| 摘要 |
<p>Apparatus for use in extracting clock signals from a digital data stream periodically generates an enable window of chosen duration at periods when a data edge is expected in the stream. If a data edge is received during a window it resets and restarts a clock pulse generator operating at the nominal frequency of the clock to be extracted. Hence the extracted clock remains in synchronism with that of the data and is unaffected by noise spikes occuring outside the window area. If a chosen period of time elapses without any data edges received then the window period is increased so as to allow for jitter in the clock rate.</p> |
