Patent ID: 8433270

Claim:
A method for tuning an oscillator frequency, produced by an oscillator unit within a radio-receiver chain, in accordance with a carrier frequency of a radio-received signal, wherein the oscillator unit comprises a digitally-controlled crystal oscillator adapted to produce an oscillator signal with said oscillator signal having the oscillator frequency; and wherein the radio-receiver chain also comprises an automatic frequency control module adapted to analog-tune the digitally-controlled crystal oscillator so as to reduce a frequency difference between the oscillator frequency and the carrier frequency, wherein the automatic frequency control module is further adapted to perform a low-pass time-filtering of said frequency difference, the method comprising: (1) measuring repeatedly the frequency difference; (2) averaging the successively obtained frequency difference measurement results; and (3) when the averaged measurement results obtained successively for the frequency difference exhibit an absolute slope value higher than or equal to a positive slope threshold, then increasing the bandwidth of the low-pass time-filtering of the frequency difference.