decibel voltage (dBV)
To simplify the calculation of voltage ratios and absolute voltage values, logarithmization is used and a defined reference value is used.
For decibelvolts (dBV), the reference value of 0 dBV corresponds to the rms value of a sinusoidal voltage of 1.0 V. This reference value has no resistance reference such as decibel milliwatt( dBm). Another voltage reference value is the Decibel Unloaded( dBu) with a reference voltage of 0.775 V. The reference voltage of 0.775 V is derived from the power of 1 mW into 600 ohms.
dBV and dBu are directly related to each other. Thus, 1 dBV corresponds to +2.2 dBu or -10 dBV corresponds to -7.8 dBu.