Digital filters for attenuating interference arriving from a wide range of angles

Digital filters for the offline multichannel processing of the signals recorded by an array of sensors are derived with the objective of extracting a desired signal arriving from a known direction. Both the desired signal and coherent interference have arbitrary waveforms. Since the direction of arrival of the interference is unknown, the array response to it is treated as a random variable, and the expected value of its squared magnitude is taken as a minimization criterion in order to attenuate the coherent interference. The output power spectrum in response to the additive random sensor noise is taken as a second criterion. A convex combination of both criteria is minimized subject to an all-pass condition for the desired signal. Simulation results are presented showing the tradeoff between attenuating interference and random noise, the effect of the angular separation between the directions of arrival of the desired signal and interference and the effect of the number of sensors of the array on the output of the array filter