GPS receiver having power management

• US 6,133,871 A
• Filed: 03/08/1996
• Issued: 10/17/2000
• Est. Priority Date: 10/09/1995
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Krasner, Norman F.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/613,966
• Time in Patent Office: 1,684 Days
• Field of Search: 342/357, 364/449.7, 364/707, 455/343
• US Class Current: 342/357.74
• CPC Class Codes: G01S 19/05 providing 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 19/254 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
• 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 2205/008 using a mobile telephone network
• 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 7/06 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
• CPC Class Codes: H04B 2001/3894 Waterproofing of transmission device

Abstract

A GPS receiver having a low power mode of operation in one embodiment includes an antenna which receives GPS signals at an RF frequency from in view satellites; a downconverter coupled to the antenna for reducing the RF frequency of the received GPS signals to an intermediate frequency (IF); a digitizer coupled to the downconverter and sampling the IF GPS signals at a predetermined rate to produce sampled IF GPS signals; a memory coupled to the digitizer storing the sampled IF GPS signals; and a digital signal processor (DSP) coupled to the memory and operating under stored instructions thereby performing operations on the sampled IF GPS signals to provide pseudorange information. In one example, after the sampled IF GPS signals have been stored in the memory, the GPS receiver front end is powered down and the DSP is powered up. The GPS receiver in one embodiment also includes other power management features.

Claims

1. A method of power management for a GPS receiver, said method comprising:

receiving at said GPS receiver, GPS signals from in view satellites and consuming power by a GPS receiving section of said GPS receiver at a first rate while receiving said GPS signals;

digitizing said GPS signals to provide a digital representation of said GPS signals;

buffering said digital representation of said GPS signals in a digital memory;

reducing power consumed by said GPS receiving section of said GPS receiver to a second rate, which is less than said first rate, after buffering said digital representation, wherein said GPS receiving section downconverts GPS radiofrequency signals to an intermediate frequency;

processing said digital representation by retrieving said digital representation from said digital memory and processing said digital representation to provide at least one pseudorange information, said processing being performed after said reducing power, said processing comprising a fast convolution operation on said digital representation of said GPS signals which are buffered in a memory;

wherein the amount of said digital representation of said GPS signals which are buffered in said memory may be varied to trade off sensitivity with power reduction.

2. A method as in claim 1 wherein less of said digital representation of said GPS signals may be buffered in order to save more power.

3. A method of power management for a GPS receiver, said method comprising:

receiving at said GPS receiver, GPS signals from in view satellites and consuming power by a GPS receiving section of said GPS receiver at a first rate while receiving said GPS signals;

digitizing said GPS signals to provide a digital representation of said GPS signals;

buffering said digital representation of said GPS signals in a digital memory;

reducing power consumed by said GPS receiving section of said GPS receiver to a second rate, which is less than said first rate, after buffering said digital representation, wherein said GPS receiving section downconverts GPS radiofrequency signals to an intermediate frequency;

processing said digital representation by retrieving said digital representation from said digital memory and processing said digital representation to provide at least one pseudorange information, said processing being performed after said reducing power, said processing comprising a fast convolution operation on said digital representation of said GPS signals which are buffered in a memory;

receiving at said GPS receiver a Doppler information of a satellite in view of said GPS receiver;

wherein the amount of said GPS signals which are buffered in said digital memory may be varied to trade off sensitivity with power reduction.

4. A method as in claim 3 wherein less of said digital representation of said GPS signals may be buffered in order to save more power.

5. A GPS mobile unit having a reduced power state, said GPS mobile unit comprising:

a receiver for receiving GPS signals from in view satellites;

a memory coupled to said receiver to store a digital representation of said GPS signals;

a processor coupled to said memory, said processor processing said digital representation of said GPS signals to provide at least one pseudorange information from said digital representation;

a power management circuit coupled to a GPS receiving section of said receiver, said power management circuit reducing power consumed by said GPS receiving section of said receiver of said GPS mobile unit from a first rate consumed while receiving said GPS signals to a second rate after storing said digital representation, wherein said GPS receiving section downconverts GPS radiofrequency signals to an intermediate frequency and wherein said power management circuit increases power consumed by said processor from a third rate consumed while receiving said GPS signals to a fourth rate after said digital representation is stored in said memory in order to process said GPS signals.

6. A GPS mobile unit as in claim 5 further comprising a communication receiver and a communication transmitter being coupled to said power management circuit.

7. A GPS mobile unit as in claim 5 wherein said power management circuit reduces power consumed by said processor.

8. A GPS mobile unit as in claim 6 wherein after said GPS mobile unit is in a reduced power state, said power management circuit returns said GPS mobile unit to an increased power consumption state after receiving a signal from said communication receiver.

9. A GPS mobile unit as in claim 5 further comprising a battery and a solar cell and a power regulator coupled to said battery and to said solar cell and to said power management circuit, said solar cell for charging said battery.

10. A GPS mobile unit as in claim 5 further comprising:

a first controlled power interconnect coupled to said receiver and to said power management circuit;

a second controlled power interconnect coupled to said memory and to said power management circuit, wherein said power management circuit reduces power by controlling the power provided to said receiver over said first controlled power interconnect and by controlling the power provided to said memory over said second controlled power interconnect.

11. A GPS mobile unit as in claim 5 wherein said power management circuit comprises a microprocessor and a plurality of power switches.

12. A GPS mobile unit as in claim 5 wherein said power management circuit comprises power control logic in a digital signal processing component and wherein said processor comprises said digital signal processing component.

13. A GPS mobile unit as in claim 12 wherein said power management circuit further comprises a plurality of power switches coupled to said power control logic.

14. A GPS mobile unit as in claim 5 further comprising a communication receiver which receives a satellite data information which comprises a Doppler information of a satellite in view of said GPS receiver.

15. A GPS mobile unit as in claim 5 wherein after said GPS mobile unit is in a reduced power state, said power management circuit returns said GPS mobile unit to an increased power consumption state.

16. A GPS mobile unit as in claim 5 further comprising a communication receiver which receives a satellite data information which comprises data representative of ephemeris for a satellite.

17. A GPS mobile unit as in claim 5 wherein said processor processes said GPS signals by performing fast convolution operations on said digital representation of said GPS signals.

18. A GPS mobile unit as in claim 17 wherein after storing said digital representation of said GPS signals in said memory, power consumed by said receiver is reduced.

19. A GPS mobile unit as in claim 17 wherein a preprocessing operation on said digital representation of said GPS signals is performed before performing said fast convolution operations.

20. A GPS mobile unit as in claim 19 wherein a postprocessing operation on the results of said fast convolution operations is performed after performing said fast convolution operations.

21. A GPS mobile unit as in claim 5 further comprising a local oscillator coupled to said receiver, said local oscillator providing a first reference signal and a communication receiver coupled to said local oscillator, said communication receiver providing a precision carrier frequency signal for calibrating said local oscillator which is used to acquire said GPS signals.

22. In a GPS system, having a mobile GPS receiver and a base unit said mobile GPS receiver having a reduced power state, a method for operating the GPS system comprising:

receiving a communication signal at the mobile GPS receiver, wherein said communication signal comprises satellite information;

placing the mobile GPS receiver into a high power state from said reduced power state after receiving said communication signal;

collecting and storing GPS data and reducing power in said mobile GPS receiver after storing said GPS data;

transmitting a representation of GPS signal data to a base unit;

computing the final position of the mobile GPS receiver in the base unit; and

using a microprocessor to control a level of a GPS receiver sensitivity in response to a selected power consumption level of the mobile GPS receiver.

23. The method of claim 22, where in the mobile GPS receiver sensitivity is controlled by the amount of data stored in the at least one memory.

24. The method of claim 23, wherein the mobile GPS receiver sensitivity is increased as the microprocessor stores more data in the at least one memory.