The Sailor
14-02-2008, 06:34
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.
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.