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The noise factor is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard noise temperature T 0 (usually 290 K). The noise factor is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise, which ...
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.
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 ...
Transmission loss (TL) in duct acoustics describes the acoustic performances of a muffler-like system.It is frequently used in the industry areas such as muffler manufacturers and NVH (noise, vibration and harshness) department of automobile manufacturers, and in academic studies.
The Y-factor method is a common measurement technique for this purpose. [1] By using a noise diode, the output noise of an amplifier is measured using two input noise levels, and by measuring the output noise factor (referred to as Y) the noise figure of the amplifier can be determined without having to measure the amplifier gain.
Many experimental and field measurements show that the acoustic attenuation coefficient of a wide range of viscoelastic materials, such as soft tissue, polymers, soil, and porous rock, can be expressed as the following power law with respect to frequency: [7] [8] [9]
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.
For both systems, also increasing the size of pipes and air canals would help to reduce noise and the energy consumption of pumps (and ventilators) by decreasing the speed of the fluid, which in turn lowers the Reynolds number and hence the turbulence (and noise) and the head loss (see hydraulic head).