3 - Digital meters

Abstract

This chapter discusses the measurement techniques of digital meters. Like analog meters, digital meters are most commonly encountered as general-purpose multimeters. Accuracy of measurements taken using digital meters, on the other hand, is not limited to the accuracy of a mechanical meter movement or to the resolution with which an observer reads the display. Instead, accuracy is purely dependent on the meter's circuits; so much higher accuracy is possible. In most digital multimeters a resistive divider chain attenuates the measure and voltage value in switched steps; so that the output voltage is within the input range of the analog-to-digital converter. Most general-purpose digital multimeters use seven-segment liquid crystal displays. In summary, although general-purpose digital multimeters tend to be slightly more expensive than analog counterparts, analog meters of the accuracy and resolution afforded by high-quality digital meters could never be made, whatever the price. Further, the digital meter has created its own marketplace, which the analog meter can never overturn.