Method and apparatus for signal processing in a satellite positioning system
First Claim
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1. A method for satellite positioning system (SPS) signal processing, said method comprising:
- receiving at an SPS receiver one or more SPS signals;
removing pseudorandom noise from said one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal; and
summing said first and second portions, at least one of said first and second portions being weighted by a weighting factor that is a function of a signal-to-noise ratio (SNR) of at least one of said one or more SPS signals to improve the sensitivity of the SPS receiver;
wherein said first portion and said second portion contain common information in said one or more SPS signals.
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Abstract
A method and apparatus for processing satellite positioning system (SPS) signals which are weak in level. In one embodiment, a SPS receiver receives at least two signal samples representing, at least in part, common information, wherein the two signal samples are associated with one or more satellite messages. By combining the two signal samples, navigational information (e.g., time, position, velocity, etc.) may be determined based on the combination of the two signal samples. According to another embodiment, the two signal samples are differentially demodulated and summed together to form the combination.
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Citations
82 Claims
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1. A method for satellite positioning system (SPS) signal processing, said method comprising:
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receiving at an SPS receiver one or more SPS signals;
removing pseudorandom noise from said one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal; and
summing said first and second portions, at least one of said first and second portions being weighted by a weighting factor that is a function of a signal-to-noise ratio (SNR) of at least one of said one or more SPS signals to improve the sensitivity of the SPS receiver;
wherein said first portion and said second portion contain common information in said one or more SPS signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
determining data bits representative of navigational information embedded in one of said first and said second portions from said combining.
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11. The method of claim 10, wherein said navigational information comprises satellite ephemeris information and wherein said common information comprises identical information in said first and said second portions.
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12. The method of claim 10, wherein said navigational information comprises error correction information.
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13. The method of claim 10, wherein said navigational information comprises a position of said SPS receiver.
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14. The method of claim 10, wherein said navigational information comprises a position of an entity.
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15. A method for processing a signal associated with a satellite positioning system, said method comprising:
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receiving at an SPS receiver a first SPS signal containing a satellite message associated with a satellite vehicle;
receiving at said SPS receiver a second SPS signal containing said satellite message associated with said satellite vehicle;
removing pseudorandom noise from said first and second SPS signals to provide a first set of signal samples of a narrowband signal and a second set of signal samples of a narrowband signal; and
summing said first and second sets of signal samples to improve the sensitivity of the SPS receiver, said summing including weighting at least one of said first and second sets of signal samples with a weight depending on a signal-to-noise ratio (SNR) of at least one of said first and second sets of signal samples;
wherein said first set of signal samples and said second set of signal samples contain common information. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
determining data bits representative of navigational information embedded in one of said first and said second sets from said combining.
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23. The method of claim 22, wherein said navigational information comprises satellite ephemeris information.
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24. The method of claim 22, wherein said navigational information comprises error correction information.
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25. The method of claim 22, wherein said navigational information comprises a position of said SPS receiver.
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26. The method of claim 22, wherein said navigational information comprises a position of an entity.
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27. A method for satellite positioning system signal processing, said method comprising:
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receiving at an SPS receiver a first SPS signal containing a first satellite message, said first satellite message associated with a first satellite vehicle;
receiving at said SPS receiver a second SPS signal containing a second satellite message, said second satellite message associated with a second satellite vehicle;
removing pseudorandom noise from said first and second SPS signals to provide a first set of signal samples of a narrowband signal and a second set of signal samples of a narrowband signal;
combining said first and second sets of signal samples to improve the sensitivity of the SPS receiver;
wherein said first set of signal samples and said second set of signal samples contain common information;
receiving at said SPS receiver a third SPS signal containing said first satellite message;
receiving at said SPS receiver a fourth SPS signal containing said second satellite message;
removing pseudorandom noise of said third and forth SPS signals to provide a third set of signal samples of a narrowband signal and a fourth set of signal samples of a narrowband signal, wherein said third and fourth sets of signal samples at least partially represent common information;
combining representations of said third and fourth sets of signal samples; and
comparing a first result generated from combining said first and second signal samples with a second result generated from combining said representations of said third and fourth signal samples to determine navigational information. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
determining data bits representative of navigational information from said combining.
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37. The method of claim 36, wherein said navigational information comprises satellite time-of-week (TOW) information.
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38. The method of claim 36, wherein said navigational information comprises satellite Almanac information.
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39. The method of claim 36, wherein said navigational information comprises a position of said SPS receiver.
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40. The method of claim 36, wherein said navigational information comprises a position of an entity.
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41. An apparatus to provide satellite positioning system (SPS) signal processing, said apparatus comprising:
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a despreader that removes pseudorandom noise from one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal;
a processor, coupled to said despreader, to combine said first portion with said second portion to improve the sensitivity of the SPS receiver;
said processor performing a summing operation to said first portion and said second portion, said summing operation including a weighting factor that is a function of a signal-to-noise ratio (SNR);
wherein said first portion and said second portion contain common information. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
a differential demodulation unit to differentially demodulate said first and second portions; and
wherein said processor comprises a summing unit, coupled to said differential demodulation unit, to sum said first and second portions.
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43. The apparatus of claim 41, wherein said processor sums said first and second portions after said processor differentially demodulates said first and second portions.
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44. The apparatus of claim 41, wherein said processor performs said summing operation following a differentially demodulating operation.
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45. The apparatus of claim 41, wherein said apparatus comprises a mobile Global Positioning Satellite (GPS) receiver.
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46. The apparatus of claim 45, wherein said mobile GPS receiver further comprises communication circuitry.
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47. The apparatus of claim 46, wherein a remote entity is accessible by said mobile GPS receiver via said communication circuitry.
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48. The apparatus of claim 47, wherein said remote entity comprises a basestation.
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49. The apparatus of claim 48, wherein said basestation comprises a communication link to a data processing network.
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50. The apparatus of claim 41, wherein said first and second portions are separated in time by a duration equal to a multiple of a frame period of said satellite message.
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51. The apparatus of claim 41, wherein said first portion is associated with a first satellite vehicle message, and said second portion is associated with a second satellite vehicle message.
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52. The apparatus of claim 41, wherein said first and second portions are associated with exactly one satellite vehicle message.
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53. The apparatus of claim 41, wherein said common information comprises a repetition of a portion of a satellite message from one SPS satellite.
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54. The apparatus of claim 41, wherein said processor determines data bits representative of navigational information embedded in one of said first and said second portions from combining said first portion with said second portion.
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55. The apparatus of claim 54, wherein said navigational information comprises satellite ephemeris information.
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56. The apparatus of claim 54, wherein said navigational information comprises error correction information.
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57. The apparatus of claim 54, wherein said navigational information comprises a position of an SPS receiver.
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58. The apparatus of claim 54, wherein said navigational information comprises time-of-week (TOW) information.
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59. An apparatus to provide satellite positioning system (SPS) signal processing, said apparatus comprising:
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means for removing pseudorandom noise from one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal; and
means for combining said first portion with said second portion to improve the sensitivity of the SPS receiver;
wherein said means for combining adds in a summing operation said first portion with said second portion, and wherein said summing operation comprises including a weighting factor, said weighting factor being a function of a signal-to-noise ratio (SNR);
wherein said first portion and said second portion contain common information. - View Dependent Claims (60, 61, 62, 63, 64, 65)
a differential demodulation unit to differentially demodulate said first and second portions; and
wherein said means for combining comprises;
a summing unit, coupled to said differential demodulation unit, to sum said first and second portions.
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61. The apparatus of claim 60, wherein said differential demodulation unit and said summing unit are included in a processor.
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62. The apparatus of claim 59, wherein said means for combining adds in a summing operation said first portion with said second portion following a differentially demodulating operation.
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63. The apparatus of claim 59, further comprising:
means for determining data bits representative of navigational information embedded in one of said first and said second portions from combining said first portion with said second portion.
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64. The apparatus of claim 63, wherein said navigational information comprises at least one of:
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a) satellite ephemeris information;
b) error correction information;
c) a position of an SPS receiver;
d) a position of an entity;
e) time-of-week (TOW) information; and
f) satellite Almanac information.
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65. The apparatus of claim 59, wherein said common information comprises a repetition of a portion of a satellite message from one SPS satellite.
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66. An apparatus to provide satellite positioning system (SPS) signal processing, said apparatus comprising:
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a correlator, said correlator receiving one or more SPS signals; and
a navigation computer coupled to the correlator, said navigation computer removing pseudorandom noise from said one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal, said navigation computer summing said first portion with said second portion, wherein said summing operation includes a weighting factor that is a function of a signal-to-noise ratio (SNR) to improve the sensitivity of the apparatus;
wherein said first portion and said second portion contain common information. - View Dependent Claims (67, 68, 69, 70, 71, 72)
a) satellite ephemeris information;
b) error correction information;
c) a position of an SPS receiver;
d) a position of an entity;
e) time-of-week (TOW) information; and
f) satellite Almanac information.
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72. The apparatus of claim 71, wherein said common information comprises a repetition of a portion of a satellite message from one SPS satellite.
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73. An apparatus to provide satellite positioning system (SPS) signal processing, said apparatus comprising:
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means for receiving at an SPS receiver one or more SPS signals;
means for removing pseudorandom noise from said one or more SPS signals to provide a first portion of a narrowband signal and a second portion of a narrowband signal;
means for summing said first and second portions, at least one of said first and second portions being weighted with a weighting factor that is a function of a signal-to-noise ratio (SNR) of at least one of said one or more SPS signals to improve the sensitivity of the SPS receiver;
wherein said first portion and said second portion contain common information in said one or more SPS signals. - View Dependent Claims (74, 75, 76, 77, 78, 79, 80, 81, 82)
means for determining data bits representative of navigational information embedded in one of said first and said second portions from said combining.
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78. The apparatus of claim 77, wherein said navigational information comprises at least one of:
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a) satellite ephemeris information;
b) error correction information;
c) a position of an SPS receiver;
d) a position of an entity;
e) time-of-week (TOW) information; and
f) satellite Almanac information.
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79. The apparatus of claim 73, wherein said first and second portions are separated in time by a duration equal to a multiple of a frame period of an SPS message.
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80. The apparatus of claim 73, wherein said first portion is associated with a first satellite vehicle, and said second portion is associated with a second satellite vehicle.
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81. The apparatus of claim 73, wherein said first and second portions are associated with exactly one satellite vehicle message.
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82. The apparatus of claim 73, wherein said common information comprises a repetition of a portion of a satellite message from one SPS satellite.
Specification