| 摘要 |
PURPOSE:To detect the envelope of a recorded frequency-modulated signal at a high speed, by setting the azimuth angle of a fixed type magnetic head so that the azimuth angle can exceedingly coincide with the azimuth angle of any one of frequency-modulated signals recorded on a magnetic tape. CONSTITUTION:A fixed head 16 for detection detects the existence/nonexitence of FM signals on a magnetic tape 1 and an FM signal S1 converted into an electric signal by means of the head 16 is supplied to an amplifier 17. The amplifier signal S2 is inputted in a peak holding circuit 19 through a rectifier circuit 18. The output of the circuit 16 is compated with a reference voltage at a comparator 21 and outputted as a signal S6. Inclined tracks 23 and 24 are recorded on the tape 1 and an azimuth angle 25 is set by rotating the track 23 clockwise by an angle theta. Another azimuth angle 26 is set by rotating the track 24 counterclockwise by the angle theta. The azimuth angle 27 of the head 16 is set so that it can coincide with the azimuth angle 26. Therefore, the difference between the peak value and minimum value of detect signals is enlarged and the envelope of a frequency-modulated signal can be detected at a high speed.
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