Modified GLRT signal detection algorithm

The problem of signal detection in unknown Gaussian interference utilizing an adaptive array is considered here. Two modified generalized likelihood ratio test (GLRT) detectors are suggested that improve on the performance of Kelly's GLRT when the interference has low-rank property and the sample support for estimating the array covariance matrix is limited. Under these adverse conditions, the sample covariance matrix might be ill conditioned. This problem may be overcome either by diagonal loading of the covariance matrix or rank reduction of the data. The two modified GLRT detectors are referred to as loaded GLRT (L-GLRT) and reduced-rank GLRT (RR-GLRT), respectively. Expressions are developed for the probabilities of false alarm and detection. The advantage of the proposed detectors is illustrated by numerical examples.