Adaptive Detection Enhancement of Partially-Correlated χ~2 Targets in an Environment of Saturated Interference

摘要

Background: Modern radars have adopted CFAR type of adaptive processing techniques to alleviate the damaging effects of the unwanted returned signals. Owing to the presence of spurious targets in practical operational environments, it is important to search a CFAR algorithm that performs well in this situation. An interference-saturated environment is commonly encountered as one of such background environments. Additionally, the characteristics of the radar targets can be regarded as the actuating tool for the radar systems to be practically designed and operationally assessed. If there is a relative motion of the target with respect to the radar, the aspect angle will be varied resulting in fluctuations in the radar cross section (RCS). The rate of these variations changes from independently in the case of consecutive pulses to significantly in the case of successive scans. Methods: The SWI model is characterized by full-correlation between the two consecutive echoes while they are de-correlated for the SWII models. Among these two boundaries, there is an interesting class which is termed as moderately fluctuating χ~2 targets. If a coherent pulse train illuminates this class of targets, a train of partially-correlated pulses will be returned. Results: The CFAR detection of this class of radar targets in an interference-saturated environment is therefore of practical interest. The scope of this paper is to evaluate the performance of the doublethreshold (DT)-CFAR processor for the situation where the radar receiver based its detection on a collection of M-pulses. An exponentially correlated return from targets exhibiting two degrees of freedom χ~2 statistics is the nature of these pulses. Conclusion: The detection performance analysis, in its exact form, is presented in the case where the operating environment is free of or contaminated with outliers. For specific values of the trimming threshold, the processor detectability loss becomes very low and the performance impairment, owing to interferers, is extremely small even for large number of interfering samples. Additionally, there is an enhancement in the detection performance when the size of the post-detection integrated pulses augments and/or the dependence of the target returns decreases, as was predicted.