Pulsed radar with improved short distance range resolution

摘要

Pulsed radar detects the presence and range of very short-range objects via small perturbations in phase and/or amplitude of relatively long duration coherently related transmit pulses. In one embodiment, echoes forming a received signal waveform from a sampling baseband radar receiver are processed at audio frequency to look for perturbations of the phase of the time-stretched received radar signal while the radar is still transmitting a long-duration pulse. In a second embodiment, the time-stretched received signal is processed to look for perturbations in the amplitude of the received radar signal. Small amplitude perturbations due to constructive and destructive interference of the transmitted and reflected signals occur in the receiver when objects are very close to the radar if the receiver is not heavily saturated. These same techniques can also be used to achieve highly accurate ranging of long-distance objects and detection of overlapping echoes from multiple objects.