Temperature-corrected frequency control with crystal oscillators for initial frequency acquisition
A communication terminal includes a crystal oscillator, a transceiver and circuitry. The crystal oscillator belongs to a specified type in which a dependence of an output frequency on temperature has one or more temperature dependence coefficients. The transceiver is arranged to operate an AFC loop...
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Zusammenfassung: | A communication terminal includes a crystal oscillator, a transceiver and circuitry. The crystal oscillator belongs to a specified type in which a dependence of an output frequency on temperature has one or more temperature dependence coefficients. The transceiver is arranged to operate an AFC loop having an initial frequency accuracy requirement that is more stringent than an uncompensated frequency accuracy of the crystal oscillator. The circuitry is arranged to determine output frequencies of the crystal oscillator at respective operating temperatures, to compute the temperature dependence coefficients based on the output frequencies and operating temperatures, to correct a frequency error in the output frequency using the dependence and the temperature dependence coefficients, to ascertain that the corrected frequency error meets the initial frequency accuracy requirement, and to subsequently correct a frequency of the received signal using the AFC loop. |
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