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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 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 contributed by a radio frequency amplifier regardless of the amplifier's gain.
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.
The noise power from a simple load is equal to kTB, where k is the Boltzmann constant, T is the absolute temperature of the load (for example a resistor), and B is the measurement bandwidth. This makes the noise figure a useful figure of merit for terrestrial systems, where the antenna effective temperature is usually near the standard 290 K ...
Underwater acoustic communication is a technique of sending and receiving messages in water. [ 1] There are several ways of employing such communication but the most common is by using hydrophones. Underwater communication is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and ...
A sound level meter (also called sound pressure level meter ( SPL )) is used for acoustic measurements. It is commonly a hand-held instrument with a microphone. The best type of microphone for sound level meters is the condenser microphone, which combines precision with stability and reliability. [ 1] The diaphragm of the microphone responds to ...
Electromagnetic interference ( EMI ), also called radio-frequency interference ( RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. [ 1] The disturbance may degrade the performance of the circuit or ...
Ambient noise level is measured with a sound level meter. [ 4] It is usually measured in dB relative to a reference pressure of 0.00002 Pa, i.e., 20 μPa (micropascals) in SI units. [ 5] This is because 20 μPa is the faintest sound the human ear can detect. [ 5] A pascal is a newton per square meter. The centimeter-gram-second system of units ...