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Noise figure (NF) and noise factor (F) are figures of merit that indicate degradation of the signal-to-noise ratio (SNR) that is caused by components in a signal chain. These figures of merit are used to evaluate the performance of an amplifier or a radio receiver, with lower values indicating better performance.
Here, k ≈ 1.38 × 10 −23 J/K is the Boltzmann constant and kT 0 is the available noise power density (the noise is thermal noise, Johnson noise). As a numerical example: A receiver has a bandwidth of 100 MHz , a noise figure of 1.5 dB and the physical temperature of the system is 290 K .
The noise factor (a linear term) is more often expressed as the noise figure (in decibels) using the conversion: = The noise figure can also be seen as the decrease in signal-to-noise ratio (SNR) caused by passing a signal through a system if the original signal had a noise temperature of 290 K. This is a common way of expressing the noise ...
In telecommunications, effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when connected to a noise-free network or amplifier, as that of the actual network or amplifier connected to a noise-free source.
where is the overall noise factor of the subsequent stages. According to the equation, the overall noise factor, F r e c e i v e r {\displaystyle F_{\mathrm {receiver} }} , is dominated by the noise factor of the LNA, F L N A {\displaystyle F_{\mathrm {LNA} }} , if the gain is sufficiently high.
Walter H. Schottky studied the problem in 1918, while studying thermal noise using Einstein's theories, experimentally discovered another kind of noise, the shot noise. [2] Frits Zernike working in electrical metrology, found unusual random deflections while working with high-sensitive galvanometers. He rejected the idea that the noise was ...
If the noise current contribution i n R s >> noise voltage e n, then reducing the source impedance by a factor of 4 reduces the i n contribution by a factor of 4 while the source's thermal noise voltage declines by factor of 2 (ideal transformer with 2:1 turns ratio gives the 4:1 Z ratio); SNR improves by 6 dB. But there's another issue.
Statistical energy analysis (SEA) is a method for predicting the transmission of sound and vibration through complex structural acoustic systems. The method is particularly well suited for quick system level response predictions at the early design stage of a product, and for predicting responses at higher frequencies.