Prevention of signal cancellation in an adaptive nulling problem

Signal cancellation is a serious problem in adaptive nulling. The problem arises when the actual direction of arrival of the signal is slightly off the assumed direction of arrival. The adaptive algorithms consider the actual signal a jammer as the direction of arrival is not exactly specified. It is shown how to prevent signal cancellation when the direction of arrival is not known exactly. Multiple look-direction constraints are used to prevent signal cancellation. This paper outlines the principles and illustrates how it can be incorporated in an adaptive nulling situation using a deterministic direct data domain approach.