| 摘要 |
PURPOSE:To discriminate signal time length without using any clock generator by counting the number of waves of an incoming analog signal and comparing the same with the number of the set time calculated from the basic number of this signal. CONSTITUTION:An analog signal S4 having time length L coming to an input terminal (a) is inputted via an amplifier 1 and a rectifier 8 to a waveform shaping circuit 9 by which it is shaped to a square wave signal S6. The signal S6 is inputted to a controller 7, which starts a counter 4 and a comparator 5. Also, it is the clock signal for the counter 4 and the number thereof, that is, the number of the repeating waves of the analog signal S4, is counted with the counter 4. The result of this counting is compared with the reference number generated in a reference time generator 6, and the result thereof is outputted at a logical level from an output terminal (b). Thereby, the cost is lowered without requiring any special clock generator. |
