DBV Scale

Another dB scale is the dBV scale which sets 0 dBV to 1 volt. Thus, a 100-volt signal is

$$20\log_{10}\left(\frac{100V}{1V}\right) =$$   40 dBV

and a 1000-volt signal is

$$20\log_{10}\left(\frac{1000V}{1V}\right) =$$   60 dBV

Note that the dBV scale is undefined for current or power, unless the voltage is assumed to be across a standard resistor value, such as 600 Ohms.