| 摘要 |
<p>The difficulty of making Doppler shift velocity measurements in a chirp pulse echo ranging system is overcome by employing a pulse frequency compression filter, suitably a SAW compressor (45), having individual outputs (64, 65, 66, 67) respectively relating to adjacent contiguous frequency bands each having a bandwidth approximately equal to the chirp frequency swing. Signal detection and processing means (70) senses the occurrence of a compressed pulse on any of the outputs and measures the amplitudes of signals on all the outputs. A computer (120) then computes the Doppler shift from the amplitude ratio of the sensed signals in adjacent frequency bands, determines the target velocity therefrom and uses the result also to correct the range measured by the counter (5).</p> |
