dB
Decibel. The decibel is a unit of power ratios. The decibel value can be expressed as:
If you work this out when power = reference_power, you will find that the dB value is zero.
As power is proportional to the square of the voltage, this formula can also be expressed as:
The reference power or reference voltage is chosen by convention, and should always be stated. We have chosen to use 1 volt peak (0.707 V RMS). Another measure is with respect to 0.775 V RMS (1 mW into 600 ohms). This is sometimes called db(m). See Initialisation settings for information on how to change the reference level.
Decibel. The decibel is a unit of power ratios. The decibel value can be expressed as:
| db = 10 x log10 (power / reference_power)
|
If you work this out when power = reference_power, you will find that the dB value is zero.
As power is proportional to the square of the voltage, this formula can also be expressed as:
| db = 20 x log10 (voltage / reference_voltage)
|
The reference power or reference voltage is chosen by convention, and should always be stated. We have chosen to use 1 volt peak (0.707 V RMS). Another measure is with respect to 0.775 V RMS (1 mW into 600 ohms). This is sometimes called db(m). See Initialisation settings for information on how to change the reference level.