GPS receiver
First Claim
1. In a GPS receiver for use with a satellite-based radio navigation system in which received signals from a plurality of satellites comprise a carrier signal modulated by phase reversals representing satellite-specific codes and data, said receiver comprising means for amplifying the signal received through an antenna, code generating means to generate any of said codes with a code delay of the generated code being controllable to sub-chip accuracy, code mixing and downconverting means to produce from the amplified signal a digital signal with a downconverted carrier frequency and multiplied by the generated code whereby the bandwidth of the portion of the digital signal originating from the satellite signal having the same code is despread when the code delay of the generated code matches or nearly matches the code delay of the satellite signal having the same code, means for computing signal parameters of the satellite signals including code delay, and means for utilizing said signal parameters from at least four of said satellite signals to provide information on the position of the antenna;
- a method of determining the code delay of said satellite signal having the same code, said method comprising the steps of;
(1) generating a plurality of said digital signals, each of said digital signals corresponding to a different code delay of the generated code from said code generating means;
(2) computing a plurality of values corresponding to each digital signal, each value being a measure of the degree of code demodulation of the corresponding digital signal and utilizing both phase and frequency information; and
(3) computing an optimum code delay of the generated code from said plurality of corresponding values to provide the code delay of said satellite signal.
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Accused Products
Abstract
A GPS receiver for use with the NAVSTAR global, satellite based radio navigation and time transfer system wherein transmission from each of a plurality of satellites, includes C/A code signals comprising a code and data modulated carrier, said receiver comprising means for receiving C/A code signals transmitted from at least four satellites and means to process the signals including an open loop estimator of signal parameters for phase-coherent estimation of a plurality of signal parameters including code delay, carrier frequency, carrier phase, carrier phase acceleration, data value and data delay.
81 Citations
25 Claims
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1. In a GPS receiver for use with a satellite-based radio navigation system in which received signals from a plurality of satellites comprise a carrier signal modulated by phase reversals representing satellite-specific codes and data, said receiver comprising means for amplifying the signal received through an antenna, code generating means to generate any of said codes with a code delay of the generated code being controllable to sub-chip accuracy, code mixing and downconverting means to produce from the amplified signal a digital signal with a downconverted carrier frequency and multiplied by the generated code whereby the bandwidth of the portion of the digital signal originating from the satellite signal having the same code is despread when the code delay of the generated code matches or nearly matches the code delay of the satellite signal having the same code, means for computing signal parameters of the satellite signals including code delay, and means for utilizing said signal parameters from at least four of said satellite signals to provide information on the position of the antenna;
a method of determining the code delay of said satellite signal having the same code, said method comprising the steps of; (1) generating a plurality of said digital signals, each of said digital signals corresponding to a different code delay of the generated code from said code generating means; (2) computing a plurality of values corresponding to each digital signal, each value being a measure of the degree of code demodulation of the corresponding digital signal and utilizing both phase and frequency information; and (3) computing an optimum code delay of the generated code from said plurality of corresponding values to provide the code delay of said satellite signal. - View Dependent Claims (2, 3, 4, 5, 6, 13, 14, 15, 16, 17, 18, 19, 20, 23)
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7. In GPS receiver for use with a satellite-based radio navigation system in which received signals from a plurality of satellites comprise a carrier signal modulated by phase reversals representing satellite-specific codes and data, said receiver comprising means for amplifying the signal received through an antenna, code generating means to generate any of said codes with a code delay of the generated code being controllable to sub-chip accuracy, code mixing and downconverting means to produce from the amplified signal a digital signal with a downconverted carrier frequency and multiplied by the generated code whereby the bandwidth of the portion of the digital signal originating from the satellite signal having the same code is despread when the code delay of the generated code matches or nearly matches the code delay of the satellite signal having the same code, means for computing signal parameters of the satellite signals including code delay, and means for utilizing said signal parameters from at least four of said satellite signals to provide information on the position of the antenna;
A method of determining the code delay of said satellite signal having the same code, said method comprising the steps of; (1) generating a plurality of said digital signals, each of said digital signals corresponding to a different code delay of the generated code from said code generating means; and (2) computing a plurality of values corresponding to each digital signal, each value being a measure of the degree of code demodulation of the corresponding digital signal and utilizing both phase and frequency information, said step of computing a plurality of values comprising the steps of (a) computing a complex frequency spectrum of at least one of said digital signals over an integration period; (b) locating a maximum bin in said frequency spectrum; and (c) performing a further downconversion on each said digital signal in the time domain to produce corresponding further downconverted signals with zero frequency and phase; and (3) computing an optimum code delay of the generated code from said plurality of corresponding values to provide the code delay of said satellite signal. - View Dependent Claims (8, 9, 10, 11, 12, 21, 22, 24, 25)
Specification