An adaptive thresholding system for functioning in nonstationary noise backgrounds

The problem of detecting target signals in an ocean environment using active sonar is complicated by the non-stationary background which usually consists of both ambient ocean noise and reverberation. In the present paper, a signal processing system capable of detecting a signal in nonstationary noise is introduced. This system makes use of the mean and variance time functions of the nonstationary noise background in order to design estimation filters which will cope with the nonstationarity. Appropriate statistics of the noise and signal (tone burst) plus noise have been obtained and are used to determine the probabilities of false alarm and detection and the receiver operating characteristics.