Noise (physics) (original) (raw)

In science, and especially in physics and telecommunication, noise is random fluctuations and the addition of external factors to the stream of target information (signal) being received at a detector.

More specifically, in physics, the term noise has the following meanings:

1. An undesired disturbance within the frequency band of interest; the summation of unwanted or disturbing energy introduced into a communications system from man-made and natural sources.

2. A disturbance that affects a signal and that may distort the information carried by the signal.

3. Random variations of one or more characteristics of any entity such as voltage, current, or data.

4. A random signal of known statistical properties of amplitude, distribution, and spectral density.

5. Loosely, any disturbance tending to interfere with the normal operation of a device or system.

Some sections copied from Federal Standard 1037C and from MIL-STD-188

See also:

• shot noise
• Johnson-Nyquist noise
• signal-to-noise ratio.
• noise level
• noise power
• noise-equivalent power
• phase noise.