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

A network-assisted navigation satellite receiver system, comprising:

• a network server with a first navigation satellite receiver for computing accurate, absolute time, and providing for connection to a data network;
• a network client with a second navigation satellite receiver and operating according to a relative time, and further providing for connection to said data network;
• 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 said offset time from the average of the fastest transit times L1 and L2;
• wherein, a solution at the network client by the offset calculator of said offset time added to said accurate, absolute time, provides for improved receiver initialization.

A method for fast initialization of a navigation satellite receiver, the method comprising the steps of:

• locking onto and tracking a first constellation of navigation satellites with a first navigation satellite receiver;
• obtaining absolute time with said first navigation satellite receiver;
• providing a server on a network for transmitting said absolute time from said first navigation satellite receiver;
• connecting as a client to said network;
• testing a path delay of said network between said server and said client to determine an offset time of said client from said server;
• obtaining at said client a report of said absolute time over said network;
• initializing a second navigation satellite receiver located at said client with said report of said absolute time and said offset time such that it may find and lock onto a second constellation of navigation satellites;
• wherein, said second navigation satellite receiver is initialized more rapidly with a priori time information.

A method for determining a path delay between a client and a server on a network, the method comprising the steps of:

• sending a first message (L1) from a server to a client at a time T1;
• receiving said first message (L1) at said client at a time T2;
• sending a second message (L2) from said client back to said server at a time T3;
• receiving said second message (L2) at said server at a time T4;
• repeating the sending of said first and second messages;
• selecting a fastest transit time of each of said first and second messages;
• and
• estimating a network path delay from only those transit times chosen in the step of selecting.