EP1550241B1

Position estimation using a network of global-positioning receivers

Abstract

This record has no abstract on file.

EP1550241B1, drawing sheet 1
Sheet 1 of 459

Term

Term ended

Expired 23 September 2023, 3 years ago.

  1. Priority
  2. Filed
  3. Granted
  4. Expired
  5. Today

54 claims: 5 independent, 49 dependent

  1. 1
    A method of estimating the location of a rover station (R) with the use of a first base station (B1) and a second base station (B2), the method comprising:(a) (202) receiving known locations of the first base station and the second base station;(b) (206) receiving measured satellite navigation data as received by the rover station, the first base station, and the second base station;(c) (208) obtaining a first time offset representative of a difference between a first offset from true GPS time of the clock of the first base station and a second offset from true GPS time of the clock of the second base station;(d) (214) generating a first set of residuals of differential navigation equations associated with a first baseline (R-B1) between the rover station and the first base station, the residuals being related to the measured satellite navigation data received by the rover station and the first base station, the locations of the satellites, and the locations of the rover station and the first base station;(e) (214) generating a second set of residuals of differential navigation equations associated with a second baseline (R-B2) between the rover station and the second base station, the residuals being related to the measured satellite navigation data received by the rover station and the second base station, the locations of the satellites, and the locations of the rover station and the second base station;(f) substituting, within the second set of residuals, an unknown time offset associated with the second baseline (R-B2) with a value composed of a sum of the first time offset and a time offset associated with the first baseline (R-B1);and (g) (218) generating, subsequent to the substitution step of (f), an estimate of the rover station's location from the first set of residuals, the second set of residuals and the first time offset.
  2. 2
    The method of Claim 1 further comprising the steps of:(h) (202) receiving the location of a third base station (B3);(i) (206) receiving measured satellite navigation data as received by the third base station;and (j) (208) obtaining a second time offset representative of the difference between the first offset from true GPS time of the clock of the first base station and a third offset from true GPS time of the clock of the third base station;(k) (214) generating a third set of residuals of differential navigation equations associated with a third baseline (R-B3) between the rover station and the third base station, the residuals being related to the satellite navigation data received by the rover station and the third base station, the locations of the satellites, and the locations of the rover station and the third base station;(1) substituting, within the third set of residuals, an unknown time offset associated with the third baseline (R-B3) with a value composed of a sum of the second time offset and a time offset associated with the first baseline (R-B1);and wherein step (g) generates, subsequent to the substitution step of (1), the estimate of the rover station's location further from the third set of residuals and the second time offset.
  3. 3
    The method of Claim 1 wherein step (c) comprises the step of generating the first time offset.
  4. 4
    The method of Claim 2 wherein step (c) comprises the step of generating the first time offset and wherein step (j) comprises the step of generating the second time offset.
  5. 5
    The method of Claim 4 further comprising the steps of generating a third time offset representative of a difference between the second offset from true GPS time of the clock of the second station and the third offset from true GPS time of the clock of the third base station, and comparing the sum of the first time offset, the second time offset and the third time offset around a loop of the base stations to the value of zero.
  6. 7
    The method of Claim 6 further comprising the steps of:obtaining a first set of satellite carrier-phase cycle ambiguities associated with the baseline between the first and second base stations;generating a second set of carrier-phase-based residuals of differential navigation equations associated with the second baseline (R-B2) between the rover station and the second base station, the second set of carrier-phase-based residuals being related to at least the measured satellite carrier-phase data received by the rover station and the second base station, the locations of the satellites, and the locations of the rover station and the second base station;and wherein step (g) generates the estimate of the rover station's location further from the second set of carrier-phase-based residuals and the first set of satellite-phase cycle ambiguities.
  7. 9
    The method of Claim 6 further comprising the step of generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals and at least one of the sets of residuals based on pseudo-range data;and wherein step (g) generates the estimate of the rover station's location further from the first set of floating ambiguities.
  8. 10
    The method of Claim 6 further comprising the steps of:generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals and at least one of the sets of residuals based on pseudo-range data;and generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein step (g) generates the estimate of the rover station's location further from the first set of fixed-integer floating ambiguities.
  9. 11
    The method of Claim 7 further comprising the step of:generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;wherein step (g) generates the estimate of the rover station's location further from the first set of floating ambiguities.
  10. 12
    The method of Claim 6 further comprising the steps of:generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein step (g) generates the estimate of the rover station's location further from the first set of fixed-integer floating ambiguities.
  11. 13
    The method of Claim 8 further comprising the step of:generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, the third set of carrier-phase-based residuals, the second set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;wherein step (g) generates the estimate of the rover station's location further from the first set of floating ambiguities.
  12. 14
    The method of Claim 8 further comprising the steps of:generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, the third set of carrier-phase-based residuals, the second set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein step (g) generates the estimate of the rover station's location further from the first set of fixed-integer floating ambiguities.
  13. 15
    The method according to any of the above claims further comprising the steps of:obtaining a first set of first ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and second base stations, and generating corrections to one or more of the residuals, the corrections being related to the first set of first ionosphere delay differentials, the locations of the first and second base stations, and an estimated location of the rover station;and modifying said one or more of the residuals with said corrections.
  14. 17
    The method of Claim 16 wherein the correction to the residuals associated with satellite "s" in one or both of the second set of residuals and the second set of carrier-phase-based residuals is related to the quantity Δ 2 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 2 , 1 I k s is the first ionosphere delay differential associated with satellite "s", and Δ 1 , 0 I ˜ k s is an estimated ionosphere delay differential associated with satellite "s" along the baseline between the rover station and first base station.
  15. 18
    The method of Claim 16 wherein the correction to the residuals associated with satellite "s" in one or both of the third set of residuals and the third set of carrier-phase-based residuals is related to the quantity Δ 3 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 3 , 1 I k s is the second ionosphere delay differential associated with satellite "s", and Δ 1 , 0 I ˜ k s is an estimated ionosphere delay differential associated with satellite "s" along the baseline between the rover station and first base station.
  16. 19
    The method of Claim 16 wherein the ionosphere delay differential from the first set and associated with satellite "s" may be denoted as Δ 1 , 2 I k s , wherein the ionosphere delay differential from the second set and associated with satellite "s" may be denoted as Δ 1 , 3 I k s , wherein the locations of the first, second, and third base stations may be represented by the vectors X 1 , X 2 , and X 3 , and wherein the estimated location of the rover station may be represented as X 0 ,k , wherein the corrections to one or more of the residuals associated with satellite "s" are related to a quantity Δ 1 , 0 I ˜ k s , where Δ 1 , 0 I ˜ k s = α Δ 1 , 2 I k s + β Δ 1 , 3 I k s , wherein α and β are constants that satisfy the relationships:X ‾ 0 , k − X 1 n = α X 2 − X 1 n + β X 3 − X 1 n X ‾ 0 , k − X 1 e = α X 2 − X 1 e + β X 3 − X 1 e where notation { * } n denotes the component of the bracketed quantity along the north direction, where notation { * } e denotes the component of the bracketed quantity along the east direction.
  17. 20
    The method of Claim 19 wherein the correction to the residuals associated with satellite "s" in one or both of the second set of residuals and the second set of carrier-phase-based residuals is related to the quantity Δ 2 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 2 , 1 I k s is the first ionosphere delay differential associated with satellite "s".
  18. 21
    The method of Claim 19 wherein the correction to the residual associated with satellite "s" in one or both of the third set of residuals and the third set of carrier-phase-based residuals is related to the quantity Δ 3 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 3 , 1 I k s is the second ionosphere delay differential associated with satellite "s".
  19. 22
    The method according to Claim 16 further comprising the steps of:modifying one or more of the above residuals to be dependent upon second order effects in the ionosphere delay corrections applied to the baselines associated with the rover station, and generating an estimate of the second order effects, and wherein step (g) generates the estimate of the rover station's location further from the estimated second order effects.
  20. 23
    The method according to Claim 16 wherein the method generates the first set of first ionosphere delay differentials and the second set of second ionosphere delay differentials from at least the navigation data that it receives from the base stations.
  21. 24
    The method according to Claim 16 further comprising the steps of:generating an initial estimate of the first set of first ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and second base stations;generating an initial estimate of second set of second ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and third base stations;generating an initial estimate of a third set of third ionosphere delay differentials associated with the satellite signals received along the baseline formed by the second and third base stations;and generating final estimates of the ionosphere delay differentials such that the sum of the final estimates of the first, second, and third ionosphere delay differentials for at least one satellite "s" around a loop of the base stations is substantially zero.
  22. 25
    The method of Claim 7 wherein the step of obtaining the first set of satellite carrier-phase cycle ambiguities comprises the step of generating the first set of satellite carrier-phase cycle ambiguities from at least the locations of the base stations, and measured satellite navigation data as received by the base stations.
  23. 26
    The method of Claim 8 wherein the steps of obtaining the first and second sets of satellite carrier-phase cycle ambiguities comprises the step of generating the first set of satellite carrier-phase cycle ambiguities from at least the locations of the first and second base stations and measured satellite navigation data as received by the first and second base stations, and the step of generating the second set of satellite carrier-phase cycle ambiguities from at least the locations of the first and third base stations and measured satellite navigation data as received by the first and third base stations.
  24. 27
    The method of Claim 26 further comprising the steps of generating a third set of satellite carrier-phase cycle ambiguities associated with the baseline between the second and third base stations, and comparing the sum of the three sets of satellite carrier-phase ambiguities around a loop of the base stations to the value of zero.
  25. 28
    A computer program which, when run on a computer processor, causes the computer processor to carry out the method of any preceding claim.
  26. 29
    An apparatus for estimating the location of a rover station (R) with the use of a first base station (B1) and a second base station (B2), the apparatus comprising:(a) means for receiving the locations of the first base station and the second base station;(b) means for receiving measured satellite navigation data as received by the rover station, the first base station, and the second base station;(c) means for obtaining a first time offset representative of a difference between a first offset from true GPS time of the clock of the first base station and a second offset from true GPS time of the clock of the second base station;(d) means for generating a first set of residuals of differential navigation equations associated with a first baseline (R-B1) between the rover station and the first base station, the residuals being related to the measured satellite navigation data received by the rover station and the first base station, the locations of the satellites, and the locations of the rover station and the first base station;(e) means for generating a second set of residuals of differential navigation equations associated with a second baseline (R-B2) between the rover station and the second base station, the residuals being related to the measured satellite navigation data received by the rover station and the second base station, the locations of the satellites, and the locations of the rover station and the second base station;and (f) means for substituting, within the second set of residuals, an unknown time offset associated with the second baseline (R-B2) with a value composed of a sum of the first time offset and a time offset associated with the first baseline (R-B1);and (g) means for generating , subsequent to the substitution of step (f), an estimate of the rover station's location from the first set of residuals, the second set of residuals and the first time offset.
  27. 30
    The apparatus of Claim 29 further comprising:(h) means for receiving the location of a third base station;(i) means for receiving measured satellite navigation data as received by the third base station;(j) means for obtaining a second time offset representative of the difference between the first offset from true GPS time of the clock of the first base station and a third offset from true GPS time of the clock of the third base station;(k) means for generating a third set of residuals of differential navigation equations associated with a third baseline (R-B3) between the rover station and the third base station, the residuals being related to the satellite navigation data received by the rover station and the third base station, the locations of the satellites, and the locations of the rover station and the third base station;(1) means for substituting, within the third set of residuals, an unknown time offset associated with the third baseline (R-B3) with a value composed of a sum of the second time offset and a time associated with the first baseline (R-B1);and wherein the means (g) for generating, subsequent to the substitution step of (1), the estimate of the rover station's location generates the estimate further from the third set of residuals and the second time offset.
  28. 31
    The apparatus of Claim 29 wherein the means (c) for obtaining the first time offset comprises means for generating the first time offset.
  29. 32
    The apparatus of Claim 30 wherein the means (c) for obtaining the first time offset comprises means for generating the first time offset and wherein the means (j) for obtaining the second time offset comprises means for generating the second time offset.
  30. 33
    The apparatus of Claim 32 further comprising means for generating a third time offset representative of the time difference between the second offset from true GPS time of the clock of the second base station and the third offset from true GPS time of the clock of the third base station, and means for comparing the sum of the first time offset, the second time offset, and the third time offset around a loop of the base stations to the value of zero.
  31. 35
    The apparatus of Claim 34 further comprising:means for obtaining a first set of satellite carrier-phase cycle ambiguities associated with the baseline between the first and second base stations;means for generating a second set of carrier-phase-based residuals of differential navigation equations associated with the second baseline (R-B2) between the rover station and the second base station, the second set of carrier-phase-based residuals being related to at least the measured satellite carrier-phase data received by the rover station and the second base station, the locations of the satellites, and the locations of the rover station and the second base station;and wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the second set of carrier-phase-based residuals and the first set of satellite-phase cycle ambiguities.
  32. 37
    The apparatus of Claim 32 further comprising means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals and at least one of the sets of residuals based on pseudo-range data;and wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of floating ambiguities.
  33. 38
    The apparatus of Claim 34 further comprising:means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals and at least one of the sets of residuals based on pseudo-range data;and means for generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of fixed-integer floating ambiguities.
  34. 39
    The apparatus of Claim 35 further comprising:means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of floating ambiguities.
  35. 40
    The apparatus of Claim 35 further comprising:means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;and means for generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of fixed-integer floating ambiguities.
  36. 41
    The apparatus of Claim 36 further comprising:means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, the third set of carrier-phase-based residuals, the second set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of floating ambiguities.
  37. 42
    The apparatus of Claim 36 further comprising:means for generating a first set of floating ambiguities for the baseline between the rover station and first base station from the first set of carrier-phase-based residuals, the second set of carrier-phase-based residuals, the first set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, the third set of carrier-phase-based residuals, the second set of satellite carrier-phase cycle ambiguities related to the baseline between the first and second base stations, and at least one of the sets of residuals based on pseudo-range data;and means for generating a first set of fixed-integer floating ambiguities for the baseline between the rover station and first base station from the first set of floating ambiguities;wherein the means (g) for generating the estimate of the rover station's location generates the estimate further from the first set of fixed-integer floating ambiguities.
  38. 43
    The apparatus according to any of the above claims 29 - 42 further comprising:means for obtaining a first set of first ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and second base stations, and means for generating corrections to one or more of the residuals, the corrections being related to the first set of first ionosphere delay differentials, the locations of the first and second base stations, and an estimated location of the rover station;and means for modifying said one or more of the residuals with said corrections.
  39. 45
    The apparatus of Claim 44 wherein the correction to the residuals associated with satellite "s" in one or both of the second set of residuals and the second set of carrier-phase-based residuals is related to the quantity Δ 2 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 2 , 1 I k s is the first ionosphere delay differential associated with satellite "s", and Δ 1 , 0 I ˜ k s is an estimated ionosphere delay differential associated with satellite "s" along the baseline between the rover station and first base station.
  40. 46
    The apparatus of Claim 44 wherein the correction to the residuals associated with satellite "s" in one or both of the third set of residuals and the third set of carrier-phase-based residuals is related to the quantity Δ 3 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 3 , 1 I k s is the second ionosphere delay differential associated with satellite "s", and Δ 1 , 0 I ˜ k s is an estimated ionosphere delay differential associated with satellite "s" along the baseline between the rover station and first base station.
  41. 47
    The apparatus of Claim 44 wherein the ionosphere delay differential from the first set and associated with satellite "s" may be denoted as Δ 1 , 2 I k s , wherein the ionosphere delay differential from the second set and associated with satellite "s" may be denoted as Δ 1 , 3 I k s , wherein the locations of the first, second, and third base stations may be represented by the vectors X 1 , X 2 , and X 3 , and wherein the estimated location of the rover station may be represented as X 0 ,k , wherein the corrections to one or more of the residuals associated with satellite "s" are related to a quantity Δ 1 , 0 I ˜ k s , where Δ 1 , 0 I ˜ k s = α Δ 1 , 2 I k s + β Δ 1 , 3 I k s , wherein α and β are constants that satisfy the relationships:X ‾ 0 , k − X 1 n = α X 2 − X 1 n + β X 3 − X 1 n X ‾ 0 , k − X 1 e = α X 2 − X 1 e + β X 3 − X 1 e where notation { * } n denotes the component of the bracketed quantity along the north direction, where notation { * } e denotes the component of the bracketed quantity along the east direction.
  42. 48
    The apparatus of Claim 44 wherein the correction to the residuals associated with satellite "s" in one or both of the second set of residuals and the second set of carrier-phase-based residuals is related to the quantity Δ 2 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 2 , 1 I k s is the first ionosphere delay differential associated with satellite "s".
  43. 49
    The apparatus of Claim 44 wherein the correction to the residual associated with satellite "s" in one or both of the third set of residuals and the third set of carrier-phase-based residuals is related to the quantity Δ 3 , 1 I k s + Δ 1 , 0 I ˜ k s , where Δ 3 , 1 I k s is the second ionosphere delay differential associated with satellite "s".
  44. 50
    The apparatus according to Claim 43 further comprising:means for modifying one or more of the above residuals to be dependent upon second order effects in the ionosphere delay corrections applied to the baselines associated with the rover station, and means for generating an estimate of the second order effects, and wherein the means (i) for generating the estimate of the rover station's location generates the estimate further from the estimated second order effects.
  45. 51
    The apparatus according to Claim 43 wherein the apparatus generates the first set of first ionosphere delay differentials and the second set of second ionosphere delay differentials from at least the navigation data that it receives from the base stations.
  46. 52
    The apparatus according to Claim 43 further comprising:means for generating an initial estimate of the first set of first ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and second base stations;means for generating an initial estimate of second set of second ionosphere delay differentials associated with the satellite signals received along the baseline formed by the first and third base stations;means for generating an initial estimate of a third set of third ionosphere delay differentials associated with the satellite signals received along the baseline formed by the second and third base stations;and means for generating final estimates of the ionosphere delay differentials such that the sum of the final estimates of the first, second, and third ionosphere delay differentials for at least one satellite "s" around a loop of the base stations is substantially zero.
  47. 53
    The apparatus of Claim 35 wherein the means for obtaining the first set of satellite carrier-phase cycle ambiguities comprises means for generating the first set of satellite carrier-phase cycle ambiguities from at least the locations of the base stations, and measured satellite navigation data as received by the base stations.
  48. 54
    The apparatus of Claim 36 wherein the means for obtaining the first and second sets of satellite carrier-phase cycle ambiguities comprises means for generating the first set of satellite carrier-phase cycle ambiguities from at least the locations of the first and second base stations and measured satellite navigation data as received by the first and second base stations, and means for generating the second set of satellite carrier-phase cycle ambiguities from at least the locations of the first and third base stations and measured satellite navigation data as received by the first and third base stations.
Independent claims48