Prevention of signal cancellation in an adaptive space-time nulling problem

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