| 摘要 |
<p>PURPOSE:To provide a measuring unit providing an internal proofreading signal and providing a hard ware executing self-proofreading for measuring accurately the tape speed of a VTR. CONSTITUTION:The internal proofreading signal 4 is selected by a selecting switch 3, and a saw-tooth-wave generating circuit 7 is subjected to sample-and- hold (S/H) with the output of a sample pulse generating circuit 6 by a S/H circuit 8. The signal subjected to S/H is inputted to one side of a zero voltage detecting circuit 10, and the output voltage is converted to a digital amount by an A/D converting circuit 11 and latched. Further, the digital value is inputted to a D/A converting circuit 12 and converted to an analog amount, and voltage is converted to time in a voltage/time converting circuit 13. The time amount is outputted to an output terminal 9 as an accurate tape speed standard value in an 1H delay circuit 5. The digital amount latched by the A/D converting circuit 11 is the value of the self-proofreading.</p> |
