Fast acquisition of GPS signal corrupted by doppler or time delay effects

• US 6,259,400 B1
• Filed: 03/15/2000
• Issued: 07/10/2001
• Est. Priority Date: 03/15/2000
• Status: Expired due to Term

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Nelson, Eric D., Higgins, William J., Corcoran, Mitchell A., Bader, John R.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/526,016
• Time in Patent Office: 482 Days
• Field of Search: 342/357.05, 342/357.06, 342/357.01, 342/357.09, 342/357.13, 701/213
• US Class Current: 342/357.22
• CPC Class Codes: F41G 7/301 Details
• CPC Class Codes: F41G 7/346 using global navigation satellite systems, e.g. GPS, GALILEO, GLONASS
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/18 Military applications
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking

Abstract

An RF translator is placed on an artillery shell. The RF translator receives a GPS signal, converts the GPS signal to an S band signal, and then transmits the S band signal. The S band signal is received by a ground antenna and it is converted back to an L1 GPS signal. The transmission of the S band signal to a ground antenna induces two effects which make fast direct P(Y) acquisitions difficult. First, since the artillery shell is moving, a carrier Doppler is induced on the S band signal. Second, the time delay caused by the transmission of the S band signal affects the nominal code phase for acquisition. Acquisition of GPS signals corrupted by second frequency data effects require special compensation if fast direct P(Y) code acquisition is desired. A carrier Doppler and a code phase compensation term allow the GPS ground receiver software to focus its search window for the carrier frequency (code rate) and the code phase (time delay). By adding in these new compensation terms, small centered searches can be used and fast direct P(Y) code acquisition is possible.

Claims

1. A method of improving acquisition of GPS information received from an artillery munition comprising:

inputting carrier Doppler compensation data into the GPS ground receiver;

inputting position estimating data for the munition into a GPS ground receiver;

inputting velocity estimating data into the GPS ground receiver or deriving velocity estimating data in the GPS ground receiver;

receiving in the artillery munition GPS navigation data, the GPS data having a first frequency;

shifting the frequency of the GPS data to a second frequency in the munition;

transmitting the frequency shifted data from the artillery munition to the GPS ground receiver;

converting the frequency shifted data back to the first frequency at the GPS ground receiver;

computing the position of the artillery munition from the first frequency data using GPS compensation software.

2. The method of claim 1 wherein the first frequency is a L1 GPS frequency.

3. The method of claim 1 wherein the first frequency is a L2 GPS frequency.

4. The method of claim 2 wherein the L1 frequency contains a C/A and a P pseudo-random ranging code.

5. The method of claim 3 wherein the L2 frequency contains a P pseudo-random ranging code.

6. The method of claim 1 wherein a code phase term is inputted to the GPS receiver software.

7. The method of claim 1 wherein both position and velocity estimating data is trajectory model data.

8. The method of claim 1 wherein the position estimating data is radar tracking data and velocity estimating data is derived in the GPS ground receiver from the radar tracking data.

9. The method of claim 1 wherein the position and velocity estimating data is inertial tracking navigation data.

10. A method of improving acquisition of GPS information received from an artillery munition comprising:

inputting code phase compensation data into the GPS ground receiver;

inputting position estimating data for the munition into a GPS ground receiver;

inputting velocity estimating data into the GPS ground receiver or deriving velocity estimating data in the GPS ground receiver;

receiving in the artillery munition GPS navigation data, the GPS data having a first frequency;

shifting the frequency of the GPS data to a second frequency in the munition;

transmitting the frequency shifted data from the artillery munition to the GPS ground receiver;

converting the frequency shifted data back to the first frequency at the GPS ground receiver;

computing the position of the artillery munition from the first frequency data using GPS compensation software.

11. The method of claim 10 wherein the first frequency is a L1 GPS frequency.

12. The method of claim 10 wherein the first frequency is a L2 GPS frequency.

13. The method of claim 11 wherein the L1 frequency contains a C/A and a P pseudo-random ranging code.

14. The method of claim 12 wherein the L2 frequency contains a P pseudo-random ranging code.

15. The method of claim 10 wherein a code phase term is inputted to the GPS receiver software.

16. The method of claim 10 wherein both position and velocity estimating data is trajectory model data.

17. The method of claim 10 wherein the position estimating data is radar tracking data and velocity estimating data is derived in the GPS ground receiver from the radar tracking data.

18. The method of claim 10 wherein the position and velocity estimating data is inertial tracking navigation data.

19. A device for improving acquisition of GPS signals from an artillery munition comprising:

a munition with an RF translator for translating a GPS signal having a first frequency to a second frequency;

a GPS ground receiver for translating the second frequency to the first frequency;

the GPS ground receiver having a computer, the computer having a memory, the memory having software that compensates for carrier frequency Doppler effect.

20. The device of claim 19 wherein the first frequency is L1 and the second frequency is an S band frequency.

21. The device of claim 19 wherein the computer memory has software inputted with position and velocity estimating data of the artillery munition.

22. The device of claim 19 wherein the computer memory has software inputted with code phase correction information.

23. The device of claim 21 wherein both position and velocity estimating data is trajectory model data.

24. The device of claim 21 wherein the position estimating data is radar tracking data and velocity estimating data is derived in the GPS ground receiver from the radar tracking data.

25. The device of claim 21 wherein the position and velocity estimating data is inertial tracking navigation data.

26. A device for improving acquisition of GPS signals from an artillery munition comprising:

a munition with an RF translator, the translator receiving a GPS signal having a first frequency and transmitting a signal having a second frequency;

a GPS ground receiver for translating the second frequency to the first frequency;

the GPS ground receiver having a computer, the computer having a memory, the memory having software that compensates for time delay in the code phase.

27. The device of claim 26 wherein the first frequency is L1 and the second frequency is an S band frequency.

28. The device of claim 26 wherein the computer memory has software inputted with position and velocity estimating data concerning the artillery munition.

29. The device of claim 26 wherein the computer memory has software inputted with carrier frequency Doppler correction.

30. The device of claim 28 wherein both position and velocity estimating data is trajectory model data.

31. The device of claim 28 wherein the position estimating data is radar tracking data and velocity estimating data is derived in the GPS ground receiver from the radar tracking data.

32. The device of claim 28 wherein the position and velocity estimating data is inertial tracking navigation data.