Land-based local ranging signal methods and systems

• US 20060022870A1
• Filed: 07/30/2004
• Published: 02/02/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Integrinautics Corporation (Kubota Corporation)
• Inventors: Cobb, H. Stewart, Zimmerman, Kurt R.
• Granted Patent: US 7,339,525 B2
• Time in Patent Office: Days
• US Class Current: 342/464
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 5/378 Combination of fed elements with parasitic elements
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0464 Annular ring patch

Abstract

To provide sub-meter accuracy in a local positioning system, ranging signals with a high modulation rate of code, such as 30 MHz, or more are transmitted. Code phase measurements may be used to obtain the accuracy without requiring relative motion or real time kinematic processing. The ISM or X-band is used for the carrier of the code to provide sufficient bandwidth within available spectrums. The length of codes used is less than or about a longest length across the region of operation, such as less than 15 kilometers in an open pit mine. The spread spectrum codes from different land-based transmitters are transmitted in time slots pursuant to a time division multiple access scheme for an increase in dynamic range. To avoid overlapping of code from different transmitters, each time slot includes or is separated by a blanking period. The blanking period is selected to allow the transmitted signal to traverse a region of operation. Differential measurements of signals received at a base station and a mobile receiver may improve accuracy.

Claims

1. In a method for determining a range from a transmitter with a ranging signal received from the transmitter, the ranging signal having a code and a carrier wave, an improvement comprising:

(a) transmitting the ranging signal with a modulation rate of the code being at least about 30 MHz.

2. The improvement of claim 1 wherein (a) comprises transmitting the modulation rate of at least about 150 MHz.

3. The improvement of claim 1 wherein (a) comprises transmitting the modulation rate of less than about 250 MHz.

4. The improvement of claim 1 further comprising:

(b) transmitting the ranging signal using an X-band carrier wave.

5. The improvement of claim 1 further comprising:

(b) transmitting the signal using an ISM band carrier wave.

6. The improvement of claim 4 wherein (b) comprises transmitting the ranging signal as the X-band signal with at least about 60 MHz bandwidth around the carrier wave, the at least about 60 MHz bandwidth around the carrier wave being at least about twice the at least about 30 MHz modulation rate of the code.

7. The improvement of claim 1 wherein the transmitter comprises a land based transmitter;

the improvement further comprising;

a receiver within a region of operation;

wherein the code has a code length in space approximately equal to a longest dimension of the region of operation.

8. The improvement of claim 7 wherein the code length in space is less than about 15 kilometers.

9. The improvement of claim 1 wherein the ranging signal is a code division multiple access signal transmitted in a time division multiple access time slot with a blank period about as long as a code length.

10. The improvement of claim 1 wherein the transmitter comprises a land based transmitter;

further comprising;

(b) receiving the ranging signal at a first receiver and a second receiver; and

(c) determining a position as a function of a differential measurement of the ranging signal between the first and second receivers, the differential measurement having a code based accuracy of better than ten centimeters.

11. The improvement of claim 10 wherein (b) comprises receiving the ranging signal at the first receiver comprising a mobile receiver and at the second receiver, the second receiver co-located with the land based transmitter.

12. The improvement of claim 10 further comprising:

(d) receiving a satellite signal at said first and second receivers;

wherein (c) comprises determining the position as a function of a differential measurement of the satellite signal between the first and second receivers as well as the differential measurement of the signal between the first and second receivers, the differential measurement of the satellite signal having a carrier wave based accuracy of better than 10 centimeters.

13. A method for determining a range between a receiver and a land-based transmitter, the method comprising:

(a) transmitting a ranging signal having a code and a carrier wave;

(b) receiving the ranging signal; and

(c) determining the range as a function of the code, the received code having an accuracy better than one meter.

14. The method of claim 13 wherein the accuracy of the code is better than about 10 centimeters.

15. The method of claim 13 wherein (a) comprises transmitting the ranging signal with a modulation rate of the code being at least about 30 MHz.

16. The method of claim 13 wherein (a) comprises transmitting the ranging signal using an X-band carrier wave.

17. The method of claim 13 wherein (a) comprises transmitting the ranging signal using an ISM band carrier wave.

18. The method of claim 13 wherein the code has a code length in space approximately equal to a longest dimension of a region of operation of the receiver and the land-based transmitter, the region of operation being less than about 15 kilometers.

19. The method of claim 13 further comprising:

(d) receiving a satellite signal at the receiver, the satellite signal having a satellite carrier wave;

(e) determining a satellite range as a function of the satellite carrier wave to within sub-meter accuracy.

20. The method of claim 13 wherein (b) comprises receiving the ranging signal at the receiver and another receiver;

and

wherein (c) comprises determining the range as a function of a differential measurement of the ranging signal between the receiver and the other receiver, the differential measurement having a code based accuracy of better than ten centimeters.

21. The improvement of claim 20 wherein the other receiver is co-located with the land based transmitter.

22. The improvement of claim 20 further comprising:

(d) receiving a satellite signal at said receiver and the other receiver;

wherein (c) further comprises determining the range as a function of a differential measurement of the satellite signal between the receiver and the other receiver.

23. A method for determining a position of a receiver within a region of operation, the method comprising:

(a) transmitting a first ranging signal from a first transmitter;

(b) transmitting a second ranging signal from a second transmitter;

wherein (a) and (b) are performed in different time slots separated by a blanking period; and

(c) determining a position, computed at the receiver, as a function of the at least first and second ranging signals.

24. The method of claim 23 further comprising:

(d) transmitting a third ranging signal from a third transmitter;

wherein the first, second and third ranging signals are transmitted sequentially with the blanking period between each of the first and second and second and third transmissions.

25. The method of claim 23 further comprising:

(d) repeating (a) and (b) at least ten times a second.

26. The method of claim 23 wherein the first and second ranging signals comprise codes having a length substantially equal to a length of the different time slots.

27. The method of claim 26 wherein the length is less than about 15 kilometers in a spatial domain.

28. The method of claim 23 wherein the blanking period has a duration substantially equal to a longest code of the first and second ranging signals in a temporal domain.

29. The method of claim 23 further comprising:

(d) determining a position as a function of at least the first and second ranging signals.

30. The method of claim 29 wherein (a) comprises transmitting the first ranging signal having a first modulation rate of a first code at least about 30 MHz, wherein (b) comprises transmitting with a second modulation rate of a second code at least about 30 MHz, and wherein (c) comprises determining the position within 10 centimeter accuracy.

31. The method claim 23 further comprising:

(d) using a number of time slots and blanking periods equal to a number of land-based transmitters, the first and second transmitters being land-based transmitters.

32. The method of claim 23 wherein (a) and (b) comprise transmitting X-band DSSS signals with a carrier wave with at least about 60 MHz available bandwidth and a modulation rate of at least about 30 MHz.

33. The method of claim 23 wherein (a) and (b) comprise transmitting ISM band DSSS signals.

34. In a method for determining relative position of a receiver from ranging signals transmitted from stationary land-based transmitters, an improvement comprising:

(a) determining the position to within sub-meter accuracy with differential ranging of the ranging signals, the ranging signals being at a substantially same center frequency, the determination being free of required movement of the receiver.

35. The method of claim 34 wherein (a) comprises determining the position to within at least 10 centimeter accuracy.

36. The method of claim 34 wherein the ranging signals have a carrier wave bandwidth of at least 60 MHz in an X-band and a modulation rate of code of at least 30 MHz.

37. The method of claim 34 wherein the ranging signals have a carrier wave in an ISM band.

38. The method of claim 34 wherein (a) comprises determining the position from differential ranging of ranging signals from at least three stationary land-based transmitters received at a reference station and the receiver.

39. The method of claim 38 wherein (a) comprises determining the position where the receiver is moving.

40. The method of claim 34 wherein (a) comprises determining a position vector from a reference station to the receiver as a function of ranges of the reference station and the receiver to the stationary land-based transmitters.

41. The method of claim 34 wherein (a) comprises determining the position from code of the ranging signals, the sub-meter accuracy being from the code having a chip width of less than ten meters.

42. The method of claim 34 wherein the center frequency of the ranging signals is an X-band frequency.

43. The method of claim 34 wherein the center frequency of the ranging signals is an ISM band frequency.