Low-frequency stochastic true RMS instrument

A stochastic instrument for true RMS measurement in the low-frequency range is presented. Variable accuracy is achieved by varying the measuring time of the instrument. Inaccuracy of 0.1% of full scale is demonstrated. A complete theory of operation of the instrument is developed and the explicit dependence of measurement error on the measured signal shape is given. Simulations and experimental results strongly confirm the described theory. Simple hardware structure allows easy implementation of parallel measurement.