convert between decibels and amplitude scale

#Convert between decibels and amplitude scale full#

Since a peak measurement is not useful for qualifying the noise performance of a system, or measuring the loudness of an audio recording, for instance, RMS measurements are often used instead.Ī potential for ambiguity exists when assigning a level on the dBFS scale to a waveform rather than to a specific amplitude, because some engineers follow the mathematical definition of RMS, which for sinusoidal signals is −3 dB below the peak value, while others choose the reference level so that RMS and peak measurements of a sine wave produce the same result.

Measurements of the true inter-sample peak levels are notated as dBTP or dB TP ('decibels true peak'). This can be prevented by careful digital-to-analog converter circuit design. Conventions differ for root mean square (RMS) measurements, but all peak measurements smaller than the maximum are negative levels.Ī digital signal that does not contain any samples at 0 dBFS can still clip when converted to analog form due to the signal reconstruction process interpolating between samples.

#Convert between decibels and amplitude scale full#

For example, a signal that reaches 50% of the maximum level has a level of −6 dBFS, which is 6 dB below full scale. The level of 0 dBFS is assigned to the maximum possible digital level. The unit is similar to the units dBov and decibels relative to overload ( dBO). The red lines indicate full scale, and the waveform is shown before and after hard clipping (grey and black outlines respectively).ĭecibels relative to full scale ( dBFS or dB FS) is a unit of measurement for amplitude levels in digital systems, such as pulse-code modulation (PCM), which have a defined maximum peak level. For other uses, see DBFS (disambiguation).