US 6,788,735 B2 · Triple multiplexing spread spectrum receiver

Abstract

A spread spectrum receiver processes signals from a plurality of sources modulated by different spread spectrum codes by sampling the signals as received to produce an integer series of sampling segments at a sampling rate at least twice a chip rate of the codes, each sampling segment containing an integer number of bits representing a fraction of a chip of the codes, time division multiplexing each sample segment into a number of channels, correlating the bits in each sample segment in each channel in parallel with a source specific series of locally generated sequential code samples differing by one bit, summing each parallel correlation, and accumulating the summed parallel correlations for each code sample in each channel at a rate at least equal to the chip rate to derive data related to each of the sources.

Claims17

Dependent claims

A method of receiving a coarse/acquisition (C/A) code comprising:

designating a plurality of multiplexing factors such that each multiplexing factor is evenly divisible by a prime factor of a number that is a number of bits in the C/A code, wherein a predetermined time period is required to transmit the number of bits;
slicing the time period into number of smaller time periods by dividing the time period by a first one of the plurality of multiplexing factors such that a plurality of sample segments of half-chip wide bits of the C/A code is processed in each of the smaller time periods;
multiplexing each sample segment by a second multiplexing factor such that each sample segment rotated for a number of different C/A code sources, wherein the number is equal to the second multiplexing factor;
generating a number of code delays for each of the number of different C/A code sources, wherein the number of code delays is equal to a third multiplexing factor;
and
correlating each rotated sample segment against a plurality of the generated code delays.

3 more elements

A method for navigating a vehicle using satellite C/A code signals, comprising:

using a first mode of navigation comprising a C/A code signal from a single satellite and cross-track hold data;
using a second mode of navigation comprising updating satellite-derived data with data derived from detecting turns of the vehicle, wherein the first and second modes including correlating first sets of code sample segments against first sets of generated code delays;
and
using a third mode of navigation to quickly reacquire satellite signals that are momentarily lost, including correlating second sets of code sample segments against second sets of generated code delays.

1 more element

Dependencies are inferred from the claim text.

Triple multiplexing spread spectrum receiver

Life of this patent

Triple multiplexing spread spectrum receiver

Life of this patent

Abstract

Claims17