Patent ID: 8451169
Filing Date: 2013-05-28
Classification: G01S

Abstract:
1. An apparatus for correcting a clock drift error, the apparatus comprising: a receiver unit for receiving a first GNSS signal from a satellite; a Doppler correction unit for obtaining a first predicted frequency by performing Doppler correction to the first GNSS signal based on Doppler information derived from the first GNSS signal; a tracking unit for processing the first GNSS signal to obtain a first tracked frequency of the satellite; a satellite-positioning unit for performing a position fix and determining a clock offset based on the position fix; a computation unit for calculating a first difference between the first predicted frequency and the first tracked frequency; a storage unit for storing the clock offset with the first difference, wherein when the receiver unit is turned off and then turned on for receiving a second GNSS signal from the satellite, the Doppler correction unit obtains a second predicted frequency, the tracking unit obtains a second tracked frequency of the satellite, and the computation unit calculates a second difference between the second predicted frequency and the second tracked frequency; and an error correction unit for computing an estimated clock offset according to the clock offset, the first difference, and the second difference.