Transfer of calibrated time information in a mobile terminal

• US 7,852,267 B2
• Filed: 07/25/2006
• Issued: 12/14/2010
• Est. Priority Date: 01/26/2004
• Status: Expired due to Fees

• Current Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Original Assignee: Cambridge Positioning Systems Limited (Qualcomm, Inc.)
• Inventors: Duffett-Smith, Peter James, Bartlett, David William, Pratt, Anthony Richard
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Nguyen; Nga X
• Application Number:
  US11/492,200
• Publication Number:
  US 20070066231A1
• Time in Patent Office: 1,603 Days
• Field of Search: 34235701-35717, 342463-464, 342/387
• US Class Current: 342/463
• 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, a first receiver capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and the first or a second receiver being capable of receiving signals from multiple transmitters of an un-calibrated stable communications system, said transmitters having offsets in their signal transmission times, from which signals un-calibrated time information carried by said un-calibrated stable communications system may be extracted together with the transmission time offsets, the method comprising the steps of

determining said transmission time offsets using only the signals transmitted by the transmitters of the un-calibrated stable communication system;

at a first terminal position where the signals from the transmitters of said un-calibrated stable communications system are available and the signals from the calibrated system are available, determining, within the terminal, first travel times of the signals from the transmitters of said un-calibrated stable communications system and the time offset between said calibrated time information extracted from the calibrated system and said un-calibrated time information extracted from the un-calibrated stable communications 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 transmitters of said un-calibrated stable communications system, and calibrating said un-calibrated time information, extracted from signals of the un-calibrated stable communications system using said first and second travel times, said transmission time offsets, and said time offset determined at the first terminal position;

wherein said method is 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 said un-calibrated stable communications system comprises said terrestrial network and said calibrated system comprises said satellite positioning system, and wherein the calibrated time information is carried by a synchronisation marker, said method 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.

2. 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 communications system.

3. A method according to claim 1, wherein one or more of said references is a signal received by a receiver.

4. A method according to claim 1, wherein one or more of said references is a signal locally generated in the mobile terminal.

5. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers, a first receiver capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and the first or a second receiver being capable of receiving signals from multiple transmitters of each of first and second un-calibrated stable communications systems, said respective transmitters having offsets in their signal transmission times, from which signals un-calibrated time information carried by each of said first and second un-calibrated stable communications systems may be extracted together with the respective transmission time offsets, the method comprising the steps of

determining said respective transmission time offsets using only the signals transmitted by the transmitters of the un-calibrated stable communication system;

at a first terminal position where the signals from the transmitters of said 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 transmitters of said first un-calibrated stable communications system and a first time offset between said calibrated time information extracted from the calibrated system and said un-calibrated time information extracted from the first un-calibrated stable communications system;

at a second terminal position where the signals from the transmitters of said first and second un-calibrated stable communications systems are available, determining, within the terminal, second travel times of the signals from the transmitters of said first un-calibrated stable communications system, third travel times of the signals from the transmitters of said second un-calibrated stable communications system, and a second time offset between said un-calibrated time information extracted from the first un-calibrated stable communications system and said un-calibrated time information extracted from the second un-calibrated stable communications 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 transmitters of said second un-calibrated stable communications system, and calibrating said un-calibrated time information, extracted from signals of the second un-calibrated stable system using said first, second, third and fourth travel times, said respective transmission time offsets, and said first and second determined time offsets;

wherein said method is 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 said un-calibrated stable communications system comprises said terrestrial network and said calibrated system comprises said satellite positioning system, and wherein the calibrated time information is carried by a synchronisation marker, said method 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;

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.

6. A method according to claim 5, wherein any two or more of the first, second, third, fourth and fifth references are the same reference.

7. A method according to claim 5, 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 communications system.

8. A method of calibrating un-calibrated time information within a mobile terminal having one or more receivers, a first receiver capable of receiving signals from which calibrated time information carried by a calibrated system can be extracted, and the first or a second receiver being capable of receiving signals from multiple transmitters of an un-calibrated stable communications system, said transmitters having offsets in their signal transmission times, from which signals un-calibrated time information carried by said un-calibrated stable communications system may be extracted together with the transmission time offsets, the method comprising the steps of

determining said transmission time offsets using only the signals transmitted by the transmitters of the un-calibrated stable communication system;

at a first terminal position where the signals from the transmitters of said un-calibrated stable communications system are available and the signals from the calibrated system are available, determining, within the terminal, first travel times of the signals from the transmitters of said un-calibrated stable communications system and the time offset between said calibrated time information extracted from the calibrated system and said un-calibrated time information extracted from the un-calibrated stable communications 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 transmitters of said un-calibrated stable communications system, and calibrating said un-calibrated time information, extracted from signals of the un-calibrated stable communications system using said first and second travel times, said transmission time offsets, and said time offset determined at the first terminal position;

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 communications system, for use within a mobile terminal capable of receiving signals from transmission sources in a terrestrial network being said un-calibrated stable communications system and from the satellites of a satellite positioning system having a time-base and being said calibrated system, 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.