| 摘要 |
<p>PURPOSE:To change over the magnetic speed at reproduction automatically so as to be coincident with a magnetic tape speed at recording by discriminating the difference between the magnetic tape speed at reproduction and the magnetic tape speed at recording at the reproduction. CONSTITUTION:The principles are utilized that a fundamental frequency of the timewise change in the amplitude of 2.fH component in a balanced modulation output of a recovered pilot signal while using a signal of 8.5.fH frequency is used as a reference signal is 15Hz when a magnetic tape recorded by the SP mode is reproduced in the LP mode, 30Hz when the tape is reproduced in the same mode as the recording mode and 30Hz when the tape is reproduced in the same mode as the recording mode and 60Hz when the magnetic tape recorded in the LP mode is reproduced in the SP mode. Then the difference in the timewise change from the 2.fH component is detected to discriminate the difference between the recording mode and the reproducing mode, that is, the difference of the magnetic tape speed between at recording and at reproduction, and the magnetic tape speed at reproduction is changed over so as to make it coincident with the magnetic tape speed at recording.</p> |
