| 摘要 |
PURPOSE:To measure an effective value of various analog physical quantities accurately at a high speed by simplifying an effective-value operating circuit by permitting part of a squaring-summing circuit to serve as a square-root circuit. CONSTITUTION:Analog signals, obtained by electrically converting various physical quantities, such as voltages and currents to be measured, are supplied to input terminal 1 and then inputted to low-pass filter 3 and clock generating circuit 4. They have high-frequency noises eliminated via low-pass filter 3 and are then inputted to A/D converter 5. Clock generating circuit 4, on the other hand, generates a clock signal with a frequency 2K times (K; natural number such as 1...) frequency f1 of the fundamental wave of the analog signal, and it is converted via A/D converter 5 into a digital signal, which is inputted to high-speed Fourier transforming circuit 6 for Fourier transform in real time. The result of the Fourier transform is squared by effective-value arithmetic circuit 7, and summed up and further the square root of it is extracted to find the effective value. Thus, the effective value can be measured accurately at a high speed. |
