| 摘要 |
PURPOSE:To output a forecast gate pulse with high accuracy and to prevent the mixture of noise by providing an UP/DOWN period counter and a limit value setting register, correcting the period of the UP/DOWN period counter alternately every time a pulse is inputted and resetting the UP/DOWN period counter. CONSTITUTION:When the 1st pulse is inputted, the UP/DOWN counter 1 is reset and an UP/DOWN changeover device 5 is set to output an UP count signal and the UP/DOWN period counter 1 starts UP count. A coincidence detection circuit 4 compares an output (t) of the UP/DOWN counter 1 with a value (tL) set in advance in a limit value setting register 3, and when t=tL is obtained, a pulse signal is outputted. The comparator 2 compares the output (t) of the UP/DOWN period counter 1 with a constant value t1 set in advance and when t>t1, a low level is outputted and when t<=t1, a high level is outputted. As a result, a forecast gate pulse holding the input pulse always at the center is obtained as an output pulse train of the comparator 2. |
