Main Page | See live article | Alphabetical index 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. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.