The following is a summarization of Canadian Signals Intelligence from the beginning until the end of WWII. Extracts are derived from "History of Canadian Communication Electronic Support Measures" (CESM) by S.A. Gray.
IN THE BEGINNING
Canadian Signals Intelligence (SIGINT) had its beginnings when the Royal Canadian Navy (RCN) began wireless intercept after WWI on request of the British Royal Navy. The first intercept site was located at Esquimalt, British Columbia in 1925. To date, all documents indicate that the operators were British and all gathered intelligence was shipped directly back to Britain. The RCN's only role was the provision of the facilities.
Upon the outbreak of WWII, the RCN promptly struck a deal with Department of Transport (DOT) to use the existing DOT monitoring stations, which were at the time, policing Canadian transmitters. As well, they were given access to DOT's HFDF stations, presently being utilized for the guidance of airplanes.
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.
DOT's commitment to the Navy's cause was strong enough for them to build an additional station near Halifax known as Hartlen Point. Built on land located at the eastern gateway to Halifax harbour, it allowed an entire view of the sea in every direction. This site began operations in late 1941 or early 1942 and was tasked with specifically DF'ing U-boat targets. No Navy personnel were employed here, only experienced DOT operators. The personnel were highly experienced operators; with the average length of experience being around eleven years.
By June 1942, fourteen operators were handling the Naval tasks at Hartlen Point. Four of them were DF operators and the remainder utilized five receivers to intercept German U-boat transmissions.
The RCN had a well co-ordinated program with DOT but was looking to expand its organization. In doing so, the Navy sought out the assistance of the Royal Canadian Air Force (RCAF) in 1941. The use of RCAF's navigational and meteorological facilities would add to the much needed directional finding capability. The RCAF agreed to man and operate the following HFDF stations: Pennfield Ridge, New Brunswick; Cap D'Espoir, Quebec; Sydney, Nova Scotia and Rivers, Manitoba. They also agreed that the RCN could have four of their own operators at each of these sites. On the west coast, Ucuelet, Coal Harbour and Allaford Bay all in British Columbia were other RCAF sites at the disposal of the Navy.
Eighty percent of the time, these RCAF stations were free for use by the RCN. The remainder of the time they were employed as training facilities. It was likewise for the DOT HFDF sites. Although appreciative, there was often frustration on the part of the Navy in regards to the sharing of facilities. It wasn't uncommon to receive "no fixes" on critical targets such as U-boats. Nevertheless, the Navy's use of RCAF and DOT facilities for conducting wireless intercept and directional fixing of enemy targets made the RCN's contribution to the war effort, without a doubt, a great success.
As of 1942, the Navy had progressed to the point where they were obtaining intercept and DF fixes from nineteen sites. This consisted of seven "'Y" stations, four DF stations and eight combined "'Y" and DF stations. Seven out of the existing twelve DF units were also used by the Flying Services (DOT or RCAF).
In the process, the RCN had become part of a worldwide "Y" organization  obtaining intelligence through the monitoring of enemy wireless. Besides the intelligence gathering, the RCN had established a network of Direction Finding stations. Through triangulation of bearings originating from ten stations in Canada and Newfoundland, another ten stations in the USA, thirteen stations in the UK, two in South Africa and five stations elsewhere around the world; they were able to fix positions of enemy units at sea.
"Y" EFFORTS IMPROVE
On 17 April, 1942, an Allied "Y" committee conference was held in Washington DC, with representatives from England, United States and Canada.
The meeting's agenda included discussions regarding the duplication of intercept messages and specifically pointing to deficiencies of the "Y" effort in Canada. Army and Navy west coast sites were duplicating their effort with east coast sites. In order to eliminate the duplication; it was recommended that Canada establish its own "Y" sub-committee within Canada allowing for collaboration between the services along with the building of closer ties between Canada and the US in these matters.
Closer ties were then made between Canada's Army, Navy and Air Force and US Forces. In January 1943, approval was granted for the linking of Canadian West Coast DF stations to the USN West Coast Net. This gave an uninterrupted circle of DF stations from Kodiak Alaska to San Diego California. As an example, the USN control station at Bainbridge Washington would now indicate the frequency to which Gordon Head BC would take a bearing with the results being passed to the USN.
The next integration between the Canadian stations and the USN west coast "Y" stations again occurred at Gordon Head. Thirteen intercept positions were allocated for specific Japanese naval frequencies in an effort to prevent duplication with the USN net. Finally in November, Bainbridge assumed control of assignments tasked to Canada.
As a result of this major organizational change, RCN operators were withdrawn from the Coal Harbour BC and Ucluelet BC DOT stations and reposted to the Gordon Head "Y" station by June 1942. Canadian stations would transmit all raw materials to US, reference Japanese traffic and would receive whatever intelligence emerged. During this time Army and Air Force personnel were attached to this section for training in Kana Morse.
On 19 May, 1943, the RCN received several recommendations from Capt Humphrey Sandwith, Chief of the British "Y" mission. His recommendations began with building a DF station at Gloucester and a communication research/DF site in Lambeth (now part of London), Ontario.
These included the repairing and reconditioning of Cap D'Espoir (recently acquired from the RCAF) and the construction of three DF/"Y" stations for an inland west coast organization. The .suggested locations for the inland organization were Grand Prairie, Red Deer and Lethbridge, Alberta. They would then be connected by a land line to a US Naval "Y" station to be erected in Montana; which in turn, would control a chain of inland USN DF stations. Building a DF' station at Masset BC, which could be controlled by Gordon Head and the establishment of an Ionospheric Measurement Station at Churchill, Manitoba. with equipment supplied by the British Admiralty. This rounded out the recommendations from the UK.
However, the RCN also had ideas of their own. In an effort to become self-reliant, the RCN decided to build a new site and expand others thus eliminating their dependency on DOT and RCAF facilities. The chosen site for this new station was Coverdale, New Brunswick  . It would have "Y" and Direction Finding capability for the purpose of monitoring German naval frequencies. Approval for the new station was granted by the Treasury Board on 23 November, 1942. Coverdale was ready for occupancy in January 1944. . Once built, the Navy could dispense with use of both the DOT "Y" and DF stations at Hartlen Point along with the combined "Y"/DF station near Ottawa. It was the combination of RCN's plans for improvement and British recommendations that eventually lead to the expansion of the Navy's involvement in "Y" activities.
On the recommendation of the British, a direction finding station was established in Gloucester, Ontario and it became operational in 1943. Post war, Gloucester's role began to change. A portion of the facility was deactivated allowing it to be used as a training ground for the Communications Special trade - the personnel who gathered signals intelligence by radio.
FEMALES MAKE THEIR MARK
In order to recruit women to replace men who were leaving for sea duty, the RCN formed the Women's Royal Canadian Naval Service (WRCNS but pronounced WRENS) on July 31 1942. 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". Women were very good at intercept and direction finding.
In July 1944,.a decision was made to replace male personnel at Gordon Head by WRCNS operators but first it required that a Japanese Morse (Kana) course to be developed at HMCS Signals School at Esquimalt, BC. Approximately eighty five WRCNS operators were trained in Kana and by October 1st, the first two classes of WRENS arrived at Gordon Head. Approximately four months later the switch was completed and from that day on, the station was operated successfully by a WRCNS staff.
In September 1944 other sites such as the DOT station at Strathburn and naval W/T station at Lambeth Ontario were employing both male and female operators with females being in the majority at Strathburn. Coverdale was mostly staffed with WRCNS staff as well.
During a visit to England by Lt. Low, he observed all "Z" operations  and classification work was performed by British WRENS who were most capable. The RCN based their decision on this observation and decided that Canadian "Z" operations should be operated by WRCNS personnel, wherever this could be done considering the locations and amenities of the isolated Canadian stations. Two RN WRENS were requested and ultimately sent to Canada to train Canadian WREN personnel for these duties. They arrived November 1943 and spent three months between NSHQ and Gloucester and Harbour Grace stations.
In early 1945 Gordon Head remained the hub of the Navy's west coast intercept operations, although intercept total was low due to unsuitable antennas and inexperienced WREN operators.
The DOT station in Winnipeg ceased providing seven operating positions to the Navy's war efforts in June on account of the improvements that were made to the antenna arrays at Gordon Head. The war was also drawing to a close.
The majority of naval operations in sites owned by DOT or RCAF were deactivated during period 1945-46
Coverdale continued to operate in a peacetime role. RCN personnel continued to operate out of the Gander facilities with equipment on loan from the American forces despite the fact that control of the airport officially returned to Newfoundland after the war. When Newfoundland entered confederation in 1949; the RCN formally acquired the property now referred to as the Old Navy site hence Naval Radio Station Gander was born.
The Navy began their concentrated efforts in Communications Research by choosing the direction finding facility situated at Gloucester Ontario, as the home for this unique trade on 29 Dec 1947. By early 1948, they had initiated Gloucester as the administrative HQ and trade school by co-locating it with HMCS GLOUCESTER. Other SIGINT facilities were built as required. These stations are covered in great detail in other parts of this web page.
 The approval date of 23 November, 1942 for the establishment of Coverdale is given in document RG24 Vol 5642 File 48-3-36 at the National Archives of Canada. Other sources on the web indicate some uncertainty as to when Coverdale was established, however the date was buried right in the file. Some blueprints indicating construction details are dated July 1942. The plans were likely prepared in anticipation of obtaining approval from the Treasury Board.
 The occupancy date of January 1944 was validated by at least four WRENS who were posted for duty at Coverdale.
 '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 "fist" and habits.
 The 'Y' designator had its origins in WWI Wireless intercepts were abbreviated as WI but pronounced as 'wye'. After WW1, the word wye was simplified to be the letter 'Y'. This definition is confirmed by a wireless operator who worked worked with Y operators during the 1930's.
Credits and References:
1) History of Canadian Communication Electronic Support Measures (CESM) by S.A. Gray
2) Library and Archives Canada. Coverdale documents RG24 Vol 5642 File 48-3-36
3) Bill Robinson <newman-robinson(at)rogers.com>
4) Robert Langille <ewcs(at)ewcs.ca> Provided the CESM file from Library and Archives Canada.