Land-based local ranging signal methods and systems

• US 20060279461A1
• Filed: 08/18/2006
• Published: 12/14/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Novariant Incorporated (Kubota Corporation)
• Inventors: Zlmmerman, Kurt R., Cobb, H. Stewart
• Granted Patent: US 7,382,318 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• 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. 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.

2. The method of claim 1 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.

3. The method of claim 1 further comprising:

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

4. The method of claim 1 wherein the first and second ranging signals comprise codes having a length substantially equal to a length of the different time slots.

5. The method of claim 4 wherein the length is less than about 15 kilometers in a spatial domain.

6. The method of claim 1 wherein the blanking period has a duration substantially equal to a longest code of the first and second ranging signals in a temporal domain.

7. The method of claim 1 further comprising:

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

8. The method of claim 7 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.

9. The method claim 1 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.

10. The method of claim 1 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.

11. The method of claim 1 wherein (a) and (b) comprise transmitting ISM band DSSS signals.