A DIFFERENTIAL-DELAY SAW CORRELATOR FOR COMBINED DSSS DESPREADING AND DPSK DEMODULATION

In this paper, we report on the design of a novel Surface-Acoustic-Wave component for the noncoherent detection of direct-sequence spread-spectrum signals with a differential phase-shift keying (DPSK) modulation format. 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 nor 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 a 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 kbps demonstrated the operation of the device.