| 摘要 |
PURPOSE:To discriminate the presence/absence of an FM sound signal by providing a side band eliminating part that damps the upper side band of an FM luminance signal which is included in a read signal and a limiter part, and detecting the level of the signal component of the outputting FM sound frequency band. CONSTITUTION:The side band eliminating part that damps the upper side band of a frequency modulated luminance signal which is supplied from the read signal of a magnetic tape consists of a high frequency band area trap 32. the signal component in the prescribed frequencny band area from the high frequency band area part of the low frequency band area chrominance signal of the outputting signal from a limiter 33 that is connected to the output side of the side band eliminating part to the low frequency band area part of the frequency modulated luminance signal is taken out at a filter part 34. The output of the filter 34 is detected at a detection circuit 34 and the level of the output signal of the filter part is detected by a level detection part that consists of an integrated circuit 36. This output from the level detecting part is compared with a reference signal at a comparator 37 and it is decided whether the frequency modulated sound signal is recorded or not.
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