| 摘要 |
A direct conversion receiver, such as a paging receiver includes a local oscillator for mixing down to baseband a received radio frequency signal having a carrier frequency which is digitally modulated (FSK). To provide automatic frequency control, instead of using a control loop, the present invention includes means which at intervals evaluates the recovered digital signal to determine whether a predetermined quality thereof is within a selected D/A conversion range. A microcontroller including a D/A converter generates a control signal for the local oscillator to maintain the oscillator at a frequency such that the signal quality remains within the selected conversion range.
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