Compensating for errors in tuning frequency of a global positioning satellite (GPS) receiver

• US 6,240,276 B1
• Filed: 04/28/1998
• Issued: 05/29/2001
• Est. Priority Date: 04/28/1998
• Status: Expired due to Term

• Current Assignee: IDTP Holdings Incorporated (InterDigital, Inc.)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Camp, William O. Jr.
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Corsaro, Nick
• Application Number:
  US09/066,956
• Time in Patent Office: 1,127 Days
• Field of Search: 455/71, 455/3.2, 455/430, 455/456, 455/352, 455/12.1, 455/502, 455/503, 455/70, 342/357, 342/357.06, 342/357.12, 342/358
• US Class Current: 455/71
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view

Abstract

In a cellular communication system, positioning receiver disposed in a mobile station is tuned based on an reference frequency error transmitted from the base station. In accordance with the transmitted reference frequency error, the mobile station adjusts the tuning frequency of the positioning receiver. As a result, the GPS receiver locks onto the GPS satellite signals at a faster speed.

Claims

1. A method for receiving position information in a positioning receiver, comprising:

generating a first reference signal at a base station;

receiving a known frequency from an external frequency source that is not a mobile station;

measuring a reference frequency error associated with a difference between said first reference signal and said known frequency;

transmitting the reference frequency error from a base station to a mobile station; and

tuning the positioning receiver in accordance with the reference frequency error.

2. The method of claim 1, wherein the reference frequency error is measured using a frequency counter.

3. The method of claim 1, wherein the known external frequency corresponds to the carrier frequency of a global positioning system.

4. The method of claim 1, wherein the positioning receiver is tuned by adjusting a local reference frequency generated by the mobile station.

5. The method of claim 1, wherein the reference frequency error is transmitted periodically.

6. The method of claim 1, wherein the reference frequency error is transmitted upon a request from the mobile station.

27. The method of claim 1, wherein the step of measuring the reference frequency error does not require any input from the mobile station.

7. A communication system, comprising:

a base station including;

a reference frequency source that generates a reference frequency for communicating RF signals within the communication system; and

a transmitter that transmits a reference frequency error that is based on the reference frequency and a known frequency, wherein said reference frequency error is determined without any signal from a mobile station; and

a mobile station including;

a receiver that receives the reference frequency error; and

a positioning receiver that is responsive to the reference frequency error for receiving a positioning signal having a known RF carrier.

8. The communication system of claim 7, wherein the base station further includes an external frequency generator that generates the known frequency using an accurate frequency source.

9. The communication system of claim 8, wherein the base station further includes a discriminator that generates the frequency error based on the difference between the reference frequency and the known frequency.

10. The communication system of claim 7, wherein the known frequency corresponds to the carrier frequency of a global positioning system.

11. The communication system of claim 7, wherein the base station includes a GPS receiver that is tuned using the reference frequency, for providing the reference frequency error.

12. The communication system of claim 7, wherein the mobile station generates a local reference frequency that is used for tuning the positioning receiver, and wherein the local reference frequency is adjusted based on the reference frequency error.

13. The communication system of claim 12, wherein the mobile station includes a phase lock loop (PLL) having a reference clock for generating the local reference frequency, wherein the reference clock is adjusted based on the reference frequency error.

14. The communication system of claim 7, wherein the base station transmits the reference frequency error periodically.

15. The communication system of claim 7, wherein the base station transmits the reference frequency error upon a request from the mobile station.

16. In a communication system that includes a mobile station which incorporates a positioning receiver that is tuned to receive positioning signals, a base station comprising:

a reference frequency source that generates a reference frequency for communicating RF signals within the communication system;

a receiver that receives a known frequency from an external frequency source that is not the mobile station; and

a transmitter that transmits to the mobile station a reference frequency error based on the reference frequency and said known frequency, for adjusting the tuning of the positioning receiver.

17. The base station of claim 16 further including an external frequency generator that generates the known frequency using on an accurate frequency source.

18. The base station of claim 17 further including a discriminator that generates the frequency error based on the difference between the reference frequency and the known frequency.

19. The base station of claim 16 further including a GPS receiver that is tuned using the reference frequency, for providing the reference frequency error.

20. The base station of claim 16, wherein the known frequency corresponds to the carrier frequency of a global positioning system.

21. In a communication system that includes a base station for communicating with mobile stations, a mobile station comprising:

a receiver that receives a reference frequency error from the base station, said reference frequency error based on a reference frequency generated by said base station, wherein said reference frequency error is determined without any input signal from the mobile station; and

a positioning receiver that is responsive to the reference frequency error for receiving a positioning signal having a known RF carrier.

22. The mobile station of claim 21 further including a local oscillator that generates a local reference frequency that is used for tuning the positioning receiver, and wherein the local reference frequency is adjusted based on the reference frequency error.

23. The mobile station of claim 22 further including a phase lock loop (PLL) having a reference clock for generating the local reference frequency, wherein the frequency of the reference clock is adjusted based on the reference frequency error.

24. The mobile station of claim 21, wherein the known frequency corresponds to the carrier frequency of a global positioning system.

25. A communication system, comprising:

an external frequency source that is not a mobile station and provides a first reference frequency;

a base station including;

a reference frequency source receiver that provides a second reference frequency that is not based on a carrier signal from a mobile station; and

a transmitter that transmits a reference frequency error that is based on a difference between the first reference frequency and the second reference frequency to a mobile-station; and

the mobile station including;

a receiver that receives the reference frequency error; and

a positioning receiver that is responsive to the reference frequency error for receiving a positioning signal having a known RF carrier.

26. A method for compensating errors in tuning a frequency of a positioning receiver that does not require any input from a mobile station, comprising the steps of:

generating a first reference frequency at a base station;

generating a second reference frequency at an external source using an accurate frequency source that is not a mobile station;

determining a reference frequency error based on the difference between the first reference frequency and the second reference frequency;

transmitting the reference frequency error from the base station to the mobile station; and

tuning the positioning receiver in accordance with the reference frequency error.