GPS receiver suspending correlation value calculation process for time period corresponding to condition of received signal

• US 6,259,402 B1
• Filed: 11/12/1999
• Issued: 07/10/2001
• Est. Priority Date: 05/26/1999
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Asai, Takashi
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US09/438,539
• Time in Patent Office: 606 Days
• Field of Search: 342/357.12
• US Class Current: 342/357.74
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: H04B 2001/70706 using a code tracking loop, e.g. a delay locked loop

Abstract

A GPS receiver being able to realize reduction of power consumption in a tracking process includes: a receiving portion receiving a signal transmitted from a satellite; a correlation value calculation portion connected to the receiving portion generating a pseudo noise signal corresponding to the satellite and calculating a correlation value of a reception signal output from the receiving portion and the pseudo noise signal; a data demodulation device connected to the correlation value calculation portion demodulating data included in the reception signal based on the correlation value every predetermined cycle; a time period determination device connected to the correlation value calculation portion seeking a condition of the reception signal at reception based on the correlation value and determining a correlation value calculation period at the correlation value calculation portion according to the condition at the reception; and a process suspension control device connected to the time period determination device and the correlation value calculation portion obtaining a suspension period of an operation relating to the calculation of the correlation value at the correlation value calculation portion based on the predetermine cycle and the correlation value calculation period and suspending the operation relating to the calculation of the correlation value at the correlation value calculation portion for the suspension period.

Claims

1. A GPS (Global Positioning System) receiver comprising:

a receiving portion receiving a signal transmitted from a satellite;

a correlation value calculation portion connected to said receiving portion, generating a pseudo noise signal corresponding to the satellite and calculating a correlation value of a reception signal output from said receiving portion and said pseudo noise signal;

a data demodulation device connected to said correlation value calculation portion, demodulating data included in said reception signal based on said correlation value every predetermined cycle;

a time period determination device connected to said correlation value calculation portion, seeking a condition of said reception signal at reception based on said correlation value and determining a correlation value calculation period at said correlation value calculation portion according to said condition at the reception; and

a process suspension control device connected to said time period determination device and said correlation value calculation portion, obtaining a suspension period of an operation relating to the calculation of said correlation value at said correlation value calculation portion based on said predetermine cycle and said correlation value calculation period and suspending the operation relating to the calculation of said correlation value at said correlation value calculation portion for said suspension period.

2. The GPS receiver according to claim 1, wherein

said time period determination device calculates a strength of said reception signal based on said correlation value and determines said correlation value calculation period based on the strength of said reception signal.

3. The GPS receiver according to claim 1, wherein

said time period determination device calculates energy of said reception signal based on said correlation value and determines said correlation value calculation period based on an amount of said energy.

4. The GPS receiver according to claim 1, wherein

said time period determination device calculates an error rate at the data demodulation based on data output from said data demodulation device, and determines said correlation value calculation period based on a value of said error rate.

5. The GPS receiver according to claim 1, wherein

said time period determination device calculates a predicted energy value of said reception signal based on said correlation value and determines said correlation value calculation period based on an amount of said predicted energy value.

6. The GPS receiver according to claim 1, wherein

said time period determination device calculates a predicted energy value of said reception signal based on almanac data contained in the signal transmitted from the satellite, and determines said correlation value calculation period based on an amount of said predicted energy value.

7. The GPS receiver according to claim 1, wherein

said time period determination device calculates a predicted energy value of said reception signal based on ephemeris data contained in the signal transmitted from the satellite, and determines said correlation value calculation period based on an amount of said predicted energy value.

8. The GPS receiver according to claim 1, wherein

said correlation value calculation portion includes,

a carrier signal generation device generating a carrier signal,

a first multiplier connected to said receiving portion and said carrier signal generation device, multiplying said reception signal by said carrier signal,

a pseudo noise signal generation device generating the pseudo noise signal corresponding to the satellite,

a second multiplier connected to said first multiplier and said pseudo noise signal generation device, multiplying an output of said first multiplier by said pseudo noise signal, and

an adder connected to an output of said second multiplier, accumulating outputs of said second multiplier.

9. The GPS receiver according to claim 8, wherein

said process suspension control device includes an addition suspension control device connected to said time period determination device and said adder, obtaining the suspension period of the operation relating to the calculation of said correlation value at said correlation value calculation portion based on said predetermined cycle and said correlation value calculation period, and suspending an accumulation process at said adder for said suspension period.

10. The GPS receiver according to claim 8, wherein

said process suspension control device is connected to a part or all of said adder, said carrier signal generation device and said pseudo noise signal generation device, and suspends operation(s) of a part or all of said adder, said carrier signal generation device and said pseudo noise signal generation device for said obtained suspension period.

11. The GPS receiver according to claim 8, wherein

said receiving portion includes,

a receiving device receiving the signal transmitted from the satellite, and

a latch having an input receiving an output of said receiving device, and wherein

said process suspension control device is connected to said time period determination device and said latch, obtains a suspension period of an operation relating to a calculation of said correlation value at said correlation value calculation portion based on said predetermined cycle and said correlation value calculation period and suspends an input to said latch for said suspension period.

12. The GPS receiver according to claim 1, wherein

said correlation value calculation portion includes,

a pseudo noise signal generation device generating the pseudo noise signal corresponding to the satellite,

a first multiplier connected to said receiving portion and said pseudo noise signal generation device, multiplying said reception signal by said pseudo noise signal,

a carrier signal generation device generating a carrier signal,

a second multiplier connected to said first multiplier and said carrier signal generation device, multiplying an output of said first multiplier by said carrier signal, and

an adder connected to an output of said second multiplier accumulating outputs of said second multiplier.

13. The GPS receiver according to claim 12, wherein

said process suspension control device includes an addition suspension control device connected to said time period determination device and said adder, obtaining the suspension period of the operation relating to the calculation of said correlation value at said correlation value calculation portion based on said predetermined cycle and said correlation value calculation period, and suspending an accumulation process at said adder for said suspension period.

14. The GPS receiver according to claim 12, wherein

said process suspension control device is connected to a part or all of said adder, said carrier signal generation device and said pseudo noise signal generation device, and suspends operation(s) of a part or all of said adder, said carrier signal generation device and said pseudo noise signal generation device for said obtained suspension period.

15. The GPS receiver according to claim 12, wherein

said receiving portion includes,

a receiving device receiving the signal transmitted from the satellite, and

a latch having an input receiving an output of said receiving device, and wherein

said process suspension control device is connected to said time period determination device and said latch, obtains a suspension period of an operation relating to a calculation of said correlation value at said correlation value calculation portion based on said predetermined cycle and said correlation value calculation period and suspends an input to said latch for said suspension period.

16. The GPS receiver according to claim 1 wherein

said receiving portion includes,

a receiving device receiving the signal transmitted from the satellite, and

a latch having an input receiving an output of said receiving device, and wherein

said process suspension control device is connected to said time period determination device and said latch, obtains a suspension period of an operation relating to a calculation of said correlation value at said correlation value calculation portion based on said predetermined cycle and said correlation value calculation period and suspends an input to said latch for said suspension period.

17. The GPS receiver according to claim 1 wherein said correlation value calculation portion outputs said correlation value every said predetermined cycle.