Method and system for processing positioning signals based on predetermined message data segment

• US 9,052,374 B2
• Filed: 01/23/2012
• Issued: 06/09/2015
• Est. Priority Date: 07/18/2001
• Status: Active Grant

• Current Assignee: Fast Location.Net, LLC
• Original Assignee: Fast Location.Net, LLC
• Inventors: Bromley, Patrick G., Jandrell, Louis H. M., Wise, Michael D.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US13/356,218
• Publication Number:
  US 20120133554A1
• Time in Patent Office: 1,233 Days
• Field of Search: 342/357.21, 342/357.25, 342/357.4, 342/357.62, 701/467, 701/468
• US Class Current: 1/1
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/17 Emergency applications
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0063 of measured values, i.e. measurement on base station and position calculation on mobile

Abstract

A method and system for determining a geolocation of an object includes collecting a positioning signal including a predetermined message data segment. A time of arrival of the predetermined message data segment may be determined in the positioning signal. Information based on the time of arrival may be provided for determination of a geolocation of an object. The time of arrival of the predetermined message data segment may be determined based on a time search for the predetermined message data segment in the positioning signal.

Claims

1. A method for synchronizing a time setting of a clock in a receiver with a Global Positioning System (GPS) time in a clock of each of a plurality of satellites, comprising:

recording a predetermined segment of a signal received from each of at least four satellites;

establishing a time of arrival of a predetermined message data sequence in each received signal;

determining a time difference of arrival for at least three pairs of satellites;

computing a location of the receiver from the time difference of arrival;

locating a HOW word in the received signal preceding the predetermined message data segment;

extracting a GPS time from the HOW word;

identifying a GPS time of transmission from each satellite of the predetermined message data sequence from the extracted GPS time and a separation between the HOW word and the predetermined message data segment;

calculating a propagation time of the signal from each satellite to the receiver based on the location of the satellites and the location coordinates of the receiver;

obtaining GPS time of receipt at the receiver of the predetermined message data sequence from the propagation time and the GPS time of transmission;

formulating a receiver clock error from the GPS time of receipt and the time of arrival for a given satellite.

2. The method of claim 1, wherein the predetermined segment is an amount of signal received in a recording session of up to six seconds.

3. The method of claim 1, wherein formulating the receiver clock error includes obtaining a best estimate of the receiver clock error using all of the satellites.

4. The method of claim 1, further comprising:

resetting the receiver clock by an amount of the receiver clock error.

5. The method of claim 4, further comprising:

determining whether the receiver clock was reset by more than a desired threshold value;

repeating the recording, establishing, determining, computing, locating, extracting, identifying, calculating, obtaining and formulating steps in response to the reset being more than the desired threshold value.

6. A system for synchronizing a time setting of a clock in a receiver with a Global Positioning System (GPS) time in a clock of each of a plurality of satellites, comprising:

means for recording a predetermined segment of a signal received from each of at least four satellites;

means for establishing a time of arrival of a predetermined message data sequence in each received signal;

means for determining a time difference of arrival for at least three pairs of satellites;

means for computing a location of the receiver from the time difference of arrival;

means for locating a HOW word in the received signal preceding the predetermined message data segment;

means for extracting a GPS time from the HOW word;

means for identifying a GPS time of transmission from each satellite of the predetermined message data sequence from the extracted GPS time and a separation between the HOW word and the predetermined message data segment;

means for calculating a propagation time of the signal from each satellite to the receiver based on the location of the satellites and the location coordinates of the receiver;

means for obtaining GPS time of receipt at the receiver of the predetermined message data sequence from the propagation time and the GPS time of transmission;

means for formulating a receiver clock error from the GPS time of receipt and the time of arrival for a given satellite.

7. The system of claim 6, wherein the predetermined segment is an amount of signal received in a recording session of up to six seconds.

8. The system of claim 6, wherein formulating the receiver clock error includes making a best estimate of the receiver clock error using all of the satellites.

9. The system of claim 6, further comprising:

resetting the receiver clock by an amount of the receiver clock error.

10. The system of claim 9, further comprising:

determining whether the receiver clock was reset by more than a desired threshold value;

repeating the recording, establishing, determining, computing, locating, extracting, identifying, calculating, obtaining and formulating steps in response to the reset being more than the desired threshold value.