An azimuthally scanning, pulse-energy system employing doppler processing of clutter-referenced received echoes of pulsed transmission, including means for improved discrimination between high-speed moving targets displaying ambiguous doppler shifts and targets of lesser velocity. The pulse repetition rate of the pulsed energy system is periodically alternated between two rates, and the received signals associated with each pulse repetition rate separately doppler processed. Variations in the apparent doppler shift of a target in response to variation in the system pulse repetition rate is deemed indicative of a target of interest.