The decodability of multiple-PRF radar waveforms

Medium PRF (pulse repetition frequency) radar offers many performance advantages, particularly for the detection of all-aspect targets in look-down. However because of the ambiguities it suffers, a complex waveform design is required to allow target range and range-rate to be decoded. The most commonly used technique is to transmit a schedule of N different PRF bursts during the time-on target, and to use M out of the N measurements to decode range and range-rate information unambiguously. The design must consider detection performance as well as decodability, particularly the effects of blind zones. This paper presents a convenient method of assessing the decodability of such a multiple-PRF waveform, a method that forms a valuable tool in the design of such waveforms. The method takes into account measurement errors and is completely general, being applicable to any form of ambiguous measurement. Thus it is equally valuable for the assessment of range decodability in range-ambiguous (high PRF) radars, of velocity decodability in velocity ambiguous (low PRF) radars, or of range and velocity decodability in medium PRF radars.