By 1941, low powered, medium and high frequency radios were widely fitted for voice communications within task groups and convoys. VHF voice radio was slowly being adopted thanks to developments in the RAF. During the period 1943 to 1945, the most important advance in wireless communications, was the tactical use of voice radio. This explosion of voice radio reduced the amount of communication passed by flag or light signals. John Powroz of Bedford Nova Scotia, describes some radio fittings when he joined the RCN. "At the time that war broke out in 1939, all RCN destroyers were fitted with Royal Navy radio gear. When I joined HMCS Restigouche in 1940, she had, in the main radio office, a single tube, Model NT1, Admiralty Pattern transmitter with a spark gap transmitter as a back up. All receivers were battery operated. A secondary radio office next door had a low power transmitter and receiver for fire control purposes. This was later torn down and replaced with a second low power transmitter, namely the Admiralty Pattern Model 60. Now, the ship had radiotelephone capability, but early in the game, only the captain was allowed to use it. In addition to the Type 60, we also had a Hallicrafters Model HT4 which was used as a voice intercom between ships. Voice communications took place on 2410 kcs. The radio office was encased in copper mesh and covered by mahogany panelling. All wiring was lead sheathed and the Morse keys were bolted to the edge of the desk. To this day I still have and still use my Admiralty Pattern AP7681 key". DIRECTION FINDING
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,...
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