Contact Noise is the irregular fluctuations that accompany a transmitted electrical signal but are not part of it and tend to obscure it. After a complete reed switch closure, the end of contact bounce will be followed by dynamic noise approaching 500 micro-volts peak to peak which decays exponentially to 50 micro-volts after approximately 3 milli-seconds.
In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects.
In communication systems, noise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference, for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measures. Noise is also typically distinguished from distortion, which is an unwanted systematic alteration of the signal waveform by the communication equipment, for example in signal-to-noise and distortion ratio (SINAD) and total harmonic distortion plus noise (THD+N) measures.