Position location using integrated services digital broadcasting—terrestrial (ISDB-T) broadcast television signals

1. A method for determining the position of a user terminal, comprising:

receiving at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal;

determining a pseudo-range between the user terminal and the DTV transmitter based on a known component in the broadcast DTV signal; and

determining a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

2. The method of claim 1 , wherein determining a position of the user terminal comprises:

adjusting the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

3. The method of claim 1 , wherein the known component is a scattered pilot carrier.

4. The method of claim 1 , wherein determining a position of the user terminal comprises:

determining an offset between a local time reference in the user terminal and a master time reference; and

determining the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

5. The method of claim 4 , further comprising:

determining a subsequent position of the user terminal using the offset.

6. The method of claim 1 , wherein determining a pseudo-range comprises:

storing a portion of the DTV signal; and

subsequently correlating the stored portion and a signal generated by the user terminal to produce the pseudo-range.

7. The method of claim 1 , wherein determining a pseudo-range comprises:

correlating the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

8. The method of claim 1 , wherein determining a position of the user terminal comprises:

determining a general geographic area within which the user terminal is located; and

determining the position of the user terminal based on the pseudo-range and the general geographic area.

9. The method of claim 8 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

10. The method of claim 1 , wherein determining a position of the user terminal comprises:

determining a tropospheric propagation velocity in a vicinity of the user terminal;

adjusting the pseudo-range based on the tropospheric propagation velocity; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

11. The method of claim 1 , wherein determining a position of the user terminal comprises:

adjusting the pseudo-range based on a terrain elevation in a vicinity of the user terminal; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

12. The method of claim 1 , further comprising:

selecting the DTV signal from a plurality of DTV signals based on an identity of an additional transmitter communicably linked to the user terminal and a stored table correlating the additional transmitter and the DTV signals.

13. The method of claim 1 , further comprising:

accepting a location input from a user; and

selecting the DTV signal from a plurality of DTV signals based on the location input.

14. The method of claim 1 , further comprising:

scanning available DTV signals to assemble a fingerprint of the location; and

selecting the DTV signal used to determine the pseudo-range from the available DTV signals based on the fingerprint and a stored table that matches known fingerprints with known locations.

15. The method of claim 1 , further comprising:

using receiver autonomous integrity monitoring (RAIM) to check the integrity of the pseudo-range based on a redundant pseudo-range from the DTV transmitter.

16. A method for determining the position of a user terminal, comprising:

receiving at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal;

determining a pseudo-range between the user terminal and the DTV transmitter based on the DTV broadcast signal; and

transmitting the pseudo-range to a location server configured to determine a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

17. The method of claim 16 , wherein determining a pseudo-range comprises:

determining a time of transmission from the DTV transmitter of a known component of the DTV broadcast signal;

determining a time of reception at the user terminal of the known component; and

determining the difference between the time of transmission and the time of reception.

18. The method of claim 16 , wherein the known component is a scattered pilot carrier.

19. The method of claim 16 , wherein determining a pseudo-range comprises:

storing a portion of the DTV signal; and

subsequently correlating the stored portion and a signal generated by the user terminal to produce the pseudo-range.

20. The method of claim 16 , wherein determining a pseudo-range comprises:

correlating the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

21. A method for determining the position of a user terminal, comprising:

receiving a pseudo-range from a user terminal, the pseudo-range determined between the user terminal and a DTV transmitter based on a DTV signal broadcast by the DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal, and wherein the pseudo-range is determined based on a known component in the ISDB-T signal; and

determining a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

22. The method of claim 21 , wherein determining a position of the user terminal comprises:

adjusting the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

23. The method of claim 21 , wherein the known component is a scattered pilot carrier.

24. The method of claim 21 , wherein determining a position of the user terminal comprises:

determining an offset between a local time reference in the user terminal and a master time reference; and

determining the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

25. The method of claim 24 , further comprising:

determining a subsequent position of the user terminal using the offset.

26. The method of claim 21 , wherein determining a position of the user terminal comprises:

determining a general geographic area within which the user terminal is located; and

determining the position of the user terminal based on the pseudo-range and the general geographic area.

27. The method of claim 26 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

28. The method of claim 21 , wherein determining a position of the user terminal comprises:

determining a tropospheric propagation velocity in a vicinity of the user terminal;

adjusting the pseudo-range based on the tropospheric propagation velocity; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

29. The method of claim 21 , wherein determining a position of the user terminal comprises:

adjusting the pseudo-range based on the terrain elevation in the vicinity of the user terminal; and

determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

30. An apparatus for determining the position of a user terminal, comprising:

means for receiving at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal;

means for determining a pseudo-range between the user terminal and the DTV transmitter based on a known component in the DTV broadcast signal; and

means for determining a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

31. The apparatus of claim 30 , wherein the means for determining a position of the user terminal comprises:

means for adjusting the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

32. The apparatus of claim 31 , wherein the known component is a scattered pilot carrier.

33. The apparatus of claim 30 , wherein the means for determining a position of the user terminal comprises:

means for determining an offset between a local time reference in the user terminal and a master time reference; and

means for determining the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

34. The apparatus of claim 33 , further comprising:

means for determining a subsequent position of the user terminal using the offset.

35. The apparatus of claim 30 , wherein the means for determining a pseudo-range comprises:

means for storing a portion of the DTV signal; and

means for subsequently correlating the stored portion and a signal generated by the user terminal to produce the pseudo-range.

36. The apparatus of claim 30 , wherein the means for determining a pseudo-range comprises:

means for correlating the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

37. The apparatus of claim 30 , wherein the means for determining a position of the user terminal comprises:

means for determining a general geographic area within which the user terminal is located; and

means for determining the position of the user terminal based on the pseudo-range and the general geographic area.

38. The apparatus of claim 37 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

39. The apparatus of claim 30 , wherein the means for determining a position of the user terminal comprises:

means for determining a tropospheric propagation velocity in the vicinity of the user terminal;

means for adjusting the pseudo-range based on the tropospheric propagation velocity; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

40. The apparatus of claim 30 , wherein the means for determining a position of the user terminal comprises:

means for adjusting each pseudo-range based on a terrain elevation in a vicinity of the user terminal; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

41. The apparatus of claim 30 , further comprising:

means for selecting the DTV signal from a plurality of DTV signals based on an identity of an additional transmitter communicably linked to the user terminal and a stored table correlating the additional transmitter and the DTV signals.

42. The apparatus of claim 30 , further comprising:

means for accepting a location input from a user; and

means for selecting the DTV signal from a plurality of DTV signals based on the location input.

43. The apparatus of claim 30 , further comprising:

means for scanning available DTV signals to assemble a fingerprint of the location; and

means for selecting the DTV broadcast signal used to determine the pseudo-range from the available DTV signals based on the fingerprint and a stored table that matches known fingerprints with known locations.

44. The apparatus of claim 30 , further comprising:

means for using receiver autonomous integrity monitoring (RAIM) to check the integrity of the pseudo-range based on a redundant pseudo-range from the DTV transmitter.

45. An apparatus for determining the position of a user terminal, comprising:

means for receiving at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal;

means for determining a pseudo-range between the user terminal and the DTV transmitter based on a known component in the DTV broadcast signal; and

means for transmitting the pseudo-range to a location server configured to determine a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

46. The apparatus of claim 45 , wherein the means for determining a pseudo-range comprises:

means for determining a time of transmission from the DTV transmitter of a component of the DTV broadcast signal;

means for determining a time of reception at the user terminal of the component; and

means for determining the difference between the time of transmission and the time of reception.

47. The apparatus of claim 45 , wherein the component is a scattered pilot carrier.

48. The apparatus of claim 45 , wherein the means for determining a pseudo-range comprises:

means for storing a portion of the DTV signal; and

means for subsequently correlating the stored portion and a signal generated by the user terminal to produce the pseudo-range.

49. The apparatus of claim 45 , wherein the means for determining a pseudo-range comprises:

means for correlating the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

50. An apparatus for determining the position of a user terminal, comprising:

means for receiving a pseudo-range from a user terminal, the pseudo-range determined between the user terminal and a DTV transmitter based on a DTV signal broadcast by the DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal, and wherein the pseudo-range is determined based on a known component in the DTV signal; and

means for determining a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

51. The apparatus of claim 50 , wherein the means for determining a position of the user terminal comprises:

means for adjusting the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

52. The apparatus of claim 50 , wherein the known component is a scattered pilot carrier.

53. The apparatus of claim 50 , wherein the means for determining a position of the user terminal comprises:

means for determining an offset between a local time reference in the user terminal and a master time reference; and

means for determining the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

54. The apparatus of claim 53 , further comprising:

means for determining a subsequent position of the user terminal using the offset.

55. The apparatus of claim 50 , wherein the means for determining a position of the user terminal comprises:

means for determining a general geographic area within which the user terminal is located; and

means for determining the position of the user terminal based on the pseudo-range and the general geographic area.

56. The apparatus of claim 55 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

57. The apparatus of claim 50 , wherein the means for determining a position of the user terminal comprises:

means for determining a tropospheric propagation velocity in a vicinity of the user terminal;

means for adjusting the pseudo-range based on the tropospheric propagation velocity; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

58. The apparatus of claim 50 , wherein the means for determining a position of the user terminal comprises:

means for adjusting the pseudo-range based on the terrain elevation in the vicinity of the user terminal; and

means for determining the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

59. A computer program product, tangibly stored on a computer-readable medium, for determining the position of a user terminal, comprising instructions operable to cause a programmable processor to:

receive at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal;

determine a pseudo-range between the user terminal and the DTV transmitter based on a known component in the DTV broadcast signal; and

determine a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

60. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

adjust the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

61. The computer program product of claim 59 , wherein the known component is a scattered pilot carrier.

62. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

determine an offset between a local time reference in the user terminal and a master time reference; and

determine the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

63. The computer program product of claim 62 , further comprising instructions operable to cause a programmable processor to:

determine a subsequent position of the user terminal using the offset.

64. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a pseudo-range comprise instructions operable to cause a programmable processor to:

store a portion of the DTV signal; and

subsequently correlate the stored portion and a signal generated by the user terminal to produce the pseudo-range.

65. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a pseudo-range comprise instructions operable to cause a programmable processor to:

correlate the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

66. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

determine a general geographic area within which the user terminal is located; and

determine the position of the user terminal based on the pseudo-range and the general geographic area.

67. The computer program product of claim 66 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

68. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to

determine a tropospheric propagation velocity in a vicinity of the user terminal;

adjust the pseudo-range based on the tropospheric propagation velocity; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

69. The computer program product of claim 59 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

adjust the pseudo-range based on the terrain elevation in the vicinity of the user terminal; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

70. The computer program product of claim 59 , further comprising instructions operable to cause a programmable processor to:

select the DTV signal from a plurality of DTV signals based on an identity of an additional transmitter communicably linked to the user terminal and a stored table correlating the additional transmitter and the DTV signals.

71. The computer program product of claim 59 , further comprising instructions operable to cause a programmable processor to:

accept a location input from a user; and

select the DTV signal from a plurality of DTV signals based on the location input.

72. The computer program product of claim 59 , further comprising instructions operable to cause a programmable processor to:

scan available DTV signals to assemble a fingerprint of the location; and

select the DTV broadcast signal used to determine the pseudo-range from the available DTV signals based on the fingerprint and a stored table that matches known fingerprints with known locations.

73. The computer program product of claim 59 , further comprising instructions operable to cause a programmable processor to:

use receiver autonomous integrity monitoring (RAIM) to check the integrity of the pseudo-range based on a redundant pseudo-range from the DTV transmitter.

74. A computer program product, tangibly stored on a computer-readable medium, for determining the position of a user terminal, comprising instructions operable to cause a programmable processor to:

receive at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal;

determine a pseudo-range between the user terminal and the DTV transmitter based on a known component in the DTV broadcast signal; and

transmit the pseudo-range to a location server configured to determine a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

75. The computer program product of claim 74 , wherein the instructions operable to cause a programmable processor to determine a pseudo-range comprise instructions operable to cause a programmable processor to:

determine a time of transmission from the DTV transmitter of a component of the DTV broadcast signal;

determine a time of reception at the user terminal of the component; and

determining the difference between the time of transmission and the time of reception.

76. The computer program product of claim 74 , wherein the component is a scattered pilot carrier.

77. The computer program product of claim 74 , wherein the instructions operable to cause a programmable processor to determine a pseudo-range comprise instructions operable to cause a programmable processor to:

store a portion of the DTV signal; and

subsequently correlate the stored portion and a signal generated by the user terminal to produce the pseudo-range.

78. The computer program product of claim 74 , wherein the instructions operable to cause a programmable processor to determine a pseudo-range comprise instructions operable to cause a programmable processor to:

correlate the DTV signal with a signal generated by the user terminal as the DTV signal is received to produce the pseudo-range.

79. A computer program product, tangibly stored on a computer-readable medium, for determining the position of a user terminal, comprising instructions operable to cause a programmable processor to:

receive a pseudo-range from a user terminal, the pseudo-range determined between the user terminal and a DTV transmitter based on a DTV signal broadcast by the DTV transmitter, wherein the DTV signal comprises a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (ISDB-T) signal, and wherein the pseudo-range is determined based on a known component in the DTV signal; and

determine a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

80. The computer program product of claim 79 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

adjust the pseudo-range based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

81. The computer program product of claim 79 , wherein the known component is a scattered pilot carrier.

82. The computer program product of claim 79 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

determine an offset between a local time reference in the user terminal and a master time reference; and

determine the position of the user terminal based on the pseudo-range, the location of the DTV transmitter, and the offset.

83. The computer program product of claim 82 , further comprising instructions operable to cause a programmable processor to:

determine a subsequent position of the user terminal using the offset.

84. The computer program product of claim 79 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

determine a general geographic area within which the user terminal is located; and

determine the position of the user terminal based on the pseudo-range and the general geographic area.

85. The computer program product of claim 84 , wherein the general geographic area is a footprint of an additional transmitter communicably linked to the user terminal.

86. The computer program product of claim 79 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

determine a tropospheric propagation velocity in the vicinity of the user terminal;

adjust the pseudo-range based on the tropospheric propagation velocity; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.

87. The computer program product of claim 79 , wherein the instructions operable to cause a programmable processor to determine a position of the user terminal comprise instructions operable to cause a programmable processor to:

adjust the pseudo-range based on the terrain elevation in the vicinity of the user terminal; and

determine the position of the user terminal based on the adjusted pseudo-range and the location of the DTV transmitter.