5 - Data Acquisition

Abstract

Analog data can be converted into digital form and transmitted over short or long distances. An analog-to-digital converter (ADC) can be made more efficient by the use of a sample and hold between the input signal and the converter's input. The conventional way to digitize data from many analog channels is done in sequence, but the parallel conversion is much more used. The parallel-conversion approach provides the advantage that multiple sensors can be strung over a larger area, in essence digitizing the analog signals right at the source and transmitting serial data rather than the original low-level analog signals. Data acquisition systems involve digitizing analog signals using analog-to-digital converters. The ADCs are followed by a digital processor that performs the needed data analysis. In a process control application, the process controller generates feedback signals that must be converted back into analog form using a DAC. The term data acquisition refers to a multichannel system. Through the feedback from the digital processor, DACs convert the digital response into analog. Often amplifiers are used in applications for data acquisition and processing where their inputs are exposed to electromagnetic interference, electrostatic discharge, and overvoltage events. Modern signal processing applications require ADCs that have wide dynamic range, high bandwidth, low distortion, and low noise.