| 摘要 |
PURPOSE:To obtain a break time counting circuit for correcting automatically a break ratio of low cost and small consumed power by using two shift registers and an adder instead of a multiplier. CONSTITUTION:The shift register 4 inputs a PCM signal S1 indicating the cycle T=80-130ms of a dial pulse in a signal in a band from an input terminal 1 and outputs a PCM signal S2 indicating 1/18 times as long as the cycle T. The shift register 5, similarly, inputs the signal S1 from the terminal 1 and outputs a PCM signal S3 indicating 1/2 times as long as the cycle T. The adder 6 inputs the output signal S2 of the register 4, the output signal S3 of the register 5 and a PCM signal S4 inputted from an input terminal 2, set and indicating a fixed time 1.5ms, adds them, obtains a cycle Yi=1.5+{(1/16)+(1/2)}Xi and outputs a PCM signal S5 indicating the break ratio of the automatically corrected dial pulse to an output terminal 3.
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