| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively measure characteristics of an FM demodulation circuit at a high speed by utilizing a general-purpose measuring instrument such as a multimeter, which only executes the voltage measurement, and a computer without requiring a measuring instrument for exclusive use. SOLUTION: A non-modulated frequency scanning signal is input to the FM demodulation circuit. Frequency/voltage characteristic data A is obtained by measuring an output voltage of the FM demodulation circuit for every frequency of the input signal. The waveform (the demodulation output waveform B) of the output voltage, when the frequency of the input signal is changed to a sine wave form, is equivalently obtained on the basis of the frequency/voltage characteristic data. The actual value of the waveform is obtained as demodulation output. Further, a demodulation distortion rate is calculated from a frequency spectrum C in which the demodulation output waveform is subjected to the Fourier transform. COPYRIGHT: (C)2005,JPO&NCIPI
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