Attenuation: 0 to 63.5 dB with 0.5 steps (near), 0 to 127 (corresponds 0 to 63.5 dB) (far)
SNR: -64.0 dB to 63.5 dB with 0.5 steps (near), -128 to 127 (corresponds -64 a 63.5 dB) (far)

See 8.3 from ANSI T1.413-1998

