Importance

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Abstract

A technique is provided using a SAW device for correlating to a plurality of different chip code sequences, such as M different chip code sequences, using fewer than M individual SAW correlators. A received signal is provided to a SAW correlator capable of recognizing a plurality of different chip code sequences. The SAW correlator is pre-programmed so as to recognize each different chip code sequence at a different frequency. The received signal is given a programmably selected frequency offset from the center frequency of the received signal (or a downconverted version thereof) and applied to the SAW correlator. The SAW correlator correlates for the particular chip code sequence at the offset frequency. The output of the SAW correlator is given an opposite frequency offset and filtered with a bandpass filter to generate a correlator output at the designated center frequency. In one embodiment, a comb generator signal is multiplied with the received signal to provide a plurality of signals at offset frequencies. The plurality of offset signals are provided to the SAW correlator which simultaneously correlates for all possible chip code sequences. The output of the SAW is connected to a plurality of bandpass filters, each attuned to one of the offset frequencies generated by the comb generator.

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First Claim