Prevention and Treatment of Noise in Control Signals

Electrical control signals transmitted between two points usually arrive more or less distorted by noise. If proper control action is to occur, the information contained in the signals must be recovered and the noise must be rejected. This recovery and rejection are accomplished by invoking the principle of contrast, discriminating between useful information and noise as a result of some characteristic difference between them. Various practical means to effect and employ such contrast are examined, and a number of selected examples are presented. The role of proper wiring layout and grounding is stressed. High level noise can do more than obscure information in a signal. A number of instances exist in which actual equipment damage has been caused by noise. A brief description, with specific illustrations follows.