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Peak signal-to-noise ratio (PSNR) is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic range, PSNR is usually expressed as a logarithmic quantity using the decibel scale.
An international milestone is the heat pump built by Escher Wyss in 1937/38 to replace the wood stoves in the City Hall of Zurich. To avoid noise and vibrations, a recently developed rotary piston compressor was used. This historic heat pump heated the town hall for 63 years until 2001. Only then was it replaced by a new, more efficient heat ...
Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to noise power, often expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise.
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 ...
The Sound Reduction Index is expressed in decibels (dB). It is the weighted sound reduction index for a partition or single component only. This is a laboratory-only measurement, which uses knowledge of the relative sizes of the rooms in the test suite, and the reverberation time in the receiving room, and the known level of noise which can pass between the rooms in the suite by other routes ...
ITU-R 468 (originally defined in CCIR recommendation 468-4, therefore formerly also known as CCIR weighting; sometimes referred to as CCIR-1k) is a standard relating to noise measurement, widely used when measuring noise in audio systems.
The heat pump itself can be improved by increasing the size of the internal heat exchangers, which in turn increases the efficiency (and the cost) relative to the power of the compressor, and also by reducing the system's internal temperature gap over the compressor. Obviously, this latter measure makes some heat pumps unsuitable to produce ...
Multiple noise processes determine the noise floor of a system. Noise can be picked up from microphone self-noise, preamp noise, wiring and interconnection noise, media noise, etc. Early 78 rpm phonograph discs had a dynamic range of up to 40 dB, [24] soon reduced to 30 dB and worse due to wear from repeated play. Vinyl microgroove phonograph ...