Information About

Dbfs




dBFS means " Decibel s 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. There is still the potential for ambiguity, since some use the RMS value of a full-scale Square Wave for 0 dBFS, and some use a Sine Wave .

  • 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

:\mathrm{DR} = \mathrm{SNR} = 20 \log_{10}(2^n) \approx 6.02 \cdot n

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.

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.


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