Reception Characteristics of a Linear Array in a Random Transmission Medium

Abstract

The fluctuation of the response-signal intensity as a result of correlated phase and amplitude fluctuations is considered in connection with the performance of various common types of linear arrays. The results of Chernov's treatment of sound transmission through a random medium are used extensively for the formulation and solution of the problem of signal degradation by phase and amplitude fluctuations. This method of solution indicates that amplitude and phase fluctuations must be considered simultaneously. A generalization of Chernov's method shows that the bearing angle of the array, relative to the direction of propagation, is of importance in connection with the autocorrelation of the phase and amplitude fluctuations. The simultaneous inclusion of phase and amplitude fluctuations as well as bearing angle effects leads to quite general results for the computation of mean signal intensities, along with higher-order moments. Explicit expressions are given for the case of large values of the parameter D=4R/ka2, where R is the range, k is the wavenumber, and a is a characteristic correlation distance for the transmission medium.