Hybrid polyphase and joint time-frequency detection

Details Hybrid polyphase and joint time-frequency detection Hybrid polyphase and joint time-frequency detection

2011-08-02

2011-08-02

Bocure, Tesfaldet (Department: 2611)

Pulse or digital communications

Spread spectrum

Direct sequence

C375S340000, C375S343000

Reexamination Certificate

active

07991043

ABSTRACT:
A demodulator in a receiver includes a correlator (240) for de-spreading a spread-spectrum signal, and a decision module (250) for detecting a preamble and for synchronizing to data frames of the spread spectrum signal. The demodulator includes symbol timers (231and233) that allow the demodulator to correlate to two preamble symbols simultaneously, where the two preamble symbols occur one-half a symbol period apart. The correlator includes a correlator structure having taps that correct for any frequency offset of a carrier signal. The correlator correlates to each of the two preamble symbols a plurality of times through oversampling, where each correlation compensates for a different amount of frequency offset. By analyzing occurrence of peaks in magnitude of the correlations, the decision module detects the preamble and selects weights for the taps to de-spread data frames received after the preamble.

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