8 - Electrical noise and mitigation

Abstract

This chapter deals with electrical noise and the ways in which noise finds a path into sensitive signal circuits. Noise, or interference, is an undesirable electrical signal, which distorts or interferes with an original signal. Noise could be transient or constant. It can be generated from within the system itself (internal noise) or from an outside source (external noise). The various methods by which noise can be reduced are by avoiding shields, separating the cabling, using shielding transformers, eliminating earth loops and using zero signal reference grounds, and signal transport ground planes. Another useful way of evaluating the effects of noise is to examine its frequency spectrum. Noise can be seen to fall into three groups: wideband noise, impulse noise, and frequency-specific noise. Generation of harmonics and how they can be filtered are also discussed in the chapter.