抄録
A digitized phase sensitive detecting system(DPD)have been developed for precision measurement of voltage ratio. The system is composed of a personal computer, an analog-to-digital converter(ADC)and a software for mesurement and data treatment. Two sinusoidal voltages of a frequency applied to the DPD are converted into discrete data, and expressed as vectors by data treatment following to the principle of usual phase sensitive detector. Then an amplitude ratio and a phase difference of the two input voltages are calculated. Estimeted uncertainties of measured values by the DPD are less than 0.008[%]for amplitude ratio and 0.05 [mrad] for any phase difference at frequency of 50[Hz].The errors of the DPD caused by harmonic distortion of the applied voltages and asynchronus sampling by the ADC are also examined using a two-phase voltage source.
