Positioning signal receiving apparatus
First Claim
1. A positioning signal receiving apparatus comprising:
- a reference clock signal generator for generating a first clock signal used as a reference clock signal in processing a positioning signal;
a reference clock counter for counting successive pulses of the first clock signal;
a low-frequency clock signal generator for supplying a second clock signal generated independently of the first clock signal, the second clock signal having a lower frequency than the first clock signal;
a positioning signal receiving section for receiving said positioning signal;
a positioning signal processor for establishing a position fix by processing the positioning signal;
an intermittent operation controller for alternately switching said positioning signal receiving apparatus between sleep conditions under which said reference clock signal generator is shut off for a specific sleep time while said low-frequency clock signal generator is kept operational and normal operating conditions under which both said reference clock signal generator and said low-frequency clock signal generator are kept operational;
a count ratio determiner for determining the ratio of the number of pulses of the first clock signal to the number of pulses of the second clock signal counted during a specific period of time preceding the sleep time; and
a reference clock count value interpolator for calculating the number of pulses of the first clock signal which should have been counted during the sleep time if said reference clock signal generator continuously generated the first clock signal from the number of pulses of the second clock signal counted during the sleep time and estimating a count value which should have been reached by said reference clock counter at the end of the sleep time by using the number of pulses of the first clock signal which should have been counted during the sleep time.
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Accused Products
Abstract
A GPS receiver is alternately switched between sleep conditions under which between sleep conditions under which a temperature-compensated crystal oscillator is shut off for a specific sleep time while a real-time clock section is kept operational and normal operating conditions under which both the temperature-compensated crystal oscillator and the real-time clock section are kept operational. The GPS receiver determines the ratio of the number of pulses of a reference clock signal to the number of pulses of a low-frequency clock signal counted during a specific period of time preceding the sleep time. The GPS receiver estimates a count value which should have been reached by a reference clock counter at the end of the sleep time if the temperature-compensated crystal oscillator continuously generated the reference clock signal based on the number of pulses of the low-frequency clock signal counted during the sleep time.
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Citations
13 Claims
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1. A positioning signal receiving apparatus comprising:
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a reference clock signal generator for generating a first clock signal used as a reference clock signal in processing a positioning signal;
a reference clock counter for counting successive pulses of the first clock signal;
a low-frequency clock signal generator for supplying a second clock signal generated independently of the first clock signal, the second clock signal having a lower frequency than the first clock signal;
a positioning signal receiving section for receiving said positioning signal;
a positioning signal processor for establishing a position fix by processing the positioning signal;
an intermittent operation controller for alternately switching said positioning signal receiving apparatus between sleep conditions under which said reference clock signal generator is shut off for a specific sleep time while said low-frequency clock signal generator is kept operational and normal operating conditions under which both said reference clock signal generator and said low-frequency clock signal generator are kept operational;
a count ratio determiner for determining the ratio of the number of pulses of the first clock signal to the number of pulses of the second clock signal counted during a specific period of time preceding the sleep time; and
a reference clock count value interpolator for calculating the number of pulses of the first clock signal which should have been counted during the sleep time if said reference clock signal generator continuously generated the first clock signal from the number of pulses of the second clock signal counted during the sleep time and estimating a count value which should have been reached by said reference clock counter at the end of the sleep time by using the number of pulses of the first clock signal which should have been counted during the sleep time. - View Dependent Claims (2, 3, 4, 5)
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6. A method of recovering a clock signal used within a positioning receiver, comprising:
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determining a relationship between a first clock signal and a second clock signal;
establishing a prior count value associated with the first clock signal when the first clock signal enters a non-operational state; and
estimating new count value of the first clock signal upon re-entering an operational state, based upon the relationship and the prior count value. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification