Abstract -A microcomputer-controlle

Abstract -A microcomputer-controlled measuring instrument for phase angle measurement in low frequency range is described. It is based on the digital measurement of the time shift between input signals. To avoid the necessity of calculation of the measured phase shift, measurement of the time shift is repeated during a constant time interval to get the average value of the phase shift independent on the period of the input signals. The measured results are displayed on the display of the instrument and can be transferred into a personal computer (PC) which can process and display these results and control the instrument via USB serial interface. The method of the average value of the phase angle measurement is described and the error sources are briefly mentioned. The construction of the instrument and the software in the instrument and in the PC are briefly described. Measured results show sufficient accuracy of the instrument.