| 摘要 |
Method and apparatus for the detection of a ground moving target using a moving platform MTI radar system are disclosed. Such a moving target is detected by comparing the power level of radar return signals passing in a difference channel of a monopulse receiver with a predetermined power level. In one embodiment, a monopulse antenna of such receiver scans a swath of ground and the power level of radar returns passing in the difference channel having a Doppler frequency equal to the Doppler frequency associated with clutter disposed along the boresight axis of such antenna is compared with a predetermined power level. When the power level of returns in such difference channel at such Doppler frequency is greater than the power level of returns from clutter disposed along the boresight axis (i.e., the predetermined power level), a moving target is indicated. Such embodiment is particularly adapted to detect "slow" moving targets, that is, targets disposed in the main beam of the monopulse antenna and having a Doppler frequency within the Doppler frequency spectrum of returns from clutter disposed within such main beam. In a second embodiment of the invention the power level of returns passing through the difference channel having a Doppler frequency outside the Doppler frequency spectrum of returns from clutter disposed within the main beam is compared with the power level of returns passing through a sum channel of such monopulse receiver having such Doppler frequency. When the former power level is less than the latter power level, a moving target is indicated. This embodiment is particularly adapted to detect "fast" moving targets (that is, targets disposed in the main beam but having Doppler frequencies outside the Doppler frequency spectrum of returns from clutter disposed in the main beam) from large stationary objects disposed outside the main beam and illuminated by the side lobes of the monopulse antenna.
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