Stand alone global positioning system (GPS) and method with high sensitivity
First Claim
1. A method for determining the position of a user terminal utilizing global positioning system (GPS) satellites, each of the GPS satellites transmitting a signal containing information indicative of the orbital parameters of the respective GPS satellite, timing and synchronization data and clock correction parameters, said method comprising the steps of:
- approximating an expected range of Doppler frequencies within which at least one GPS satellite should be located;
within this range, searching for and acquiring a first GPS signal from a first GPS satellite at the user terminal strong enough to demodulate, the first GPS signal containing information indicative of the orbital parameters of the first GPS satellite, timing and synchronization data and clock correction parameters;
demodulating the first GPS signal to obtain time of week information;
measuring code phase synchronization for the first GPS signal utilizing the time of week information;
searching for and acquiring second, third and fourth GPS signals at the user terminal from second, third and fourth GPS satellites, respectively;
measuring code phase synchronizations for the second, third and fourth GPS signals utilizing the time of week information; and
calculating the position of the user terminal utilizing the code phase synchronizations of the first through fourth GPS signals.
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Accused Products
Abstract
A method is provided for determining the position of a user terminal utilizing global positioning system (GPS) satellites, each of the GPS satellites transmitting a signal containing information indicative of the orbital parameters of the respective GPS satellite, timing and synchronization data and clock correction parameters. The method includes the steps of approximating an expected range of Doppler frequencies within which at least one GPS satellite should be located, within this range, searching for and acquiring a first GPS signal from a first GPS satellite at the user terminal strong enough to demodulate, the first GPS signal containing information indicative of the orbital parameters of the first GPS satellite, timing and synchronization data and clock correction parameters, demodulating the first GPS signal to obtain time of week information, measuring code phase synchronization for the first GPS signal utilizing the time of week information, searching for and acquiring second, third and fourth GPS signals at the user terminal from second, third and fourth GPS satellites, respectively, measuring code phase synchronizations for the second, third and fourth GPS signals utilizing the time of week information, and calculating the position of the user terminal utilizing the code phase synchronizations of the first through fourth GPS signals.
177 Citations
37 Claims
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1. A method for determining the position of a user terminal utilizing global positioning system (GPS) satellites, each of the GPS satellites transmitting a signal containing information indicative of the orbital parameters of the respective GPS satellite, timing and synchronization data and clock correction parameters, said method comprising the steps of:
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approximating an expected range of Doppler frequencies within which at least one GPS satellite should be located; within this range, searching for and acquiring a first GPS signal from a first GPS satellite at the user terminal strong enough to demodulate, the first GPS signal containing information indicative of the orbital parameters of the first GPS satellite, timing and synchronization data and clock correction parameters; demodulating the first GPS signal to obtain time of week information; measuring code phase synchronization for the first GPS signal utilizing the time of week information; searching for and acquiring second, third and fourth GPS signals at the user terminal from second, third and fourth GPS satellites, respectively; measuring code phase synchronizations for the second, third and fourth GPS signals utilizing the time of week information; and calculating the position of the user terminal utilizing the code phase synchronizations of the first through fourth GPS signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for determining the position of a user terminal utilizing global positioning system (GPS) satellites, each of the GPS satellites transmitting a signal containing information indicative of the orbital parameters of the respective GPS satellite, timing and synchronization data and clock correction parameters, said method comprising the steps of:
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approximating an expected range of Doppler frequencies within which at least one GPS satellite should be located; within this range, searching for a first GPS satellite signal strong enough to demodulate; if the first GPS satellite signal strong enough to demodulate is located, acquiring and demodulating the first GPS satellite signal to obtain time of week information; if the first GPS satellite signal strong enough to demodulate cannot be located, acquiring the first GPS satellite signal at the user terminal and utilizing a real time clock at the user terminal to approximate time of week information; measuring code phase synchronization for the first GPS satellite signal utilizing the time of week information; searching for and acquiring second, third and fourth GPS satellite signals at the user terminal from second, third and fourth GPS satellites, respectively; measuring code phase synchronizations for the second, third and fourth GPS satellite signals utilizing the time of week information; and calculating the position of the user terminal utilizing the code phase synchronizations of the first through fourth GPS satellite signals. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification