Satellite and local system position determination

• US 7,271,766 B2
• Filed: 07/30/2004
• Issued: 09/18/2007
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Novariant Incorporated (Kubota Corporation)
• Inventors: Cobb, H. Stewart, Lawrence, David G., Montgomery, Paul Y., Zimmerman, Kurt R.
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Mull; Fred H.
• Application Number:
  US10/909,184
• Publication Number:
  US 20070040744A1
• Time in Patent Office: 1,145 Days
• Field of Search: 342/357.02, 342/357.06, 342/357.14, 342/450, 342/457, 342463-464
• US Class Current: 342/464
• CPC Class Codes: G01S 1/24 the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations , e.g. LORAN systems
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/31 Acquisition or tracking of other signals for positioning
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

In a local positioning system, augmentation of the land-based system is provided by receiving signals from a GNSS. The signals from the land-based positioning system have a code phase accuracy better than one wavelength of a carrier of the signals from the GNSS. Different decorrelation may be used for signals from a satellite than from a land-based transmitter, such as using a digital decorrelator for signals from the satellite and an analog decorrelator for signals from a land-based transmitter. The receivers may include both a GNSS antenna and a local antenna. The phase centers of the two antennas are within one wavelength of the GNSS signals from each other. The local antenna is sized for operation in the X or ISM-bands of frequencies. The GNSS antenna is a patch antenna where the microwave antenna extends away from the patch antenna in at least one dimension.

Claims

1. A method for determining a position of a receiver from transmitted signals, the method comprising:

(a) measuring at least a first range from first signals for a global navigation satellite system;

(b) measuring at least a second range from second signals for a local positioning system; and

(c) determining the position of the receiver from the measurements of (a) and (b);

wherein the measurements of the second signals for the local positioning system have a code phase range accuracy better than one wavelength of a carrier of the first signals from the global navigation satellite system;

wherein (a) comprises measuring from the first signals, the first signals having a carrier with a wavelength greater than 15 cm, and wherein (b) comprises measuring from the second signals, the measurements of the second signals have better than 2 cm code phase range accuracy.

2. The method of claim 1 wherein (a) comprises measuring from the first signals for one of:

the Global Positioning System, GLONASS, Galileo or combinations thereof.

3. The method of claim 1 further comprising:

(d) digital de-correlating the first signals prior to (a), the first signals being first direct-sequence, spread spectrum signals; and

(e) analog de-correlating the second signals prior to (b), the second signals being second direct-sequence, spread spectrum signals.

4. The method of claim 1 wherein the second signals have a second code modulation rate at least ten times a first code modulation rate of the first signals.

5. The method of claim 1 wherein (a) comprises measuring a carrier phase of the first signals from at least five satellites, and wherein (c) comprises performing a real-time kinematic measurement as a function of the carrier phases of the first signals.

6. The method of claim 1 wherein (a) comprises measuring the first signals from at least one and fewer than four satellites, wherein (b) comprises measuring the second signals from only one land based transmitter, and wherein (c) comprises determining the position with a first accuracy more accurate than a second accuracy determined from a differential global navigation system solution, using only satellites, with a similar dilution of precision.

7. The method of claim 1 wherein (a) comprises measuring the first signals from at least two and fewer than five satellites, wherein (b) comprises measuring the second signals from at least one land based transmitter, a total number of the at least two satellites and at least one land based transmitter being at least five and wherein (c) comprises performing a real-time kinematic measurement as a function of the carrier phases of the first signals augmented with the measurements of (b).

8. The method of claim 1 wherein (b) comprises measuring a code phase of the second signals from at least four land based transmitters;

further comprising;

(d) determining a position estimate as a function of the code phases of the second signals; and

(e) determining integer ambiguity of carrier phase of the first signals as a function of the position estimate;

wherein (c) comprises refining the position estimate as a function of the first signals and the determination of the integer ambiguity, a dilution of precision of the position being based on the at least four land based transmitters and at least one satellite.

9. The method of claim 1 wherein (a) comprises measuring a third range for a global navigation system;

and (b) comprises measuring a code phase of the second signals from at least four land based transmitters;

further comprising;

(d) determining a position estimate as a function of the code phases of the second signals; and

(e) determining integer ambiguity of carrier phase of the first signals as a function of the position estimate;

wherein (c) comprises refining the position estimate as a function of the first signals and the determination of the integer ambiguity.

10. A method for determining a position of a receiver from transmitted signals, the method comprising:

(a) measuring at least a first range from first signals for a global navigation satellite system;

(b) measuring at least a second range from second signals for a local positioning system; and

(c) determining the position of the receiver from the measurements of (a) and (b);

wherein the measurements of the second signals for the local positioning system have a code phase range accuracy better than one wavelength of a carrier of the first signals from the global navigation satellite system;

wherein (b) comprises measuring from the second signals with a modulation rate of a code being at least 30 MHz carried in the X-band, ISM band or combinations thereof.

11. A system for determining a position of a receiver from transmitted signals, the system comprising:

a global navigation satellite system receiver operable to measure at least a first range from first signals from at least a first satellite;

a local positioning system receiver operable to measure at least a second range from second signals from at least a first land based transmitter, wherein the second signals for the local positioning system have a code phase range accuracy better than one wavelength of a carrier of the first signals from the global navigation satellite system; and

a processor operable to determine the position of the receiver from the measurements of the global navigation satellite system receiver and the local positioning system receiver;

wherein the first signals have a carrier with a wavelength greater than 15 cm, and the second signals have better than 2 cm code phase range accuracy.

12. The system of claim 11 wherein the global navigation satellite system receiver comprises:

a first analog-to-digital converter;

a first code generator; and

a digital mixer operable to mix a first code output by the first code generator with the first signals output by the first analog-to-digital converter;

wherein the local positioning system receiver comprises;

a second code generator;

an analog mixer operable to mix a second code output by the second code generator with the second signals; and

a second analog-to-digital converter operable to convert the mixed second code and second signals from analog to digital.

13. The system of claim 11 wherein the second signals have a second code modulation rate at least ten times a first code modulation rate of the first signals.

14. The system of claim 11 wherein the global navigation satellite system receiver is operable to measure a carrier phase of the first signals from at least five satellites, and the processor is operable to perform a real-time kinematic measurement as a function of the carrier phases of the first signals.

15. The system of claim 11 wherein the global navigation satellite system receiver is operable to measure the first signals from at least one and fewer than four satellites, wherein the local positioning system receiver is operable to measure the second signals from only one land based transmitter, and wherein the processor is operable to determine the position with a first accuracy more accurate than a second accuracy determined from a differential global navigation system solution, using only satellites, with a similar dilution of precision.

16. The system of claim 11 wherein the global navigation satellite system receiver is operable to measure the first signals from at least two and fewer than five satellites, wherein the local positioning system receiver is operable to measure the second signals from the at least first land based transmitter, a total number of the at least two satellites and the at least first land based transmitter being at least five and wherein the processor is operable to perform a real-time kinematic measurement as a function of the carrier phases of the first signals augmented with the measurements of the second signals.

17. The system of claim 11 wherein the local positioning system receiver is operable to measure a code phase of the second signals from at least four land based transmitters including the first land based transmitter;

and

wherein the processor is operable to determine a position estimate as a function of the code phases of the second signals, operable to determine an integer ambiguity of carrier phase of the first signals as a function of the position estimate, and is operable to refine the position estimate as a function of the first signals and the determination of the integer ambiguity, a dilution of precision of the position being based on the at least four land based transmitters and at least one satellite.

18. The system of claim 11 wherein the local positioning system receiver is operable to measure a code phase of the second signals from at least four land based transmitters including the first land based transmitter;

and

wherein the processor is operable to determine a position estimate as a function of the code phases of the second signals, operable to determine an integer ambiguity of carrier phase of the first signals as a function of the position estimate, and is operable to refine the position estimate as a function of the first signals and the determination of the integer ambiguity.

19. A system for determining a position of a receiver from transmitted signals, the system comprising:

a global navigation satellite system receiver operable to measure at least a first range from first signals from at least a first satellite;

a local positioning system receiver operable to measure at least a second range from second signals from at least a first land based transmitter, wherein the second signals for the local positioning system have a code phase range accuracy better than one wavelength of a carrier of the first signals from the global navigation satellite system; and

a processor operable to determine the position of the receiver from the measurements of the global navigation satellite system receiver and the local positioning system receiver;

wherein the second signals have a modulation rate of a code being at least 30 MHz carried in the X-band, ISM band or combinations thereof.