| 摘要 |
<p>PURPOSE:To shorten the lead-in time of a running control servo system for a magnetic tape by detecting a stop position of the magnetic tape from a comparison output obtained by comparing the amplitudes of four pilot signals in a reproduced signal. CONSTITUTION:The reproduced signal of a magnetic head is supplied to the input terminal of a balanced modulator 6a and the 1st pilot signal of the reproduced signal is supplied thereto as well to output beat signals fa and fb between the 2nd pilot signal and other pilot signals. The outputs of respective modulators are applied through BPFs 7a and 7b, and 7c and 7d to detectors 8a and 8b, and 8c and 8d to generate signals with corresponding amplitudes, which are compared by comparators 9a and 9b. Thus, output signals O1 and O2 based upon the comparison results and a head switching signal are conducted to output terminals 33 and 34. Consequently, which of plural areas specified in the lengthwise direction of the magnetic tape a magnetic tape is position in is specified by the signals O1 and O2.</p> |
