Detection of radar targets using higher-order statistics

Abstract

A signal detection system, preferably for use with a coherent radar system elects certain combination of input signal samples in a block of signal samples to derive a test statistic which is unbiased by Gaussian noise. Products of pairs of sample values are stored in a data sample look-up table. An index look-up table is created by scanning through possible combinations of addresses and excluding those combinations of sample values which would be redundant over other combination and would result in a contribution to biasing by noise. Pairs of addresses from the index look-up table are then used in sequence to access first and second products from the data sample look-up table. The first product is multiplied by the complex conjugate of the second product and the (quadruple product) result is averaged to form a test statistic which is insensitive to position and constant velocity. Detection of the signal is determined by testing the real part of the averaged test statistic against a threshold. To allow such detection for an accelerating target, a lag index is derived for each combination of addresses in the index look-up table and the accumulation and averaging is done while sorting in accordance with the lag index. Dynamic adjustment of the test statistic compensates for time-varying clutter such as ocean waves, and allow the signal detector to track a substantially constant false alarm rate.

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