Abstract: A range tracking technique for producing a ground return signal in an FMCW radar system. The radar system produces an IF signal having frequencies within a range extent band, the IF signal including a ground return component having frequencies in a narrower ground return band. The range tracker includes a tracking system, a search system, and a controller. The tracking system receives the IF signal and a track control signal, and bandpass filters the IF signal to produce the ground return signal. The search system also receives the IF signal, together with a search control signal from the controller. The search system includes a second bandpass filter for bandpass filtering the IF signal to produce a band power signal. The controller receives and stores samples of the band power signal, and identifies the ground return component. The location of the ground return is used to adjust the track control signal, to keep the first passband centered on the ground return.

Abstract: A ground speed determining radar system for take off roll and landings and roll out maneuvers has a ground based modulating radar reflector and a carrier based radar. The radar transmits microwave energy to the reflector where it is modulated by rotating spaced reflectors and returned to the radar receiver. The receiver is a heterodyne receiver having a log IF stage and a fast time control (FTC) circuit for attenuating clutter and an acquisition loop circuit, lock-on circuit and tracking loop circuit. The acquisition loop circuit includes a center, gate, modulation bandpass filter, switch, acquisition sweep generator and gate generator; the lock-on circuit adds a delay line and a good data indicator to the loop acquisition circuit, and the track loop circuit includes early/late gates, early/late gate low pass filters, subtractor, integrator, the switch and gate generator.