Automatic synchronous tuning of narrowband receivers of a wireless location system for voice/traffic channel tracking

• US 6,646,604 B2
• Filed: 03/25/2002
• Issued: 11/11/2003
• Est. Priority Date: 01/08/1999
• Status: Expired due to Term

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US10/106,089
• Publication Number:
  US 20020186167A1
• Time in Patent Office: 596 Days
• Field of Search: 342/450, 342/457, 342/463, 342/465, 455/456.1, 455/457
• US Class Current: 342/465
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: G01S 5/0284 Relative positioning
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

In a wireless location system, narrowband receivers are used in a mode, known as automatic synchronous or sequential tuning, in which the receivers are tuned sequentially and in unison to a plurality of predefined RF channels. Signal transmissions of interest in these channels are digitally recorded and used in location processing. A location record or report is generated to identify an estimated location of one or more wireless transmitters. The identity of the located transmitter(s) is determined by matching the location record to data indicating which wireless transmitters were in use at a time corresponding to the location record, and which cell sites and RF channels were used by each wireless transmitter. This method is especially suited for voice or traffic channel tracking of wireless mobile transmitters, such as cellular telephones.

Claims

1. A method for use in a wireless location system to locate a wireless transmitter using a plurality of narrowband receivers, comprising:

(a) causing said plurality of receivers to follow an automatic sequential tuning mode of operation in which the receivers sequentially and in unison tune to a plurality of predefined RF channels and receive signal transmissions in said channels; and

(b) performing location processing on the signals received during the automatic sequential tuning mode of operation.

2. A method as recited in claim 1 and further comprising generating a location record and using the location record to determine the identity of a wireless transmitter being located.

3. A method as recited in claim 2, wherein the location record identifies a time stamp, RF channel, and location.

4. A method as recited in claim 3, wherein the transmissions are TDMA transmissions and the location record further identifies a time slot.

5. A method as recited in claim 4, wherein the location record further identifies a cell site.

6. A method as recited in claim 5, wherein the location record is matched to data indicating which wireless transmitters were in use at the time, and which cell sites, RF channels, and time slots were used by each wireless transmitter.

7. A method as recited in claim 1, wherein the transmission are AMPS transmissions.

8. A method as recited in claim 7, wherein the bandwidth of the narrowband receivers is larger than the bandwidth of the received signals.

9. A method as recited in claim 2, wherein one or more wireless transmitters are determined to be of interest, and wherein a location record is generated for each wireless transmitter of interest and the received signals from remaining wireless transmitters are discarded.

10. A method as recited in claim 1, wherein steps (a) and (b) are performed without determining the identity of the wireless transmitters being located.

11. A method as recited in claim 1, wherein said predefined RF channels are voice or traffic channels.

12. A method as recited in claim 1, wherein one or more location estimations are determined to be high priority, and the method allows for preemption of scheduling for high priority location estimations.

13. A method as recited in claim 1, wherein the wireless location system employs time difference of arrival (TDOA) and/or angle-of-arrival (AOA) for location estimation.

14. A method as recited in claim 1, further comprising allowing for periods of time in the sequential tuning process in which random tuning is allowed.

15. A method for use in a wireless location system to locate wireless transmitters using a plurality of narrowband receivers, comprising:

(a) using said plurality of receivers in a mode of operation in which the receivers sequentially and in unison are tuned to a plurality of predefined RF channels and receive signal transmissions in said channels;

(b) performing location processing on the signals received during step (a); and

(c) generating a location record identifying an estimated location of at least one wireless transmitter.

16. A method as recited in claim 15, wherein said predefined RF channels are voice channels.

17. A method as recited in claim 15, wherein said predefined RF channels are traffic channels.

18. A method as recited in claim 15, wherein the transmissions are TDMA transmissions and the location record further identifies a time stamp, RF channel, and time slot.

19. A method as recited in claim 15, wherein the transmissions are AMPS transmissions.

20. A method as recited in claim 15, wherein the transmissions are CDMA transmissions.

21. A method as recited in claim 15, wherein the transmissions are GSM transmissions.

22. A method as recited in claim 15, wherein the transmissions are control channel transmissions.

23. A method as recited in claim 15, wherein the transmissions are packet channel transmissions.

24. A method as recited in claim 15, further comprising allowing for periods of time in the sequential tuning process in which random tuning is allowed.

25. A wireless location system (WLS) overlaid on an associated wireless communications system, comprising:

a pluraity of geographically separated signal collection systems comprising narrowband receivers; and

means for sequentially and in unison tuning said receivers to a plurality of predefined RF channels, and for recording signal transmissions in said channels.

26. A WLS as recited in claim 25 and further comprising means for performing location processing on the recorded signals.

27. A WLS as recited in claim 26 and further comprising means for generating a location record identifying an estimated location of at least one wireless transmitter.

28. A WLS as recited in claim 27 and further comprising means for identifying the at least one transmitter by matching the location record to data indicating which wireless transmitters were in use at a time corresponding to the location record, and which cell sites and RF channels were used by each wireless transmitter.

29. A WLS as recited in claim 25, wherein said predefined RF channels are voice channels.

30. A WLS as recited in claim 25, wherein said predefined RF channels are traffic channels.

31. A WLS as recited in claim 27, wherein the transmissions are TDMA transmissions and the location record further identifies a time stamp, RF channel, and time slot.

32. A WLS as recited in claim 25, wherein the transmissions are AMPS transmissions.

33. A WLS as recited in claim 32, wherein the bandwidth of the narrowband receivers is less than the bandwidth of the transmissions.

34. A WLS as recited in claim 25, wherein the transmissions are CDMA transmissions.

35. A WLS as recited in claim 25, wherein the transmissions are GSM transmissions.

36. A WLS as recited in claim 25, wherein the transmissions are control channel transmissions.

37. A WLS as recited in claim 25, wherein the transmissions are packet channel transmissions.

38. A WLS as recited in claim 25, further comprising means for identifying one or more location estimations as high priority, and means for preempting scheduling of frequency resources for high priority location estimations.

39. A WLS as recited in claim 25, further comprising means for allowing for periods of time in the sequential tuning process in which random tuning is allowed.