| 摘要 |
A method and apparatus for the processing of return signal data in a single channel, medium pulse repetition frequency, pulse doppler radar receiver in which discrete sidelobe return signals are prevented from being recognized as true targets. The return signal data is processed by a clutter cancellation circuit, which in the preferred embodiment is a doppler filter bank, to remove main beam clutter and a constant false alarm rate threshold circuit to remove area sidelobe clutter return signals. The return signal data is temporarily stored as data blocks which are representative of the return data in the interpulse period of each pulse repetition frequency. The data blocks are unfolded over a predetermined range and two parallel correlations are simultaneously performed over the predetermined range to identify discrete sidelobe clutter return signals. One of the parallel correlations is performed directly on the unfolded data block and the other is performed on the unfolded data which has been compared to a time varying threshold level which varies as a function of range and which is responsive to the area sidelobe clutter return signals such that the discrete sidelobe clutter return signals may be detected from a comparison of the correlations. The discrete sidelobe return signals thus determined are folded into data blocks which are used to blank the sidelobe discrete return signals from the output of the constant false alarm rate threshold circuit. With the sidelobe discrete return signals blanked, the data blocks are unfolded over a second predetermined range and correlated to determine the true range of the target. In an alternative embodiment, the time varying threshold level is not responsive to the area sidelobe clutter return signals, but the returned signals are normalized with respect to the level of the area sidelobe clutter return signals to improve the detection of sidelobe discrete return signals.
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