Further Generalization of the Low-Frequency True-RMS instrument

Abstract

In this paper, it is shown that the use of random uniform dither in harmonics measurement can significantly shorten the word of applied A/D converter and shorten the word of applied base function (sine and/or cosine), stored in memory, without accuracy loosing. This fact enables design of simple instrument for harmonics measurement. It is proven theoretically, by simulation and by experiment that 6-bit dithered A/D converter word, 8-bit dithered base function word, and 6 x 8 (14-bits) multiplier word assure measurement of 16 harmonics (16 sine and 16 cosine components) with 13-bit accuracy. Putting n such simple devices in parallel it is possible to measure n x 16 harmonics simultaneously. The measurement of 1 x 16 harmonics is realized in the small PLD chip.