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Term: Decibels relative to full scale

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Term: Decibels relative to full scale


The term dB FS (or dBFS) means decibels relative to full scale. It is used for amplitude levels in digital systems with a maximum available peak level, e.g., PCM encoding, where 0 dB FS is assigned to the maximum level. A signal that reaches 50 percent of the maximum level would, for example, have a value of -6 dB FS. All peak measurements will be negative numbers.

Digital signals without any samples that reach the peak of 0 dB FS can still clip when converted to analog due to intersample peaks. Various official standards pertaining to signal measurement define full scale in terms of a sinewave tone of 997 Hz, thereby avoiding tones at any sub-multiple of common sampling frequencies.

Wikipedia article on dB FS
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