Radio receiver
First Claim
1. A radio receiver for use with direct sequence spread spectrum signals which have been spread in frequency by a pseudo random noise (PRN) sequence having a repetition frequency, comprising means for producing a pair of quadrature related signals in respective channels from a received direct sequence spread spectrum signal, comb filtering means for respectively filtering the quadrature related signals at n times the repetition frequency to produce comb-filtered signals, where n is an integer, and means for non-coherently demodulating and despreading the comb-filtered signals.
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Accused Products
Abstract
A radio receiver (16) for direct sequence spread spectrum signals incorporates a quadrature zero-IF architecture, means for comb filtering (36,37) the two quadrature related channels (I and Q) and a means of non-coherent demodulation of each channel; the non-coherent demodulating means comprising delays (40,41) and mixers (42,43). This process obviates the need for locally generated versions of the spreading code used to produce the signals and considerably shortens the time-consuming process of correlating the received and the locally generated codes at receiver switch-on.
155 Citations
17 Claims
- 1. A radio receiver for use with direct sequence spread spectrum signals which have been spread in frequency by a pseudo random noise (PRN) sequence having a repetition frequency, comprising means for producing a pair of quadrature related signals in respective channels from a received direct sequence spread spectrum signal, comb filtering means for respectively filtering the quadrature related signals at n times the repetition frequency to produce comb-filtered signals, where n is an integer, and means for non-coherently demodulating and despreading the comb-filtered signals.
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2. A radio receiver for use with the NAVSTAR global positioning system (GPS), said system comprising means for producing a plurality of satellite transmission, each satellite transmission including a coarse/acquisition (C/A) code having a repetition frequency;
- wherein said receiver comprises means for producing a pair of quadrature related signals in respective channels from a received satellite transmission, comb filtering means for respectively filtering the quadrature related signals at n times the repetition frequency of the coarse/acquisition (C/A) code to produce comb-filtered signals, where n is an integer, and means for non-coherently demodulating and despreading the comb-filtered signals.
- View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11)
Specification