GPS satellite signal tracking method for GPS receivers
First Claim
1. A satellite signal tracking method for a GPS receiver comprising the steps of:
- performing a narrow-band search for satellite signals when the satellite signal from a GPS satellite being tracked is interrupted for more than a specified period of time; and
switching over the narrow-band search to a wide-band search for searching the satellite signals when the narrow-band search fails to recapture any of the satellite signals within a predetermined duration of time.
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Accused Products
Abstract
When reception of satellite signals is lost, for example, one minute, satellite signals are searched firstly in accordance with a narrow-band search mode by varying a search frequency within a range of Doppler frequency shift estimated by a moving speed of a GPS receiver, for example, ±600 Hz for a vehicle-mounted GPS receiver, for a duration which is determined by dividing a capture range (±150 Hz) by a rate of Doppler shift (40 Hz/sec) and, secondly, switching over the search mode from the narrow-band search to a wide-band search if recapturing of the satellite signal is failed through the narrow-band search within the predetermined duration (3 minutes 45 seconds) for recapturing the lost satellite signals, and thereby providing a expeditious two-step search method for decreasing a time required in recapturing the lost satellite signals.
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Citations
9 Claims
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1. A satellite signal tracking method for a GPS receiver comprising the steps of:
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performing a narrow-band search for satellite signals when the satellite signal from a GPS satellite being tracked is interrupted for more than a specified period of time; and switching over the narrow-band search to a wide-band search for searching the satellite signals when the narrow-band search fails to recapture any of the satellite signals within a predetermined duration of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification