A differential-delay SAW correlator for combined DSSS despreading and DPSK demodulation

The design of a novel SAW (surface-acoustic-wave) component for the noncoherent detection of DS/SS (direct-sequence spread-spectrum) signals with a DPSK (differential phase-shift keying) modulation format is presented. In the considered differential-delay correlator, both the correlation function for despreading and the delay function for DPSK demodulation are merged into a single device. Due to the absence of a separate delay line, no bandwidth-limiting effects no high insertion losses occur in the delay branch of the DPSK demodulator. In addition, an exact match between the correlator output and its one-symbol-delayed replica is obtained. Experiments on an ST-quartz differential-delay correlator with a center frequency of 98.5 MHz, a chip rate of 12.3 MHz and a symbol rate of 195.4 kb/s demonstrated the operation of the device.<
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