ADC 320F - Manual (Page 58)

Rate Adaptive Transmission
50 Megabit Modem 310F and 320F User Manual
You can configure the Megabit Modem 310F and 320F startup margin setting. This setting
defaults to 4 dB but may be set from 0 - 15 dB. The modems will attempt to come up at the
programmed margin setting. Setting the margin high allows for a cushion against changing line
conditions and impulse noise. Setting the margin low provides less protection but allows the
modems to come up at a higher data rate (if in rate-adaptive mode) or at a longer loop length (if
in fixed data rate mode). The default setting of 3 dB is recommended and provides an overall
BER better than 10
-10 . Reducing the setting to 0 dB will provide a BER of less than 10 -7 and
is not recommended.