and Naval Radio CFF (1940-1947)

Upon the outbreak of WWII, the RCN promptly struck a deal with the Department of Transport (DOT) to use the existing DOT monitoring stations, which were at the time, policing Canadian transmitters and spectrum. As well, they were given access to DOT's HFDF stations, which were being utilized for the guidance of commercial aircraft.

The initial DOT HFDF sites to provide assistance to the Navy were: St. Hubert, Quebec; Shediac, New Brunswick; St. Louisburg, Cape Breton; and Botwood in Newfoundland. The use of the Botwood facility required approval from Britain, since Newfoundland was still a British colony in 1939. Although the Navy received fixes as early as September 1939, it wasn't until 8 December 1939 that they began to receive wireless intercepts. The Ottawa Monitoring Station was one such facility.
The monitoring station had humble beginnings. It was first located in the Radio Test Rooms on Wellington Street (west of Bay St.) in Ottawa.  The function had no official name and was simply an assignment for one man, to monitor specified frequencies. Traffic was therefore handled by an employee of DOT, Radio Division, Ottawa.  Operations were hampered by unwanted interference caused by electrical noise produced by  streetcars and power lines.

As a result, the operation moved to empty greenhouses at the Experimental Farm but high humidity levels within the greenhouse affected the radio equipment. The operation was moved again - this time to  the J. R. Booth farmhouse near the corner of Baseline Rd. and Prescott Hwy. (now Prince of Wales Dr). The Booth house and barn sites were situated in the southerly fields of the Central Experimental Farm. Only the barns of that farmstead are still standing (as of 2015). The Greenhouses have been expanded since the 1940s.

As tensions with Germany mounted, the farmhouse was soon overflowing with radio receiving equipment meant to intercept enemy communications. More operators were added to the staff and more monitoring frequencies were assigned. Naval HQ requested more coverage and the build-up of staff began. Very soon, the bedrooms of the Booth farmhouse were fully occupied with receiving positions were overflowing into the hallways and the living room. There was no Direction Finder in Ottawa at the time, but a DOT DF station at St. Hubert in Quebec was connected to the Ottawa monitoring  station by a dedicated telephone line  which was  used as an intercom. All mobiles (German submarines) were reported to St. Hubert by the DOT intercept operators. In the summer of 1941 a new building was erected to accommodate VAA (a  DOT-only transmitting station) , the frequency measuring equipment, and 16 operating positions, as well as a teletype room, and offices. This new art-déco structure was built on the west side of the Experimental Farm, near what is now Merivale Road.

A phased-in  move of operators from the Booth farmhouse to the new station took place from October to December of 1941. A Direction Finder outfit was also installed at the same location but  in a  smaller satellite building located about 400 yards away from the main building. The station staffing grew to a peak of 125 before the end of the war in Europe. This also included civilian female operators taken on strength in the 1944-45 time frame.

In 1941, this art deco structure was erected on the grounds of the Experimental Farm to accommodate the growth of DOT intercept operations.  It was built on the west side of the Experimental Farm, near what is now Merivale Road. (Photo credit unknown) 
This was the DF shack installed for the Ottawa Monitoring Station.A Bellini-Tosi goniometer was used at the DF console, however it was connected to an Adcock antenna array instead of the usual crossed loops. The opposite Adcock verticals were connected with underground cables so they functioned as loops - thus the four verticals simulated a set of crossed loops. (From the collection of Ernie Brown VA3OEB)

The National HRO receiver (similar to this example) along with an external  goinometer, was used for DF operations but the exact model variant is not known at this time. The National Radio Company kept the same basic receiver in continuous production from 1935 to 1964. Frequency range is 1700 KHz to 30000 KHz. (Photo by the late Andre Guibert)

Using the HRO receiver in both the DF shack and in the monitor/intercept  positions, meant that the DF operator used the same dial settings and coil plug-ins as the monitoring operator asking for a bearing. The DF operator tried to memorize as many of the dial settings and coil numbers as possible for taking bearings on a 'mobile' (submarine) when one was heard.  The mobile  was easily recognized by two things. The uniform spacing of CW from the coast station would suddenly change to handkeying  along with change of speed.  The subs used the same frequencies  as the coast stations that were sending messages to them.

Once the coded German messages were intercepted, they — along with similar messages picked up from other  stations — were transferred to a place only known as “Admiralty” to be deciphered and analyzed at Bletchley Park in London by Alan Turing’s team of codebreakers.

It is important to note that Radio CFF (1940-1947) refers specifically to the Naval Radio Station on the Prescott Highway.  It does NOT include the DOT Monitoring Station which was located more than 2 km west in a field of the Experimental Farm bounded on the south by Baseline Rd. and on the west by Merivale Rd.. In Building 136, CFF received and transmitted messages between naval service headquarters  Allied authorities, ships at sea and frequently intercepted enemy radio transmissions.
This map differentiates the Monitoring Station sites from Radio CFF. :
1 = T. R. Booth farmhouse 
2 = New building 1941 
3 = Direction Finder Shack
4 = Wireless Station CFF located on the Experimental Farm
(Graphic courtesy Ernie Brown) 
The DOT monitoring station was receive-only,  therefore this function had no call sign.  DOT station VAA was also co-located here but its function was strictly for DOT communication with its Northern stations in the Hudson Bay area and beyond.  This DOT Monitoring Station was intended to augment and expand the interception of enemy wireless signals.  CFF told the DOT facility what stations and frequencies to monitor.  CFF retained the search function to detect new frequencies used by the enemy. This was a voluntary dedication of manpower by DOT to augment the work of RCN and allow them to spread their own resources as deemed necessary.  The monitoring functions did overlap to some degree, but that allowed the RCN more freedom to check out other possible uses of their manpower. At the DOT station, one man continued the civilian  monitoring function he had been doing for years.

At the Monitoring Station and up to 1943, the operators were all male.  Late in 1943 and until the end of the war, female operators became part of the operating staff.  The female staff became came to play a very significant to role to the operation. There was no RCN presence at the DOT station, but all DOT intercepted enemy 'traffic' was forwarded to RCN. At CFF, the staff was presumed to be mainly that of WRENS.

At the end of hostilities in Europe, some of the Ottawa staff were assigned to learn the Japanese ‘KANA’ code, and were transferred to Vancouver. Others were assigned to tours of duty to northern stations, or were transferred to the growing number of Radio Range stations being installed in the Western Provinces. Station VAA
There is no evidence to show that WRENS staffed CFF. The Frequency Monitoring function remained at the Ottawa DOT station for many years thereafter.


Prior to 1940, naval radio station CFF shared accommodations at RCAF Station Rockcliffe in Ottawa in what Commander Art Hewitt described as "an old barn".  Army and Air Force receiving  stations were also housed here, an arrangement considered very unsatisfactory. In 1940, Commander Hewitt who was the Chief Petty officer in charge of the naval radio station, was assigned the job of relocating it from Rockcliffe.

First, rough sketches of a receiving station were drawn up for approval then given to Public Works in order that they would draw up  specifications. It also had to be decided where to situate  the new station,. After scouting likely sites, it was decided that the Experimental Farm in Ottawa offered the best location. It was ideal because there were no other buildings in the vicinity and it was  free of electrical noise. Once  permission was obtained to install the facility, construction was completed in short order. Although the building was modest, the surrounding fence was anything but. Laid out to enclose a square that measured approximately 230 feet a side, the eight foot fence was tipped with several strands of barbed wire. For added security, the metal fence posts were set into a
concrete foundation but the area's gradual slope toward the northeast meant that a large section of it tended to resemble a windowless wall. This helped give rise to speculation among some Farm personnel that much of the installation was actually a system of underground bunkers.

The building's placement at a distance from the highway and the tendency of the naval personnel to keep to themselves helped the station to maintain a low profile. George Guest, a leading telegraphist at the station until December 1941, recalls that "when things were quiet, we skied on the hill." They also skied to work in winter or paddled to work in summer, via the Rideau Canal.

Once CFF became operational, it linked naval headquarters in Ottawa with Allied naval headquarters, ships at sea and other locations as distant as Bermuda and Sierra Leone. Station personnel also intercepted encrypted German, Italian and Russian military and diplomatic communications traffic. When not occupied with other messages, the operators on duty "sniped" - slang for intercepted - other Allied traffic. On one occasion,
they followed, intercepted transmissions between Royal Navy warships in persuit and the ultimate sinking of the German battleship Bismarck.

A rare glimpse inside the naval radio station CFF. It was constructed on the Experimental Farm in 1940. George Guest, the leading telegraphist who installed the station's radio equipment, is standing on the right. The photo dates from 1940-41 before Mr. Guest transferred out. (From the  collection of the late George Guest). 
Now the story become a little hazy. Former WREN Elsa Lessard, indicates that CFF operated from Building 136 on the Experimental Farm. It is not known at this time if all operations were confined to this one building or not.   The occupancy date of Building 136 is not known either, however Agriculture Canada records indicate that Building 136, was constructed in 1942.  Occupancy by the navy would have been anytime afterwards. Radio scientist John Belrose indicates that CFF operated from here (Bldg136?) during  the  1944-47 time frame.
This plaque, mounted on a large rock in what is now the Fletcher Wild Life Gardens in the Experimental Farm, was unveiled on 1 May 1993. It commemorates the operation of station CFF during WWII.  (From the collection of John Gilbert) 

The plaque reads:


After CFF stood down in 1947, the facility was occupied  by the Radio Propagation Laboratory. Radio scientist John Belrose writes: "  The Radio Propagation Laboratory evolved from Section 6 of the Operational Intelligence Centre (OIC/6) of the Royal Canadian Navy (RCN) during WW II. It originally occupied small huts on the Prescott Highway, which, in the years 1944-47 housed a naval HF radio station, operating under the call sign CFF" This would suggest that Building 136 was occupied by the navy in 1944. If anyone can refine these dates, please contact

An inventory of Central Experimental Farm buildings dated 1997 has Building 136 being now called the "Bio-Control Building".

If anyone can fill in the gaps, please contact

Contributors and References:

1) Ernie Brown  VA3OEB
2) Ottawa Citizen article by Andrew King
3) History of Canadian Signals Intelligence & Direction Finding by Robert Lynn Wortman
4) John Gilbert <jgilbert(at)>
5) Elsa Lessard <elsal(at)>
6) ,
7) Helen Smith`s book "Ottawa`s Farm: A History of the Central Experimental Farm" , pp 91-93. General Store Publishing House, 1996.

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Mar 24/15