| 摘要 |
PURPOSE:To output a fixed ''1'' level through the discrimination of the presence of a signal at pulse intervals of a bipolar signal is shorter than a time constant T assumed as a threshold value, and to output a fixed ''0'' level through the discrimination of the absence of signals when it is longer than the threshold value. CONSTITUTION:When the pulse interval of the bipolar signal is shorter than the time constant T, the 1st monostable multivibrator 2 is triggered with a unipolar pulse, the pulse of the other polarity passes through a logical product circuit 6 and is inputted to the 2nd monostable multivibrator 4 having a time constant 2T while the vibrator 2 keeps the ''1'' level for the time constant T, and an output terminal 103 is fixed to the ''1'' level representing the presence of signals. When the interval is longer than the T, since the pulse inputted from an input terminal 102 is inputted after the operation of the vibrator 2 is finished, the pulse is blocked at the circuit 6 and not inputted to the vibrator 4, then the output terminal 103 is fixed to the ''0'' level representing the absence of signals. |
