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Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

decibel (dB)
a unit of measure that describes the ratio between two quantities in terms of a base 10 logarithm. For example, the ratio between the power level at the input and output of an amplifier is called the power gain and may be expressed in decibels as follows:

G(dB) = 10 log10 ( Pout / Pin )

Terms such as dBm, dBuV, dBW indicate that the decibel measurement was made relative to an established standard. A common power measure reference is 0 dBm, which is defined to be 1 mW (milliwatt, 0.001W). A common voltage reference is 1 μV (1 microvolt).