Method and system for processing positioning signals in a stand-alone mode
First Claim
1. A method for processing positioning signals in a ranging receiver in a stand-alone mode, comprising:
- collecting pseudorange samples from positioning signals received at the ranging receiver from a plurality of satellites, the pseudorange samples comprising message data modulation, each satellite having an associated Gold code;
selecting a previously determined carrier frequency offset (CFO) from a plurality of directly extracted CFOs;
compensating the pseudorange samples for the selected CFO;
removing the message data modulation from the pseudorange samples;
stacking the pseudorange samples for each satellite;
correlating the Gold code associated with each satellite to generate a pseudorange time sequence for the satellite;
determining whether an adequate correlation peak exists in each pseudorange time sequence; and
determining a pseudorange for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence.
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Abstract
A method for processing positioning signals in a ranging receiver in a stand-alone mode is provided. The method includes collecting pseudorange samples from positioning signals received at the ranging receiver from a plurality of satellites. The pseudorange samples comprise message data modulation. Each satellite has an associated Gold code. A previously determined carrier frequency offset (CFO) is selected from a plurality of directly extracted CFOs. The pseudorange samples are compensated for the selected CFO. The message data modulation is removed from the pseudorange samples. The pseudorange samples are stacked for each satellite. The Gold code associated with each satellite is correlated to generate a pseudorange time sequence for the satellite. A determination is made regarding whether an adequate correlation peak exists in each pseudorange time sequence. A pseudorange is determined for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence.
102 Citations
58 Claims
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1. A method for processing positioning signals in a ranging receiver in a stand-alone mode, comprising:
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collecting pseudorange samples from positioning signals received at the ranging receiver from a plurality of satellites, the pseudorange samples comprising message data modulation, each satellite having an associated Gold code;
selecting a previously determined carrier frequency offset (CFO) from a plurality of directly extracted CFOs;
compensating the pseudorange samples for the selected CFO;
removing the message data modulation from the pseudorange samples;
stacking the pseudorange samples for each satellite;
correlating the Gold code associated with each satellite to generate a pseudorange time sequence for the satellite;
determining whether an adequate correlation peak exists in each pseudorange time sequence; and
determining a pseudorange for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
Fourier transforming the stacked pseudorange samples to generate a first result stack;
retrieving a Fourier-transformed, time-reversed series of the Gold code for the satellite to generate a second result stack;
multiplying the first result stack by the second result stack to generate a third result stack; and
inverse-Fourier transforming the third result stack to generate the pseudorange time sequence for the satellite.
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7. The method of claim 1, an adequate correlation peak comprising a correlation peak sufficiently above a noise-background threshold.
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8. The method of claim 7, an adequate correlation peak comprising a correlation peak at least 6 dB above the noise-background threshold.
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9. The method of claim 1, further comprising determining whether a maximum number of stacked pseudorange samples has been exceeded when no adequate correlation peak exists in at least one pseudorange time sequence.
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10. The method of claim 9, the maximum number of stacked pseudorange samples based on a sampling time associated with collecting the pseudorange samples.
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11. The method of claim 10, the sampling time comprising about 1 to about 30 seconds.
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12. The method of claim 9, further comprising providing a weak signal indicator when the maximum number of stacked pseudorange samples has been exceeded.
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13. The method of claim 9, further comprising collecting additional pseudorange samples when the maximum number of stacked pseudorange samples has not been exceeded.
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14. The method of claim 1, determining a pseudorange comprising applying a multi-path correcting centroid calculation to determine a substantially exact location of a center of each correlation peak.
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15. The method of claim 1, collecting pseudorange samples comprising collecting pseudorange samples for approximately 0.1 seconds, the pseudorange samples comprising a minimum carrier-to-noise density ratio of approximately 20 dB.
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16. A system for processing positioning signals in a ranging receiver in a stand-alone mode, comprising:
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a computer-processable medium; and
logic stored on the computer-processable medium, the logic operable to collect pseudorange samples from positioning signals received at the ranging receiver from a plurality of satellites, the pseudorange samples comprising message data modulation, each satellite having an associated Gold code, to select a previously determined carrier frequency offset (CFO) from a plurality of directly extracted CFOs, to compensate the pseudorange samples for the selected CFO, to remove the message data modulation from the pseudorange samples, to stack the pseudorange samples for each satellite, to correlate the stacked samples with the Gold code associated with each satellite to generate a pseudorange time sequence for the satellite, to determine whether an adequate correlation peak exists in each pseudorange time sequence, and to determine a pseudorange for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A system for processing positioning signals in a ranging receiver in a stand-alone mode, comprising:
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means for collecting pseudorange samples from positioning signals received at the ranging receiver from a plurality of satellites, the pseudorange samples comprising message data modulation, each satellite having an associated Gold code;
means for selecting a previously determined carrier frequency offset (CFO) from a plurality of directly extracted CFOs;
means for compensating the pseudorange samples for the selected CFO;
means for removing the message data modulation from the pseudorange samples;
means for stacking the pseudorange samples for each satellite;
means for correlating the Gold code associated with each satellite to generate a pseudorange time sequence for the satellite;
means for determining whether an adequate correlation peak exists in each pseudorange time sequence; and
means for determining a pseudorange for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
means for Fourier transforming the stacked pseudorange samples to generate a first result stack;
means for retrieving a Fourier-transformed, time-reversed series of the Gold code for the satellite to generate a second result stack;
means for multiplying the first result stack by the second result stack to generate a third result stack; and
means for inverse-Fourier transforming the third result stack to generate the pseudorange time sequence for the satellite.
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37. The system of claim 31, an adequate correlation peak comprising a correlation peak sufficiently above a noise-background threshold.
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38. The system of claim 37, an adequate correlation peak comprising a correlation peak at least 6 dB above the noise-background threshold.
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39. The system of claim 31, further comprising means for determining whether a maximum number of stacked pseudorange samples has been exceeded when no adequate correlation peak exists in at least one pseudorange time sequence.
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40. The system of claim 39, the maximum number of stacked pseudorange samples based on a sampling time associated with collecting the pseudorange samples.
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41. The system of claim 40, the sampling time comprising about 1 to about 30 seconds.
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42. The system of claim 39, further comprising means for providing a weak signal indicator when the maximum number of stacked pseudorange samples has been exceeded.
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43. The system of claim 39, further comprising means for collecting additional pseudorange samples when the maximum number of stacked pseudorange samples has not been exceeded.
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44. The system of claim 31, the means for determining a pseudorange comprising means for applying a multi-path correcting centroid calculation to determine a substantially exact location of a center of each correlation peak.
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45. The system of claim 31, the means for collecting pseudorange samples comprising means for collecting pseudorange samples for approximately 0.1 seconds, the pseudorange samples comprising a minimum carrier-to-noise density ratio of approximately 20 dB.
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46. A ranging receiver for a wireless device, the ranging receiver operable to process positioning signals and comprising:
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an antenna operable to receive the positioning signals from a plurality of satellites, the positioning signals comprising pseudorange samples, the pseudorange samples comprising message data modulation, each satellite having an associated Gold code; and
a digital signal processor coupled to the antenna and to the wireless device, the digital signal processor operable to select a previously determined carrier frequency offset (CFO) from a plurality of directly extracted CFOs, to compensate the pseudorange samples for the selected CFO, to remove the message data modulation from the pseudorange samples, to stack the pseudorange samples for each satellite, to correlate the Gold code associated with each satellite to generate a pseudorange time sequence for the satellite, to determine whether an adequate correlation peak exists in each pseudorange time sequence, and to determine a pseudorange for the ranging receiver based on the correlation peaks when an adequate correlation peak exists in each pseudorange time sequence. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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Specification