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Computing network path delays so accurate absolute time can be forwarded from a server to a client

  • US 6,941,109 B2
  • Filed: 02/19/2002
  • Issued: 09/06/2005
  • Est. Priority Date: 02/19/2002
  • Status: Active Grant
First Claim
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1. A network-assisted navigation satellite receiver system, comprising:

  • a network server with an initialized first navigation satellite receiver for discerning accurate, absolute satellite system time;

    a network client remote from the network server and associated with an uninitialized second navigation satellite receiver that does not yet know said satellite system time;

    an interconnecting network between the network server and the network client, and that imposes a non-deterministic time delay on messages, and for communicating a network-transmission delay-corrected estimate of said satellite system time from the network server to the network client;

    a message latency testing means for determining the fastest transit times of messages from the network server to the network client (L1), and for determining the fastest transit times of return messages from the network client to the network server (L2); and

    an offset calculator for computing the average of the fastest transit times L1 and L2 and from that said network-transmission delay-corrected estimate of said satellite system time for the network client;

    wherein, said network-transmission delay-corrected estimate of said satellite system time is provided for use by said second navigation satellite receiver to quicken its initialization.

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