Cellphone GPS positioning system

• US 20070040741A1
• Filed: 08/08/2005
• Published: 02/22/2007
• Est. Priority Date: 08/08/2005
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Loomis, Peter
• Granted Patent: US 7,295,156 B2
• Time in Patent Office: Days
• US Class Current: 342/357.430
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset

Abstract

A mobile GPS location system. The location system includes a mobile radio transceiver for transmitting a radio positioning signal and receiving a responsive radio system signal having a radio positioning system (RPS)-based time and position derived from the radio positioning signal; a mobile global positioning system (GPS) receiver; and a code range selector using the RPS-based time and position for selecting a code search range. The mobile GPS receiver uses the code search range for focusing a code phase search to a narrow range for rapidly acquiring a GPS signal. The RPS-based time and position are derived from a plurality of radio signal times-of-arrival (TOA)s determined by a plurality of system units from the radio positioning signal.

Claims

1. A location system, comprising:

a mobile radio transceiver for transmitting a radio positioning signal and receiving a radio system signal having a radio positioning system (RPS)-based time and an RPS-based position jointly derived from said radio positioning signal; and

a mobile global navigation satellite system (GNSS) receiver including a code range selector using said RPS-based time and said RPS-based position for selecting a code search range and a code recovery circuit using said code search range for acquiring a GNSS signal.

2. The system of claim 1, wherein:

said RPS-based time and said RPS-based position are jointly derived from a plurality of radio signal times-of-arrival (TOA)s determined from said radio positioning signal for a plurality of system locations, respectively.

3. The system of claim 2, wherein:

said RPS-based time and said RPS-based position are derived by resolving a plurality of equations in the form of;

TOA_j−

TOT=[(X_j−

X)²+(Y_j−

Y)²]^1/2/C

where the TOT is the RPS-based time;

the (X, Y) is the RPS-based position;

the (X_j, Y_j) is a jth one of said system locations;

the TOA_j is the TOA at said jth system location; and

the C is the speed of light.

4. The system of claim 2, wherein:

said RPS-based time and said RPS-based position are derived by resolving a plurality of equations in the form of;

TOA_j−

TOT=[(X_j−

X)²+(Y_j−

Y)²+(Z_j−

Z)²]^1/2/C

where the TOT is the RPS-based time;

the (X, Y, Z) is the RPS-based position;

the (X_j, Y_j, Z_j) is a jth one of said system locations;

the TOA_j is the TOA at said jth system location; and

the C is the speed of light.

5. The system of claim 1, wherein:

the code range selector includes a search width sizer for using an expected accuracy of said RPS-based time and an expected accuracy of said RPS-based position for determining a search width for said code search range.

6. The system of claim 5, wherein:

said expected accuracy the search width sizer further uses an RPS line-of-sight matrix for determining said search width.

7. The system of claim 5, wherein:

said GNSS signal is a global positioning system (GPS) signal having a pseudorandom noise (PRN) code; and

said search width is between five and twenty-five chips for said code.

8. The system of claim 1, wherein:

the code range selector includes a bootstrap clock for determining an elapsed time from a time-of-transmission (TOT) of said radio positioning signal and a GNSS time estimator for using said TOT elapsed time and said RPS-based time for providing an RPS-based GNSS time estimate; and

the code range selector uses said RPS-based GNSS time estimate for selecting said code search range.

9. The system of claim 8, wherein:

the code range selector further includes a chip pointer for combining said RPS-based GNSS time estimate with a transit time of said GNSS signal for predicting a code phase for said code search range.

10. The system of claim 9, wherein:

the code search range selector further includes a satellite locator for using said RPS-based GNSS time estimate with GNSS orbital parameters for determining a location-in-space for a GNSS signal source transmitting said GNSS signal; and

a transit time calculator for using said RPS-based position with said location-in-space for determining said transit time.

11. The system of claim 1, further comprising:

a plurality of system units for determining a plurality of radio signal times-of-arrival TOAs, respectively, from said radio positioning signal; and

a server for determining said RPS-based time and said RPS-based position from said radio signal TOAs.

12. The system of claim 1, wherein:

said GNSS receiver is a global positioning system (GPS) receiver; and

said GNSS signal is a GPS signal.

13. A mobile location method, comprising:

transmitting a radio positioning signal from a mobile unit;

receiving a radio system signal in said mobile unit having a radio positioning system (RPS)-based time and an RPS-based position jointly derived from said radio positioning signal;

selecting a code search range according to said RPS-based time and said RPS-based position; and

acquiring a GNSS signal using said selected code search range.

14. The method of claim 13, wherein:

said RPS-based time and said RPS-based position are jointly derived from a plurality of radio signal times-of-arrival (TOA)s determined from said radio positioning signal for a plurality of system locations, respectively.

15. The method of claim 14, wherein:

said RPS-based time and said RPS-based position are derived by resolving a plurality of equations in the form of;

TOA_j−

TOT=[(X_j−

X)²+(Y_j−

Y)²]^1/2/C

where the TOT is the RPS-based time;

the (X, Y) is the RPS-based position;

the (X_j, Y_j) is a jth one of said system locations;

the TOA_j is the TOA at said jth system location; and

the C is the speed of light.

16. The method of claim 14, wherein:

said RPS-based time and said RPS-based position are derived by resolving a plurality of equations in the form of;

TOA_j−

TOT=[(X_j−

X)²+(Y_j−

Y)²+(Z_j−

Z)²]^1/2/C

where the TOT is the RPS-based time;

the (X, Y, Z) is the RPS-based position;

the (X_j, Y_j, Z_j) is a jth one of said system locations;

the TOA_j is the TOA at said jth system location; and

the C is the speed of light.

17. The method of claim 13, wherein:

selecting said code search range includes determining a search width for said code search range from an expected accuracy of said RPS-based time and an expected accuracy of said RPS-based position.

18. The method of claim 17, wherein:

determining said search width further includes using an RPS line-of-sight matrix for determining said search width.

19. The method of claim 17, wherein:

said GNSS signal is a global positioning system (GPS) signal having pseudorandom noise (PRN) code; and

said search width is between five and twenty-five chips for said code.

20. The method of claim 13, wherein:

selecting said code search range includes;

determining an elapsed time in said mobile unit from a time-of-transmission (TOT) of said radio positioning signal;

using said TOT elapsed time with said RPS-based time for providing an RPS-based GNSS time estimate; and

using said RPS-based GNSS time estimate for selecting said code search range.

21. The method of claim 20, wherein:

selecting said code search range further includes combining said RPS-based GNSS time estimate with a transit time of said GNSS signal for predicting a code phase for said code search range.

22. The method of claim 21, wherein:

selecting said code search range further includes using said RPS-based GNSS time estimate with GNSS orbital parameters for determining a location-in-space for a GNSS signal source transmitting said GNSS signal; and

using said RPS-based position with said location-in-space for determining said transit time.

23. The method of claim 13, further comprising:

determining a plurality of radio signal times-of-arrival (TOA)s at a plurality of system positions, respectively, from said radio positioning signal; and

determining said RPS-based time and said RPS-based position from said radio signal TOAs.

24. The method of claim 13, wherein:

said GNSS receiver is a global positioning system (GPS) receiver; and

said GNSS signal is a GPS signal.