Patent ID: 6111911
Filing Date: 2000-08-29
Classification: H04B

Abstract:
A direct sequence spread spectrum system, comprising:a transmitter configured to transmit a direct sequence spread spectrum signal that includes a carrier frequency modulated by a direct sequence chip code, a phase synchronizing preamble, and modulating information; anda receiver configured to receive the transmitted direct sequence spread spectrum signal with both chip code phase uncertainty and frequency uncertainty between the carrier frequency of the transmitter and a local reference frequency of the receiver and to demodulate the modulating information, comprising,a despreader which despreads the received direct sequence spread spectrum signal to produce a despread signal,a plurality of parallel filters having adjacent bandpass ranges, each parallel filter having the despread signal applied thereto and each parallel filter having a bandwidth less than said frequency uncertainty,an operator mechanism configured to detect outputs of said parallel filters and to select a parallel filter based on the detected parallel filter outputs to resolve said carrier frequency uncertainty, anda demodulator configured to demodulate data having a data bandwidth at the output of the selected filter.