Long life portable global position system receiver

• US 5,448,773 A
• Filed: 02/05/1992
• Issued: 09/05/1995
• Est. Priority Date: 02/05/1992
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Woo, Arthur N., Gilman, David J., McBurney, Paul W., Weber, Lynn
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): VO, NGUYEN THANH
• Application Number:
  US07/831,870
• Time in Patent Office: 1,308 Days
• Field of Search: 455/343, 455/33.1, 455/38.3, 455/54.1, 455/56.1, 455/9, 455/12.1, 455/13.4, 455/89, 342/357
• US Class Current: 455/343.6
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A global positioning system (GPS) receiver having a radio frequency (RF) circuitry to receive position signals from a plurality of satellites and to provide an intermediate frequency (IF) signal to a correlator circuitry for generating a pseudo range and a Doppler measurement for calculating a position fix. The GPS receiver further has a power supply system which has at least one battery and an alternative external power connector for connecting to an external power source. The GPS receiver further has a microprocessor having a read only memory (ROM). The microprocessor is electrically connected to the RF circuitry and the power supply system. Since the GPS receiver does not need to constantly process all the GPS position signals that are available to it to provide a useful tool, the ROM includes a program for automatically controlling the power supply to the RF circuitry so that battery power is conserved.

Claims

1. A global positioning system (GPS) receiver having a radio frequency (RF) circuitry to receive position signals from a plurality of satellites and to provide an intermediate frequency (IF) signal to a correlator circuitry for generating a pseudo range and a Doppler measurement for calculating a position fix, the GPS receiver further comprising:

a power supply system having at least one battery and an alternative external power connector for connecting to an external power source; and

a microprocessor having a read only memory, the microprocessor being electrically connected to said RF circuitry and the power supply system; and

an executable program stored in said memory for automatically controlling the power supply system to provide on/off power control to said RF circuitry, and having means for computing a velocity vector of the GPS receiver for determining a required number of satellites wherefrom said position signals must be received for computing said position fix to satisfy a position accuracy requirement, said executable program further includes means for determining from monitoring said position signals received from said plurality of satellites an actual number of satellites wherefrom said position signals are being received, said executable program controls the power supply system to cut off battery power to said RF circuitry for a predetermined duration of time when said actual number of satellites is greater or equal to said required number of satellites wherefrom said position signals must be received, wherein a saving of battery power is provided whenever the power supply system is not provided with said external source of power at said alternative external power connector.

2. The GPS receiver of claim 1, wherein:

said executable program in said memory further includes means for determining a time gap duration between successive RF circuitry power-on periods as a function of said velocity vector of the GPS receiver wherein a dead reckoning (DR) error is reduced.

3. The GPS receiver of claim 2 wherein:

said executable program in said memory further includes means for a GPS user to input at least one threshold speed; and

said executable program further includes means to determine if speed of the GPS receiver is greater than said threshold speed, and adjusting said time gap duration between said RF circuitry power-on periods as a function of said velocity vector of the GPS receiver when the speed of the GPS receiver is greater than said threshold speed.

4. The GPS receiver of claim 1, wherein:

said executable program in said memory further includes means for storing a plurality of historical position fix data and a list of visible satellites, and if said actual number of satellites wherefrom said position signals are being received is less than said required satellites wherefrom said position signals must be received, said executable program further includes means by using said historical position fix data and said list of visible satellites to determine if an additional RF circuitry power-on is to be performed.

5. The GPS receiver in accordance with claim 1, wherein:

said executable program in said memory further includes means for determining if one of said satellites is lost and if said lost satellite has a low elevation and to discontinue a satellite acquisition for said lost satellite with said low elevation.

6. A GPS receiver in accordance with claim 1 wherein:

said executable program in said memory further includes means for determining if said actual number of satellites is less than said required number of satellites wherefrom said position signals must be received;

said executable program further includes means for determining if a two dimensional position fix is sufficient and available, and to turn off the RF power when said actual number of satellites is less than said required number of satellites during a period of time, wherein the battery power is conserved.

8. The GPS receiver of claim 1, further comprising:

man-machine interface means for user input of a number representing a threshold velocity;

comparator means coupled to the man-machine interface means and navigation computer means for determining if said computed velocity vector exceeds said threshold velocity; and

power-on frequency adjusting means connected to the comparator means and the power switch means for increasing the on-time of the receiver section whenever said computed velocity vector exceeds said threshold velocity, otherwise the on-time of the receiver section is not affected.

7. A battery-operated global positioning system (GPS) receiver with extended battery life operation, comprising:

a battery connected to power said GPS receiver;

a receiver section for receiving position signals from a plurality of orbiting GPS satellites;

power switch means connected between the receiver section and the battery for turning power on and off to the receiver section in response to a control signal; and

navigation computer means connected to the receiver section for tracking said plurality of orbiting satellites and to the power switch means for turning on power to the receiver section with said control signal when the navigation computer means requires updates of said position signals to provide a position fix for said GPS receiver, wherein the battery life of the battery is extended by periodically powering-off the receiver section, and includes means for computing a velocity vector of said GPS receiver that influences the minimum number of GPS satellites providing said position signals that must be received for computing said position fix to a predetermined position accuracy, and further includes means for extending and shortening the time that said control signal causes the receiver section to be powered-on or powered-off in response to the time necessary to receive said position signals from said minimum number GPS satellites.

9. A battery-operated global positioning system (GPS) receiver with extended battery life operation, comprising:

a battery connected to power said GPS receiver;

a receiver section for receiving position signals from a plurality of orbiting GPS satellites;

power switch means connected between the receiver section and the battery for turning power on and off to the receiver section in response to a control signal;

navigation computer means connected to the receiver section for tracking said plurality of orbiting satellites and to the power switch means for turning on power for a period of time to the receiver section with said control signal when the navigation computer means requires updates of said position signals to provide a position fix for said GPS receiver, wherein the battery life of the battery is extended by periodically powering-off the receiver section;

constellation means connected to the navigation computer means for determining if the number of GPS satellites accessed by the receiver section exceeds a required predetermined number of GPS satellites; and

shut-down means connected to the power switch means and constellation means for turning-off power to the receiver section whenever there are lost satellites, but a sufficient number of GPS satellites have been accessed after a period of time to make available a good position fix.