On the design of the target-signal filter in adaptive beamforming

Abstract

This brief deals with the improvement of jammer suppression for adaptive broadband beamforming. The analysis is carried out with a two-microphone Griffiths-Jim beamformer and a single jammer signal. By examining the derived optimal filter, a design strategy for the constant target-signal filter in the main channel of the adaptive beamformer is given. This leads to a substantial reduction in the required filter length of the adaptive filter, while maintaining the same jammer suppression. Furthermore, a faster rate of convergence can be achieved, as there are fewer filter coefficients that have to be adapted. The brief concludes with measurement results from a real-time implementation of an adaptive beamformer, showing that the proposed design method is effective, even when more than two microphones are used.