Patent ID: 6114992
Filing Date: 2000-09-05
Classification: G01S,H04B

Abstract:
An efficient process for acquiring multiple satellite signals having a common transmission frequency, each signal having a unique identification code, wherein a received signal frequency from each satellite is offset from the common transmission frequency due to a Doppler shift and receiver clock imprecision, said method comprising the steps of:constructing probability distributions relating to the probable frequency of a subsequent satellite signal given one or more known satellite signal frequencies;storing the probability distributions as statistical data;acquiring a first satellite signal at a first received frequency;using the first frequency in conjunction with the stored statistical data to establish a range of all possible frequencies that could correspond to the frequency of a second satellite signal and then constructing a first window within this range that limits the range to only those frequencies that are determined to have a sufficiently high probability of correspondence; andsearching for a second satellite signal using a modified sample comparison approach within the range of frequencies defined by the first window.