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Low-energy consumption location of movable objects

  • US 9,606,238 B2
  • Filed: 03/03/2016
  • Issued: 03/28/2017
  • Est. Priority Date: 03/06/2015
  • Status: Active Grant
First Claim
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1. A system for locating a movable object, the system comprising:

  • a mobile station configured to be associated with the movable object, the mobile station comprising;

    a radio frequency (RF) mobile communication system configured to operate an RF link having an RF link frequency in an RF band that is not licensed for cellular communications;

    a mobile station clock;

    a mobile global navigation satellite system (GNSS) receiver; and

    a dead reckoning system including a non-GNSS sensor, the dead reckoning system configured to use measurements from the non-GNSS sensor to provide an estimated position for the mobile station; and

    a base station located at a fixed position, the base station comprising;

    a base RF communication system configured to bidirectionally communicate with the mobile communication system over the RF link;

    a base station clock;

    a base GNSS receiver; and

    a hardware processor,wherein the base station is configured to;

    receive, from the mobile station over the RF link, the estimated position of the mobile station determined by the dead reckoning system;

    determine satellite acquisition information that includes a set of GNSS satellites predicted to be viewable at the estimated position of the mobile station and GNSS code phases associated with each GNSS satellite in the set, the set of GNSS satellites including at least a minimum number of GNSS satellites;

    synchronize the base station clock to a time representative of the set of GNSS satellites;

    communicate, to the mobile station over the RF link, the satellite acquisition information;

    receive, from the mobile station over the RF link, chip transition time information associated with the set of GNSS satellites;

    determine, based at least in part on the chip transition time information, an updated position for the mobile station; and

    communicate, to the mobile station over the RF link, the updated position, andwherein the mobile station is configured to;

    communicate, to the base station over the RF link, the estimated position of the mobile station determined by the dead reckoning system;

    exchange, with the base station over the RF link, clock timing information;

    synchronize, based at least partly on the clock timing information, the mobile station clock to the base station clock that is representative of the time for the set of GNSS satellites;

    receive, from the base station over the RF link, the satellite acquisition information;

    wake up the mobile GNSS receiver;

    acquire, by the mobile GNSS receiver based on timing of a GNSS code phase transition, GNSS signals from at least some of the GNSS satellites in the set of GNSS satellites;

    put the mobile GNSS receiver to sleep;

    determine, from the acquired GNSS signals, the chip transition time information associated with the GNSS code phases for the at least some of the GNSS satellites in the set; and

    communicate, to the base station over the RF link, the chip transition time information.

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