Primary Surveillance Radar (PSR) computes target positions by determining the range and azimuth of transmitted and reflected radio frequency energy. It is a passive surveillance system and therefore does not rely on information transmitted from the aircraft.
Primary radar is used in the following applications:
- Terminal surveillance radar (TSR) – In general, a short range PSR (80 NM) operating on 1,250 to 1,350 MHz complements secondary surveillance radar (SSR) for terminal operations.
- Precision approach radar (PAR) – A high-definition, short- range PSR operating on 9,000 to 9,180 MHz and is used as an approach aid. PAR provides the controller with altitude, azimuth and range information of high accuracy to assist pilots in executing approaches. While PAR is mainly a military system, it is available at some civilian airports and may be used by civilian pilots. Civil aircraft approach limits are published in the Canada Air Pilot (CAP) and the Restricted Canada Air Pilot (RCAP).
- Airport surface detection equipment (ASDE) – Surveillance of surface traffic is provided at airports where traffic warrants it. ASDE is a high-definition PSR operating on 16 GHz. Tower controllers use ASDE to monitor the position of aircraft and vehicles on the manoeuvring areas of the airport (runways and taxiways), particularly during conditions of reduced visibility.
- Weather radar – Weather radar is a PSR used by the Meteorological Service of Canada to monitor for hazardous weather conditions.