Patent ID: 8031024
Filing Date: 2011-10-04
Classification: H03L

Abstract:
1. A wireless communication terminal, comprising: a crystal oscillator, which belongs to a specified type of crystal oscillators in which a dependence of an output frequency as a function of temperature has one or more temperature dependence coefficients that vary among the crystal oscillators belonging to the specified type; a transceiver, which is arranged to operate an Automatic Frequency Control (AFC) loop having a frequency accuracy requirement for initial AFC synchronization that is more stringent than an uncompensated frequency accuracy of the given crystal oscillator; and circuitry, which is arranged to determine two or more output frequencies of the crystal oscillator at two or more respective operating temperatures, to compute the one or more temperature dependence coefficients for the crystal oscillator based on both of the two or more determined output frequencies and the two or more operating temperatures, and, while the AFC loop is unlocked and before receiving a signal to be tracked by the AFC loop, to correct a frequency error in the output frequency of the crystal oscillator using the dependence and the computed temperature dependence coefficients so as to obtain a corrected frequency error that meets the frequency accuracy requirement of the AFC loop, wherein the transceiver is configured, after correction of the frequency error by the circuitry, to receive the signal, to lock the AFC loop on the received signal, and to correct a frequency of the received signal using the locked AFC loop.