A 50 MHz phased array beamformer using a novel ‘one sample per pixel’ variable sampling technique

A digital receive beamformer implementing a `one sample per pixel´ variable sampling technique is described. The sampling method reduces the maximum required sampling rates by a factor of 3, and reduces the data rate by a factor of 2 in comparison to previous work on variable sampling. The sampling method is capable of estimating the pulse envelope to within 3dB for pulse bandwidths up to 83.0%. The beamforming methods have been implemented on an FPGA with maximum transmit and receive delays errors measured to be less than ±0.125 and ±1.0ns respectively. The beamformer generates images from a 64 element high frequency phased array, with 64 lines, 512 pixels per line, and 1 focal zone.