| 摘要 |
PURPOSE:To easily detect a dropout based upon the disturbance of a waveform by controlling the change of the ratio of a side band wave signal component to the carrier signal component of a reproduced RF signal to emphasis the disturbance of the waveform. CONSTITUTION:A boosting circuit 15 in a video signal reproducing device changes the relative signal level of a side band wave signal component to a carrier signal component in the spectrum signal component of a reproduced RF signal SRF and outputs a comparing signal SBO increasing the disturbance of the waveform. The waveform of the signal SBO is compared with a dropout detecting reference signal VDO by a comparing means 16, a frequency converting signal SCOM to be changed when the waveform of the signal SBO crosses the signal VDO is sent from the means 16 and a dropout detecting signal SDET based upon the frequency change of the signal SCOM is sent from a frequency detecting circuit 18. When the dropout is generated and the disturbance of the reproduced RF signal is increased, the dropout based upon the disturbance can be easily detected.
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