Random Signals and Noise

Noise is defined as an unwanted signal interfering with a desired signal. The noise process can be natural or man-made. Examples of natural noise are noise in electronic circuits and atmospheric disturbances. Man-made noise sources include 60- Hz interference from power lines, interference from other users in a CDMA communication system, and noise from an automobile ignition system. This appendix will study random processes and their statistical properties, and develop useful tools for analyzing noise in communication systems.