Abstract
We consider the problem of adaptive signal detection in the presence of Gaussian noise with unknown covariance matrix. We propose a parametric radar detector by introducing a design parameter to trade off the target sensitivity with sidelobes energy rejection. The resulting detector merges the statistics of Kelly's GLRT and of the Rao test and so covers Kelly's GLRT and the Rao test as special cases. Both invariance properties and constant false alarm rate (CFAR) behavior for this detector are studied. At the analysis stage, the performance of the new receiver is assessed and compared with several traditional adaptive detectors. The results highlight better rejection capabilities of this proposed detector for mismatched signals. Further, we develop two two-stage detectors, one of which consists of an adaptive matched filter (AMF) followed by the aforementioned detector, and the other is obtained by cascading a GLRT-based Subspace Detector (SD) and the proposed adaptive detector. We show that the former two-stage detector outperforms traditional two-stage detectors in terms of selectivity, and the latter yields more robustness.
Highlights
Adaptive detection of signals embedded in Gaussian or nonGaussian disturbance with unknown covariance matrix has been an active research field in the last few decades
A Whitened Adaptive Beamformer Orthogonal Rejection Test (ABORT) (W-ABORT) [12, 13] is proposed to address adaptive detection of distributed targets embedded in homogeneous disturbance via GLRT and the useful and fictitious signals orthogonal in the whitened space, which has an enhanced rejection capability for side lobe signals
It is worth noting that the Rao test exhibits discrimination capabilities of mismatched signals better than those of the ABORT, it does not consider a possible spatial signature mismatch at the design stage
Summary
Adaptive detection of signals embedded in Gaussian or nonGaussian disturbance with unknown covariance matrix has been an active research field in the last few decades. It is worth noting that the Rao test exhibits discrimination capabilities of mismatched signals better than those of the ABORT, it does not consider a possible spatial signature mismatch at the design stage From another point of view, increased robustness to mismatch signals can be obtained by two-stage tunable receivers that are formed by cascading two detectors (usually with opposite behaviors), in which case, only data vectors exceeding both detection thresholds will be declared as the target bearings [19,20,21,22,23]. If the value of the design parameter is bigger than or equals to unity, this new detector leads to worse detection performance than Kelly’s receiver To circumvent this drawback, a two-stage detector is proposed, which consists of the AMF followed by the proposed parametric adaptive detector and can be taken as an improved alternative of the two-stage detector in [18].
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