in 1971 all SIGINT operations were transferred to 770 Squadron, Gander, Newfoundland.

An except from The War History of the Radio Branch, NRC provides an excellent summary of the early developments in direction finding technology. "From 1933 onwards, direction finding equipment of the cathode ray type (CRDF) was produced by the Radio Laboratories of the National Research Council of Canada (NRC) .The first of such sets, which was AC powered, was produced in 1935 and operated on the enormous wavelength of 25,000 meters (12 kHz) for atmospherics investigations. This development led naturally to design and construction of other CRDF instruments.
D/F sets were built for shore based stations to demonstrate their utility in the ship-to-shore direction finding service which was then operated by the Department of Transport. The equipment was given a year's trial by NRC personnel in Halifax and ended in 1940. Sets were also built for operation in an aircraft but the later advent of radar made this application less attractive.

Development of a short wave set for operation in ground stations began in September 1938. This initiative was of great interest to the Royal Canadian Air Force (RCAF) amongst others. A laboratory model was completed in December 1939. Preliminary field trials of this set, which employed two bands to cover the frequency range of 1.5 to 7.2 mcs, continued until May 1940. In December 1941, a request was made by the RCN for further development of the short wave CRDF set to a stage suitable for operational use in interception work. After some improvements were made, especially in the antenna, satisfactory demonstrations and field trials were held in April 1942. A joint committee of the three armed services was formed for the purpose of laying down specifications for a pilot model to be built by Sparton Radio of Canada.

A prototype antenna system was installed by the NRC Radio Branch at a site near London, Ontario. Final demonstrations to the services were held in December 1942 and February 1943 when the pilot models and the antenna design were approved. Orders for about 100 CRDF sets and antennas were placed by the services with Sparton during the spring of 1943. The first production antennas were shipped to the Navy in September 1943 and the first receivers early in March 1944. Field trials of the production units were conducted by the Radio Branch at a naval installation and the results of these trials were submitted to the CRDF committee for approval.

The first production antennas were shipped to the RCN in September 1943 and the first receivers early in March 1944. A CRDF set was installed at all stations of the SUPRAD group including Coverdale. There were four production models available.

1) "A" Band set covering 2.7 to 6.8 mcs (Whip length 35 feet)
2) "B" Band set covering 6.5 to 13.0 mcs (Whip length 25 feet)
3) "C" Band set covering 12.5 to 25.0 mcs (Whip length 18 feet)
4) "ABC" band set covering 2.7 to 25.0 mcs

Here are the results when the resonant frequencies of the whips are calculated. Note the frequency of resonance with respect to band boundaries:

For A band, 2.7 to to 6.8 Mhz , the 35 foot length is resonant at 7.02 mHz . Mid range is 4.7 mHz
For B band, 6.5 to 13. MHz, the 25 foot length is resonant at 9.84 mHz. Mid range is 9.25 mHz
For C band 12.5 to 25.0 mHz, the 18 foot length is resonant at 13.66 mHz but mid band is 18.75 mHz

The ABC set, while sacrificing some sensitivity and accuracy in parts of the spectrum, had the advantage of requiring only one operator to cover the whole short wave band. The production model was the most sensitive, visual DF unit used during the WWII, having an overall sensitivity of 0.5 to 1.5 microvolts per metre over most of the spectrum and bearing indication accurate to one degree. Some of the difficulties encountered in direction finding, owing to the arrival of fading sky wave signals at the antenna, were eliminated by the use of the "lock-dot" circuit. This shows on the cathode ray tube screen, only those portions of a signal which arrive only by the most direct route from the transmitter. Other portions of the sky wave which, due to the vagaries of the ionosphere follow devious paths, are eliminated". This feature was considered to be state-of-the-art and was highly classified, not only in wartime but also in the ten year period after the war.

In the RCN, the CRDF was designated as the CNF4. "Following the acceptance tests on the production equipment, NRC assisted in installation work at a second naval station where difficulties were encountered in the use of lead covered transmission lines from the antennas to the operation huts Means of testing these cables were devised and further investigations by the Radio Branch brought about a change in the cable design. NRC engineers gave considerable assistance to Sparton in the original design of the CRDF production model and to some of the problems which arose later. Assistance was also given to the Canadian Army Signals Corps in the first installation of a CRDF in a mobile unit in the fall of 1944. Several of these units were later shipped to the Far East".

Ray White a ex-RCN radio operator recalls the period. "Development of the CNF4 followed the first Canadian efforts in that field in 1942 when Bill McLeish and Jack Lee of the NRC produced the first CNF4 which was used at stations like Coverdale, NB; Gloucester, Ontario; Masset, British Columbia etc. At the time, there were rumours that the Army and RCAF had CNF4 D/F sets but this was never confirmed. I knew Jack personally from his many visits to Arctic radio stations. He was with us when we installed the CNF4 in Frobisher Bay (now Iqaluit) and constructed the ground mat for the Adcock antenna array in the summer 1954".

Andre Guibert a vintage electronics collector in Quebec, owns a CNF4/DFR-23 set. The front panel of his set has an integrated nameplate with the following designator: "D/F HF C.R. Type Receiver". A subtitle on the manual further defines it as the model DFR-23. On the inside of the CRT chassis, another tag indicates "D/F H.F. Receiver. RCAF Ref 10D/6645 S/N 36. Made in 1945".
........................(article continues)

Ray White summarizes the D/F operations at Coverdale during the war years. " The intercept operators, (not necessarily the D/F operators) would search the appropriate bands for the established characteristics of enemy signals. The German high speed transmissions of that era were not really all that fast and were generally repeated after a few seconds. Both shipboard and shore based HF/DF operators could get a quick bearing. Individual stations could only obtain a bearing. Several bearings from different stations were required to establish a reliable fix. The search operators would use whatever communications receivers were available at the time. This could have included the RCA AR-88, the Canadian Marconi CSR5, and the National HRO.
In addition to these random searches through the appropriate bands, the allied stations had the advantage of decrypts of intercepted broadcasts from German Navy HQ which used the Enigma crypto machine and to which the Allies recovered the monthly keys quite rapidly, especially in the latter part of the war. German Navy HQ, using the fleet broadcast transmitter DAN1, would send messages which established the current reporting frequencies. If we, the Allies, were capable of doing this, and reports say we were, we would know what frequencies to scan for activity. Assisting us in this is the fact that there was a general radio silence by Allied ships and shore stations other than the encrypted broadcasts from stations like NSS, CFH etc. With a comparatively quiet band to work with, the chances of a signal being a potential enemy target was quite good.

There was no formal DF network set up with the U.S. during WWII. This was to come in 1950. As far as is known, the USN worked independently of RCN DF operation during that period".

After Special Wireless Station Coverdale opened its doors, the station was quickly staffed by personnel from the Women's Royal Canadian Naval Service. Abbreviated as WRCNS, it is pronounced as WRENS. The organization was established in July 31 1942 in order to recruit women to replace men who were leaving for sea duty. Capt. Eustace Brock became the Director and Lt Cdr Isabel Macneill, OBE, became the C.O. of the WRCNS training establishment, namely HMCS Conestoga which was commissioned on June 1, 1943 in Galt Ontario. She was the first woman in the British Commonwealth to hold an independent naval command. There were 22 different job categories open to women, depending on their background and experience. They filled many jobs in every naval base in Canada. Just one year after the WRCNS was established, they were already earning high praise for their efforts. The WRCNS motto was: To free a man for service afloat.
................................(article continues)

............ In the early spring of 1943 we took over duties at #1 Station, Gloucester which had been opened shortly before by the male navy. We remained there (with some intervals at HMCS Signal School, St. Hyacinthe for further training) and operated the station (with one CRDF shack) until sometime in late 1943 or early 1944. We were then transferred to Coverdale to open the new station on February 6, 1944. Workmen were still finishing off some of the building when we moved in. In a letter written to her family on Feb 19, 1944, a former W/T Alice Rutherford said "It is like camping. ----we have no sheets, no doors no water 90% of the time and workmen are everywhere".
.............................(article continues)

The Ops (Operations) building had a huge room, also with a dividing wall. Along the outside of each section was a continuous table on which were arranged our Marconi Model CSR5 Receivers. The picture I have of the Ops Room shows seven Wrens wearing headphones sitting in front of these receivers. However, I would guess that there were two dozen or so on a watch. Way off in a field somewhere were Wrens manning the HF/DF (Huff Duff) shack, containing the new High Frequency Direction Finding equipment. All I remember are green-glowing cathode-ray tubes with sine waves streaking across their round faces. When we alerted these Wrens that a U-boat was transmitting on such and such a frequency they would take the bearings. This data was transmitted to Whitehall in the UK and Map Plotters took over. Movies and oodles of books have been written about this part of the war when the Allies deciphered German Enigma messages. Occasionally we would get a report back that the “traffic” (as the noise coming over the receiver was called) copied on a specific watch had resulted in putting that sub out of commission. By 1944 this was happening quite frequently.

In May 1994, I was visiting my watch leader and long-time friend Elsie (nee Houlding) Michaels in Victoria. She had a favour to ask. Would I choose a safe place for something she had kept all these years from Coverdale? The Canadian War Museum is now the custodian of the message received on Elsie’s watch in German plain language from the German Admiral Doenitz telling all his forces that Hitler was dead! Coverdale had scooped the Allies with this news. Of course, it's too late to reprimand her now. Actually, I think she did Canada a favour – it is probably the only existing record".

This is translation of the message sent by Karl Doenitz after Hitler committed suicide April 30/1945.

......................................(see translated message at end of post)

Vin Crane also recalls other details about Coverdale. "The main ops room contained the W/T set up for operators, a "Z" room , a teletype room , a workshop for the wireless technicians and an office. Z Intelligence was a term that encompassed techniques known as Radio Finger Printing and TINA.
The former was the process used to catalogue a specific transmitter on a ship through its distinct characteristics with the aim of locating it at future date.
TINA was a method used to recognize specific radio operators by their Morse code habits.
Captured transmissions were forwarded to the navy's Operational Intelligence, Section 7 in Ottawa for analysis.
There were seven watches with two on at any one time and one watch off. Each watch had twelve operators so there were twenty four on duty. Each shack had an operator and the "Z" room had one or two on at a time. All W/Ts (or at least most of them) were trained on the CRDF (CNF-4) set so they could rotate through the shacks.

..........................(please open source link at the end of these excerpts to view two photographs summer and winter conditions circa 1944-45)

German navy control stations (at least four) sent out continuous messages in four letter code. Our operators copied all these for transmission by teletype to Ottawa NSHQ for decoding. Their frequencies changed often so it was always a case of some operators being on search for them and any other strange traffic.

Each hour, the control stations had a five minute silent period during which the U-boats could come up to transmit non-emergency messages such as weather reports. During the rest of the hour, a U-boat would break into control traffic whenever there was an urgent message. Examples of these were sighting reports and success reports. The operators could sometimes hear them tuning and were able to get early bearings . Occasionally it was possible to to identify a certain operator and submarine because of his keying rhythm. Whenever there was a sighting, particularly when it involved a pack of subs, life for the operators could get very hectic as they would all be trying to obtain bearings at the same time. Coverdale's bearings were rushed immediately to Ottawa so they could take whatever action was necessary. An example would be the rerouting of convoys upon the detection of a wolf pack. We also had a continuous contest going with the Harbour Grace, (Newfoundland) D/F station to submit our bearings in before theirs".

Alice Adams was a 'Z' operator at Coverdale for a few months before leaving for Kana training at St.Hycanithe, Quebec. She recalls. "We worked two on a shift with three signals officers in an adjacent room. Our duty watch was alerted to the U-boat transmissions by the intercept operators in the Operations Room. Quickly, we tuned into the frequency given by the operator, then our job was to photograph the signal. The signals officers had expertise in identifying the images produced by the signals. As I remember, they worked closely with NSHQ.".

It is believed that the National RBJ and Sparton XV receivers were used for 'Z' intelligence work but its not confirmed at this time. 'Z' intelligence continued until the German surrender in May 1945.

.......................(article continues through to the end with details of the various uses to which the site was put until it's closure in 1971)

source j.proc.ca (http://jproc.ca/rrp/rrp2/coverdale.html)

Elsie's copy of the Doenitz message





Little h

Brian Wentzell
21-10-2012, 23:53
Harry: The WRCNS were very important participants in the navy as were their compatriots in the Canadian Army and RCAF. Today we have a fully integrated military where women have commanded ships (including HMCS Halifax), army units and air force organisations.

I had not read Doenitz's message before. It was clear he knew the war was coming to a rapid conclusion. Imagine the excitement at Coverdale when that message was received.


24-10-2012, 15:14
Below please find excerpts regarding the WWII HF/DF activities of HMCS GLOUCESTER, which have been taken from one of the articles in Jerry Proc's excellent online articles, see:-


Developed by: Jerry Proc
Last updated: September 28/12



Naval Radio Station Gloucester (pronounced "Gloster"), call sign CGI, was established as a HFDF facility on February 23,1943. During the war years the station was officially known as "Number 1 Station HMCS Bytown" and for brevity it was sometimes referred to as "No. 1". From December 1, 1950 to April 1, 1953 the name was changed to HMCNRS . Between 1953 and 1966 the base was known as HMCS Gloucester, then CFS Gloucester until it closed.

Commissioned in 1950, HMCS GLOUCESTER became not only a training facility, but also the home of the Special Communications Branch. Its Commanding Officer was the Senior Officer for all Special Radio Stations (SOSRS) and was responsible for the administration and supervision of all Special Communication Stations. The Special Communications branch was tasked with the responsibililty of signals intelligence. Gloucester's motto became "Knowledge through Discipline".

MapQuest map indicatating the location of HMCS Gloucester (My comment - see attachment)


1943 - 1945

Gloucester played a vital role in the Allied efforts of World War II and for years afterwards during the Cold War. Its primary role in 1943 was to pinpoint the location of German U-boats in the North Atlantic using radio direction finding equipment. This was accomplished by intercepting Morse Code transmissions from the subs as they radioed to headquarters in Germany and the French coast.

Dorothy Robertson, a Wren (Women's Canadian Naval Service) who served at Gloucester recorded her wartime experiences in a booklet titled “I Go (Not) Down to The Sea in Ships”. Using excerpts from her writings, here's how one Wren made the journey from recruit to trained operator and in doing so provides a glimpse into the early years of the station.


After completing basic training in Galt, Ontario, some 15 Wrens were drafted for further training as wireless telegraphists (W.T.'s) in January 1943. Their training would take place at the luxury resort hotel called Guild of All Arts located in what is now Scarborough, Ontario. The Guild was struggling financially in the straitened conditions of wartime pleasure so the owners viewed the Wrens as their financial saviours. Not only did the Wrens stay there but the Guild continued to operate as hotel for civilians.

Upon their arrival in Toronto they were met by Gwen Hoey, who by the way, was already quite proficient in Morse code. This group of 15 new recruits were reinforcements to the first class numbering about 40 who had already been at the Guild for two months and were already quite advanced in their training. Accommodation at the Guild was doubled (ie two people to a single room, 4 to a double, etc) but the even-tempered nature of the new group helped them to endure the compressed living conditions.

In the next three months, people like Chief Barry or Leading Telegraphists Irene Carter and Gertrude Jardine indoctrinated the Wrens into the mysteries of Morse code. To break from the tedium of copying Morse from the buzzers, there were lectures on naval wireless procedure from the Chief. In what turned out to be quite a surprise, the Wrens were being taught German naval procedure! They were coached in the location and call signs of the German navy’s coastal stations, the makeup and probable meaning of various types of messages and above all, how to distinguish between the incessant traffic from the shore stations (of little interest) and the infrequent traffic from U-boats in which there was vital interest. There was further training in the use of Direction Finding sets. The "unbreakability" of the Enigma code was also stressed in class but we all know now that Bletchley Park was decoding Enigma during the war.


While these recruits were in training, a new intercept station was being built near Ottawa. Officially it was known as No 1 station, HMCS Bytown and No. 1 for short. Some weeks before the opening, Chief Barry travelled to Ottawa to inspect the almost finished station and reported back to the Wrens that were going to be housed in extraordinary luxury such as “lilac-coloured powder rooms”. When eventually viewed by the expectant occupiers, the accommodation turned out to be a single large room with numerous cubicles for an assortment of useful equipment and painted a pale lavender. It was not exactly the Wrens idea of luxury living but things could be far worse.

There were four buildings at Gloucester when it opened its doors. The largest, Building No. 1, was the barracks which included accommodation cabins (eight women to each one), the Ward Room and the Officers quarters, Sick bay, the fo'c'sle (lounge), the mess, and the galley were also included in this ‘U’ shaped building.

Building No.2 , the Operations Building, was the most important one. The true heart of the building was the Operations Room. It was large, light, airy and reasonably pleasant, where the operators worked 24 hours per day, 7 days per week intercepting radio traffic from positions at a continuous table that ran three sides of the room. The watch supervisor had her table on the fourth side, from which she went around to collect the messages, sort them, and pass them on to the teletype operator next door for transmission to NSHQ ( Naval Service Headquarters) in Ottawa. The Regulating Office (ie administrative and disciplinary centre) was also located in the Operations Building. It was presided over by a Regulating Petty Officer.

Building No. 3 was the garage in which liberty boats (ie panel trucks) were housed. Three sailors lived on the second floor. No .1 was an all-female station except for these three gallants, classified as unfit for sea duty, who were expected to do certain maintenance and other such duties considered beyond the normal physical strength of a woman. They gents were very popular but were also wise enough to keep to themselves when off duty. The liberty boats, were extremely important to the station since that was the only way to ferry personnel and supplies. The No. 1 station, sometimes referred to as "the hayfield", was some 17 miles distant from Ottawa and it was also three miles from the nearest highway. A bus ran along the highway, only three or four times a day, but never in sync with the Wren’s off hours. So the only means of going to Ottawa for a few hours of rest and relaxation was by liberty boat.

These three buildings were grouped together inside a perimeter fence and were connected by a series of boardwalks. To the casual visitor, it appeared that No. 1 Station only consisted of three buildings but a mile away and across five fields, virtually invisible from the main station, stood Building #4. Small and seemingly insignificant, it was the DF shack and was known simply as #4. It consisted of a single room, about the size of the average living room, with a few chairs and tables, a pot-bellied iron stove, a chemical toilet in a tiny cubicle, and three CRT type DF sets.

Only some of the personnel at No 1 station were trained as DF operators. For each watch and two at a time, they made their way from the main station, through the first gate in the fence, across five private fields while squeezing though barbed wire and finally through the gate of No.4. In addition, they lugged sandwiches, jugs of water, coal, pads of paper and flashlights at night. It was not an easy trek during winter. The reason for why there were no gates or stiles in the fences was a simple one. There was a feud between the local farmers and the navy. The farmers resented the navy because they occupied what was said to be the best hayfield in the area. As a gesture of displeasure, they refused to install or allow the navy to install stiles over the intervening fences. Hence the DF operators had to battle with the barbed wire six times a day.


When the Wrens first arrived at “No.1” they had a couple of days of practice to become accustomed to watch keeping hours before being thrown into the real thing. For some reason, those first days were divided into four-hour watches, the traditional Navy way, of course, but not what they were soon to experience. The switch to "real" duty brought nominal eight hour watches, though only one was actually eight hours. The 24-hour day ran thus: 0100 to 0900 (graveyard watch); 0900 to 1800 (the day watch) and 1800 to 0100 (the evening watch). As far as anyone could figure out, the rationale for this peculiar system was for the convenience of the cooks who could deal with breakfast and supper for the ongoing and off going watches in quick succession.

The nine hour day was a killer. One was not allowed to leave one's receiver except for the relief of nature when the supervisor took over for a few minutes. Eating a meal of sandwiches had to be done at the receiver with the earphones on and pencil poised in case something came up.

Real complaints began to gather over the reorganization of watches. It came as a result from a peculiarly thoughtless piece of reasoning originating in the higher echelons of the Wrens in Bytown. When organized into four watches working three days on each watch followed by three days off, Wrens were allowed to apply for "weekend" leave, which in a 12-day week usually did not coincide with Saturday and Sunday. Also, these three days constituted exactly 72 hours, from 0900 to 0900 hours. The actual days of the week did not worry the personnel. All went well until someone noticed that the Wrens were taking more than the official allotment of one "72" and one "48" leaves a month. Orders came that the Wrens were to have their watches altered.

With the new schedule, the Wrens were now to work six days on each watch before getting three days off. They had to be reorganized into seven watches, two working at the same time, and because a run of six graveyards was considered too much, it was further decreed that they should follow the six day-watches with three evenings, three graveyards, three evenings again, three graveyards, and at last the exact, 72 hours off. This schedule left them dead tired.

It is easy to see that a 21-day "week" adds up to exactly three weeks of the ordinary variety, with each of the seven watches beginning its leave always on the same day of the week. With this type of schedule, it was not possible to travel to Toronto and back. Eventually the schedule was modified slightly to accommodate Toronto bound travellers.

This killing schedule of 21-day weeks lasted a couple of months, until the Medical Officer noticed an alarming increase in the number of operators who developed twitches and minor but irritating symptoms associated with exhaustion, probably exaggerated by a general feeling of grievance and ill-treatment. He investigated and ordered an immediate return to the more normal watch system.


In the summer of 1943, Wrens returning from leave were extremely surprised to learn that No 1. station was closed and would remain that way for about six weeks. For some weeks, personnel had been coming down with dysentery and the epidemic became so acute that on one occasion only the supervisor and a single operator turned up for duty. Frantic investigation revealed a serious fault in the drains - they had been installed incorrectly. Once the Medical Officer diagnosed the problem, he closed the station immediately and all the Wrens had one hour to pack before vehicles arrived to take them away.
............................(article continues)

By the fall of 1943, the problems that caused the dysentery outbreak were corrected. Everyone survived St. Hyacinthe and returned back to No.1 with a greater appreciation of their luck.
............................(article continues)


In early spring 1944 an upheaval occurred at No.1 Station. Almost before the station had been completed it had been discovered that the Ottawa region was not the ideal place for reception of overseas wireless signals, something the Canadian Broadcasting Commission had discovered some years before. In the evening, signals boomed in but towards midnight they began to fade, and by the time the Graveyard Watch arrived, the air was silent as far as German shore stations were concerned, and remained so for several hours.

The Wrens had scarcely settled into No 1 before construction was started on a new station outside of Moncton, New Brunswick called Coverdale2. . As soon as it was ready, most of the senior operators (W.T.’s) were reassigned to Coverdale. A new batch came from Ste. Hyacinthe to replace the vacancies at No. 1. Four of the original crew who arrived on Easter in 1943 volunteered to stay at No.1 as supervisors. They were Dorothy Duncan, Alice Russell, Dorothy Robertson and Celia Weiser who was in overall charge of the direction-finding hut.
..........................(article continues)

During wartime, D/F bearings obtained at Gloucester and other D/F locations were plotted on a wall mounted map. Pieces of coloured string were attached across the map whenever a bearing was obtained. Operators waited to hear from other D/F stations in the UK, Bermuda, Labrador or Africa that were homing in on the same signals from either enemy ships or U-boats. Once a cross bearing was plotted, the intersection of the strings indicated the source of the enemy signals. Accuracy was limited to a 25 mile radius from the intersection. Within minutes, Allied aircraft flying on patrol, could be dispatched to the target area.

When the aircraft arrived at the intercept point, they could put down their sonobuoys and listen for the enemy if nothing was sighted visually. The first operational sonobuoy which saw wide use was the American AN/CRT-1 which became available in June 1942. Operational use began in August of that year. This sonobuoy had 6 available radio frequencies, an omni-directional hydrophone and could operate for 6 hours before exhausting its battery. Several buoys had to be used in order to triangulate a target.

In February 1943, a design of a directional sonobuoy was started which resulted in the AN/CRT-4. Testing commenced in early 1945. This sonobuoy had a rotating 11 degree beam that rotated through 360 degrees every 12 to 20 minutes depending on sea state. Rotation was achieved by a special sea anchor that dropped from the buoy on entering the water. This anchor caused wave action to rotate the buoy through its search pattern. The AN/CRT-4 was introduced too late to have any effect on the outcome of the naval war.

1945 to 1948 - TRANSITION

By 1945, Gloucester's role began to change, with a portion of the facility being deactivated and used as a training ground for the Communicator Special trade. Eventually the site became the official school for the Special Communications Branch with its first course commencing in 1948.

Gloucester became the headquarters of SOSRS (Senior Officer for all Special Radio Stations) and had a full Commander as the Commanding Officer. in 1951. He was responsible for the administration and supervision of all Special Communication Stations. Churchill and Coverdale both had LCDRs as CO. All the others, Gander, Chimo, Aklavik and Masset, were NRS, and were tenders to Gloucester. Masset and Gander had Commissioned Officer (SB) as the OIC. Aklavik, Gander and Chimo had a Chief in charge.

During the Cold War, Gloucester was kept busy tracking Soviet vessel movements. The Soviets use of a technology called "burst transmission" made the job more difficult until the introduction of automation which would help an operator to capture the adversary's transmission and help him to figure out the point of origin.

The RCN also began their concentrated efforts in Communications Research by choosing the direction finding facility situated at Gloucester as the home for this unique business on 29 Dec 1947. By early 1948, they had initiated Gloucester as the administrative HQ and trade school by co-locating it with NRS Gloucester (HFDF).
...........(the article continues through to the end, with Gloucester new Post- WWII role in connection with Special Radio Operators)

source jproc.ca (http://www.jproc.ca/rrp/glo.html)

My Comment; The excerpts included above have been included in the thread, as a further reference to the contribution made by the WCRNS in their role as HF/DF operators during WWII.

The attachments are included to enable comparison between Gloucester and Coverdale.

Attachments; The caption under the attached photographs read:-

1st...HMCS Gloucester was located roughly south-east of Ottawa. Navan was the location of Gloucester's (CGI) transmitter site, commonly referred to as the Orleans transmitter site. When Glo was a member of the Atlantic HFDF Net, it reported from this site to Net Control near Washington using CW.

2nd...Coverdale as it appeared in 1944. The two buildings are the Operations Room (right) and the Wren's living quarters (left). The only other building was a smaller one behind the barracks which had the garages and work sheds with living quarters above for the male personnel on base. The three D/F shacks were accessible by walking across the fields. In the middle of a very heavy and cold winter, Wrens had to make their way through high drifts and whiteouts to get to the D/F shacks so it was anything but pleasant. To make things interesting, there was even an odd bull in amongst the cows roaming the fields -- just another challenge! (Photo courtesy Vin Crane)

3rd...(My comment- another of Coverdale)The winter of 1944-45. This photo gives an idea of the conditions that the Wrens had to endure while hiking out to the D/F shacks. Compare this to the summertime photo above. (Photo courtesy Vin Crane)

Little h

24-10-2012, 20:52
Here are several excerpts which give an insight to the organisation to in the United States by the United States Navy and US Coast Guard who provided shore based HF/DF cover for the Atlantic in WWII Dec 1942 - May 1945.


Battle of the Atlantic, Vol. 1
Allied Communications Intelligence
December 1942 - May 1945
(SRH - 009)


No single aspect of the Second World War is full of mysticism and speculation as much as ULTRA. Just the mere mention of ULTRA with a campaign brings mythical overtones. As the word implies, ULTRA means something beyond or on the other side of moderation. Yet ULTRA was not a weapon system with phenomenal power. It simply was the code-word for the information obtained through communications intelligence during the war. like other forms of intelligence its significance depended on its timeliness, reliability, and appreciation by commanders. As it will be shown in this volume and its companions, the mere possession of ULTRA intelligence would not be a sole factor in deciding any engagement. This was especially true in the Battle of the Atlantic.
....................(the article continues)

Prior to addressing the role of communications intelligence in the Battle of the Atlantic, it would be helpful to review its development in the U.S. Navy. The importance of the Atlantic prior to the Second World War was overshadowed by the threat of the Japanese in the Pacific. The suddenness of war in Europe in 1939 caught the American naval communications intelligence organization off guard. Nevertheless, the American naval organization was able to begin world-wide collection, direction finding and evaluation of communications intelligence as intercepts were obtained. The origin of ULTRA as a concept was not of American origin and was not adopted until collaboration with the British during the war.

The code-word ULTRA was of British origin. The word was used to identify the source of intelligence for those who
had access and need to know. By using this identifying caveat the recipients of the intelligence would immediately appreciate the source as highly reliable. Specifically, ULTRA intercepts were decoded Enigma-generated German military and diplomatic messages sent by radio. Yet this special intelligence had a series of code-words for its designation.4 HYDRO was the first code-word associated with this form of intelligence used by the Royal Navy. Throughout the war Winston Churchill preferred to use the code-word BONIFACE as his designated source of communications intelligence instead of the military-inspired terms. The Royal Navy replaced HYDRO with the word HUSH and by mid-1941 adopted ULTRA as the final caveat.5 The increased collaboration between the British and U.S. navies in the field of communications intelligence necessitated complementary security measures.6

The incorporation of security measures for this special intelligence in the U.S.Navy lacked specific guidance. While the U.S. Navy was involved in communications intelligence since the end of the First World War it did not have formal security measures like the British. There was no adoption of caveats to the security classification until June of 1942.7 The June 1942 a Chief of Naval Operations (CNO) directive established that there should not be any mention as to the origin of the intelligence in correspondence and that either the code-word ULTRA or ZEAL should be used at the beginning of a message.

The incorporation of the new security measures failed to be employed as envisaged by the CNO. The American office
responsible for the origin of much of ULTRA intelligence did not always follow the directive. Correspondingly, Admiralty messages to the U.S. did not begin to receive ULTRA designations until late 1942.8 U.S. naval messages to the Admiralty did not receive ULTRA caveats until January 1943.9 This lackluster employment of the security criteria required more attention within the American navy.

In March 1943 the CNO reaffirmed the needs of security and special handling of communications intelligence. The earlier security directive was superseded and the new policy required all material derived from cryptanalytical means to be stamped either as ULTRA or SUPER in addition to the usual security classification.10 Cryptanalytical means was the method used to break the cryptographic security of enemy radio messages. Any hint of this type of work would naturally cause the enemy to change codes and setback the codebreaking efforts. Inner office correspondence by OP-20-G did not adopt the ULTRA caveat until the spring of 1944.11 Once the formalities of classification management were settled, U.S. and British naval correspondence followed similar guidelines.

The U.S. Navy was deeply involved in the field of communications intelligence since the mid-1920's. This effort was under the supervision of the Director of Naval Communications (OP-20) who oversaw all aspects of collection, evaluation, and dissemination of communications intelligence for the U.S. Navy. The office directly responsible was the "Communication Security Section" (OP-20-G).12 As tensions began to rise during the late 1930's, OP-2D-G was faced with two threats on opposite sides of the globe. The predominant emphasis of cryptanalytical work was directed towards the solution of encrypted Japanese traffic. This reflected the dominance that War Plan ORANGE had in the navy. The technical advances of the Germans in the Atlantic had reduced the efforts of OP-20-G to that of traffic analysis.13 Up to the reorganization of OP-20-G, following the Pearl Harbor attack, communications intelligence in the Atlantic theater received a low priority.
..................................(the article continues)

Time and the, lack of attention had a degrading effect on the shore based naval radio direction finders. In 1924 the Navy had 52 medium frequency D/F stations in operation on both coasts. By 1941, 22 remained in commission of which only six or seven were in effective operating condition.16 Most of the sites had deteriorated due to poor maintenance, fire, storm damage and other unexplainable acts. In July 1941, the navy formally transferred custody of these original D/F stations to the U.S.Coast Guard.

The development of high frequency direction finding (HF/DF) operations began in the early 1930's. Originally envisaged in 1933 and amended in 1935 the development of strategic HF/DF sites world-wide was proposed.17 Of the eleven chosen locations, four were to be situated on the Atlantic coast.18 Winter Harbor, Maine, received the highest priority of the Atlantic sites and was operational in early 1935. Yet the first American fix on a foreign vessel by HF/DF came from the Cavite site in the Philippines in late July 1936.19 Despite this accomplishment, the reliability of the HF/DF equipment was poor and an extensive development program was initiated to identify an ideal apparatus for naval service. By June 1938 an advanced HF/DF unit had been installed at Winter Harbor. Despite the placement of new equipment at the East Coast locations, the Atlantic HF/DF group would have only the primary mission of "training" and would be manned "intermittently."20 Finally, by July 1939, the new Direction Finder Policy was promulgated and officially established the Strategic Tracking Organization.21

The end of 1940 saw dramatic improvements to the American naval communications intelligence organization. By December OP-20-G had successfully tracked by HF/DF both German submarines and surface raiders in the Atlantic.22 Training of both enlisted and officer personnel was progressing rapidly. Technical innovations were also being rapidly incorporated into communications intelligence efforts. There was also the strengthening of collaboration with the British against adversaries in the field of communications intelligence.

Organization of the Atlantic intercept and HF /DF capabilities received considerable attention in the spring of 1941. In April the British Admiralty supplied the U.S. Navy with one of their latest Marconi Adcock HF/DF sets for test and evaluation.2323 In May it was decided that all remaining Naval Navigational Direction Finder Stations would be transferred tothe U.S. Coast Guard. The transfer of these sites would provide new opportunities for OP-20-G. J, The growth of HF/DF sites required additional OP-20-G personnel. The maneuver with the U.S. Coast Guard helped ease the personnel crunch at OP-20-G. New sites in 1941 included Greenland; Charleston, South Carolina; and Toro Point, Canal Zone. Two additional sites were projected for 1942 at Cabo Rojo, Puerto Rico and another to be located at either Trinidad or Brazil. Additionally, in May, a continuous watch officer for control of the Atlantic Strategic HF/DF net was initiated. By December 1941 the U.S. Navy had a global strategic HF/DF system in place with centralized control. It consisted of three net control stations (Atlantic, Pacific, and West Coast) that controlled 20 HF/DF sites.

Radio interception gradually supplemented HF/DF as a form of communication intelligence. Site selection for interception operations was similar to that for the HF/DF stations. Bar Harbor, Maine was involved in intercept activities as early as November 1931. The station was subsequently relocated across Frenchman Bay at Winter Harbor in early 1935.24 While the primary concentration of its activities had been diplomatic traffic between Europe and Tokyo it was also well situated for other forms of radio interception.

At some point in 1931, interest was taken to intercepting Russian radio traffic. Eight special Underwood typewriters were ordered to be made with Russian (Cyrillic) type-set keys.25 In 1933 Bar Harbor's activities had "been diverted" from its normal diplomatic interests to concentrate on other topics. At the time the Soviets were becoming more active both militarily and diplomatically. They had been experiencing difficulties with the Japanese in the Far East and were engaged in collaboration in naval affairs with the Germans and Italians. In diplomatic affairs the Soviets had begun treaty negotiations with France, Germany, and several other countries.26 The onset of war in Europe in September 1939 brought about a declaration of national emergency in the United States and a new view of priorities. Intercept reorganization came during the first week of September. Winter Harbor was relegated to HF/DF only. Interception for the Atlantic theater during this time frame fell upon stations at Jupiter, Florida and Cheltenham, Maryland.27 The missions of these shore based stations would change later in the war with Chatham, Massachusetts replacing Cheltenham as the primary interception site.
.........................(the article continues)

Interest by American communications intelligence in the Atlantic and European areas continued to mount. The first indicated liaison of American and British communications intelligence personnel came in the spring of 1940. Two American naval representatives visited the British HF/DF station on the island of Bermuda.39 They had observed British operations, net procedures and the employment of fixed antenna equipment.

A formal, and highly secret, agreement concerning naval communications had been made between the British and American governments in 1937.40 The agreement had been made at the instigation of the British Admiralty and was so secret that only one American officer active duty was aware of its existence. Three hundred fifty copies of a publication covering the complete description of the American communications organizations and procedures were held in the Europe.41 In the event of war the American naval communications representative, would provide the publications to the British.

In October 1940, the Special Naval Observer (SPECNAVO), London, was approached by an Admiralty representative concerning further collaboration in communications intelligence.42 The British provided information concerning positions, frequency coverage, control stations, and linkages of these stations with the Admiralty. The British requested that the Americans reciprocate the exchange of information. This request was granted and similar information on American communications intelligence activities was sent to London on 20 November.43

Afloat communications intelligence continued to contribute to the European effort. The transfer of Station F was accomplished once more with the arrival of the new commander and his flagship, the USS Omaha. In fact, the new commander of the squadron, Rear Admiral Charles E. Courtney, recently relieved as Director of Naval Communications (OP-20) and aware of the importance of Station F. The transfer of Station F occurred after 5 July 1940 and returned to its collection duties. Primary coverage would now center on Italian naval circuits in the Mediterranean. The ensuing naval battles throughout the summer were covered by Station F and relayed on to Washington. Early in October 1940 Squadron 40T was recalled from duty in Europe due to the increased risk of conflict with the belligerents

The need for more accurate communications intelligence in Europe was being felt by OP-20-G. Previously, the majority of intelligence gained from communications had come from HF/DF and traffic analysis. The rapid growth of intercepts of European messages allowed the Americans to begin a dedicated attack on decrypting this traffic.44 The incorporation of attacking European generated intelligence into OP-20-G seems to have begun around July 1940. A two-person European branch was added to the cryptanalytical section.45

The interest in European traffic intensified by October 1940. Losses of merchant shipping to U-boats reached a new high in October. The continued reliance of radio communications by the U-boats represented a weakness that could be exploited. The communications intelligence situation was made worse when the Japanese made drastic changes to their main naval cipher systems in December.46 OP-20-G had no immediate solution to the Japanese changes and recovery was not near. At the time there were only five officers and two civilians working in the cryptanalytical section.47 The threat from the V-boats seemed to be increasing as the months passed. Thus, OP-20-G was forced to address European cipher system. Work was divided up in the office with the hope that a break would be possible.

Two separate sections for attacking European traffic were created.48 The first, headed by Agnes Driscoll centered on German naval systems. The second, headed by Lieutenant Lee W. Parke, concentrated on Italian naval systems. There was some prior work on German systems, but it was of no avail. Commander Safford hoped that the employment of Mrs. Driscoll in the effort would produce favorable results.49

In early 1941 the collaboration between American and British navies intensified. In January the United States decided to give the British one of the PURPLE machines for breaking Japanese diplomatic message traffic. The machine was escorted by four military officers; two were from OP-20-G.50 The Americans hoped the British would reciprocate the offer by giving a copy of the German ENIGMA machine cipher. Instead the British exhibited their efforts against the ENIGMA and presented them with all the keys that had been recovered and a paper analog of the cipher.51 The American mission also was given a copy of the latest British HF/DF unit for evaluation.52

The American contingent returned and applied what they had learned from the British to their work against the European ciphers. However, the work was time consuming and showing little progress. Further collaboration continued on the only truly dependable intelligence resource available at the time: HF/DF. By July the reproduction of British codes and ciphers for HF /DF reporting was being carried out for joint use.53

In the spring of 1941 sought to improve the interception effort with the Atlantic sites. In March direct commercial teletype service was authorized for the Winter Harbor and Amagansett radio intercept facilities.54 This development allowed the stations to forward intercepts immediately to Washington upon receipt. While the primary emphasis was on Japanese diplomatic traffic other "messages of unusual nature appearing to be of sufficient importance to warrant attention" would also be forwarded.55 The result was improving coverage of radio circuits and minimizing delays in getting the intercepts to the cryptanalysts.

Establishment of coverage by the radio intercept stations was promulgated in the fall of 1941. Atlantic stations served as four of the five major intercept facilities on the continental United States.56 The primary and secondary missions of the Atlantic stations were:

Station ---------------Primary57 ------------------- Secondary
W (Winter Harbor)---Italian Naval ---------------- Axis Diplomatic

M (Cheltenham)-----German Naval---------------- Axis Diplomatic

G (Amagansett)----- Diplomatic---------------------None

J (Jupiter)------------ Diplomatic---------------------None

........................(the article continues with org USN organisational details)

By 24 June 1942 OP-20-G had evolved into an efficient and well organized office. When a break finally came with the German ciphers in December 1942 a further reorganization took place within OP-20-G.60 The need existed for a separate division for handling intelligence acquired on the Pacific and Atlantic theaters.

The creation of the "Atlantic Section" within OP-20-G did not develop until January 1943.61 Prior to this Atlantic communications intelligence correlation was conducted by the office primarily concerned with Pacific theater matters. It is known that the Atlantic Section was functioning well prior to the TORCH landings in North Africa in November 1942.62 A small section was established in early 1942, but the increase of traffic overwhelmed the limited staff. Two officers from the Pacific Section of OP-20-G were reassigned to the Atlantic section to assume watch over non-German Atlantic activities.63 Due to the delays, involved in processing the intercepts, the Atlantic Section was not a key element in direct support for the TORCH landings. Nevertheless, the experience obtained aided in the clarification of organizing the office to support current operations.

While the need existed for proper correlation of Atlantic communications intelligence the development of such a unit was slow in going. The initial head of the informal Atlantic Section was Lieutenant Willard "Van" O. Quine in the fall of 1942. The Atlantic Section, formally known as OP-20-GI-2, was officially established when its designated officer in charge, Lieutenant Commander Bernard F. Roeder, assumed his duties after returning from the Pacific in January 1943. From that point on, the Atlantic Section served as the correlation and dissemination branch for all Atlantic related communications intelligence.

................(the article continues with List of Abbreviations and Footnotes)

source HyperWarFoundation (http://www.ibiblio.org/hyperwar/ETO/Ultra/SRH-009/SRH009-Intro.html)

Little h

Caption for the attachment reads:-
Atlantic Strategic HF/DF Net by December 1941

25-10-2012, 16:50
.... and for some of the HF/DF activities conducted in UK shorebased facilities, here is one operator's account:-


Admiralty Civilian Shore Wireless Service by Michael
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Archive List > Royal Navy

Contributed by Michael
People in story: Dermod J. Kirwan
Location of story: U.K. and Jamaica
Article ID: A8259825
Contributed on: 04 January 2006
Admiralty Civilian Shore Wireless Service.

During World War 11 I was a civilian radio operator employed by the Admiralty, and the service of which I was a member was known as the Civilian Shore Wireless Service, sometimes referred to facetiously as the Co-operative Wholesale Society because of the similarity of the initials. The work was interception of enemy naval signals and taking direction finding bearings on enemy ships which were mostly submarines.

In 1940 I was working as a radio operator in an aviation radio station in Ireland. One day a friend of mine showed me an application form for the Admiralty Civilian Shore Wireless Service and some information which came with it. Entrants were required to be able to receive morse at 20 words per minute. My friend changed his mind but I filled out the application form. Three weeks passed, during which they may have been “vetting “ me in case I would turn out to be a spy, and then I got an invitation to attend for interview at the signal school of the Royal Navy barracks in Portsmouth on Monday 27th May 1940 at 9a.m. The first question I was asked was “Assuming that you pass this interview, would you be able to start with us today?
I joined a class of about twenty men. During a course at Portsmouth R.N. Signal School we were told that submarines could only transmit when they were on the surface, and when they were submerged they could receive, but only on low frequencies. When on the surface they could of course receive on all frequencies. When they surfaced they had to dry out their antennas. They did this by pressing their key which made a particular sound which we had been trained to recognise. The moment we heard this we had to call out the frequency to the controller who was permanently connected to several DF stations and they would hopefully be able to locate the U boat position very precisely.

At Portsmouth we also learned and practiced the morse symbols for accented vowels, which are extra to the ordinary letters, figures, and punctuation marks which every radio operator must learn for his certificate. Other skills learned on the course included target practice with the .45 revolver, known officially as a pistol, never a “hand gun” in those days. We also had rifle practice but ammunition for this was limited to only five rounds each.

After three weeks in Portsmouth I was transferred to Flowerdown R.N. W/T station near Winchester. In the main building there were perhaps forty operators on duly, some of them civilians and some were girls in the uniform of the W.R.N.S., all copying traffic from German or Italian stations.
The German radio stations controlling the Battle of the Atlantic were Lorient, R X Ú, and Berlin Á D A. Four letter code was used, and naval ships used no call signs, transmitting their messages on the same frequency as the shore stations and using a prefix which distinguished between a weather report W W, and an enemy sighting report É É, which we called an E bar, (morse symbol ..-..).
There were also prefixes for other categories of messages.

The German broadcasts would come up on known frequencies, at the same time, ten minutes past the hour, long messages of four letter groups The message would then be repeated from another base in the area so that should any of their intended recipients miss a group or letter for any reason there was a second chance for their operators (as us as well) to check the message and insert any missing letters or groups. By using another station to repeat the message there was the chance that the second station might not have the same atmospheric disturbances as the originator. Ships were not supposed to ask for groups to be repeated for fear of being D/F ed but occasionally they did. If so the operator shouted the frequency and the control person would direct, via his land lines, his choice of D/F stations to that frequency.

I had been there a couple of weeks in Flowerdown when one morning a supervisor came round and said “Has anyone had experience of short wave direction finding?” I was the only one who answered and I stood up and told him of my experiences at an aviation radio station in Ballygirreen.

From then on, until May 1945, I was continuously employed on taking bearings on enemy ships, mostly submarines, when they transmitted with their radio, and after Flowerdown I served at Cooling Marshes, on the Thames Estuary, Lydd on the Southeast coast of England, Kingston (Jamaica) and Wick in the north of Scotland.

We had Direction Finding stations at strategic points around the U.K. so that when an enemy submarine transmitted with his radio, provide that at least two of our stations got bearings his position could be determined and so a convoy might be diverted out of danger or its escort reinforced.

At Cooling Marshes we were having air raids every night, so I had some anxious times with enemy bombs exploding nearby and our anti-aircraft shells exploding overhead and showering their fragments all around. In the end of April 1941 we got instructions to close up the radio station at Cooling Marshes and transfer to Lydd, near Dungeness, where a better site for a D/F station had been found.

This really sounds like ancient history, but it was decided that when the time came to warn the people of England that Hitler’s invasion had started the church bells were to be rung all over the land, and the signal for this to be done was to be the code word “Cromwell”. Therefore there was no bell for Mass, or Church of England, or other religious service.

On Sunday, September the 8th I went on duty at 8 a.m. from my lodgings in the nearby village of Littleton and in those days my instructions were to collect a rifle and ammunition at the main receiving station and to take them with me to the building known as D/F one. On arrival at my place of duty I was surprised to see two armed soldiers at the door, and I was even more surprised on going inside to see that Mr. Kenward, whom I was relieving had two revolvers on the table beside the receiver.

His reply to my question “What is it all about?” was “Oh haven’t you heard? The church bells have been rung, and the Germans have landed. Hardly had he said this when we heard the sound of a large formation of aircraft approaching. It was a day of low grey clouds, just below which and partly shrouded in mist we saw the twin engined planes, several abreast and more behind them.

I don’t know if the others with me expected a low level bombing or machine gun attack, but my own expectation was that we were going to be in action against paratroopers within minutes and that we might shoot some of them on their way down. Of course, we were all looking anxiously towards the oncoming aircraft, when one of the soldiers was the first to see the markings and called out “Its all right, they are ours”. I can truly say I was never more relieved in my life. The explanation of the mistaken ringing of the church bells came to me long after the war in a book called “Invasion 1940” by Peter Fleming. It seems that there was doubt or confusion in London among highly placed persons as to whether “Cromwell” meant that an invasion was imminent, or that the Germans had actually landed. The night of 7th/8th September was that of the first heavy air attack on London. At the same time there was a concentration of enemy ships sighted off Calais, and so in the belief that the invasion of England was on the way, the dread code word was sent out .

In the summer of 1942 I accepted a transfer abroad where there was a good overseas allowance. In July I crossed the Atlantic from the Clyde to New York. The crossing took 14 days and on several occasions the escort dropped depth charges, I suppose when the presence of submarines was suspected. I was instructed to take the train to Miami and Pan American airways to Kingston, Jamaica.

I spent two and a half years in Jamaica, and might have been longer had I not got a succession of very severe attacks of asthma, with which I was laid up on three or four occasions in the British Military Hospital in the kind and gentle care of Queen Alexandra’s Nursing Service. Finally it was found that I was allergic to the tropical vegetation so I was sent back to the UK via Miami and the “Queen Elizabeth” ship from New York to the Clyde. I left pier 90 North River in New York during the night of February 28th/ March 1st crowded with fifteen thousand American soldiers. My passport bears the stamp of the Immigration Officer, Clyde Ports dated 6th March, 1945, and with that my travels to distant lands were over.

My next posting was to Wick in the north of Scotland, which was a very severe change of climate, but by then the war was nearly over and eventually I was transferred to Winchester where I retired from the CSWS on 25th March, 1947. I could have stayed on to retiring age because the interception service was necessary to try and find out what potential enemies were plotting but I decided to apply again for the job I had in Ballygirren prior to the war. Therefore I continued at Ballygirreen for 31 years from 1947 to 1978 when I retired at the age of 69.

HF D/F was a war winner. D/F bearings reached the Admiralty Submarine Tracking Room before the decrypted translated texts and often enabled control to warn convoy escorts that they had been sighted within a few minutes of the event. The Bismarck would not have been sunk but for HF D/F and many, many convoys were kept clear of U boats or at least given an advance warning of an impending attack.

Dermod J. Kirwan.
source BBC-WW2 People's War (http://www.bbc.co.uk/history/ww2peopleswar/stories/25/a8259825.shtml)

Little h

25-10-2012, 18:09
Another article by a former member of the WRNS at Flowerdown during WWII . This time no mention of the HF/DF effort, but reference is made to a Royal Navy presence at the site.


Life in London and in the WRNS by agecon4dor
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Archive List > United Kingdom > London

Contributed by agecon4dor
People in story: Josie Page
Location of story: London/Winchester
Background to story: Royal Navy
Article ID: A4241242
Contributed on: 22 June 2005

This story was submitted to the People’s War web site by a volunteer on behalf of Josie Page and has been added to the site with her permission. She fully understands the site’s terms and conditions.
..........................(the article continues)

In 1942 I decided to join the WRNS. After six months training in wireless telegraphy (Morse Code) I landed up at HMS Flowerdown (it sounds like something from a Gilbert and Sullivan opera) which had previously been a civilian station. We had four watches, 6 pm — midnight, 1 pm — 6 pm, 8 am — 1 pm and midnight — 8 am. Then the day off to sleep and the next day commenced at 6 pm again (each day beginning a watch earlier). Flowerdown was a few miles outside Winchester on the Andover road.

Food was more plentiful than in civie street. We were issued with two suits, the one kept for best was referred to as the “tiddley suit” and we had a pair of bell-bottom trousers also. Black stockings when nylons came in were “one up” on the other services! We cycled around Hampshire but invariably got lost as all the signposts were removed! When American Servicemen in lorries took us to dances we were inevitably late getting there and in the small hours, getting back. The drivers went round in circles in the dark and we were perished. We were not keen on the Yanks, much preferring our own Matelotes but candidly admitting we went for the food.

We worked alongside the sailors and our work was to intercept the German Naval Enigma. We were referred to as a “Y” station and there were other “Y” stations including Wick and Scarborough. The German Naval Code, which we intercepted, was sent on to Bletchley Park although we knew none of this at the time. When we took on this work we were sworn to secrecy and believe it or not even those “in their cups” never leaked it. Only comparatively recently has the tale been told. How awful of Churchill that he ordered so much at Bletchley to be burned and destroyed at the end.

Through the taking of exams I had become a Petty Officer after 18 months and by the Autumn of 1945 was demobbed
......................(the article continues through to the end)
source BBC-WW2 People's War ( where the full article can be read.

Little h

21-01-2014, 10:48
I went to the WWII week at the Russian Arctic Convoy Museum last year, we had a couple of talks by an expert on u-Boats and one person asked him what was the most important factor in countering the U-Boats. I think most there expected him to say the breaking of the various codes by Bletchley Park or perhaps radar but he said HF/DF was more important.

I have been finding a few of the onshore RN WWII DF stations after seeing a reference to one at Oban whilst visiting the Bletchley Park museum. That one has left no trace but I did find someone locally who confirmed the location and its footprint can be seen on the postwar aerial photographs. But I have found ones on Tiree and Sheigra that still have buildings and mast bases. Another can be seen on aerial photographs of Shetland but none been back up to see on the ground. Just one building left of the one at Kilwinning. I am sure there could be others that have been forgotten.

A few pictures of them here (http://www.flickr.com/photos/doffcocker/collections/72157633485016121/).

22-01-2014, 18:33
I went to the WWII week at the Russian Arctic Convoy Museum last year, we had a couple of talks by an expert on u-Boats and one person asked him what was the most important factor in countering the U-Boats. I think most there expected him to say the breaking of the various codes by Bletchley Park or perhaps radar but he said HF/DF was more important.

I have been finding a few of the onshore RN WWII DF stations after seeing a reference to one at Oban whilst visiting the Bletchley Park museum.......

Not forgetting the shipborne HF/DF contribution, see this short excerpt from:-

Captain Walker RN Part Two

Contributed by ateamwar
People in story: Captain Frederick Walker
Background to story: Royal Navy
Article ID: A5024297
Contributed on: 12 August 2005

This story appears courtesy of and with thanks to Mike Kemble and Captain Frederick Walker

..................and Bletchley Park was experiencing problems with the Shark Enigma signals. Allied merchant fleet losses were appalling. The need now switched from lack of ships, aircraft and weapons to the need for new tactics, training and manning at all levels. American-built escorts would soon start to arrive in great numbers and the tactics for these new support groups would need to be completed and revised. In February 1943, HMS Starling was launched from Fairfield in Glasgow. When HMS Starling was due for commissioning, Captain Walker requested Admiralty that as many as possible of his former ship's company should be the nucleus of his new command. Although a large number of STORK personnel had been sent to other ships, almost half did in fact join Starling. After she was launched and carried out her gunnery and anti-submarine trials she was ordered to Londonderry to have the 291-radar set removed and the latest HF/DF gear fitted. This last-minute modification gave Walker the opportunity to avoid the training at Tobermory and train his own crew.

Source; WW2 The People's War (http://www.bbc.co.uk/history/ww2peopleswar/stories/97/a5024297.shtml)

Little h

Mitch Hinde
22-01-2014, 20:58
Hi All

If you go to the HMS Cavalier site and scan through the picture gallery there is a shot of the wireless office with a beautiful view of a unit in the centre of the pic with two large dials, a ship borne HF/DF set. We had the same set on St Brides Bay.

Mitch Hinde

22-01-2014, 21:57
Hi All

If you go to the HMS Cavalier site and scan through the picture gallery there is a shot of the wireless office with a beautiful view of a unit in the centre of the pic with two large dials, a ship borne HF/DF set. We had the same set on St Brides Bay.

Mitch Hinde


I spent many hundreds of hours in front of just such a piece of equipment in 3rd W/T Offices and EWO's .

Calibration every four hours etc etc.

Little h

Mitch Hinde
22-01-2014, 22:22

Used it once I seem to recall during a SEATO exercise off Singapore.

Mitch Hinde

SEATO South East Asia Treaty Organisation.

22-01-2014, 23:16

Used it once I seem to recall during a SEATO exercise off Singapore.

Mitch Hinde

SEATO South East Asia Treaty Organisation.


That information surprised me a tad. I was not aware that General Service sparkers were taught how to use the FHB receiver and it's associated power pack.

Where were (G) sparkers given their course on the Morse and Voice procedures to be used when keeping watch on the circuits linking other HF/DF equipped ships?

Little h

Mitch Hinde
22-01-2014, 23:48
Hi Harry

The set was in the only WT office we had. Was shown how to use it by the POtel. Didn't have any secret squirrels on board so someone had to use it or it was redundant.

Mitch Hinde

23-01-2014, 01:03
Hi All

If you go to the HMS Cavalier site and scan through the picture gallery there is a shot of the wireless office with a beautiful view of a unit in the centre of the pic with two large dials, a ship borne HF/DF set. We had the same set on St Brides Bay.

Mitch Hinde

Ah Mitch,

If only I had read your post properly .... it's the two large dials that give the game away ... much more likely that it be the MFA or MFB receiver for the FM11 or FM12 MF/DF outfit.... not the FHB HF/DF receiver outfit.

Usually installed in the main wireless office the MF/DF type FM12 was tuned to International Distress frequency and a loudspeaker watch was kept whilst at sea.

See; http://www.rnmuseumradarandcommunications2006.org.uk/FM11%20FM12.pdf

Little h

Mitch Hinde
23-01-2014, 01:09
Hi All

Harry, sorry, memory must have faded over the years. Never did see FH4 or other related equipment.

Mitch Hinde

23-01-2014, 01:51
Hi All

Harry, sorry, memory must have faded over the years. Never did see FH4 or other related equipment.

Mitch Hinde

No harm done Mitch - 'All's well that ends well' mate - tempus fugit ... and all that;)

Little h

23-01-2014, 16:20
The Wolf Packs
Allied advances in the field of electronics changed Wolf Pack tactics considerably. The introduction of the ship-borne High-Frequency-Direction-Finder, known as "Huff-Duff," fitted in increasing numbers of ships from the end of 1942 onward, enabled convoy escorts to take accurate bearings up to 25 km on U-boats, which transmitted near convoys.The effectiveness of this was much enhanced by the German practice of abandoning radio silence, once contact was established with a convoy. This resulted in the loss of many boats and crews, who did not realize they were announcing their location to the enemy.

Another major development was radar. In darkness or in fog, the ship-borne radar on board of the Allied escorts (and airplanes) robbed the U-boats of their prime advantage: invisibility. These two factors, with advances in defensive and offensive escort tactics, better depth-charges, and the reading of transmissions because of the breaking of Enigma, made the Wolf Pack tactic obsolete.Although we suspected certain advancements, we had no knowledge of the electronic advances on the Allied side. We did not know anything of the Huff-Duff system or Enigma until after the end of the war. Once U-boats lost their invisibility, their technical and tactical limitations became obvious. The Wolf Pack tactic had lost its effectiveness.While on the surface, even when facing single escorts, a U-boat's self defense capabilities were very low. When forced to submerge, the chances of escaping a persistent hunt by an experienced team of warships--and the convoy escorts became more experienced as the war progressed -- were limited by the low underwater speed and endurance.


During the pre-war years and the first two years of the war, U-boats conducted two-week tactical training excercises in the Baltic Sea. These exhausting exercises consisted of simulated attacks on convoys, formed of eight or more ships protected by escorts and airplanes. I engaged in these both as a commander of a U-boat, and later in the war as a Flotilla commander.

When attacking convoys early in the war, I always tried to pass the escorts and, if possible, attack from between the lines of the merchant ships. I had to keep in mind that I could not launch an attack from a distance less than 300 meters. Otherwise, we risked blowing ourselves up with our own torpedos. Between the lines of the convoy I had some freedom to maneuver, because the merchant ships were bound to a certain order that did not allow them--even if they saw my U-boat--to change their course considerably, even to ram me.
Eric Topp

The advances in Allied technology were evident when I attacked a convoy in 1942 on its way from Gibraltar to England. This convoy was under the command of the famous convoy-leader John Walker. The Wolf Pack system failed. Of the several U-boats that tried to attack this convoy, only my boat was able to attack during the night at a distance of 3,000 meters. The other boats were prevented from approaching close enough or were sunk. Huff-Duff, radar, and advanced tactics defeated our best effort


22-11-2014, 10:12
I went to the WWII week at the Russian Arctic Convoy Museum last year, we had a couple of talks by an expert on u-Boats and one person asked him what was the most important factor in countering the U-Boats. I think most there expected him to say the breaking of the various codes by Bletchley Park or perhaps radar but he said HF/DF was more important.

I have been finding a few of the onshore RN WWII DF stations after seeing a reference to one at Oban whilst visiting the Bletchley Park museum. That one has left no trace but I did find someone locally who confirmed the location and its footprint can be seen on the postwar aerial photographs. But I have found ones on Tiree and Sheigra that still have buildings and mast bases. Another can be seen on aerial photographs of Shetland but none been back up to see on the ground. Just one building left of the one at Kilwinning. I am sure there could be others that have been forgotten.

A few pictures of them here (http://www.flickr.com/photos/doffcocker/collections/72157633485016121/).

I have been going through the Admiralty War Diaries (free access on FOLD3 until the end of the month). Plenty of reports various enemy vessels with bearings from various DF stations.

Also found some for ships in distress with bearing from Sheigra Radio. I think the prewar GPO stations like Sheigra and Tiree must have continued doing a similar function of taking distress calls, getting bearings and possibly being able to answer them. This would explain why these sites were not on the map of RN DF stations that I saw. I don't know whether they would be able to take bearings on U-Boats for the main DF network though.