An Application of Saw Convolves to High Bandwidth Spread Spectrum Communications

A spread spectrum communications subsystem that is based on the separated medium acoustoelectric convolver is described. The subsystem generates minimum-shift-keyed (MSK) waveforms with the aid of SAW filters and performs differential-phase-shift-keyed (DPSK) data demodulation with acoustoelectric convolvers. The convolver provides a BT product of 2200 with a 3-dB bandwidth of 100 MHz. The signals processed by the subsystem have a BT product of 1100. In this paper, the subsystem, the generation of MSK waveforms, and the use of acoustoelectric convolvers are described. Important subsystem performance characteristics, including dynamic range (≅50 dB), contribution to implementation loss (≅1 dB), DPSK demodulation, and distortion levels are illustrated and discussed.