INTER-MUSIC PART DETECTOR FOR AUTOMATIC MUSIC SELECTING PLAYER

摘要

PURPOSE:To detect surely inter-music parts by processing again a waveform which passes a band-pass filter. CONSTITUTION:The output signal of an optical sensor 1 which passes a buffer amplifier 2 is inputted to a band-pass filter 3, and its band width is so set that only the frequency of a sensor output signal for an inter-music part is taken out in accordance with the search speed by the filter 3. Thus, only the signal component of an inter-music waveform passes the filter 3. That is, not only the inter-music signal of an essential inter-music position but also a noise component approximating the inter-music waveform which is caused by the variance of the reflection factor in sound grooves of a record disc having an ununiform pitch of sound grooves passes the band-pass filter 3 as it is. The output signal of a limiter 6 is allowed to pass a high-pass filter 7 to attenuate extremely the signal level of the noise component with respect to the signal level of the inter-music signal, that is, the SN ratio is improved considerably.