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Reference-related dBs

In case of reference-related dBs, dB is defined as 10∙log(P/Pref) or 20∙log(V/Vref). In the table below you find the most commonly used dBs.

dBVVref = 1VRMSdBV = 20∙log(V/1VRMS)
dBWPref = 1WdBW = 10∙log(P/1W)
dBjVref = 1mVRMSdBj = 20∙log(V/1mVRMS)
dBmPref = 1mWdBm = 10∙log(P/1mW)
dBu (=dBv)Vref = √0.6V = 0.775VRMS  (0.6V is the voltage across a 600 ohm resistor dissipating 1mW)dBu = 20∙log(V/0.775VRMS)

Examples: 0dBV = 1V = 60dBj; 0dBW = 1W = 30dBm.

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