Continuous Drift Angle from a Search Radar

Noncoherent Doppler permits determination of the ground course as the azimuth of a null in the clutter Doppler returns and, therefore, can be a frequency insensitive adjunct to a pilotage search radar, especially where weight and/or power is at a premium. This stands in contrast to the customary coherent Doppler navigators which relate the frequency changes upon reflection, fore and aft, to the drift angle. An X-band self-coherent Doppler implementation developed that 88 per cent of the drift-angle measurement was within ± 1° of a concurrent optical measurement.