noise temperature

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noise temperature

(system temperature) See sensitivity.

Noise Temperature


an effective quantity that serves as a measure of the noise power in radio receivers. The noise temperature Tn 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 Tn/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 Tn by the equation Tn = (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.


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

noise temperature

[′nȯiz ‚tem·prə·chər]
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.
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