| 摘要 |
<p>PURPOSE:To reduce the malfunction due to dropout of recording signal, by making easy for the detection of control signal, through the recording of audio band frequency on the track on the same tape as instruction tone and the separation of the instruction tone from the control signal at the detection. CONSTITUTION:The output of a preamplifier 1 is shaped 2 into a pulse signal, and when the frequency of this pulse signal is lower than 1/tau1, bistable multi- vibrators 8, 16 set with monostable multivibrators 4, 12 are reset with retriggerable monostable multivibrators 3, 11 after tau1 and tau1'. Further, monostable multivibrators 4, 12 also are cleared with delay circuits 5, 13 after tau3. Further, when the input frequency of the circuit 1 is lower than f1, the output of the gates 9, 17 is all ''high'', and if the signal keeps for time tau2 at the frequency between f1 and f1', the output of the gate 9 of the f1 detection circuit only is ''low'', and if the frequency is higher than f1' and the signal keeps for tau2 or more, the output of the gates 9, 17 is ''low''. Thus, the instruction tone and the control signal are distincted with the time constant tau2.</p> |
