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Timed-based ephemeris identity in assistance data and assistance data request messages

  • US 9,465,114 B2
  • Filed: 10/26/2007
  • Issued: 10/11/2016
  • Est. Priority Date: 11/03/2006
  • Status: Active Grant
First Claim
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1. A method comprising:

  • generating a time indication value for a first navigation signal, wherein the first navigation signal is an ephemeris type message;

    generating a time indication value for a second navigation signal, wherein the second navigation signal is the ephemeris type message, and wherein the time indication values of the first and second navigation signals are provided in a same message structure for comparison, wherein the ephemeris type message is a CNAV-1 ephemeris type message which does not include a time indication value or a CNAV-2 ephemeris type message which includes a time indication value;

    wherein the generating of a time indication value for one or both of the first and second navigation signals includes deriving a value based on a value for a time of receipt of the respective navigation signal and a value for a time of a beginning of a week when the navigation signal is a CNAV-1 ephemeris type message, and obtaining the time indication value from a received navigation signal when the navigation signal is a CNAV-2 ephemeris type message;

    providing, to an assistance server;

    a) the time indication value for the first navigation signal included as a first identifier of first ephemeris information included in the first navigation signal based on a first time interval between the first ephemeris information and an end of a week previous to the first ephemeris information, and b) the time indication value for the second navigation signal as a second identifier of second ephemeris information included in the second navigation signal based on a second time interval between the second ephemeris information and an end of a week previous to the second ephemeris information;

    in an instance in which the time indication value for the first navigation signal is less than the time indication value for the second navigation signal, determining the second ephemeris information is more current than the first ephemeris information and updating a current ephemeris information as the second ephemeris information on the assistance server; and

    in an instance in which the time indication value for the first navigation signal is greater than the time indication value for the second navigation signal, determining the first ephemeris information is more current than the second ephemeris information and leaving the current ephemeris information on the assistance server unchanged.

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