Land-based local ranging signal methods and systems

• US 7,339,525 B2
• Filed: 07/30/2004
• Issued: 03/04/2008
• 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, Zimmerman, Kurt R.
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Mull; Fred H.
• Application Number:
  US10/909,020
• Publication Number:
  US 20060022870A1
• Time in Patent Office: 1,313 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 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 position with ranging signals received from a plurality of land-based transmitters, the ranging signals each having a code and a carrier wave, an improvement comprising:

(a) transmitting the ranging signals 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 signals using an X-band carrier wave.

5. The improvement of claim 4 wherein (b) comprises transmitting the ranging signals 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.

6. The improvement of claim 1 further comprising:

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

7. The improvement of claim 1 wherein the transmitters comprise land based transmitters;

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 each 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 transmitters comprise land based transmitters

further comprising:

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

(c) determining the position as a function of a differential measurement of the ranging signals 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 signals at the first receiver comprising a mobile receiver and at the second receiver, the second receiver co-located with one of the land based transmitters.

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 measurements of the satellite ranging signals 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. The improvement of claim 1 wherein (a) comprises transmitting with the modulation rate being at least 30 MHz.

14. 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 at a mobile receiver; and

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

wherein (a) comprises transmitting the ranging signal with a modulation rate of the code being at least 30 MHz;

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.

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

16. The method of claim 14 wherein (a) comprises transmitting the ranging signal using an X-band carrier wave.

17. The method of claim 14 wherein (a) comprises transmitting the ranging signal using an ISM band carrier wave.

18. The method of claim 14 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 14 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 14 wherein the other receiver is co-located with a land based transmitter.

21. The method of claim 14 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.