Monday, January 17, 2011


The AN/SPS-12 was an L-band, medium surveillance radar which was developed to detect aircraft and surface vessels. It was primarily an air search radar which was fitted on the original Canadian DDE class destroyers. Target range of the AN/SPS-12 was presented on an A-type indicator. Bearing data was also provided for presentation on PPI units. Provision was also made to connect IFF equipment to the radar set. The AN/SPS-12 had a maximum range of 200 miles and operated in the frequency range of 1250 to 1350 Mcs.

In 1960-61, the Flag Officer Atlantic Coast and the Vice Chief of the Naval Staff (Admirals Dyer and Brock) became very concerned about the problems being experienced with fighting equipment in the RESTIGOUCHE class. The culprits named were, in order of importance:  the 3-inch/70 gun, the SQS-503 sonar and the SPS-12 radar. The source for this was:  Minutes and papers, 11th Senior Officers' Conference, November 20-21, 1961, file NSS 1279-188, now in the National Archives.

An investigation revealed that the radar equipment, unlike the gun and the sonar, to be blameless. The difficulty was the poor quality of maintenance in the fleet at the time. During this period one must remember that the trade structure of the Navy had been turned upside down in 1960 and electrical officers had been removed from ships, as a result of the Tisdall report.  In the short run, shipboard maintenance  suffered badly. Later on, the addition of a parametric RF amplifier (the Dicke-Fix receiver, developed at the Defence Research Telecommunications Establishment in Ottawa) greatly improved the performance of the SPS-12, and made it much less sensitive to mistuning then so common in the fleet".

Specifications for the AN/SPS-12

Type: L-band air search radar
First delivered: September 1953
Frequency range: 1250 to 1350 Mcs
Range: 200 miles
Peak Power Output: 500 kilowatts
Wavelength: 22.2 to 24 Cm
Pulse Length: Long pulse - 4 microseconds; Short pulse - 1 microsecond
PRR: Long range - 300; Short range - 600 (Could be varied as an anti-jamming measure)
Receiver IF: 30 Mcs
Beamwidth: Vertical - 30 degrees; Horizontal - 3 degrees
Antenna rotation: Auto-clockwise; 2.5 to 15 rpm's; Emergency 10 rpm