Method and apparatus for automated differential GPS processing

• US 5,928,306 A
• Filed: 08/22/1996
• Issued: 07/27/1999
• Est. Priority Date: 08/22/1996
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: France, Peter Glen, Perreault, Paul D.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): DONNELLY, ARTHUR D
• Application Number:
  US08/702,761
• Time in Patent Office: 1,069 Days
• Field of Search: 342/357, 342/457, 342/451, 701/207, 701/300
• US Class Current: 701/207
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]

Abstract

GPS position information is collected and stored in a computer system. The GPS position information includes time-stamps that indicates when the GPS position information was collected. The computer system uses the time stamps to generate an error correction file name for an error correction file that can be used to correct the GPS position information. Using the generated error correction file name, the computer system connects to a file server that stores differential GPS error correction files and copies the needed differential GPS error correction file. The computer system connects to the DGPS file server using the File Transfer Protocol of the global Internet. The computer system then corrects the GPS position information in the computer system using the retrieved DGPS error correction file.

Claims

1. A computer implemented method of correcting GPS position information, said method comprising:

storing GPS position information in a computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

opening a connection from said computer system to a base station coordination computer;

requesting said base station coordination computer for an address of a file server that contains DGPS error correction files from a base station closest to a position indicated by said GPS position information;

generating at least one DGPS error correction file name based upon said time-stamp;

connecting said computer system to a file server associated with said nearest DGPS base station;

copying a DGPS error correction file on said file server having said DGPS error correction file name into said computer system; and

correcting said GPS position information in said computer system using said DGPS error correction file.

2. The method of claim 1 wherein said step of generating at least one error correction file name comprises:

generating a file name based upon a time and a date when said GPS position information was collected; and

adding a suffix that identifies a DGPS error correction file.

3. The method of claim 1 wherein said step of correcting said GPS position information comprises:

decompressing said DGPS error correction file; and

applying said error correction file to said GPS position information.

4. A computer implemented method of correcting GPS position information, said method comprising:

storing GPS position information in a computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

examining said GPS position information to determine a nearest DGPS base station;

generating at least one DGPS error correction file name based upon said time-stamp;

connecting said computer system to a file server associated with said nearest DGPS base station;

opening an File Transfer Protocol connection from said computer system to said file server;

executing a "get" operation to get a DGPS error correction file having said DGPS error correction file name into said computer system; and

correcting said GPS position information in said computer system using said DGPS error correction file.

5. A computer system for correcting said GPS position information, said computer system comprising:

a computer system having GPS position information that needs to be corrected, said computer system coupled to a network;

at least one base station server coupled to said network, said base station server having a network address, said base station server having DGPS error correction files from an associated DGPS base station at a known position; and

a base station coordination computer, said base station coordination computer having the network addresses of said base station server computers and the known position of said associated DGPS base stations.

6. The computer system of claim 5 wherein said network comprises the global Internet.

7. A method of correcting GPS position information, said method comprising:

storing GPS position information in a computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

accessing a DGPS web site using a web browser on said computer system;

downloading an applet from said DGPS web site, said applet examining said GPS position information to determine a nearest DGPS base station;

generating at least one error correction file name based upon said time-stamp;

connecting said computer system to a file server associated with said nearest DGPS base station;

copying an error correction file on said file server having said error correction file name into said computer system; and

correcting said GPS position information in said computer system using said error correction file.

8. A computer implemented method of correcting GPS position information, said method comprising:

storing GPS position information in a computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

locating at least one DGPS error correction file based upon said time-stamp, said locating comprising

scanning a directory for at least one DGPS error correction file, said step of scanning comprising determining a start time and a end time for each DGPS error correction file,

selecting at least one DGPS error correction file based upon a time and a date when said GPS position information was collected, and

correcting said GPS position information in said computer system using said error correction file.

9. The method of claim 8 wherein said step of locating at least one DGPS error correction file comprises:

generating a file name based upon a time and a date when said GPS position information was collected; and

adding a suffix that identifies a DGPS error correction file; and

examining said directory for a file with said generated file name.

10. The method of claim 8 wherein said step of locating at least one DGPS error correction file further comprises:

generating a DGPS error correction file name based upon a time and a date when said GPS position information was collected; and

using a first DGPS error correction file having said DGPS error correction file name if said first DGPS error correction file exists;

scanning saidu directory for a second DGPS error correction file if said first DGPS error correction file does not exist, said step of scanning comprising determining a start time and a end time for each DGPS error correction file; and

selecting said second DGPS error correction file based upon said time and said date when said GPS position information was collected.

11. A method of correcting GPS position information, said method comprising:

generating DGPS error correction information on a DGPS base station, said DGPS base station having a known location;

storing said DGPS error correction information on a DGPS server coupled to said base station, said DGPS server coupled to a network;

collecting GPS position information with a rover GPS system, said rover GPS system having a wireless network connection;

coupling said rover GPS system to said DGPS server with said wireless network device;

processing said GPS position information with said DGPS error correction information.

12. The method of correcting GPS position information as claimed in claim 11 wherein said wireless network connection on said rover GPS system comprises a wireless Internet access.

13. The method of correcting GPS position information as claimed in claim 11 wherein said rover GPS system couples to said DGPS server using telnet protocol and said DGPS server streams DGPS correction information to said rover GPS unit.

14. The method of correcting GPS position information as claimed in claim 11 wherein said rover GPS system couples to said DGPS server and said rover GPS unit transmits said GPS position information to said DGPS server.

15. A method of correcting GPS position information, said method comprising:

storing GPS position information in a local computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

determine a nearest DGPS base station that has DGPS error correction information with a dedicated DGPS correction program;

accessing a DGPS server having said DGPS error correction information from said nearest DGPS base station using a dedicated DGPS correction program running on said local computer system;

correcting said GPS position information in said local computer system using said DGPS error correction information.

16. The method of correcting GPS position information as claimed in claim 15 wherein said DGPS server is a World Wide Web server using HyperText Transport Protocol (HTTP).

17. The method of correcting GPS position information as claimed in claim 15 wherein said step of accessing a DGPS server having said DGPS error correction information comprises streaming said DGPS error correction information to said local computer system.

18. A method of correcting GPS position information, said method comprising:

storing GPS position information in a local computer system, said GPS position information having at least one time-stamp that indicates when said GPS position information was collected;

accessing DGPS web server using a web browser on said local computer system;

streaming DGPS error correction information from said DGPS web server to said local computer system;

correcting said GPS position information in said local computer system using said error correction information.

19. The method of correcting GPS position information as claimed in claim 18 wherein said step of correcting said GPS position information in said local computer system using said error correction information comprises passing said error correction information to a plug-in error correction program that works with said web browser.