Fundamentals of Interfacing Experiments with Computers

This chapter describes the most important issues student need to consider when collecting data on a computer and when performing Fourier analysis in the lab. Some of this may already be obvious to they, but there are some important subtleties that most people find surprising. In a typical experiment, a small-amplitude signal is filtered and amplified, then converted to digital form, and finally collected on a computer. The Analog-to-digital output goes to some other digital circuit, e.g., a chip that stores the number in computer memory. Each input of this chip, and every input of every digital circuit, effectively has a “comparator” that compares the input voltage with a threshold value. The process of connecting a computer to an experiment is called “interfacing.” There are common approaches: using a commercial general purpose analog-to-digital and digital-to-analog interface, typically with USB connection, and using a microcontroller.