Hardware dynamic beamforming

Abstract

The hardware architecture of a programmable, time domain, digital beamformer built by the Marine Physical Laboratory is discussed. The Dynamic Beamformer permits the incorporation of slow changes in element positions and/or beam steering directions while carrying out the real-time formation of 1300 beams from 32 input sensors. The sensors are distributed in an arbitrary but known manner over a maximum aperture of 2 s in time delay, or 800 l at the uppermost operating frequency of 400 Hz. Oversampling the sensor signals by a factor of 2.5 above the Nyquist rate is shown to permit the use of a simple, two-point linear interpolation filter to achieve the time-delay quantization intervals required. Element-(as opposed to beam-) level recording of the original sensor data provides a flexible and compact mechanism for postexperiment data analysis.