Shifted band beamformer: Theory and concept

Abstract

This paper introduces a fundamentally different beamformer structure which can be used to process bandpass sensor signals.The beamformer operates directly on frequency translated versions of the input signals to compute a frequency translated version of the beam output. This new technique, which is referred to as the shifted band beamformer, is functionally a time domain beamformer but it combines attributes of both time and frequency domain beamforming. It is especially compatible with systems where the sensor data is initially basebanded to facilitate the use of bandwidth sampling procedures. Beamformer vernier delay and throughput requirements are relaxed since the delay quantization and beam output rate depends on the highest frequency component of the basebanded signal rather than that of the bandpass signal. The shifted band beamformer can also use interpolation [R. G. Pridham and R. A. Mucci, “A Novel Approach to Digital Beamforming,” J. Acoust. Soc. Am. 63, 425–434 (1978)] to achieve further hardware savings. Relationship between the new structure and frequency domain beamforming is also discussed.