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In electronics, noise is an unwanted disturbance in an electrical signal. [ 1]: 5. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics and central to thermodynamics. Any conductor with electrical resistance will generate thermal noise inherently.
The noise figure is the difference in decibel (dB) between the noise output of the actual receiver to the noise output of an "ideal" receiver with the same overall gain and bandwidth when the receivers are connected to matched sources at the standard noise temperature T0 (usually 290 K).
An RF receiver system is typically made up of an antenna and a receiver, and the transmission line(s) that connect the two together. Each of these is a source of additive noise . The additive noise in a receiving system can be of thermal origin ( thermal noise ) or can be from other external or internal noise-generating processes.
Noise floor. Measurement from a spectrum analyzer showing a noise-like measurement from an unspecified component. In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system, where noise is defined as any signal other than the one being monitored.
Antenna gain-to-noise-temperature ( G/T) is a figure of merit in the characterization of antenna performance, where G is the antenna gain in decibels at the receive frequency, and T is the equivalent noise temperature of the receiving system in kelvins. The receiving system noise temperature is the summation of the antenna noise temperature and ...
Noise temperature (antenna) In radio frequency (RF) applications such as radio, radar and telecommunications, noise temperature of an antenna is a measure of the noise power density contributed by the antenna to the overall RF receiver system. It is defined as "the temperature of a resistor having an available thermal noise power per unit ...
A low-noise block downconverter ( LNB) is the receiving device mounted on satellite dishes used for satellite TV reception, which collects the radio waves from the dish and converts them to a signal which is sent through a cable to the receiver inside the building. Also called a low-noise block, [ 1][ 2] low-noise converter ( LNC ), or even low ...
With noise present, if a radio source is so weak and far away that the radio signal in the receiver has a lower amplitude than the average noise, the noise will drown out the signal. The level of noise in a communications circuit is measured by the signal-to-noise ratio (S/N), the ratio of the average amplitude of the signal voltage to the ...