Low power GPS receiver system and method of using same

• US 6,212,133 B1
• Filed: 07/26/1999
• Issued: 04/03/2001
• Est. Priority Date: 07/26/1999
• Status: Expired due to Fees

• Current Assignee: Ocean Sensor, Inc.
• Original Assignee: David Jacobs, Kim Mccoy
• Inventors: Jacobs, David, McCoy, Kim
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H.
• Application Number:
  US09/360,789
• Time in Patent Office: 617 Days
• Field of Search: 342/357.12, 342/357.06, 73/1.44, 702/89, 368/14, 368/1, 368/9, 368/10, 701/213
• US Class Current: 368/9
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G04G 19/00 Electric power supply circuits specially adapted for use in electronic time-pieces
• CPC Class Codes: G04R 20/04 Tuning or receiving; Circuits therefor
• CPC Class Codes: G04R 60/10 inside cases

Abstract

A new and improved low power GPS signal receiver system includes a GPS signal receiver device and control processor for powering up the signal receiver device for a first sufficient period of time to locate and acquire a time signal from a single GPS satellite and then powering down the GPS signal receiver device after establishing a local time and for waiting another sufficient period of time after receiving a user request to update time before powering up the signal receiver device to facilitate about an immediate sync on another GPS navigation message subframe indicative of the time maintained by said single GPS satellite vehicle. Once the second sufficient period of time has elapsed, the control processor powers up the GPS signal receiver device for a third sufficient period of time to acquire and process 29 bits of subframe message information indicative of time maintained by the GPS satellite vehicle. Once the time maintained by such a single GPS satellite vehicle has been obtained and processed, the control processor powers downs the GPS signal receiver device to a low power standby mode to wait for another user request to update time.

Claims

1. A method of determining a Universal Coordinated Time value, comprising:

activating a GPS signal receiver device to a full power mode of operation for a sufficient period of time to acquire only one subframe of a GPS navigation message indicative of time correction parameters;

processing the acquired one subframe of said GPS navigation message to update and display a current Universal Coordinated Time value; and

deactivating said GPS signal receiver device to a low power standby mode of operation until such time as a user desires to further update the current Universal Coordinate Time value.

2. A method according to claim 1, wherein the acquired one subframe of said GPS navigation message is acquired from a single GPS satellite.

3. A method according to claim 2, wherein the acquired one subframe of said GPS navigation message is only indicative of time in seconds.

4. A method according to claim 2, wherein the acquired one subframe of said GPS navigation message is only indicative of time in weeks and seconds.

5. A method according to claim 1, wherein said sufficient period of time is truncated when the subframe includes a specific week sequence of bits that corresponds to a current week sequence of bits stored in said GPS signal receiver device.

6. A method according to claim 5, wherein said sufficient period of time is less than six seconds in duration.

7. A method according to claim 1, wherein said sufficient period of time is about six seconds in duration.

8. A method according to claim 1, further comprising:

activating said GPS signal receiver device to a full power mode of operation for another sufficient period of time to acquire only another single subframe of a GPS navigation message indicative of time correction parameters;

processing the acquired another subframe of said GPS navigation message to update and display another current Universal Coordinated Time value having an increased accuracy; and

deactivating said GPS signal receiver device to a low power standby mode of operation until such time as a user desires to further update the current Universal Coordinate Time value.

9. A method according to claim 1, further comprising:

storing a current week sequence of bits derived from the only one subframe of said GPS navigation message.

10. A method according to claim 9, further comprising:

activating said GPS signal receiver device to a full power mode of operation for another sufficient period of time to acquire only another single subframe of a GPS navigation message indicative of time correction parameters;

processing the acquired another subframe of said GPS navigation message to update and display another current Universal Coordinated Time value having an increased accuracy;

deactivating said GPS signal receiver device to a low power standby mode of operation until such time as a user desires to further update the current Universal Coordinate Time value; and

truncating said sufficient period of time when the subframe includes a specific week sequence of bits that corresponds to the current week sequence of bits stored in said GPS signal receiver device.

11. A system for determining a Universal Coordinated Time value, comprising:

a time calculating device for processing only one subframe of a GPS navigation message indicative of time correction parameters and for causing a current Universal Coordinated Time value to be updated and displayed for a user; and

a user interface responsive to the user for activating said time calculating device to a full power mode of operation for a sufficient period of time to acquire the only one subframe of said GPS navigation message indicative of time correction parameters;

said time calculating device returning to a low power standby mode of operation for displaying time only after said time calculating device processes the only one subframe of a GPS navigation and causes the displaying of the updated Universal Coordinated Time value.

12. A time keeping device, comprising:

an encasement having a front face display for providing a user with a visual indication of time;

a lid mounted removably to the front face of said encasement for protecting said front face display, said lid having embedded therein a thin loop wire antenna for capturing GPS satellite signals;

a time calculating device coupled to said antenna for processing captured GPS satellite signals, said time a time calculating device for processing only one subframe of a single GPS navigation message indicative of time correction parameters and for causing a current displayed time value to be updated for visualization by a user; and

a user interface responsive to the user for activating said time calculating device to a full power mode of operation for a sufficient period of time to acquire the only one subframe of said GPS navigation message indicative of time correction parameters;

said time calculating device returning to a low power standby mode of operation for displaying time only after said time calculating device processes the only one subframe of a GPS navigation and causes the displaying of the updated time value.

13. A time keeping device according to claim 12, wherein said time calculating device is a time and position calculating device.

14. A time keeping device according to claim 12, wherein said time calculating device process only the time relevant portions of the acquired GPS navigation message.

15. A time keeping device according to claim 13, wherein said time and positioning calculating device further processes satellite ephemeris information for determining user position information.

16. A time keeping device according to claim 15, further comprising:

a memory device coupled to said time and positioning device for storing the satellite ephemeris information to increase the accuracy of the displayed time value.

17. A time keeping device according to claim 14, wherein said time calculating device processes only the seconds portions of the acquired GPS navigation message.

18. A time keeping device according to claim 14, wherein said time calculating device recognizes repeated bit sequences in the GPS navigation message for improved power efficiency purposes.

19. A time keeping device according to claim 14, wherein said time calculating device includes a GPS receiver.

20. A time keeping device according to claim 19, wherein said GPS receiver can convert L1 GPS signals and L2 GPS signals.

21. A method of determining a Universal Coordinated Time value, comprising:

determining a sync time in response to a user initiating a request to acquire time;

activating a GPS signal receiver device at about said sync time from a low power standby mode of operation to a full power mode of operation for a sufficient period of time to enable a control processor to acquire a next available single subframe of time information from said single GPS satellite, said sufficient period of time being sufficient to acquire only 29 bits of said GPS navigation message indicative of time correction parameters and to process the acquired 29 bits of said GPS navigation message for updating a current Universal Coordinated Time value; and

deactivating said GPS signal receiver device to said low power standby mode of operation.

22. A method according to claim 21, wherein said sufficient period of time is between about 0.03 seconds and about 6.0 seconds.

23. A method according to claim 21, wherein said sufficient period of time is substantially less than 6.0 seconds.

24. A method according to claim 23, wherein said sufficient period of time is substantially greater than 6.0 seconds when the user has traveled a significant distance from an original time acquisition location.