Study on Continuous Frequency Compensation Method of Broadband AC Measurement

摘要

Gain error and nonlinear error of measurement systems vary with the frequency of signal in broadband AC measurement. The output of measurement system y is the function of f, frequency of signal, and x, input signal of system, namely, y=F[p(x),f]. When f and x change continuously, the conversion characteristic of the system forms a curved surface of conversion. So it is very difficult to achieve automatic broadband calibration of a measurement system according to a single function. A new method of calibration of curved surface in different frequency ranges based on an AC RMS-DC converter structured by logarithmic amplifier and antilogarithmic amplifier is presented in this paper. It calibrates continuously with frequency changes in the whole band of the measurement system. The results of calibration shows that the method is effective and the accuracy achieved was 0.04% in the frequency range between 50Hz and 30kHz.