Apparatus and method for maintaining time synchronization in AGPS receiver
First Claim
1. A global positioning apparatus of a personal portable terminal which uses an Assisted Global Positioning System (AGPS) scheme in a Code Division Multiple Access (CDMA) communication system, the global positioning apparatus comprising:
- a reference clock for providing a reference frequency;
a CDMA baseband processor for processing signals transmitted to and received from a CDMA base station;
a GPS baseband processor for processing GPS baseband signals transmitted to and received from a GPS satellite;
an AGPS message receiver unit for receiving a Doppler value of a GPS signal from an AGPS server in order to scan at least one GPS satellite signal;
an operation part for performing an operation for an estimation of a location of the personal portable terminal, receiving the GPS signal, and measuring a Doppler value of the GPS signal; and
a processing part for calculating a time error by using results of the operation by the operation part and obtaining a pseudorange from the GPS satellite by using the calculated time error.
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Accused Products
Abstract
An apparatus and method are provided for obtaining a location of a CDMA personal portable terminal according to an AGPS scheme. The method includes receiving a Doppler value of a satellite from an AGPS server, receiving a satellite signal and measuring a Doppler value of the satellite by using the received satellite signal, calculating a code frequency bias ψb by using a difference between the received Doppler value and the measured Doppler value, calculating a code bias φb in consideration of the calculated code frequency bias ψb and a search duration, and calculating a pseudorange of the satellite by compensating for the calculated code bias φb.
16 Citations
25 Claims
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1. A global positioning apparatus of a personal portable terminal which uses an Assisted Global Positioning System (AGPS) scheme in a Code Division Multiple Access (CDMA) communication system, the global positioning apparatus comprising:
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a reference clock for providing a reference frequency;
a CDMA baseband processor for processing signals transmitted to and received from a CDMA base station;
a GPS baseband processor for processing GPS baseband signals transmitted to and received from a GPS satellite;
an AGPS message receiver unit for receiving a Doppler value of a GPS signal from an AGPS server in order to scan at least one GPS satellite signal;
an operation part for performing an operation for an estimation of a location of the personal portable terminal, receiving the GPS signal, and measuring a Doppler value of the GPS signal; and
a processing part for calculating a time error by using results of the operation by the operation part and obtaining a pseudorange from the GPS satellite by using the calculated time error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for global positioning of a personal portable terminal which uses an Assisted Global Positioning System (AGPS) scheme in a Code Division Multiple Access (CDMA) communication system, the method comprising the steps of:
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receiving a Doppler value of a satellite from an AGPS server;
receiving a satellite signal and measuring a Doppler value of the satellite by using the received satellite signal;
calculating a code frequency bias ψ
b by using a difference between the received Doppler value and the measured Doppler value;
calculating a code bias φ
b in consideration of the calculated code frequency bias ψ
b and a search duration; and
calculating a pseudorange of the satellite by compensating for the calculated code bias φ
b. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification