Glossary definition of 'Full-scale amplitude'

(FS) (AES17 standard) A signal whose amplitude is the maximum which can be accommodated by the EUT. In the case of a sine, this amplitude is 0dBFS. For systems where the output is accessible in the digital domain, full scale is defined as the RMS voltage of a 997Hz sine wave whose positive peak value reaches the positive digital full scale. For systems where the digital signal is not accessible, or where digital full scale cannot be reached, full scale is defined as the level 0.5dB below that where 1% THD+N or 0.3dB compression occurs (whichever comes first) at the EUT output for a 997Hz sine wave.