Position determining system

• US 6,342,854 B1
• Filed: 02/17/2000
• Issued: 01/29/2002
• Est. Priority Date: 09/19/1995
• Status: Expired due to Term

• Current Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Original Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Inventors: Grainge, Keith James Bruno, Duffett-Smith, Peter James
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US09/506,014
• Time in Patent Office: 712 Days
• Field of Search: 342/463, 342/457
• US Class Current: 342/457
• CPC Class Codes: G01S 1/045 Receivers
• CPC Class Codes: G01S 5/0205 Details
• CPC Class Codes: G01S 5/0284 Relative positioning
• 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

Abstract

The invention relates to a position determining system, for receiving digital telephone signals transmitted by a number of transmission sources BTS. The system has a pair of receiving stations, CBU and CRU, one at a known position O and another on a roving object R; a position determining processor CPP; and means for passing a link signal, L1 and L2, from each of the receiving stations to the position determining processor, the link signal containing information about the signals received at the receiving station from the transmission sources. Each of the receiving stations is arranged to receive the signals from the respective transmission sources substantially simultaneously. The position determining processor is arranged to compare the information received from the one receiving station with the information received at the other receiving station, and to determine the time delay between the respective signals received at both receiving stations in order to determine the position of the roving object.

Claims

1. A position determining system, for receiving broadband telecommunication signals transmitted by a plurality of transmission sources at fixed positions equal at least to a number of dimensions in which movement of a mobile telecommunications transceiver is to be monitored, the system comprising:

first and second receiving stations, the first receiving station being at a known position and the second receiving station comprising said mobile telecommunications transceiver, each of the receiving stations being arranged to receive and record portions of the telecommunication signals from the respective plurality of transmission sources substantially simultaneously;

a position determining processor;

said first receiving station having means for transmitting a first link signal from the first receiving station to the position determining processor and said second receiving station having means for transmitting a second link signal from the second receiving station to the position determining processor, the first link signal containing information derived from the recorded telecommunication signals received at the first receiving station from the plurality of transmission sources and the second link signal containing information derived from the recorded telecommunication signals received at the second receiving station from the plurality of transmission sources; and

wherein the position determining processor is arranged to compare the information received from the first link signal with the information received from the second link signal, and to determine a time delay between the respective telecommunication signals received and recorded at the first and second receiving stations in order to determine the position of the mobile telecommunications transceiver.

2. A position determining system according to claim 1 in which the first and second receiving stations receive the signals from the plurality of transmission sources sequentially and in the same sequence as each other.

3. A position determining system according to claim 1, wherein each of the receiving stations is also arranged to receive a second signal from one or more of the transmission sources.

4. A position determining system according to claim 1, wherein the position determining processor is co-located with one of the receiving stations.

5. A position determining system according to claim 4, wherein the first or second link signal is passed from the respective first or second receiving station to the other receiving station and from the other receiving station to the position determining processor.

6. A position determining system according to claim 1, wherein the position determining processor is located remote from the receiving stations.

7. A position determining system according to claim 1, wherein a signal providing information about the position of the roving object is passed from the position determining processor to at least one of the receiving stations.

8. A position determining system according to claim 1, further comprising a monitoring station and wherein a signal providing information about the position of the roving object is passed from the position determining processor to the monitoring station.

9. A position determining system according to claim 8, further comprising:

a database server connected to said position determining processor, said database server containing data elements relating to a plurality of known positions;

means for passing information about the position of the roving object determined by the position determining processor to the database server;

means for retrieving data elements related to the position determined by the position determining processor; and

means for passing the data elements to one of the receiving stations or to the monitoring station.

10. A position determining system according to claim 9, wherein at least one of the receiving stations or the monitoring station includes a display and the position of the roving object is displayed on the display.

11. A position determining system according to claim 10, wherein the display comprises a dot matrix display.

12. A position determining system according to claim 10, wherein the database server contains graphical information and said graphical information is passed to at least one of the receiving stations or the monitoring station and displayed on the display to indicate the position of the roving object.

13. A position determining system according to claim 1, wherein the transmission sources and receiving stations comprise components of a digital cellular telephone network.

14. A position determining system according to claim 13, wherein the digital cellular telephone network is a GSM network.

15. A position determining system according to claim 1, wherein the receiving stations monitor the strength of the signals of plural transmission sources and select a plurality of sufficiently strong signals for reception.

16. A position determining system according to claim 1, wherein each of the receiving stations is arranged to receive and record portions of the signals from the respect transmission sources substantially simultaneously by monitoring for receipt of a specific portion of the transmitted signals.

17. A position determining system according to claim 15, wherein each of the receiving stations is arranged to receive and record portions of the signals from the plurality of transmission sources substantially simultaneously by means independent of the transmitted signals.

18. A method of determining the position of a mobile telecommunications transceiver, the method comprising:

transmitting broadband telecommunication signals from a plurality of transmission sources at fixed locations equal at least to a number of dimensions in which movement of said mobile telecommunications transceiver is to be monitored;

receiving the signals at first and second receiving stations, the first receiving station being at a known position and the second receiving station comprising said mobile telecommunications transceiver, each of the receiving stations being arranged to receive and record portions of the telecommunication signals from the respective plurality of transmission sources substantially simultaneously;

transmitting a first link signal from the first receiving station to a position determining processor, and a second link signal from the second receiving station to the position determining processor, the first link signal containing information derived from the recorded telecommunication signals received at the first receiving station from the plurality of transmission sources and the second link signal containing information derived from the recorded telecommunication signals received at the second receiving station from the plurality of transmission sources;

comparing the information received at the position determining processor from the first link signal with the information received from the second link signal; and

determining a time delay between the respective signals received at the first and second receiving stations in order to determine the position of the mobile telecommunications transceiver.

19. A method according to claim 18, wherein the broadband telecommunication signals are digital cellular telephone network transmission signals.