Mathematical comparison of the effects of multipath interference on estimates yielded by. additive and multiplicative processors

This analysis considers the use of additive and multiplicative processing techniques to estimate a signal level in an ocean environment that is conducive to an interfering arrival, such as a surface reflected arrival. Representing the auto- and cross-correlation functions as decaying exponentials having different effective correlation times facilitates the evaluation of the integral expressions for the variance. By varying these effective correlation times and the measurement geometry (to change the delay time of the interfering arrival) the sensitivity of the estimate on the input characteristics can be observed. The parameters that are found to govern the system performance are input signal-to-noise ratio, the degree of input noise correlation, and the amount of signal decorrelation. The results show that the estimates yielded by the system depend heavily on input signal-to-noise ratio with the multiplicative processor generally outperforming its additive counterpart for most cases at low input signal-to-noise ratios. [Work sponsored by Office of Naval Research.]