| 摘要 |
PURPOSE:To utilize a low frequency meter by multiplying measured signal and reference signal having desired frequency by each other, to permit them to pass a low-pass filter and to obtain the frequency signal of the difference component of the frequencies to be measured. CONSTITUTION:From a test point 23, the output of measured signal having frequency fx is generated, and a wave is detected by a wave detection circuit 30 via a BPF 25; and when it is detected said signal exceeds signal from a reference level generator 32 by a comparator 31, then by a regulation driver controlling circuit 29, precision regulation is started. Signal from the test point 23 is multiplied by the signal of frequency fo from a reference signal generating circuit 26 with a multiplying circuit 24, and by permitting them to pass an LPF 27, the signal of the frequency of ¦fx-fo¦ is obtained, and is measured with a frequency counter 28. By the regulation driver controlling circuit 29, frequency to be measured is regulated to be minimized. |
