Canada, USA, the UK, and Australia developed a system of station designators for their SIGINT stations. These designators were used for ease of reference on logs and reports and the format was as follows:

Two letters for the country, ( ie US, UK, CA, AU) followed by a letter indicating the service: N for Navy, M for   Army, A for Air Force, and F for Joint Services.  The designators did more than merely indicating which station had taken a given HFDF bearing or made an intercept.  When plotters and traffic analysts used the information, they would only have to consult a list of stations to determine potential validity or utility of  bearings. If necessary, these designators could be located on charts to determine the station's proximity to target areas.

An example in the UK would be GCRE Knockholt which bore the designation UKF100 The abbreviation meant  Government Communications Research Establishment; Knockholt , It was also known as the FORDE Ivy Farm (Foreign Office Research and Development Establishment) and was notable for its non-morse intercepts during WWII. The RN station at Scarborough near Scotland was UKN125.

In Canada, RCN stations were assigned CAN prefixes, Army stations (Ladner, Leitrim)  were CAM and Air Force (Whitehorse) were CAA.

Aklavik CAN92 Alert CAX1 [1] Bermuda ??
Chimo  CAN94  Churchill CAN99 [4] Coverdale CAN96
Frobisher Bay CAN94 [2] Gander  CAN90 Gloucester CAN97
Inuvik CAN92 [3] Ladner/VWS  CAM93 Leitrim CAM98
Masset CAN91 Whitehorse CAA95    

[1] In the test period prior to September 1958, Alert was CAX1 and Resolute was CAX2. When Resolute was closed and Alert was chosen as the High Arctic station,  Alert retained the CAX1 designator until the Armed Forces Unification in 1968 at which time all designators became CAFxx. In the 1990's, a numerical designator was assigned to Alert but its not known at this time.

For purposes of logistics and transportation in the experimental period prior to September 1958, Resolute Bay was referred to as  "Alto Near" and Alert was "Alto Far".

[2] When Chimo closed down, its station designator was passed on to Frobisher Bay.

[3] When Aklavik closed down, its station designator was passed on to Inuvik.

[4] Re-issued to CDSE. See below.

Doug Stewart adds. "These station designators, were in fact SIGINT designators to be used with the SIGINT  product reports and applied only to SIGINT communications networks. With the advent of the Armed Forces Unification, the individual station prefixes changed to CAF. When Maritime Command (Marcom) formed Cryptologic Direct Support Elements (CDSE) within The Fleet there became a requirement for a SIGINT designator so that CDSE could function with USN and RN cryptologic commands. At that time Churchill had closed. At my suggestion, Churchill's previous designator CAF99 was subsequently approved for CDSE usage.

When I was directing the CDSE deployments, we generally employed a single ship as CAF99. On the deployment where we employed a second ship, that ship was designated CAF99A. In our early days we also shared the USN SIGINT comms  thereby allowing us to solicit technical support. The primary purpose of CDSE was tactical support to the Task Force. The USN  also used those initials and figure designator. Had CDSE existed prior to Unification, we would have probably employed CAN  followed by a number".


Radio historian Tom Brent explains the naming convention for SIGINT strations prefixed with SWS (Special Wireless Stations). "The term "Special Wireless Station" in its capitalized form should only be applied to signals intelligence stations operated by the Canadian Army/Royal Canadian Corps of Signals (a.k.a. RCCS or RC Sigs) since it is a specific name of a group or organization. For instance, #1 Special Wireless Station was located at Leitrim (Ottawa), #2 SWS was northeast of Grande Prairie, Alberta,  #3 SWS was in Victoria and #4 SWS was on the Chilcotin Plateau, west of Williams Lake, B.C.  It can get a little confusing with RC Sigs because they also used the term Special Wireless Group.  For example, #1 SWG  spent many months in the Victoria area (Gordon Head Army base and Pat Bay) prior to shipping off to Australia late in the war. To further add to the confusion, RC Sigs also used the term "Special Wireless Section".

I have never come across any reference to, or identification of, the Royal Canadian Navy signals intelligence stations using a numeric identifier. In my own writings and musings, I avoid using "special wireless station" when referring to the RCN sites, instead preferring to use terms such as "signals intelligence station" or "signals intercept site". Capitalizing Special Wireless Station imparts a very different meaning to it than if all the letters are in lower case."

Credits and References:

1) Ray White <legerwhite(at)>
2) Don Bowman
3) Earle Smith - VE6NM <ve6nm(at)>
4) Douglas Stewart <dougjoy(at)>
5) Tom Brent

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Dec 17/20