Receivers for navigation satellite systems

Claim 2

A navigation satellite system receiver comprising: an antenna for receiving an incoming coded, time-based, spread-spectrum, continuous signal which includes navigational data from a plurality, P, of satellites; and convolver means, connected to receive signals from said antenna for (a) convolving segments of said signal with codes therein by Fourier transforming said segments, (b) cyclically shifting points of the Fourier transform to produce a transform of a near baseband signal, (c) multiplying said shifted points with corresponding points of a pre-computed transform of a segment of spread spectrum code to give a resultant signal, and (d) inverse transforming said resultant signal to produce a correlation peak at a point having a position which gives the relative shift between said incoming signal and said code.

Claim 3

A receiver for a navigation satellite system, comprising: an antenna adapted to receive coded, time-based, spreadspectrum, continuous signals which include navigational data from a plurality, P, of satellites; means connected to said antenna for deriving baseband I and Q components from said signals; means for digitizing said I and Q components; a Fast Fourier Transform processor connected to receive said digitized I and Q components and to transform said components and their respective codes and to provide a first transformed signal; multiplier means connected to said processor, for receiving said first transformed signal and multiplying together said transformed components and their codes to provide a multiplied signal; an inverse Fast Fourier Transform processor connected to said multiplier means, for inverse transforming said multiplied signal and providing a second transformed signal; and amplitude scanning means connected to said inverse Fast Fourier Transform processor, for determining correlation peaks in said second transformed signal.

Claim 4

A receiver for a navigation satellite system, comprising: an antenna adapted to receive coded, time-based, spreadspectrum, continuous signals which include navigational data from a plurality, P, of satellites; means connected to said antenna for deriving baseband I and Q components from said signals; means for digitizing said I and Q components; a Fast Fourier Transform processor connected to receive said digitized I and Q components and to transform said components and their respective codes and to provide a first transformed signal; multiplier means connected to said processor, for receiving said first transformed signal and multiplying together said transformed components and their codes to provide a multiplied signal; an inverse Fast Fourier Transform processor connected to said multiplier means, for inverse transforming said multiplied signal and providing a second transformed signal; and amplitude scanning means connected to said inverse Fast Fourier Transform processor, for determining correlation peaks in said second transformed signal.

Claim 5

A receiver for a navigation satellite system, having an antenna adapted to receive coded, time-based, spreadspectrum, continuous signals which include navigational data from a plurality, P, of satellites, comprising: means connected to said antenna for deriving baseband I and Q components from said signals; means for digitizing said I and Q components; a Faster Fourier Transform processor connected to receive said digitized I and Q components and to transform said components and their respective codes and to provide a first transformed signal; multiplier means connected to said processor, for receiving said first transformed signal and multiplying together said transformed components and their codes to provide a multiplied signal; an inverse Fast Fourier Transform processor connected to said multiplier means, for inverse transforming said multiplied signal and providing a second transformed signal; and amplitude scanning means connected to said inverse Fast Fourier Transform processor, for determining correlation peaks in said second transformed signal.

Claim 6

A receiver for a navigation satellite system, having an antenna adapted to receive coded, time-based, spreadspectrum, continuous signals which include navigational data from a plurality, P, of satellites, comprising: means connected to said antenna for deriving baseband I and Q components from said signals; means for digitizing said I and Q components; a Faster Fourier Transform processor connected to receive said digitized I and Q components and to transform said components and their respective codes and to provide a first transformed signal; multiplier means connected to said processor, for receiving said first transformed signal and multiplying together said transformed components and their codes to provide a multiplied signal; an inverse Fast Fourier Transform processor connected to said multiplier means, for inverse transforming said multiplied signal and providing a second transformed signal; and amplitude scanning means connected to said inverse Fast Fourier Transform processor, for determining correlation peaks in said second transformed signal.