Total correction strategy

• US 6,701,253 B2
• Filed: 02/19/2002
• Issued: 03/02/2004
• Est. Priority Date: 02/19/2002
• Status: Active Grant

• Current Assignee: Furuno Electric Co, Ltd, Seiko Epson Corporation (Seiko Group)
• Original Assignee: eRide, Inc. (Furuno Electric Co, Ltd), Seiko Epson Corporation (Seiko Group)
• Inventors: Edwards, Stephen J., McBurney, Paul W.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/079,217
• Publication Number:
  US 20030163256A1
• Time in Patent Office: 742 Days
• Field of Search: 701/214, 701/213, 701/215, 342/357.01, 342/357.02, 342/357.06, 342/357.03, 342/357.1, 342/357.12, 342/358
• US Class Current: 701/214
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view

Abstract

A navigation-satellite receiver network comprises a server connected to the Internet to provide real-time correction information to clients. The server includes a GPS receiver that provides for tracking of a constellation of navigation satellites. When a client is online, it can receive satellite position and velocity information in the form of a polynomial and coefficients. Clock, ionosphere, troposphere, and other corrections are all bundled into one polynomial. The client therefore never computes or uses almanac or ephemeris.

Claims

1. A network-assisted navigation satellite receiver system, comprising:

a network server with a first navigation satellite receiver for computing accurate time, and satellites'"'"' positions and velocities from ephemeris and almanac data;

a polynomial constructed to encode satellite position and velocity (SPV);

a second polynomial to encode the satellite corrections;

a network client with a second navigation satellite receiver that does not compute satellites'"'"' positions and velocities from ephemeris and almanac data, and that requests and uses the polynomial; and

an interconnecting network for communicating information dependent on the polynomial;

wherein, a user position and velocity solution at the network client is limited to fixed-integer, fixed LSB value arithmetic calculations.

2. The system of claim 1, wherein the interconnecting network further provides for a subscription to updated ones of the polynomial for a fee.

3. The system of claim 1, wherein the network server supports real-time corrections to the network client at one of three assistance levels, autonomous, demi-autonomous with satellite position and velocity (SPV) information, and demi-autonomous with initial SPV information to speed up the first fix.

4. The system of claim 1, wherein the network server provides measured, measured-adjusted, and computed ionospheric and tropospheric corrections, and when the network client makes a request from the network server, a best estimate of a user position is given toga pre-position engine, and any satellite vehicles (SV'"'"'s) to be searched are determined;

wherein, for each SV model, a correction polynomial is constructed with its reference time synchronized to such model.

5. A method for supplying and using real-time corrections for GPS receivers on the Internet, the method comprising the steps of:

acquiring and tracking a first satellite constellation with a first navigation satellite receiver using ephemeris and almanac calculations, and obtaining clock, atmospheric, and other real-time correction information for a local area;

encoding said clock, atmospheric, and other real-time correction information for a local area into a single polynomial;

acquiring and tracking a second satellite constellation with a second navigation satellite receiver that does not use ephemeris and almanac calculations, wherein said first and second navigation satellite receivers are collocated within said local area;

transmitting said polynomial from a network server connected to the first navigation satellite receiver to a network client connected to the second navigation satellite receiver; and

computing position and velocity of said second navigation satellite receiver with information encoded in said polynomial.

6. The method of claim 5, wherein the step of computing avoids complex calculations and permits substantial savings in computer software and hardware needed to support such in said second navigation satellite receiver.