dBFS
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dBFS means "decibels full scale". It is an abbreviation for decibel amplitude levels in digital systems which have a maximum available level (like PCM encoding). 0 dBFS is assigned to the maximum possible level.[1]
There is a potential for ambiguity when assigning a level on the dBFS scale to a waveform rather than to a specific amplitude, since some derive the characteristic level of the waveform from its peak amplitude value, while others use its RMS amplitude value.[2]
- In the case of a FS square wave = 0 dBFS, all possible dBFS measurements are negative numbers. A sine wave of larger amplitude than −3 dBFS would be clipping by this convention.
- In the case of a FS sine wave = 0 dBFS, a FS square wave would be at +3 dBFS.
The measured dynamic range of a digital system is the ratio of the full scale signal level to the RMS noise floor. The theoretical dynamic range of a digital system is often derived by the equation
This comes from a model of quantization noise equivalent to a uniform random fluctuation between two neighboring quantization levels. For instance, 16-bit audio has a quoted dynamic range of 96.33 dB.[1]
To make an equivalent measurement of a system's noise floor, the full-scale square wave convention is used. A signal which fluctuates randomly between two neighboring quantization levels will measure at −96.33 dBFS with this convention.
References
- ^ a b Price, Jim. "Understanding dB". Professional Audio. Retrieved 2007-03-13.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ "Decibel - Voltage ratios for electric signals". sizes.com. Retrieved 2007-03-13.
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