The search radar set is used in antisubmarine warfare, search and rescue, navigation and weather avoidance. The system provides information in range from 0 to 100 nautical miles, and azimuth from 0 to 360 degrees relative to the aircraft heading.
The radar set consists of a radar set control, a range and bearing control panel, and an azimuthrange indicator which are located at the centre of the TACCO/SENSO sonar operator station. A transmitter receiver is located on the starboard side of the rear fuselage compartment and an antenna assembly is mounted on the upper fuselage.
True heading information is supplied to the azimuth-range indicator from the CRA 3 in the GHARS, thereby ensuring correct positioning of the heading marker on the display. If there should be a loss of heading information, with TRUE selected on
the azimuth-range indicator HEADING selector, the radar heading marker will remain fixed at the point of failure and the azimuth scan will stabilize to a relative picture oriented on the fixed heading marker. Selection of ACFT on the indicator HEADING selector will regain proper sweep stabilization and a normal relative radar picture oriented on the heading marker which positions to the top of the radar indicator.
The radar antenna is stabilized by pitch and roll reference signals from the gyro unit through the electronics unit in the GHARS thereby maintaining the desired antenna position over various aircraft pitch and roll angles up to +20 degrees. Should the GHARS pitch and roll references be interrupted, the radar antenna will align to the helicopter horizontal axis resulting in a deterioration of radar performance during turning or pitching manoeuvres. The manual TILT control remains effective and can be used to regain an acceptable radar picture to the limits of the servos (+8 degrees).
The APS-503 Radar consits of: