The metric for noise performance of a circuit is noise figure or noise factor.

If a preamplifier has been used prior to A / D conversion, the noise introduced by the amplifier can be an important contributing factor towards the overall SNR.

In addition to their small size, the surface normal operation of VCSOAs leads to a number of advantages, including low power consumption, low noise figure, polarization insensitive gain, and the ability to fabricate high fill factor two-dimensional arrays on a single semiconductor chip.

Sound intensity follows an inverse square law with distance from the source ; doubling the distance from a noise source reduces its intensity by a factor of four, or 6 dB.

The noise factor is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise.

The noise figure is obtained by expressing the noise factor in decibels ( dB ).

The noise factor F of a system is defined as:

The noise figure is the noise factor, given in dB:

The noise factor of a device is related to its noise temperature :< ref > with some rearrangement from T < sub > e </ sub >= T < sub > 0 </ sub >( F-1 ).</ ref >

Attenuators have a noise factor F equal to their attenuation ratio L when their physical temperature equals.

More generally, for an attenuator at a physical temperature, the noise temperature is, giving a noise factor of:

If several devices are cascaded, the total noise factor can be found with Friis ' Formula:

where is the noise factor for the n-th device and is the power gain ( linear, not in dB ) of the n-th device.

From this belief is derived the practical orientation of our policy on the `` uncommitted '' ( `` neutralist '', `` contested '' ) nations, especially on those whose leaders make the most noise -- Nehru, Tito, Nkrumah, Sukarno, Betancourt, etc..

The radio radiation of the sun which is reflected from the moon and planets should be negligible compared with their thermal emission at centimeter wave lengths, except possibly at times of exceptional outbursts of solar radio noise.

One of the greatest problems associated with automatic leveling is establishing a true level in the presence of high-level acceleration noise.

Below this level, the amplifier gain Af is proportional and is of small value, in order to provide adequate noise filtering.

The effect is that the platform returns from an off-level position at a rapid rate until it is nearly level, at which point the platform is controlled by a proportional servo with low enough frequency response so that the noise has little effect on the leveling process.

If high accuracy is required in preflight leveling, it is usually necessary to integrate or doubly integrate the accelerometer outputs ( this also minimizes the noise problem ).

A traditional Lao explanation is that the moon was being swallowed by a toad, and the remedy was to make all possible noise, ideally with firearms.

As a result of having an actuator controlled precisely with air pressure via a servosystem, the movement is very fluid and there is very little noise.

In practice an analog signal is subject to electronic noise and distortion introduced by communication channels and signal processing operations, which can progressively degrade the signal-to-noise ratio.

The primary disadvantage of analog signaling is that any system has noise – i. e., random unwanted variation.

This is impossible to recover, since amplifying the signal to recover attenuated parts of the signal amplifies the noise ( distortion / interference ) as well.

Even if the resolution of an analog signal is higher than a comparable digital signal, the difference can be overshadowed by the noise in the signal.

One of the most important components of analytical chemistry is maximizing the desired signal while minimizing the associated noise.

Thermal noise is white noise meaning that the power spectral density is constant throughout the frequency spectrum.

The root mean square value of the thermal noise in a resistor is given by

Shot noise is a type of electronic noise that occurs when the finite number of particles ( such as electrons in an electronic circuit or photons in an optical device ) is small enough to give rise to statistical fluctuations in a signal.

Electronic noise is defined as unwanted disturbances superposed on a useful signal that tend to obscure its information content.

" Musicologist Jean-Jacques Nattiez summarizes the relativist, post-modern viewpoint: " The border between music and noise is always culturally defined — which implies that, even within a single society, this border does not always pass through the same place ; in short, there is rarely a consensus ... By all accounts there is no single and intercultural universal concept defining what music might be.

SNR is defined as the ratio of a signal power to the noise power within the desired signal ; it compares the level of a desired target signal to the level of background noise ( atmospheric noise and noise generated within the receiver ).

Throughput over analog channels is defined entirely by the modulation scheme, the signal to noise ratio, and the available bandwidth.

The use of such a literal definition produces other problems, since the area around the church is no longer residential and the noise of the area makes it unlikely that many people would be born within earshot of the bells anymore, although The Royal London Hospital, Guy's Hospital and St Thomas ' hospital are both within the defined area covered by the sound of the Bow Bells.

Though the noise level of 16-bit audio systems ( such as CD players ) is commonly quoted ( on the basis of calculations that take no account of subjective effect ) as − 96 dB relative to FS ( full scale ), the best 468-weighted results are in the region of − 68 dB relative to Alignment Level ( commonly defined as 18 dB below FS ) i. e. − 86 dB relative to FS.

The noise figure NF is defined as:

The noise power spectral density generated by all these sources () can be described by assigning to the noise a temperature as defined above:

In those cases a reference to the amplifier's noise temperature itself, rather than the noise figure defined according to room temperature, is more appropriate.

It is defined as the ratio of signal power to the noise power.

Signal-to-noise ratio is defined as the power ratio between a signal ( meaningful information ) and the background noise ( unwanted signal ):

The newer software defined radios use embedded high performance ADCs that provide higher dynamic range and are more resistant to noise and RF interference.

Professional small arms and artillery users such as military and police personnel, etc., have to be issued with adequate suppressors or hearing protection to reduce noise to levels as defined by law, since an employer has to anticipate legal action and compensations in cases where an employee that used the provided protective gear suffers work-induced health damage.

An impulse can be measured by creating a sufficiently loud noise ( which must have a defined cut off point ).

# In aeronautics, night flying restrictions may restrict aircraft operations over a defined period in the nighttime, to limit the disruption of aircraft noise on the sleep of nearby residents.