Patent ID: 6075987
Filing Date: 2000-06-13
Classification: G01S

Abstract:
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; andcalculating the position of the user terminal utilizing the code phase synchronizations of the first through fourth GPS signals.