GPS receiver utilizing a communication link

• US 5,841,396 A
• Filed: 12/04/1996
• Issued: 11/24/1998
• Est. Priority Date: 03/08/1996
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Krasner, Norman F.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/759,523
• Time in Patent Office: 720 Days
• Field of Search: 342/357, 364/449.7, 364/449.9, 364/449.95, 701/213, 701/214
• US Class Current: 342/357.75
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/38 Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile
• CPC Class Codes: G06F 2221/2111 Location-sensitive, e.g. geographical location, GPS
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 21/28 : Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H03D 7/163 : the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03J 2200/11 : Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 7/04 : where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H03J 7/047 : Automatic frequency control using an auxiliary signal, e.g. low frequency scanning of the locking range or superimposing a special signal on the input signal
• CPC Class Codes: H03J 7/06 : using counters or frequency dividers
• CPC Class Codes: H04B 1/00 : Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
• CPC Class Codes: H04B 1/0007 : wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage
• CPC Class Codes: H04B 1/28 : the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 1/3805 : with built-in auxiliary receivers

Abstract

A precision carrier frequency signal for calibrating a local oscillator of a GPS receiver which is used to acquire GPS signals. The precision carrier frequency signal is used to calibrate the local oscillator such that the output of the local oscillator, which is used to acquire GPS signals, is modified by a reference signal generated from the precision carrier frequency signal. The GPS receiver locks to this precision carrier frequency signal and generates the reference signal. In another aspect of the invention, satellite almanac data is transmitted to a remote GPS receiver unit from a basestation via a communication link. The remote GPS receiver unit uses this satellite almanac data to determine approximate Doppler data for satellites in view of the remote GPS receiver unit.

Claims

1. A method of calibrating a local oscillator in a mobile GPS receiver, said method comprising:

receiving a precision carrier frequency signal from a source providing said precision carrier frequency signal;

automatically locking to said precision carrier frequency signal and providing a reference signal;

calibrating said local oscillator with said reference signal, said local oscillator being used to acquire GPS signals.

2. A method as in claim 1 wherein said receiving step comprises extracting said precision carrier frequency signal from a data signal containing satellite data information communicated over a communication link.

3. A method as in claim 2 wherein said satellite data information comprises a satellite almanac information for a plurality of satellites in view of said mobile GPS receiver.

4. A method as in claim 2 wherein said satellite data information comprises data representative of ephemeris for a satellite.

5. A method as in claim 2 wherein said communication link is selected from the group consisting of a two-way pager link or a cellular telephone link or personal communication system or specialized mobile radio or a wireless packet data system.

6. A method as in claim 2 wherein said communication link is a radio frequency communication medium.

7. A method as in claim 1 wherein said automatic frequency control logic comprises one of a phase lock loop or a frequency lock loop or a block phase estimator.

8. A method as in claim 7 wherein said reference signal provides a reference frequency which is compared to a frequency provided by said local oscillator to calibrate said local oscillator.

9. A method as in claim 1 wherein said mobile GPS receiver receives a data signal containing satellite data information which comprises a Doppler information of a satellite in view of said mobile GPS receiver.

10. A mobile GPS receiver comprising:

a first antenna for receiving GPS signals;

a downconverter coupled to said first antenna, said first antenna providing said GPS signals to said downconverter;

a local oscillator coupled to said downconverter, said local oscillator providing a first reference signal to said downconverter to convert said GPS signals from a first frequency to a second frequency;

a second antenna for receiving a precision carrier frequency signal from a source providing said precision carrier frequency signal;

an automatic frequency control (AFC) circuit coupled to said second antenna, said AFC circuit providing a second reference signal to said local oscillator to calibrate said first reference signal of said local oscillator, wherein said local oscillator is used to acquire said GPS signals.

11. A mobile GPS receiver as in claim 10 further comprising a comparator coupled to said AFC circuit and to said local oscillator, said comparator comparing said first reference signal and said second reference signal to adjust the frequency of said first reference signal from said local oscillator.

12. A mobile GPS receiver as in claim 11 wherein said AFC circuit comprises a phase lock loop coupled to a receiver which is coupled to said second antenna.

13. A mobile GPS receiver as in claim 10 further comprising a receiver coupled to said second antenna, said receiver for receiving said precision carrier frequency signal from said second antenna, wherein said receiver receives said precision carrier frequency signal with a data signal containing satellite data information communicated through said second antenna.

14. A mobile GPS receiver as in claim 13 wherein said satellite data information comprises a Doppler information of a satellite in view of said mobile GPS receiver.

15. A mobile GPS receiver as in claim 14 wherein said satellite data information comprises an identification of a plurality of satellites in view of said mobile GPS receiver and a corresponding plurality of Doppler information for each satellite of said plurality of satellites in view of said mobile GPS receiver.

16. A mobile GPS receiver as in claim 13 wherein said satellite data information comprises data representative of ephemeris for a satellite.

17. A method of using a basestation to calibrate a local oscillator in a mobile GPS receiver, said method comprising:

producing a first reference signal having a precision frequency;

modulating said first reference signal with a data signal to provide a precision carrier frequency signal;

transmitting said precision carrier frequency signal to said mobile GPS receiver, said precision carrier frequency signal being used to calibrate a local oscillator in said mobile GPS receiver, said local oscillator being used to acquire GPS signals.

18. A method as in claim 17 wherein said data signal contains satellite data information which comprises a satellite almanac information for a plurality of satellites in view of said mobile GPS receiver.

19. A method as in claim 17 wherein said data signal contains satellite data information which comprises data representative of ephemeris for a satellite.

20. A method as in claim 17 wherein said data signal contains satellite data information which comprises a Doppler information of a satellite in view of said mobile GPS receiver.

21. A basestation for providing a calibration signal for use in a mobile GPS receiver to calibrate a local oscillator in said mobile GPS receiver, said basestation comprising:

a first source for a first reference signal have a precision frequency;

a modulator coupled to said first source and to a second source of satellite data information said modulator providing a precision carrier frequency signal;

a transmitter coupled to said modulator, said transmitter for transmitting said precision carrier frequency signal to said mobile GPS receiver, said precision frequency signal being used to calibrate said local oscillator, said local oscillator being used to acquire said GPS signals.

22. A basestation as in claim 21 wherein said precision carrier frequency signal has a first frequency which is substantially different from a frequency of said GPS signals.

23. A basestation as in claim 21 wherein said satellite data information comprises data representative of ephemeris for a satellite in view of said mobile GPS receiver.

24. A basestation as in claim 21 further comprising a processor coupled to said transmitter, said processor instructing said transmitter to transmit to said mobile GPS receiver.

25. A basestation as in claim 24 wherein said processor determines a plurality of satellites in view of said mobile GPS receiver and obtains said satellite data information for each satellite of said plurality of satellites, and wherein said processor instructs said transmitter to transmit to said mobile GPS receiver an identification of said plurality of satellites and said satellite data information.

26. A basestation as in claim 25 wherein said satellite data information comprises Doppler information for said plurality of satellites.

27. A basestation as in claim 25 wherein said satellite data information comprises data representative of ephemeris for said plurality of satellites.

28. A basestation as in claim 21 wherein said satellite data information comprises a Doppler information of a satellite in view of said mobile GPS receiver.

29. A method of deriving a local oscillator signal in a mobile GPS receiver, said method comprising:

receiving a precision carrier frequency signal from a source providing said precision carrier frequency signal;

automatically locking to said precision carrier frequency signal and providing a reference signal;

using said reference signal to provide a local oscillator signal to acquire GPS signals.

30. A method as in claim 29 wherein said receiving step comprises extracting said precision carrier frequency signal from a data signal containing satellite data information communicated over a communication link.

31. A method as in claim 30 wherein said satellite data information comprises a satellite almanac information for a plurality of satellites in view of said mobile GPS receiver.

32. A method as in claim 30 wherein said satellite data information comprises data representative of ephemeris for a satellite.

33. A method as in claim 30 wherein said communication link is selected from the group consisting of a two-way pager link or a cellular telephone link or personal communication system or specialized mobile radio or a wireless packet data system.

34. A method as in claim 30 wherein said communication link is a radio frequency communication medium.

35. A method as in claim 29 wherein said step of using said reference signal comprises providing said reference signal to a frequency synthesizer and producing said local oscillator signal from said reference signal and said frequency synthesizer.

36. A method as in claim 29 further comprising downconverting GPS signals received through a GPS antenna, said downconverting step using said local oscillator signal to downconvert said GPS signals.

37. A method as in claim 29 wherein said step of using said reference signal comprises downconverting GPS signals received through a GPS antenna, said downconverting using said local oscillator signal to downconvert said GPS signals.

38. A mobile GPS receiver comprising:

a first antenna for receiving GPS signals;

a downconverter coupled to said first antenna, said first antenna providing said GPS signals to said downconverter, said downconverter having an input for receiving a local oscillator signal to convert said GPS signals from a first frequency to a second frequency;

a second antenna for receiving a precision carrier frequency signal from a source providing said precision carrier frequency signal;

an automatic frequency control (AFC) circuit coupled to said second antenna, said AFC circuit being coupled to said downconverter to provide said local oscillator signal which is used to acquire said GPS signals.

39. A mobile GPS receiver as in claim 38 further comprising a frequency synthesizer coupled to said AFC circuit and to said downconverter, said downconverter receiving said local oscillator through said frequency synthesizer.