Understanding Noise

In a previous post I covered the fundamentals of test engineering — sensors, continuous and discrete signals, and data quality. This post will cover topics related to electrical noise which affects the accuracy of data gathered from sensors and instruments.

noise — unwanted signals that are coupled with information carrying signals and cause errors in measurement or data transmission.

Electrical noise is the bane of test engineers. Noise can be constant, or variable based on the source and can vary in frequency and amplitude. While some types of noise are present everywhere and unavoidable (called internal noise), there are many external sources of noise which are coupled onto signal wires. This concept of noise superimposed onto an underlying signal is shown in the illustration below.

The challenge of a test engineer is eliminating the noise component without affecting the underlying signal. Elimination or mitigation of noise is critical in designing accurate and robust test systems. Noise can be reduced or eliminated through hardware and software solutions. But before discussing how noise can be managed, it is important to understand why it exists and how it gets coupled onto our signals.

Why does noise exist?

Ask why enough times and you end up in the quantum realm and start questioning the nature of reality. However, engineering is an applied science. We don’t question the nature of the rules governing this universe, we simply exploit them to achieve our…