The photograph shows the equipment during testing in 1941.
The parabolic antennas of the GL MARK III C-type radar are amounted on a trailer known as an Accurate Position Finder (APF). The purpose of this type of system, also known as a Ground Coastal Radar, developed at the National Research Council of Canada, was to detect enemy aircraft. The Canadian army finally selected it for installation along the St Lawrence River in 1943.
Reproduced with the authorization of the National Research Council of Canada