Array processors for simultaneous noise and interference suppression or simultaneous signal-to-noise and resolution enhancement

A symmetrical treatment is described of signal and interference arrivals, both spatially coherent across the aperture of a receiving array and appearing in a generalized ambient-noise background. By separating the coherent interference from the rest of the noise background, it is possible to implement a simple form of adaptive suppression of the interference, particularly when the latter is time varying and the remainder of the noise is stationary. Optimal processors are derived for simultaneous suppression of noise and interference, and for enhancement of the signal-to-noise ratio after elimination of interference. The processor for the latter case is shown to be a suboptimum version of the former. Both deterministic and stochastic interference are considered, as well as interference whose arrival time is synchronized with that of the desired signal (e.g., unwanted signal multipath arrivals, reverberation, etc.). Processors for two or more simultaneous and independent interference sources are described. Finally, the interference descriptor can be reinterpreted as a generalized resolution measure, so as to describe processors that simultaneously maximize the signal-to-noise ratio and the signal time resolution, or the signal-to-noise ratio and a combination of arrival angle and time resolution. Subject Classification: [43]60.30.