Saturday, December 5, 2009

Formula-for-Signal-Noise-Ratio-Calculation

  • Explain the formula for Signal to Noise Ration Calculation - Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering measurement, also used in other fields (such as scientific measurements, biological cell signaling), defined as the ratio of a signal power to the noise power corrupting the signal.

    In less technical terms, signal-to-noise ratio compares the level of a desired signal (such as music) to the level of background noise. The higher the ratio, the less obtrusive the background noise is.

    In engineering, signal-to-noise ratio is a term for the power ratio between a signal (meaningful information) and the background noise:

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    where P is average power and A is root mean square (RMS) amplitude (for example, typically, RMS voltage). Both signal and noise power (or amplitude) must be measured at the same or equivalent points in a system, and within the same system bandwidth.

    Because many signals have a very wide dynamic range, SNRs are usually expressed in terms of the logarithmic decibel scale. In decibels, the SNR is, by definition, 10 times the logarithm of the power ratio. If the signal and the noise is measured across the same impedance then the SNR can be obtained by calculating 20 times the base-10 logarithm of the amplitude ratio:

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