Position location using broadcast analog television signals

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

a receiver adapted to receive, at the user terminal, a broadcast analog television signal; and

a pseudorange unit adapted to generate a pseudorange based on the broadcast analog television signal; and wherein

the location of the user terminal is determined based on the pseudorange and a location of the transmitter of the broadcast analog television signal.

2. The apparatus of claim 1 , further comprising:

a processor adapted to determine the location of the user terminal based on the pseudorange and the location of the transmitter of the broadcast analog television signal.

3. The apparatus of claim 1 , wherein the pseudorange unit is further adapted to generate the pseudorange based on a periodic component in the broadcast analog television signal and a predetermined reference signal based on the periodic component.

4. The apparatus of claim 3 , wherein:

the receiver is further adapted to receive parameters describing the predetermined reference signal; and

the processor is further adapted to generate the predetermined reference signal based on the parameters.

5. The apparatus of claim 3 , wherein the periodic component is a horizontal synchronization pulse.

6. The apparatus of claim 3 , wherein:

the receiver is further adapted to receive parameters describing the derivative of the periodic component; and

the processor is further adapted to generate the predetermined reference signal based on the parameters.

7. The apparatus of claim 6 , wherein the periodic component is selected from the group comprising:

a horizontal synchronization pulse;

a horizontal blanking pulse; and

a horizontal blanking pulse and a horizontal synchronization pulse.

8. The apparatus of claim 7 , wherein:

the pseudorange unit is further adapted to generate a second pseudorange based on the broadcast analog television signal and a second predetermined reference signal, wherein the second predetermined reference signal is based on the horizontal synchronization pulse; and

the processor is further adapted to produce a refined pseudorange based on the pseudorange and the second pseudorange; and wherein

the position of the user terminal is determined based on the refined pseudorange and the location of the transmitter of the broadcast analog television signal.

9. The apparatus of claim 1 , wherein the periodic component is a chrominance burst, and wherein the processor is further adapted to resolve ambiguity in the pseudorange resulting from cycle ambiguity in the chrominance burst.

10. The apparatus of claim 1 , wherein the position at the user terminal is determined by adjusting the pseudorange based on a difference between a transmitter clock at the transmitter of the broadcast analog television signal and a known time reference, and determining the position of the user terminal based on the adjusted pseudorange and the location of the transmitter of the broadcast analog television signal.

11. The apparatus of claim 1 , wherein the processor is further adapted to:

determine a further pseudorange based on a further broadcast analog television signal; and

project the pseudorange and the further pseudorange to an instant of time, thereby eliminating any first order term in the clock of the user terminal.

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

means for receiving, at the user terminal, a broadcast analog television signal; and

means for generating a pseudorange based on the broadcast analog television signal; and wherein

the location of the user terminal is determined based on the pseudorange and a location of the transmitter of the broadcast analog television signal.

13. The apparatus of claim 12 , further comprising;

means for determining the location of the user terminal based on the pseudorange and the location of the transmitter of the broadcast analog television signal.

14. The apparatus of claim 12 , wherein the means for generating a pseudorange generates the pseudorange based on a periodic component in the broadcast analog television signal and a predetermined reference signal based on the periodic component.

15. The apparatus of claim 14 , wherein:

the means for receiving receives parameters describing the predetermined reference signal; and

the means for determining generates the predetermined reference signal based on the parameters.

16. The apparatus of claim 14 , wherein the periodic component is a horizontal synchronization pulse.

17. The apparatus of claim 14 , wherein:

the means for receiving receives parameters describing the derivative of the periodic component; and

the means for determining generates the predetermined reference signal based on the parameters.

18. The apparatus of claim 17 , wherein the periodic component is selected from the group comprising:

a horizontal synchronization pulse;

a horizontal blanking pulse; and

a horizontal blanking pulse and a horizontal synchronization pulse.

19. The apparatus of claim 18 , wherein:

the means for generating generates a second pseudorange based on the broadcast analog television signal and a second predetermined reference signal, wherein the second predetermined reference signal is based on the horizontal synchronization pulse; and

the means for determining produces a refined pseudorange based on the pseudorange and the second pseudorange; and wherein

the position of the user terminal is determined based on the refined pseudorange and the location of the transmitter of the broadcast analog television signal.

20. The apparatus of claim 12 , wherein the periodic component is a chrominance burst, wherein,

the means for determining resolves ambiguity in the pseudorange resulting from cycle ambiguity in the chrominance burst.

21. The apparatus of claim 12 , wherein the position of the user terminal is determined by adjusting the pseudorange based on a difference between a transmitter clock at the transmitter of the broadcast analog television signal and a known time reference, and determining the position of the user terminal based on the adjusted pseudorange and the location of the transmitter of the broadcast analog television signal.

22. The apparatus of claim 12 , wherein the means for determining:

determines a further pseudorange based on a further broadcast analog television signal; and

projects the pseudorange and the further pseudorange to an instant of time, thereby eliminating any first order term in the clock of the user terminal.

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

receiving, at the user terminal, a broadcast analog television signal; and

generating a pseudorange based on the broadcast analog television signal; and wherein

the location of the user terminal is determined based on the pseudorange and a location of the transmitter of the broadcast analog television signal.

24. The method of claim 23 , further comprising:

determining the location of the user terminal based on the pseudorange and the location of the transmitter of the broadcast analog television signal.

25. The method of claim 23 , wherein generating the pseudorange comprises:

generating the pseudorange based on a periodic component in the broadcast analog television signal and a predetermined reference signal based on the periodic component.

26. The method of claim 25 , further comprising:

receiving parameters describing the predetermined reference signal; and

generating the predetermined reference signal based on the parameters.

27. The method of claim 25 , wherein the periodic component is a horizontal synchronization pulse.

28. The method of claim 25 , further comprising:

receiving parameters describing the derivative of the periodic component; and

generating the predetermined reference signal based on the parameters.

29. The method of claim 28 , wherein the periodic component is selected from the group comprising:

a horizontal synchronization pulse;

a horizontal blanking pulse; and

a horizontal blanking pulse and a horizontal synchronization pulse.

30. The method of claim 29 , further comprising:

generating a second pseudorange based on the broadcast analog television signal and a second predetermined reference signal, wherein the second predetermined reference signal is based on the horizontal synchronization pulse; and

producing a refined pseudorange based on the pseudorange and the second pseudorange; and wherein

the position of the user terminal is determined based on the refined pseudorange and the location of the transmitter of the broadcast analog television signal.

31. The method of claim 23 , wherein the periodic component is a chrominance burst, further comprising:

resolving ambiguity in the pseudorange resulting from cycle ambiguity in the chrominance burst.

32. The method of claim 23 , wherein the position of the user terminal is determined by adjusting the pseudorange based on a difference between a transmitter clock at the transmitter of the broadcast analog television signal and a known time reference, and determining the position of the user terminal based on the adjusted pseudorange and the location or transmitter of the broadcast analog television signal.

33. The method of claim 23 , further comprising:

determining a further pseudorange based on a further broadcast analog television signal; and

projecting the pseudorange and the further pseudorange to an instant of time, thereby eliminating any first order term in the clock of the user terminal.

34. Computer-readable media embodying instructions executable by a computer to perform a method for determining the position of a user terminal, the method comprising:

receiving, at the user terminal, a broadcast analog television signal; and

generating a pseudorange based on the broadcast analog television signal; and wherein

the location of the user terminal is determined based on the pseudorange and a location of the transmitter of the broadcast analog television signal.

35. The media of claim 34 , wherein the method further comprises:

determining the location of the user terminal based on the pseudorange and the location of the transmitter of the broadcast analog television signal.

36. The media of claim 34 , wherein generating the pseudorange comprises:

generating the pseudorange based on a periodic component in the broadcast analog television signal and a predetermined reference signal based on the periodic component.

37. The media of claim 36 , wherein the method further comprises:

receiving parameters describing the predetermined reference signal; and

generating the predetermined reference signal based on the parameters.

38. The media of claim 36 , wherein the periodic component is a horizontal synchronization pulse.

39. The media of claim 36 , wherein the method further comprises:

receiving parameters describing the derivative of the periodic component; and

generating the predetermined reference signal based on the parameters.

40. The media of claim 39 , wherein the periodic component is selected from the group comprising:

a horizontal synchronization pulse;

a horizontal blanking pulse; and

a horizontal blanking pulse and a horizontal synchronization pulse.

41. The media of claim 40 , wherein the method further comprises:

generating a second pseudorange based on the broadcast analog television signal and a second predetermined reference signal, wherein the second predetermined reference signal is based on the horizontal synchronization pulse; and

producing a refined pseudorange based on the pseudorange and the second pseudorange; and wherein

the position of the user terminal is determined based on the refined pseudorange and the location of the transmitter of the broadcast analog television signal.

42. The media of claim 34 , wherein the periodic component is a chrominance burst, wherein the method further comprises:

resolving ambiguity in the pseudorange resulting front cycle ambiguity in the chrominance burst.

43. The media of claim 34 , wherein the position of the user terminal is determined by adjusting the pseudoranges based on a difference between a transmitter clock at the transmitter of the broadcast analog television signal and a known time reference, and determining the position of the user terminal based on the adjusted pseudorange and the location of the TV transmitter.

44. The media of claim 34 , wherein the method further comprises:

determining a further pseudorange based on a further broadcast analog television signal; and

projecting the pseudorange and the further pseudorange to an instant of time, thereby eliminating any first order term in the clock of the user terminal.