System and method for using data phase to reduce position ambiguities

• US 8,558,737 B2
• Filed: 06/08/2012
• Issued: 10/15/2013
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: SkyBitz, Inc. (Ametek Incorporated)
• Original Assignee: SkyBitz, Inc. (Ametek Incorporated)
• Inventors: Brosius, John W. III
• Primary Examiner(s): Phan, Dao
• Application Number:
  US13/492,312
• Publication Number:
  US 20120242541A1
• Time in Patent Office: 494 Days
• Field of Search: 342/357.21, 342/357.26, 342/357.33, 342/357.41, 342/357.43, 342/357.74, 342/453, 342/457, 342/458, 701/412
• US Class Current: 342/357.43
• CPC Class Codes: G01S 19/12 wherein the cooperating elements are telecommunication base stations
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station

Abstract

A geographic tracking system with minimal power and size required at the mobile terminal collects observation data at the mobile terminal and forwards the data to a processor, which calculates the position. The mobile terminal is configured to measure both code phase and data phase of a GPS satellite signal. The code phase and data phase information enables the processor to reduce the number of candidate points to be considered.

Claims

1. A method, comprising:

identifying a range intersection curve, said range intersection curve representing a first arc on the surface of the earth that is defined by a known position of a communication satellite and a first range distance;

identifying a code/data phase intersection curve, said code/data phase intersection curve representing a second arc on the surface of the earth that is defined by a known position of a GPS satellite and a second range distance that is consistent with a code phase measurement and a data phase measurement of a GPS satellite signal;

identifying an initial position point based on a determined intersection point between said range intersection curve and said code/data phase intersection curve; and

determining a final position of said mobile terminal using said initial position point.

2. The method of claim 1, wherein said initial position point is said determined intersection point.

3. The method of claim 1, wherein said determining a final position comprises determining using a plurality of code phase measurements for a respective plurality of GPS signals.

4. The method of claim 1, wherein said determining a final position comprises determining using a plurality of code phase measurements for a respective plurality of GPS signals and at least one data phase measurement for a GPS signal.

5. The method of claim 1, wherein said determining a final position comprises performing an iterative calculation process.

6. The method of claim 5, wherein said iterative calculation process is performed on only said initial position point.

7. A method, comprising:

determining an initial position point using a code phase measurement and a data phase measurement, said determining using a code/data phase intersection curve that represents an arc on the surface of the earth that is defined by a known position of a GPS satellite and a range distance that is consistent with said code phase measurement and said data phase measurement; and

performing an iterative calculation process on said initial position point to produce a final position solution for a mobile terminal.

8. The method of claim 7, further comprising receiving said code phase measurement and said data phase measurement via a communication satellite.

9. The method of claim 8, wherein said determining comprises determining using a range intersection curve based on a determined range from said mobile terminal to said communication satellite.

10. The method of claim 9, wherein said initial position point is on said range intersection curve.

11. The method of claim 7, wherein said performing comprises performing on only said initial position point.

12. A method, comprising:

determining an initial position point using a code phase measurement and a data phase measurement of a GPS satellite signal, said initial position point being determined using a range intersection curve that represents an arc on the surface of the earth, said arc being defined by a known position of a communication satellite and a range distance from said communication satellite to a mobile terminal, wherein said initial position point on said range intersection curve is consistent with said code phase measurement and said data phase measurement; and

performing an iterative calculation process on said initial position point to produce a final position solution for said mobile terminal.

13. The method of claim 12, further comprising receiving said code phase measurement and said data phase measurement via a communication satellite.

14. The method of claim 12, wherein said performing comprises performing on only said initial position point.