Associating a universal time with received signal

• US 7,978,136 B2
• Filed: 03/13/2007
• Issued: 07/12/2011
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Original Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Inventors: Hansen, Paul, Pratt, Anthony Richard, Duffett-Smith, Peter James
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): MCGUE, FRANK J
• Application Number:
  US12/225,860
• Publication Number:
  US 20090273518A1
• Time in Patent Office: 1,582 Days
• Field of Search: 342/360, 342/387
• US Class Current: 342/387
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements

Abstract

A method of associating a universal time with time of arrival information of an identified component of a signal at a terminal of a radio positioning system is disclosed. In the method a marker signal with an associated universal time tag is obtained from a timing device (or the marker signal is obtained from an independent oscillator and a universal time tag assigned to the marker signal), and the time or phase relationship between the marker signal (or between the time of arrival information of said identified component respectively) and the oscillator is measured. The time of arrival information of said identified component relative to the oscillator is determined and the universal time corresponding to the time of arrival information of said identified component is calculated from said universal time tag and said measured time or phase relationship, before the calculated universal time is associated with said time of arrival information.

Claims

1. A method of associating a universal time with time of arrival information of an identified component of a signal at a terminal of a radio positioning system, the method comprising the steps of

obtaining a marker signal with an associated universal time tag from a timing device;

measuring the timing relationship between the marker signal and an independent oscillator that is independent of the timing device;

determining time of arrival information of said identified component relative to the independent oscillator;

calculating the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said measured timing phase relationship; and

associating the calculated universal time with said time of arrival information.

3. A method according to claim 1 or claim 2, wherein the time of arrival information is the instant of reception or a delayed time corresponding to the instant when the identified component is detected.

4. A method according to claim 1 or claim 2, wherein the time of arrival information relates to the predicted future time of arrival of an identified component of the received signal.

5. A method according to claim 1 or claim 2, wherein a plurality of measurements of time of arrival information are combined to produce a better estimate of a future, current, or past event.

6. A method according to claim 1 or claim 2, wherein the marker signal is an identifiable transition, such as the arrival of a data word or a change in state of a binary logic device, or a flag in a software program running on a processor, or the point at which at least one particular analogue value is reached in a phase-measuring device.

7. A method according to claim 1 or claim 2, wherein the universal time tag associated with a marker signal generated by the timing device specifies the universal time of the marker itself.

8. A method according to claim 1 or claim 2, wherein the tag is a message or a data word sent between software programs running on one or more processors.

9. A method according to claim 1 or claim 2, wherein the tag is obtained from a register or a clock kept in alignment with the universal time by the timing device.

10. A method according to claim 1 or claim 2, wherein the time-tag specifies a universal time which is incorrect and the error in the time marker is determined in the case in which the universal time of the receipt of the identified component is already known.

11. A method according to claim 1 or claim 2, wherein the marker signal is measured relative to the phase of the independent oscillator.

12. A method according to claim 11, wherein the phase is determined by the use of a counter triggered by the independent oscillator.

13. A method of finding the position of a terminal of a communications network which includes the method of claim 1 or claim 2.

2. A method of associating a universal time with time of arrival information of an identified component of a signal, the method comprising the steps of

obtaining a marker signal from an independent oscillator;

assigning a universal time tag from a timing device to the marker signal, the independent oscillator being independent of the timing device;

determining time of arrival information of said identified component relative to the independent oscillator;

calculating the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said determined relative time of arrival information; and

associating the calculated universal time with said time of arrival information.

14. A method of associating a universal time with time of arrival information of an identified component of a signal at a terminal of a radio positioning system, the method comprising the steps of

obtaining a marker signal with an associated universal time tag from a timing device;

measuring the timing relationship between the marker signal and an independent oscillator;

determining time of arrival information of said identified component relative to the independent oscillator;

calculating the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said measured timing phase relationship; and

associating the calculated universal time with said time of arrival information;

wherein two time marker signals and their time tags, separated by an appropriate time interval, are provided by the timing device, the respective difference in the independent oscillator phases or the counter states is then used to calculate the oscillator frequency, and the calculated oscillator frequency used to correct for the error in the estimated time of arrival information.

15. A radio terminal of a radio positioning system, the terminal having

a timing device for generating a marker signal whose universal time is known;

an independent oscillator that is independent of the timing device; and

a processor arranged to obtain the marker signal from the timing device, to measure the timing relationship between the marker signal and the independent oscillator, to determine time of arrival information of said identified component relative to the oscillator, to calculate the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said measured timing phase relationship; and

to associate the calculated universal time with said time of arrival information.

17. A radio terminal according to claim 15 or claim 16, which comprises a terminal of a communications network.

18. A radio terminal according to claim 15 or claim 16, wherein the independent oscillator is a free-running oscillator.

19. A radio terminal according to claim 15 or claim 16, wherein the marker signal is measured relative to the phase of the independent oscillator in the processor.

20. A radio terminal according to claim 19, the processor including a counter triggered by the independent oscillator, to determine the phase.

21. A radio terminal according to claim 20, wherein the counter is a hardware device.

22. A radio terminal according to claim 20, wherein the counter is a software component running in the processor.

16. A radio terminal of a radio positioning system, the terminal having

a timing device generating a universal time-tag;

an independent oscillator that is independent of the timing device; and

a processor arranged to obtain a marker signal from the independent oscillator, to assign the universal time tag to the marker signal, to determine time of arrival information of said identified component relative to the oscillator, to calculate the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said determined relative time of arrival; and

to associate the calculated universal time with said time of arrival information.

23. A method of associating a universal time with time of arrival information of an identified component of a signal, the method comprising the steps of

obtaining a marker signal from an independent oscillator;

assigning a universal time tag to the marker signal;

determining time of arrival information of said identified component relative to the independent oscillator;

calculating the universal time corresponding to the time of arrival information of said identified component from said universal time tag and said determined relative time of arrival information; and

associating the calculated universal time with said time of arrival information;

wherein two time marker signals and their time tags, separated by an appropriate time interval, are provided by the timing device, the respective difference in the independent oscillator phases or the counter states is then used to calculate the oscillator frequency, and the calculated oscillator frequency used to correct for the error in the estimated time of arrival information.