Angel discrimination in the ARSR-4 joint use radar

The air route surveillance radar (ARSR-4) is a long-range radar system that will be installed at 43 locations around the perimeter of the US. A major source of clutter for this system will be birds. The magnitude of the problem and the solutions proposed to mitigate the problem are described. Techniques that will reduce the false target rate to manageable proportions without significantly degrading the detection of real targets are described. These adaptive techniques confine the discrimination to only the range azimuth and altitudes where angel activity is present, and subside automatically when the angel activity decreases. The single scan velocity evaluator, the selective raising of detection thresholds, and the scan-to-scan correlator all combine to control the number of false targets due to angel activity in angel-infested areas without significant impact to the radar detection performance.