- Noise level
In
telecommunication , noise level is thenoise power , usually relative to a reference.In atmospheric sound transmission, "'noise level" is the
noise power of the longitudinal sound wave relative to a point of reference."Note:" Noise level is usually measured in
decibel s (dB) for relative power or picowatts for absolute power. A suffix is added to denote a particular reference base or specific qualities of the measurement. Examples of noise-level measurement units are dB(A),dBm ,dBm0 ,dBrn ,dBrnC , dBrn("f"1 − "f"2), dBrn(144-line).----Noise levels are usually viewed in opposition to
signal level s and so are often seen as part of asignal-to-noise ratio . Telecommunication systems strive to increase the signal level to noise level ratio in order to effectively transmit data. In practice, if the transmitted signal falls below the level of the noise (often designated as thenoise floor ) in the system, data can no longer be decoded at the receiver. Noise levels in telecommunication systems are a product of both internal and external sources to the system includingshot noise ,thermal noise , and ambientelectromagnetic interference .
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