| 摘要 |
PURPOSE:To extract exactly a bit synchronizing signal corresponding to a reproducing speed from a reproducing signal by providing a relative speed detecting means for detecting a relative speed at the time of reproducing a signal from a rotation control means and a tape running means, and a bit synchronizing signal extracting means for obtaining a phase synchronization against the reproducing signal and extracting the bit synchronizing signal. CONSTITUTION:A variation of a bit rate can be estimated by detecting a relative speed of a cylinder at the time of reproduction and a magnetic tape. Therefore, a relative speed detecting circuit 21 is connected to a cylinder rotation control circuit 8 and a tape running control circuit 9, a cylinder FG signal and a capstan FG signal are extracted from the respective control circuits, a cylinder rotating speed and a tape running speed are detected, and from both of then, a relative speed at the time of reproduction is detected. Subsequently, by an output of the relative speed detecting circuit 21, a voltage control circuit 22 is controlled and a voltage required for varying a center frequency of a voltage control oscillator 19 is supplied to a voltage adding circuit 23 so as to follow a variation of the bit rate.
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