In telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

s, effective input noise temperature is the source noise temperature in a two-port

Computer port (hardware)

In computer hardware, a port serves as an interface between the computer and other computers or peripheral devices. Physically, a port is a specialized outlet on a piece of equipment to which a plug or cable connects...

 network

Telecommunications network

A telecommunications network is a collection of terminals, links and nodes which connect together to enable telecommunication between users of the terminals. Networks may use circuit switching or message switching. Each terminal in the network must have a unique address so messages or connections...

 or amplifier

Amplifier

Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...

 that will result in the same output

Output

Output is the term denoting either an exit or changes which exit a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation.-In control theory:...

 noise power

Noise power

In telecommunication, the term noise power has the following meanings:# The measured total noise per bandwidth unit at the input or output of a device when the signal is not present.# The power generated by a random electromagnetic process....

, when connected to a noise-free network or amplifier, as that of the actual network or amplifier connected to a noise-free source. If F is the noise figure

Noise figure

Noise figure is a measure of degradation of the signal-to-noise ratio , caused by components in a radio frequency signal chain. The noise figure is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard...

numeric and 290 K the standard noise temperature, then the effective noise temperature is given by T _n = 290(F-1).