Providing time sychronization to a gps locator
First Claim
1. A method for calibrating a network time of a communications network that has at least one cell and that transmits a control channel signal including a plurality of known bit sequences according to the network time from at least one base transceiver station into the at least one cell of the communications network, to provide an absolute time reference for a local clock in a mobile unit located in one of the at least one cell, comprising the steps of:
- a) providing;
i) a source, of a standard time, that transmits at least one synchronization signal; and
ii) a transceiver operative to communicate with the communications network and with the mobile unit;
b) synchronizing the local clock with said standard time;
c) synchronizing the network time of the communications network with the local clock;
d) calculating a time offset, according to the local clock, of the network time of the communications network from said standard time;
ad e) calculating an absolute time reference as a sum of said time offset and said standard time.
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Accused Products
Abstract
A method and system for knowing positioning system standard time at a mobile unit with respect to a system, such as the Global Positioning System, when normal, direct measurement may be impracticable owing to low signal-to noise ratio, by calibrating the timing signal of an available communication network, such as a cellular telephone transmission network (610, 615). A time reference is set for the communication network with respect to the positioning system at a time when an adequate signal-to-noise ratio prevails and the offset of a timing event in the communication network control signal measured by means of the mobile unit'"'"'s internal clock may be determined (620, 625). Subsequent times are measured with respect to this time reference by using the internal clock to measure time intervals therefrom.
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Citations
13 Claims
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1. A method for calibrating a network time of a communications network that has at least one cell and that transmits a control channel signal including a plurality of known bit sequences according to the network time from at least one base transceiver station into the at least one cell of the communications network, to provide an absolute time reference for a local clock in a mobile unit located in one of the at least one cell, comprising the steps of:
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a) providing;
i) a source, of a standard time, that transmits at least one synchronization signal; and
ii) a transceiver operative to communicate with the communications network and with the mobile unit;
b) synchronizing the local clock with said standard time;
c) synchronizing the network time of the communications network with the local clock;
d) calculating a time offset, according to the local clock, of the network time of the communications network from said standard time;
ade) calculating an absolute time reference as a sum of said time offset and said standard time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification