| 摘要 |
A digital data recovery circuit for recovering digital data recorded on a magnetic record medium along with still-image video signals in a frequency mulitplexed relationship employs two phase-control-loops, in which the first loop corrects absolute or DC phase errors and the second phase-control-loop corrects AC phase errors evidenced as abrupt phase shifts of the digital data signal caused by changes in rotation of the magnetic record by using a horizontal synchronization signal derived from the video signal, and in which the outputs of loop filters included in the first and second phase-control loops, respectively, are combined to provide a control signal for a voltage controlled oscillator that provides a demodulating carrier signal so that a synchronous detector can detect the digital data signal, thereby to cause the synchronous detector to lock onto even abrupt phase shifts in the carrier of the digital data signal.
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