Spread-spectrum synchronizer using a SAW convolver and recirculation loop

Segments of a long biphase coded waveform were correlated in a degenerate acoustic convolver, and the resulting correlation peaks were summed in a SAW recirculation loop. Using a 9 Mchip/s wave-form, 730 µs of waveform was correlated, giving an experimental SNR increase of 40 dB. This system can be used to reduce substantially the acquisition time for synchronization of a direct sequence spread-spectrum communication receiver.