| 摘要 |
<p>A tape timer uses pulses (42) generated by a control track previously recorded on magnetic tape to determine the magnitude of phase shift between said control track pulses and pulses (30) generated by a mechanical tachometer in contact with the magnetic tape. The pulses generated by said mechanical tachometer are counted and said counting sequence used to generate a pulse to up-date a tape timer. In response to a detected phase shift, the count sequence is dynamically adjusted by an amount determined by the magnitude of the phase shift in such a manner as to reduce said phase shift. </p> |
