Apparatus and method for determination of a receiver position

• US 6,295,022 B1
• Filed: 11/11/1999
• Issued: 09/25/2001
• Est. Priority Date: 05/25/1999
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Dutka, Stephen C.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US09/438,349
• Time in Patent Office: 684 Days
• Field of Search: 342/357.01, 342/357.06, 342/352, 701/213, 701/214, 455/12.1
• US Class Current: 342/357.29
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/42 Determining position

Abstract

A method of accurate determination of a fixed position using global positioning system uses pseudo-range output over a predetermined measurement period from a stand-alone GPS receiver located at the fixed position, the pseudo-range output being measured from an ensemble of spacevehicles at each time t over the measurement period, and historical ephemerides of the ensemble of space vehicles over the same measurement period to eliminate errors caused by selective availability. The historical ephemerides of the ensemble of space vehicles corresponding to each measurement time t are determined, and using the pseudo-range output and the historical ephemerides, a position solution at each time t is computed. The accurate position in earth-centered earth-fixed coordinates is then the average of all the position solutions at each time t over the measurement period.

Claims

1. A post-processing, single fixed receiver method of determining the position of the fixed receiver using a global positioning system (GPS), comprising:

obtaining from a GPS receiver pseudo-range outputs over a predetermined measurement period, the pseudo-range outputs measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides.

2. The post-processing, single fixed receiver method as set forth in claim 1, wherein obtaining from a GPS receiver pseudo-range output comprises obtaining time tagging of the pseudo-range output over the predetermined measurement.

3. The post-processing, single fixed receiver method as set forth in claim 1, wherein obtaining from a GPS receiver pseudo-range output comprises obtaining pseudo-range output having the time of measurement a transmitter identifier, and the pseudo-range as a function of the time of arrival of a range signal.

4. The post-processing, single fixed receiver method as set forth claim 1, wherein obtaining from a GPS receiver pseudo-range output comprises obtaining pseudo-range output having clock data, ephemerides data, and almanac data.

5. A method of determining the position of a stand-alone global positioning system (GPS) receiver, the receiver generating a plurality of pseudo-range data over a measurement period, comprising:

receiving from the receiver the plurality of pseudo-range data over the measurement period, the pseudo-range data measured for an ensemble of at least four space vehicles at each of a plurality of times “

t”

over the measurement period;

receiving historical ephemerides of the ensemble of space vehicles over the measurement period;

determining from the received ephemerides an orbit for each space vehicle over the measurement period; and

determining intermediate historical ephemerides between the historical ephemerides in each orbit for each of the plurality of times “

t”

during the measurement period;

determining a position solution for each of the plurality of times “

t”

utilizing the plurality of pseudo-range data and the ephemerides.

6. The method as set forth in claim 5, wherein determining a position solution at each time “

t”

comprises;

determining an initial receiver position;

determining, in response to the historical ephemerides and the initial receiver position, a range from each space vehicle to the receiver;

determining a difference between the range of each space vehicle and the receiver pseudo-range output;

determining errors of the initial receiver position in response to the difference between the range of each space vehicle and the receiver pseudo-range output;

correcting the errors in the initial receiver position; and

iteratively repeating the above steps until the errors approach zero.

7. A post-processing, single fixed receiver method for minimizing the broadcast ephemerides error component of the position determination of the fixed receiver, the errors resulting from selected availability, comprising:

obtaining from a GPS receiver pseudo-range output over a predetermined measurement period, the pseudo-range output having a selected availability error and measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides.

8. A post-processing, single fixed receiver method of determining the position of the fixed receiver using a global positioning system (GPS), comprising:

computing a position solution for the receiver for each of a plurality of times “

t”

utilizing pseudo-range output measurement from an ensemble of space vehicles at each of the plurality of times “

t” and

historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

; and

averaging the position solution for each of the times “

t”

over the measurement.

9. The post-processing, single fixed receiver method as set forth in claim 8 wherein averaging the position solution comprises:

summing all position solutions of each axis; and

dividing the summed position solution for each axis by the number of precision solutions for each axis.

10. A method of determining the position of a fixed receiver using a global positioning system (GPS), comprising:

obtaining from a GPS receiver pseudo-range output over a predetermined measurement, the pseudo-range output measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

, determining the historical ephemerides comprising determining an orbit defined by the historical ephemerides, and determining intermediate historical ephemerides between the historical ephemerides in the orbit; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides.

11. The method as set forth in claim 10, determining the orbit comprises fitting an orbit to the historical ephemerides.

12. A method of determining the position of a fixed receiver using a global positioning system (GPS), comprising:

obtaining from a GPS receiver pseudo-range outputs over a predetermined measurement period, the pseudo-range output measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides, wherein determining a position solution for each of the plurality of times “

t”

comprises;

determining an initial receiver position;

determining, in response to the historical ephemerides and the initial receiver position, a range from each space vehicle to the receiver;

determining a difference between the range of each space vehicle and the receiver pseudo-range output;

determining errors of the initial receiver position in response to the difference between the range of each space vehicle and the receiver pseudo-range output;

correcting the errors in the initial receiver position; and

iteratively repeating the above steps until the errors approach zero.

13. A method for minimizing the broadcast ephemerides error component of the position determination of a fixed receiver, the errors resulting from selective availability, comprising:

obtaining from a GPS receiver pseudo-range output over a predetermined measurement, the pseudo-range output having a selected availability error and measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

, determining the historical ephemerides comprising determining intermediate ephemeride points corresponding to the time of each pseudo-range output measurement; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides.

14. A method for minimizing the broadcast ephemerides error component of the position determination of a fixed receiver, the errors resulting from selected availability, comprising:

obtaining from a GPS receiver pseudo-range output over a predetermined measurement period, the pseudo-range output having a selected availability error and measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

, determining historical ephemerides comprises determining an orbit defined by the historical ephemerides, and determining intermediate historical ephemerides between the historical ephemerides in the orbit; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides.

15. A method for minimizing the broadcast ephemerides error component of the position determination of a fixed receiver, the errors resulting from selected availability, comprising:

obtaining from a GPS receiver pseudo-range output over a predetermined measurement period, the pseudo-range output having a selected availability error and measured from an ensemble of space vehicles at each of a plurality of times “

t”

over the measurement period;

determining the historical ephemerides of the ensemble of space vehicles corresponding to each of the plurality of times “

t”

; and

determining a position solution for each of the plurality of times “

t”

utilizing the pseudo-range output and the historical ephemerides, determining a position solution for each of the plurality of times “

t”

comprises;

determining an initial receiver position;

determining, in response to the historical ephemerides and the initial receiver position, a range from each space vehicle to the receiver;

determining a difference between the range of each space vehicle and the receiver pseudo-range output;

determining errors of the initial receiver position in response to the difference between the range of each space vehicle and the receiver pseudo-range output;

correcting the errors of the initial receiver position; and

iteratively repeating the above steps until the errors approach zero.