| 摘要 |
PURPOSE:To accurately detect an average level even when an AC signal changes with the lapse of time and output time is short. CONSTITUTION:An AC signal 1 is inputted to a detecting circuit 2, and a detecting signal 3 being an envelope component of the AC signal 1 is outputted. A V-F converter 4 outputs a pulse signal 5 which is in proportion to a level of the detecting signal 3 and has a frequency sufficiently high to a change with the lapse of time of the detecting signal 3. A counter 6 asynchronously and continuously counts the pulse signal 5, and outputs a count value 7. A count value in constant time to an average level of the AC signal is prestored in a memory 8. A logical operation part 10 takes in the count value 7 in the timing of constant time, and finds the count value per time. The logical operation part 10 also calls out data 9 of an average level of the AC signal 1 corresponding to the count value per time from the memory 8, and outputs it as an average level 11 of the AC signal in constant time. |
