A Digital Beamformer for Narrowband Sonar Systems.

Abstract : Near the end of 1968, the study of geometric quantization of input data for digital replica correlation led to the concept of a digital beamformer using the same technique. (Geometric A/D (GAD) provides a wide digital dynamic range with a small number of bits.) Such a beamformer was proposed, using quadrature sampling and digital phase shifting to approximate desired time delays. A computer simulation was used to determine feasibility and, as a result, a particular version applicable to narrowband systems using cylindrical arrays was implemented and tested. Results show that such a system provides a good approximation to a fully linear, phase shift beamformer. (Author)