Transfer of calibrated time information in a mobile terminal

• US 20070066231A1
• Filed: 07/25/2006
• Published: 03/22/2007
• Est. Priority Date: 01/26/2004
• Status: Active Grant

• Current Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Original Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Inventors: Pratt, Anthony, Duffett-Smith, Peter, Bartlett, David
• Granted Patent: US 7,852,267 B2
• Time in Patent Office: Days
• US Class Current: 455/67.110
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements

Abstract

A method of and system for calibrating un-calibrated time information within a mobile terminal 101 is disclosed. The terminal has a receiver 203 capable of receiving signals from which calibrated time information carried by a calibrated system (a satellite positioning system) can be extracted, and a receiver 200 capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system (a cellular communications system) may be extracted. The time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system is determined at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available. The un-calibrated time information extracted from signals of the un-calibrated stable system received at a second terminal position is calibrated from known or determined travel times of the signals from the un-calibrated stable system at the second terminal position and the time offset which has been determined.

Claims

1. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted, the method comprising the steps of

at a first terminal position where the signals from the un-calibrated stable system are available and the signals from the calibrated system are available, determining, within the terminal, first travel times of the signals from the un-calibrated stable system and the time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system;

and

at a second terminal position, where calibrated time information is not available, determining, within the terminal, second travel times of the signals from the un-calibrated stable system; and

calibrating un-calibrated time information, extracted from signals of the un-calibrated stable system using said first and second travel times and the time offset determined at the first terminal position.

3. A method according to claim 1, in which the travel times of the signals received by the terminal from the un-calibrated stable system are deduced from the timing advance or the round trip travel time values of the signals received by the terminal from the un-calibrated stable system.

4. A method according to claim 1, in which the travel times of the signals received by the terminal from the un-calibrated stable system are calculated from the relative positions of the terminal and the un-calibrated stable system.

5. A method according to claim 4, in which the position of the un-calibrated stable system is obtained from a database.

6. A method according to claim 4, in which the position of the un-calibrated stable system is decoded from signals received by the terminal from the un-calibrated stable system.

7. A method according to claim 4, in which the position of the terminal is calculated using measurements of the signals received by the terminal from the un-calibrated stable system.

8. A method according to claim 1, for use within a mobile terminal capable of receiving signals from transmission sources in a terrestrial network and from the satellites of a satellite positioning system having a time-base, wherein the calibrated time information is carried by a synchronisation marker, further comprising the steps of

at a preliminary terminal position, measuring the relative offsets in time, phase or frequency with respect to a first reference, of the signals received by the terminal from a plurality of the transmission sources in the terrestrial network;

at the first terminal position, measuring the relative offsets in time, phase or frequency with respect to a second reference, of the signals received by the terminal from the same transmission sources;

calculating the transmission time offsets, relative to a third reference, of the signals transmitted by the transmission sources and received by the terminal;

constructing a list of the relative transmission time offsets;

calculating the first terminal position;

wherein the time offset is determined between the third reference and the time-base of the satellite positioning system; and

at the second terminal position when satellite time-base time information is required to be determined, measuring the relative offsets in time, phase or frequency with respect to the third reference of the signals received by the terminal from at least three of said plurality of the transmission sources in the terrestrial network, determining the second position of the terminal; and

creating the synchronisation marker with respect to the satellite positioning system time-base using one or more members of the list of transmission time offsets, said second terminal position, and said time offset between the third reference and the time base of the satellite positioning system.

10. A method according to claim 1, wherein the mobile terminal is assisted by a server connected to the terminal via a communications link, the server carrying out the computations necessary for the extraction, of the un-calibrated time information from the un-calibrated stable system.

12. A method according to claim 8, wherein one or more of said references is a signal received by a receiver.

13. A method according to claim 8, wherein one or more of said references is a signal locally generated in the mobile terminal.

14. A method according to claim 1, in which the mobile terminal is assisted by a server connected to the terminal via a communications link, the server carrying out the computations necessary for the extraction of the un-calibrated time information from the un-calibrated stable system, for use within a mobile terminal capable of receiving signals from transmission sources in a terrestrial network and from the satellites of a satellite positioning system having a time-base, wherein the calibrated time information is carried by a synchronisation marker, the method further comprising the steps of

at a first terminal position, measuring the relative offsets in time, phase or frequency, of the signals received by the terminal from a plurality of the transmission sources in the terrestrial network;

sending said measurements to a computing node;

calculating the first terminal position;

calculating the transmission time offsets, relative to a reference, of the signals transmitted by the transmission sources and received by the terminal;

adjusting the transmission time offsets for the transmission delays to the calculated first terminal position of the signals from the respective transmission sources;

constructing a first list of the adjusted relative transmission time offsets;

sending said first list of adjusted relative transmission time offsets to the terminal;

wherein the time offset is determined between the reference and the time-base of the satellite positioning system;

at a second terminal position when satellite time-base time information is required to be determined, measuring the relative offsets in time, phase or frequency, of the signals received by the terminal from a plurality of the transmission sources in the terrestrial network, at least a one of which transmission sources was measured at the first terminal position;

sending said measurements to a computing node;

calculating the second terminal position;

calculating the transmission time offsets, relative to the reference, of the signals transmitted by the transmission sources and received by the terminal;

adjusting the transmission time offsets for the transmission delays of the signals from the respective transmission sources to the calculated second terminal position;

constructing a second list of the adjusted relative transmission time offsets;

sending said second list of adjusted relative transmission time offsets to the terminal; and

creating the synchronisation marker with respect to the satellite positioning system time-base using one or more said members of each of said first and second lists of adjusted transmission time offsets, and said time offset between the reference and the time-base of the satellite positioning system.

35. A medium carrying a set of instructions which, when loaded into a mobile terminal containing satellite positioning system components, enables the terminal to carry out the method according to claim 1.

38. A method of determining the position of a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted in order to determine the position of the mobile terminal, wherein the calibrated time information is calibrated in accordance with the method of claim 1.

39. A method according to claim 1, wherein the un-calibrated stable system comprises a clock running inside the mobile terminal.

2. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by first and second un-calibrated stable systems may be extracted, the method comprising the steps of

at a first terminal position where the signals from the first un-calibrated stable system are available and the signals from the calibrated system are available, determining, within the terminal, first travel times of the signals from the first un-calibrated stable system and a first time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the first un-calibrated stable system;

at a second terminal position where the signals from the first and second un-calibrated stable systems are available, determining, within the terminal, second travel times of the signals from the first un-calibrated stable system, third travel times of the signals from the second un-calibrated stable system, and a second time offset between un-calibrated time information extracted from the first un-calibrated stable system and un-calibrated time information extracted from the second un-calibrated stable system; and

at a third terminal position, where calibrated time information from the calibrated system is not available, determining, within the terminal, fourth travel times of the signals from the second un-calibrated stable system, and calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system using said first, second, third and fourth travel times and said first and second determined time offsets.

9. A method according to claim 2, for use within a mobile terminal capable of receiving signals from transmission sources in a terrestrial network and from the satellites of a satellite positioning system having a time-base, wherein the calibrated time information is carried by a synchronisation marker, further comprising the steps

at a preliminary terminal position, measuring the relative offsets in time, phase or frequency with respect to a first reference, of the signals received by the terminal from a plurality of the transmission sources in the terrestrial network;

at the first terminal position, measuring the relative offsets in time, phase or frequency with respect to a second reference, of the signals received by the terminal from the same transmission sources;

calculating the transmission time offsets, relative to a third reference, of the signals transmitted by the transmission sources and received by the terminal;

constructing a list of the relative transmission time offsets;

calculating the first terminal position;

wherein the time offset is determined between the third reference and the time-base of the satellite positioning system;

at the second terminal position, where the signals from the satellite positioning system are impaired or not available, measuring the relative offsets in time, phase or frequency with respect to a fourth reference, of the signals received by the terminal from at least one of the same and other transmission sources in the terrestrial network;

calculating the transmission time offsets, relative to a fifth reference, of the signals transmitted by the transmission sources and received by the terminal;

constructing a list of the relative transmission time offsets;

calculating the second terminal position;

wherein the time offset is determined between the fifth reference and the third reference; and

at the third terminal position when satellite time-base time information is required to be determined, measuring the relative offsets in time, phase or frequency with respect to the fifth reference of the signals received by the terminal from at least three of the transmission sources in the terrestrial network, determining the third position of the terminal, and creating the synchronisation marker with respect to the satellite positioning system time-base using one or more members of the list of transmission time offsets, said second terminal, position, said third terminal position, said time offset between the fifth and third references, and said time;

offset between the third reference and the time-base of the satellite positioning system.

11. A method according to claim 9 wherein any two or more of the first, second, third, fourth and fifth references are the same reference.

15. A system for calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted, the system comprising

means for determining the travel times of the signals from the un-calibrated stable system to the terminal;

time offset determination means for determining the time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system at a first terminal position where the signals from the un-calibrated stable system are available, and the signals from the calibrated system are available; and

calibration means for calibrating un-calibrated time information, extracted from signals of the un-calibrated stable system, using travel times of the signals from the un-calibrated stable system determined at the first and second terminal positions and the time offset determined at the first position.

17. A system according to claim 15, including a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted.

18. A system according to claim 17, wherein the mobile terminal includes a first receiver capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted and a second receiver capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted.

19. A system according to claim 17, wherein the mobile terminal further includes a third receiver capable of receiving signals from which un-calibrated time information carried by a second un-calibrated stable system may be extracted.

20. A system according to claim 15, wherein the time offset determination means is disposed within a mobile terminal of a satellite positioning system.

21. A system according to claim 15, wherein the calibration means is disposed within a mobile terminal of a satellite positioning system.

22. A system according to claim 15, wherein the calibrated system comprises a clock disposed in the mobile terminal.

23. A system according to claim 15, wherein the calibrated system comprises one or more satellites of a satellite positioning system.

24. A system according to claim 15, wherein the un-calibrated system comprises one or more transmitters of a radio system.

25. A system according to claim 24, wherein the one or more transmitters comprise transmitters of a broadcast system.

26. A system according to claim 24, wherein the one or more transmitters comprise transmitters of a communications system.

27. A system according to claim 15, wherein the travel times of the signals received by the terminal from the un-calibrated stable system are deduced from the timing advance or the round trip travel time values of the signals received by the terminal from the un-calibrated stable system.

28. A system according to claim 15, in which the travel times of the signals received by the terminal from the un-calibrated stable system are calculated from the relative positions of the terminal and the un-calibrated stable system.

29. A system according to claim 28, in which the position of the un-calibrated stable system is obtained from a database.

30. A system according to claim 29, wherein the database is maintained within the mobile terminal.

31. A system according to claim 29, wherein the database is maintained within a server to which the mobile terminal can be connected in use.

32. A system according to claim 28, in which the position of the un-calibrated stable system is decoded from signals received by the terminal from the un-calibrated stable system.

33. A system according to claim 28, in which the position of the terminal is calculated using measurements of the signals received by the terminal from the un-calibrated stable system.

34. A system according to claim 15, wherein the un-calibrated stable system comprises a clock running inside the mobile terminal.

16. A system for calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by first and second un-calibrated stable systems may be extracted, the system comprising

means for determining the travel times of the signals from the un-calibrated stable systems to the terminal;

time offset determination means for determining a first time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the first un-calibrated stable system at a first terminal position where the signals from the first un-calibrated stable system are available and the signals from the calibrated system are available;

time offset determination means for determining a second time offset between un-calibrated time information extracted from the first un-calibrated stable system and un-calibrated time information extracted from the second un-calibrated stable system at a second terminal position where the signals from the first and second un-calibrated stable systems are available; and

calibration means for calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system, at a third terminal position, using the travel times of the signals from the un-calibrated stable systems received at the first, second and third terminal positions, and said first and second determined time offsets.

36. A mobile terminal of a satellite positioning system, the terminal including

means for determining the travel times of the signals from an un-calibrated stable system to the terminal;

time offset determination means for determining the time offset between calibrated time information extracted from the satellite positioning system and un-calibrated time information extracted from the un-calibrated stable system at a first terminal position where the signals from the un-calibrated stable system are available, and the signals from the satellite positioning system are available; and

calibration means for calibrating un-calibrated time information, extracted from signals of the un-calibrated stable system received at a second terminal position, from the travel times of the signals from the un-calibrated stable system determined at the first and second terminal positions and said time offset determined at the first terminal position.

37. A mobile terminal of a satellite positioning system, the terminal including

means for determining the travel times of the signals from un-calibrated stable systems to the terminal;

time offset determination means for determining, at a first terminal position where the signals from the first un-calibrated stable system are available and the signals from the satellite positioning system are available, the time offset between calibrated time information extracted from the satellite positioning system and un-calibrated time information extracted from a first un-calibrated stable system; and

time offset determination means for determining, at a second terminal position where the signals from the un-calibrated stable systems are available, a second time offset between un-calibrated time information extracted from the first un-calibrated system and un-calibrated time information extracted from the second un-calibrated stable system; and

calibration means for calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system, received at a third terminal position, from the travel times of the signals from the un-calibrated stable systems received at the first, second and third terminal positions, and said first and second determined time offsets.

40. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted, the method comprising the steps of

determining the time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available;

and

calibrating un-calibrated time information, extracted from signals of the un-calibrated stable system received at a second terminal position, from known or determined travel times of the signals from the un-calibrated stable system at the second terminal position and said determined time offset.

41. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted and capable of receiving signals from which un-calibrated time information carried by first and second un-calibrated stable systems may be extracted, the method comprising the steps of

determining a first time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the first un-calibrated stable system at a first terminal position where the signals from the first un-calibrated stable system are available, the travel times of the signals from the first un-calibrated stable system are known or determined, and the signals from the calibrated system are available;

determining a second time offset between un-calibrated time information extracted from the first un-calibrated system and un-calibrated time information extracted from the second un-calibrated stable system at a second terminal position where the signals from the first and second un-calibrated stable systems are available, and the travel times of the signals from the first and second un-calibrated stable systems are known or determined; and

calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system received at a third terminal position, from known or determined travel times of the signals from the second un-calibrated stable system at the third terminal position and said first and second determined time offsets.

42. A system for calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system may be extracted, the system comprising

time offset determination means for determining the time offset between calibrated time information extracted from the calibrated, system and un-calibrated time information extracted from the un-calibrated stable system at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available;

and

calibration means for calibrating un-calibrated time information, extracted from signals, of the un-calibrated stable system received at a second terminal position, from known or determined travel times of the signals from the un-calibrated stable system at the second terminal position and said determined time offset.

43. A system for calibrating un-calibrated time information within a mobile terminal having one or more receivers capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and capable of receiving signals from which un-calibrated time information carried by first and second un-calibrated stable systems may be extracted, the system comprising

time offset determination means for determining a first time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the first un-calibrated stable system at a first terminal position where the signals from the first un-calibrated stable system are available, the travel times of the signals from the first un-calibrated stable system are known or determined, and the signals from the calibrated system are available;

time offset determination means for determining a second time offset between un-calibrated time information extracted from the first un-calibrated system and un-calibrated time information extracted from the second un-calibrated stable system at a second terminal position where the signals from the first and second un-calibrated stable systems are available, and the travel times of the signals from the first and second un-calibrated stable systems are known or determined; and

calibration means for calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system received at a third terminal position, from known or determined travel times of the signals from the second un-calibrated stable system at the third terminal position and said first and second determined time offsets.

44. A mobile terminal of a satellite positioning system, the terminal including

time offset determination means for determining the time offset between calibrated time information extracted from the satellite positioning system and un-calibrated time information extracted from an un-calibrated stable system at a first terminal position;

where the signals;

from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the satellite positioning system are available; and

calibration means for calibrating un-calibrated time information, extracted from signals of the un-calibrated stable system received at a second terminal position, from known or determined travel times of the signals from the un-calibrated stable, system at the second terminal position and said determined time offset.

45. A mobile terminal of a satellite positioning system, the terminal including

time offset determination means for determining the time offset between calibrated time information extracted from the satellite positioning system and un-calibrated time information extracted from a first un-calibrated stable system at a first terminal position where the signals from the first un-calibrated stable system are available, the travel times of the signals from the first un-calibrated stable system are known or determined, and the signals from the satellite positioning system are available;

and

time offset determination means for determining a second time offset between un-calibrated time information extracted from the first un-calibrated system and un-calibrated time information extracted from the second un-calibrated stable system at a second terminal position where the signals from the first and second un-calibrated stable systems are available, and the travel times of the signals from the first and second un-calibrated stable systems are known or determined; and

calibration means for calibrating un-calibrated time information, extracted from signals of the second un-calibrated stable system received at a third terminal position, from known or determined travel times of the signals from the second un-calibrated stable system at the third terminal position and said first and second determined time offsets.