average noise figure; average noise factor (or )

The ratio of (1) the total output noise power within an output frequency band when the noise temperature of all input terminations is at the reference noise temperature, T₀, at all frequencies that contribute to the output noise to (2) that part of (1) caused by the noise of the signal-input termination within the signal-input frequency band. (Ref. IEC 747‑1.)

NOTE 1 The abbreviation is often used in place of symbol ; however, symbol is preferred.

NOTE 2 This ratio may be expressed logarithmically in decibels (dB).

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