noise temperature

(system temperature) See sensitivity.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

noise temperature

[′nȯiz ‚tem·prə·chər]

(electricity)

The temperature at which the thermal noise power of a passive system per unit bandwidth would be equal to the actual noise at the actual terminals; the standard reference temperature for noise measurements is 290 K.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Noise Temperature

an effective quantity that serves as a measure of the noise power in radio receivers. The noise temperature T_n is equal to the temperature of the matched impedance (the dummy antenna) at which its thermal noise power is equal to the noise power of the given device. The ratio T_n/T₀ (T₀ = 290°K) is called the relative noise temperature.

The concept of noise temperature is used in radio engineering to estimate the noise of electronic and semiconductor devices that are designed for the amplification and conversion of electric signals. In radio astronomy it is used to describe sources of cosmic radio-frequency radiation. It is also used to determine the noise contribution made by a radio receiver to the useful signal in the course of its processing. The noise figure (or noise factor) F, which is related to T_n by the equation T_n = (F – 1)T₀, is also used in the last case.

The noise temperature of an actual object is usually determined by comparing it with the noise temperature of a given standard noise generator.

REFERENCE

Van der Ziel, A. Flukluatsii v radiotekhnike i fizike. Moscow-Leningrad, 1958. Pages 25–10. (Translated from English.)

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References in periodicals archive

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