| 摘要 |
<p>PURPOSE:To detect control signals stably within a short time with a simple apparatus by recording two kinds of signals subsequently alternately in tracks as control signals. CONSTITUTION:A signal F of continuous sine wave (or square wave) of a constant frequency and a program search signal H being the positive components of two half periods are subsequently alternately recorded as control signals in the tracks of a recording medium. Then, the audio signal S and control signals are detected from a playback head 21 through a preamplifier 22 and are applied to a speaker 25 via volume controller 23 and main amplifier 24. These are also inputted to positive-, negative period amplifiers 26, 27 where they are integrated and waveform shaped, after which only the program search signal H is outputted from an AND circuit 35 through the action of monostalbe multivibrators 31, 33, etc. and is delayed and defferentiated to reset a register 39. This signal also becomes clock input, etc. of the register 39 by way of AND circuits 40, 41, causing the control signal to be outputted. Hence, malfunction by the noise and audio signal S is eliminated and the need for any filter is eliminated.</p> |
