Decibel
dB or not dB? Everything you ever wanted to know about decibels but were afraid to ask...
"The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level."
"An increase of 3 dB corresponds to an approximate doubling of power."
"The definitions of the decibel and bel use base-10 logarithms."
Prefix is "dB"
or
where X is the actual value of the quantity being measured, X0 is a specified or implied reference level, and then XdB is the quantity expressed in units of decibels, relative to X0
An increase/decrease of 1 dB corresponds to an approximate quarter power gain/loss. (ie 1=>1.25)
An increase/decrease of 2 dB corresponds to an approximate half power gain/loss. (ie 1=>1.50)
An increase/decrease of 3 dB corresponds to an approximate doubling of power gain/loss. (ie 1=>2)
An increase/decrease of 6 dB corresponds to an approximate quadrupling of power gain/loss. (ie 1=>4)
An increase/decrease of 9 dB corresponds to an approximate eight times the power gain/loss. (ie 1=>8)
An increase/decrease of 10 dB corresponds to an approximate ten times the power gain/loss. (ie 1=>10)
An increase/decrease of 20 dB corresponds to an approximate one hundred times the power gain/loss. (ie 1=>100)
So a change of 10 dB would be a change of 10 times the power. For example: To convert 1 kW (one kilowatt, or 1000 W) to decibels, use the formula (with base measure being 1 W):
