Frequency-domain GSC beamforming with enhanced robustness against mistracking

In a real environment, the interference rejection of the generalized sidelobe canceller (GSC) microphone array with adaptive blocking matrix (ABM) deteriorates by mistracking of target, which may be caused by either steering error or misdetection of the adaptation mode control. As a remedy, the tap coefficients of the ABM filters are constrained to leak the interference into the sidelobe canceling path. One inherent problem of the conventional ABM structure is the incoherent spread of filter coefficients for a different signal frequency, which leads to insufficient suppression of low frequency interference in the case of mistracking. To improve the interference rejection against mistracking, we propose an enhanced frequency-domain GSC with a new pulse-width constrained ABM in which the spread of filter coefficients is less sensitive to the signal spectrum. An experiment in a real environment shows that the loss of interference rejection caused by mistracking is reduced from 6.31 dB to 1.06 dB.