Adaptive matched subspace detectors and adaptive coherence estimators

We adapt the matched subspace detectors (MSDs) of Scharf (1991) and Scharf and Friedlander (see IEEE Trans. Signal Proc., vol.42, no.8. p.2146-57, 1994) to unknown noise covariance matrices in order to produce adaptive MSDs that may be applied to signal detection in radar, sonar, mobile communication, and DOA estimation. A special case of the adaptive MSD uses the Reed (1974) ratio statistic and a special cease of the adaptive CFAR MSD uses an adaptive coherence estimator (ACE). We compare and contrast the invariances and performance of the two detectors and discuss extensions of them that make them maximum likelihood MSDs.