Global positioning apparatus and method for using a temperature compensated oscillator to perform a position fix
First Claim
Patent Images
1. A global positioning receiver unit, having an active state and a sleep state, for use in a global positioning system (GPS), comprising:
- a temperature controlled oscillator configured to generate a clock signal; and
a unit controller configured to track GPS time based on the clock signal while the receiver unit is in the sleep state, wherein, upon the receiver unit entering the active state from the sleep state, (i) if the duration of the sleep state from which the active state is entered is less than a threshold value, the unit controller performs a position fix based on a satellite signal and a GPS time tracked by the unit controller and (ii) if the duration of the sleep state is not less than the threshold, the unit controller performs the position fix without relying on the GPS time tracked by the unit controller.
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Abstract
A global positioning receiver unit utilizes a temperature compensated oscillator and a unit controller. The temperature compensated oscillator generates a clock signal, and the unit controller is configured to track GPS time based on the clock signal while the receiver unit is in a sleep state. The unit controller is further configured to perform a position fix based on a satellite signal and the GPS time tracked by the unit controller.
39 Citations
12 Claims
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1. A global positioning receiver unit, having an active state and a sleep state, for use in a global positioning system (GPS), comprising:
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a temperature controlled oscillator configured to generate a clock signal; and a unit controller configured to track GPS time based on the clock signal while the receiver unit is in the sleep state, wherein, upon the receiver unit entering the active state from the sleep state, (i) if the duration of the sleep state from which the active state is entered is less than a threshold value, the unit controller performs a position fix based on a satellite signal and a GPS time tracked by the unit controller and (ii) if the duration of the sleep state is not less than the threshold, the unit controller performs the position fix without relying on the GPS time tracked by the unit controller. - View Dependent Claims (2, 3, 4)
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5. A global positioning receiver unit for use in a global positioning system (GPS), comprising:
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temperature compensated means for generating a clock signal; means for tracking GPS time based on the clock signal while the receiver unit is in a sleep state; means for transitioning the receiver unit from the sleep state to an active state wherein transitioning includes comparing a configurable threshold value with a value indicative of time elapsed since a transition of the receiver unit to the sleep state; means for acquiring a satellite signal; and means for performing a position fix based on the satellite signal and a GPS time maintained in the tracking means, when the value indicative of time elapsed is less than the threshold value, and for performing the position fix based on the satellite signal without relying on the GPS time maintained in the tracking means, when the value indicative of time elapsed exceeds the threshold value.
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6. A global positioning receiver unit for use in a global positioning system (GPS), comprising:
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a temperature controlled oscillator configured to generate a clock signal; and a unit controller configured to track GPS time based on the clock signal while the receiver unit is in a sleep state, the unit controller configured to determine a time value indicative of a duration that the receiver unit is in the sleep state, the unit controller configured to perform, if the time value is less than a threshold value, a position fix based on a satellite signal and the GPS time tracked by the unit controller, the unit controller further configured to perform, if the time value exceeds the threshold value, a position fix based on the satellite signal and time data determined from a sub-frame of the satellite signal. - View Dependent Claims (7)
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8. A global positioning method, comprising:
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generating a clock signal via a temperature controlled oscillator within a global positioning receiver unit; tracking global positioning system (GPS) time based on the clock signal while the receiver unit is in a sleep state; determining a value indicative of an amount of time elapsed between a transition of the receiver unit to the sleep state and a transition of the receiver unit to an active state; performing a comparison between the value and a threshold value; acquiring a satellite signal, in an active state; and in the active state, (i) when the value is less than the threshold value, performing a position fix based on the satellite signal and a GPS time tracked in the tracking step, and (ii) when the value exceeds the threshold value, performing the position fix based on the satellite signal without relying on the GPS time tracked in the tracking step. - View Dependent Claims (9, 10)
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11. A global positioning method for use on a global positioning receiver unit of a global positioning system (GPS), comprising:
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generating a clock signal via a temperature compensated oscillator; maintaining time data based on the clock signal while the receiver unit is in a sleep state;
the time data indicative of GPS time;determining a value indicative of a duration that the receiver unit is in the sleep state; performing a comparison between the value and a threshold value; acquiring a satellite signal; and (i) performing a position fix based on the acquired signal and the maintained time data, when the comparison indicates that the value is less than the threshold value, and (ii) performing the position fix based on the acquired signal and without relying on the maintained time data, when the comparison indicates that the value is not less than the threshold value. - View Dependent Claims (12)
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Specification