System and method for GPS signal acquisition
First Claim
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1. A method for acquiring a GPS signal having a predefined coarse acquisition frame period, the method comprising:
- receiving a GPS signal portion over the coarse acquisition (C/A) frame period;
storing the received GPS signal portion;
correlating the received GPS signal portion to each of a plurality of versions of a reference coarse acquisition (C/A) code to obtain a respective plurality of autocorrelation values; and
selecting a peak value among the autocorrelation values,wherein correlating the received GPS signal portion comprises;
(i) correlating the received GPS signal portion to a reference coarse acquisition code to obtain a first autocorrelation value;
(ii) circularly-shifting the reference coarse acquisition code to obtain a shifted reference coarse acquisition code;
(iii) correlating the received GPS signal portion to the circularly-shifted reference coarse acquisition code to obtain a second autocorrelation value andrepeating (ii) and (iii) until the reference C/A code has shifted through one complete revolution, whereby the received GPS signal portion is correlated to each of the reference and shifted versions of the C/A code.
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Abstract
A method for acquiring a GPS signal includes receiving a GPS signal portion over a coarse acquisition (C/A) frame period. The received GPS signal portion is stored and correlated to each of a plurality of versions of a reference coarse acquisition code to obtain a respective plurality of autocorrelation values. A peak value is selected among the autocorrelation values, the peak value corresponding to a version of the reference coarse acquisition code which is most aligned with the received GPS signal.
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Citations
20 Claims
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1. A method for acquiring a GPS signal having a predefined coarse acquisition frame period, the method comprising:
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receiving a GPS signal portion over the coarse acquisition (C/A) frame period; storing the received GPS signal portion; correlating the received GPS signal portion to each of a plurality of versions of a reference coarse acquisition (C/A) code to obtain a respective plurality of autocorrelation values; and selecting a peak value among the autocorrelation values, wherein correlating the received GPS signal portion comprises; (i) correlating the received GPS signal portion to a reference coarse acquisition code to obtain a first autocorrelation value; (ii) circularly-shifting the reference coarse acquisition code to obtain a shifted reference coarse acquisition code; (iii) correlating the received GPS signal portion to the circularly-shifted reference coarse acquisition code to obtain a second autocorrelation value and repeating (ii) and (iii) until the reference C/A code has shifted through one complete revolution, whereby the received GPS signal portion is correlated to each of the reference and shifted versions of the C/A code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for acquiring a GPS signal having a predefined coarse acquisition frame period, the system comprising:
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receiver circuitry configured to receive a GPS signal portion over the coarse acquisition (C/A) frame period; circuitry configured to store the received GPS signal portion; a correlator configured to correlate the received GPS signal portion to each of a plurality of versions of a reference coarse acquisition (C/A) code to obtain a respective plurality of autocorrelation values; and a comparator configured to select a peak value among the autocorrelation values, wherein the correlator comprises; (i) means for correlating the received GPS signal portion to a reference coarse acquisition code (2201) to obtain a first autocorrelation value; (ii) means for circularly-shifting the reference coarse acquisition code to obtain a shifted reference coarse acquisition code; (iii) means for correlating the received GPS signal portion to the circularly-shifted reference coarse acquisition code to obtain a second autocorrelation value and means for repeating (ii) and (iii) until the reference C/A code has shifted through one complete revolution, whereby the received GPS signal portion is correlated to each of the reference and shifted versions of the C/A code. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A computer program product, resident on a computer-readable medium, operable to execute instructions for acquiring a GPS signal having a predefined coarse acquisition frame period, the computer program product comprising:
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instruction code to receive a GPS signal portion over the coarse acquisition (C/A) frame period; instruction code to store the received GPS signal portion; instruction code to correlate the received GPS signal portion to each of a plurality of versions of a reference coarse acquisition (C/A) code to obtain a respective plurality of autocorrelation values; and instruction code to select a peak value among the autocorrelation values, wherein instruction code to correlate the received GPS signal portion comprises; (i) instruction code to correlate the received GPS signal portion to a reference coarse acquisition code to obtain a first autocorrelation value; (ii) instruction code to circularly-shift the reference coarse acquisition code to obtain a shifted reference coarse acquisition code; (iii) instruction code to correlate the received GPS signal portion to the circularly-shifted reference coarse acquisition code to obtain a second autocorrelation value and instruction code to repeat (ii) and (iii) until the reference C/A code has shifted through one complete revolution, whereby the received GPS signal portion is correlated to each of the reference and shifted versions of the C/A code. - View Dependent Claims (18, 19, 20)
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Specification