Of an active device, over the bandwidth of interest, the contribution by the device itself to thermal noise at its output. The noise figure is usually expressed in decibels (dB), and is with respect to thermal noise power at the system impedance, at a standard noise temperature (usually 20o C, 293 K) over the bandwidth of interest. It is determined… (Read More →)

The noise power, usually relative to a reference.
Note: Noise level is usually measured in 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 dBa, dBa(F1A), dBa(HA1), dBa0, dBm, dBm(psoph), dBm0, dBm0P, dBrn, dBrnC, dBrn(f1-f2), dBrn(144-line), pW, pWp,… (Read More →)

1. The power generated by a random electromagnetic process.
2. Interfering and unwanted power in an electrical device or system.
3. In the acceptance testing of radio transmitters, the mean power supplied to the antenna transmission line by a radio transmitter when loaded with noise having a Gaussian amplitude-vs. -frequency distribution.

The noise power in a bandwidth of 1 Hz, i.e., the noise power per hertz at a point in a noise spectrum.
Note: The noise-power density of the internal noise that is contributed by a receiving system to an incoming signal is expressed as the product of Boltzmann's constant, k, and the equivalent noise temperature, Tn. Thus, the noise-power density… (Read More →)

1. Reduction of the noise power level in electrical circuits.
2. The process of automatically reducing the noise output of a receiver during periods when no carrier is being received.

At a pair of terminals, the temperature of a passive system having an available noise power per unit bandwidth at a specified frequency equal to that of the actual terminals of a network.
Note: The noise temperature of a simple resistor is the actual temperature of that resistor. The noise temperature of a diode may be many times the actual… (Read More →)

1. Interfering and unwanted voltage in an electronic device or system.
2. In optical communications, the rms component of the optical detector output electrical voltage with no incoming signal present.

A specific amplitude-vs. -frequency characteristic that permits a measuring set to give numerical readings that approximate the interfering effects to any listener using a particular class of telephone instrument.
Note 1: Noise weighting measurements are made in lines terminated either by the measuring set or the class of instrument.
Note 2: The most widely used noise weightings were established by… (Read More →)

A notch, i.e., a dip, in the noise frequency spectrum characteristic of a device, such as a transmitter, receiver, channel, or amplifier, from external sources or internal sources.
Note: The noise window is usually represented as a band of lower amplitude noise in a wider band of higher amplitude noise. [From Weik '89]

1. In facsimile or display systems, such as television, a nonuniformity in the black area of the image, i.e., document or picture, caused by the presence of noise in the received signal.
2. A signal or signal level that is supposed to represent a black area on the object, but has a noise content sufficient to cause the creation of… (Read More →)