Abstract: There is disclosed a synthetic aperture radar arranged to survey a region from a mobile location. Radar pulses are transmitted in sets, the pulses from each set being transmitted from congruent positions. The returned echoes of the pulses of each set are then compared to substantially remove signals relating to static targets. The signals relating to the doppler shifts of returns from moving targets are processed by a correlator covering a frequency band sufficient to include such signals or further signals indicative of them and produced as a result of the sampling nature of the pulsed radar.