Time division satellite acquisition
First Claim
1. A method, comprising:
- determining a higher one of at feast one or more satellites during at least one or more predetermined intervals;
generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired; and
upon acquiring at least one or more satellites in the list, determining the present time based on the information contained in the list without use of a real-time clock.
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Accused Products
Abstract
A GPS system device acquires satellites after a power-on event without requiring a need for a real time clock. A list of the highest visible satellites for a given periodic interval is computed and referenced by time. The list can be stored in a non-volatile or battery backed memory during a power off state or can be generated at power up prior to satellite acquisition. When the GPS system device is powered on, satellites from the list are searched using a multi-channel correlator until at least one of the satellites is acquired. The present time is estimated based upon the relationship to the list of the satellite, and satellite visibility is computed. The multi-channel correlator is then updated to search satellites that are likely to be visible based upon the acquired satellite. The search for satellites is further refined by the observation of the handover word provided by an acquired satellite. When a minimum number of satellites are acquired, normal satellite tracking and position computation may occur.
62 Citations
30 Claims
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1. A method, comprising:
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determining a higher one of at feast one or more satellites during at least one or more predetermined intervals;
generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired; and
upon acquiring at least one or more satellites in the list, determining the present time based on the information contained in the list without use of a real-time clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9)
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8. A method, comprising:
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determining a higher one of at least one or more satellites during at least one or more predetermined intervals;
generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired;
upon acquiring at least one or more satellites in the list, determining the present time based on the information contained in the list; and
observing a handover word from an acquired at least one or more satellites in the list, computing present satellite visibility based upon the handover word, and searching for at least one or more presently visible satellites computed in said computing step.
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10. An apparatus, comprising:
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means for determining a higher one of at least one or more satellites during at least one or more predetermined intervals;
means for generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
means for searching for at least one or more of the satellites in the list until at least one more of the satellites in the list is acquired; and
upon acquiring at least one or more satellites in the list, means for determining the present time based on the information contained in the list without use of a real-time clock. - View Dependent Claims (11, 12, 13, 14, 15, 16, 18)
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17. An apparatus, comprising:
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means for determining a higher one of at least one or more satellites during at least one or more predetermined intervals;
means for generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
means for searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired;
upon acquiring at least one or more satellites in the list, means for determining the present time based on the information contained in the list; and
means for observing a handover word from an acquired at least one or more satellites in the list, means for computing present satellite visibility based upon the handover word, said searching means being capable of searching for at least one or more presently visible satellites computed by said present satellite visibility computing means.
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19. A computer program product, capable of being read by a machine, for causing a machine to implement steps for acquiring satellites in a GPS system without the need for a real time clock, the steps comprising:
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determining a higher one of at least one or more satellites during at least one or more predetermined intervals;
generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired; and
upon acquiring at least one or more satellites in the list, determining the present time based on the information contained in the list without use of a real-time clock. - View Dependent Claims (20, 21, 22, 23, 24, 25, 27)
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26. A computer program product, capable of being read by a machine, for causing a machine to implement steps for acquiring satellites in a GPS system without the need for a real time clock, the steps comprising:
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determining a higher one of at least one or more satellites during at least one or more predetermined intervals;
generating a list containing information on the higher one of the at least one or more satellites for each of the at least one or more predetermined intervals;
searching for at least one or more of the satellites in the list until at least one or more of the satellites in the list is acquired;
upon acquiring at least one or more satellites in the list, determining the present time based on the information contained in the list; and
observing a handover word from an acquired at least one or more satellites in the list, computing present satellite visibility based upon the handover word, and searching for at least one or more presently visible satellites computed in said computing step.
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28. A method of determining a present time in a GPS receiver, the method comprising the steps of:
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determining for a plurality of predetermined time intervals a highest elevation satellite for each of the predetermined time intervals;
generating a list containing information on each of the highest elevation satellites for each of the predetermined time intervals, when the GPS receiver is powered-on, searching for at least one of the highest elevation satellites in the list until a satellite signal is acquired therefrom; and
upon acquiring the satellite signal, determining the present time of the GPS receiver based on the information in the list without use of a real-time clock. - View Dependent Claims (29, 30)
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Specification