C
ONFIGURING
I
NTERFACE
S
ETTINGS
FOR
VDSL P
ORTS
10-11
This minimum margin indicates the amount of increase in impulse noise
that the system can tolerate under operational conditions while still
ensuring required transmission quality.
This parameter is used to set the time span of impulse noise protection,
as seen at the input to the de-interleaver, for which err ors can be
completely corrected by the error correcting code, regardless of the
number of errors within the errored DMT symbols.
Note that this parameter only applies to interleaved channels. Refer to
ITU-T G.993.2 for a full description of the methods used to calculate
the minimum level of impulse noise protection.
•Noise Margin – The signal-to-noise margin.
-Target – Configures the targeted signal-to-noise margin that VDSL
ports must achieve to successfully complete initialization.
(Range: 0-62, in units of 0.5 dB; Default: 12 dB)
This parameter sets the noise margin that transceivers must achieve
with a Bit Error Rate (BER) of 10-7 or better to successfully
complete initialization. It indicates the maximum amount by which
the reference crosstalk noise level can be increased during a BER test
without causing the modem to fail the BER requirement.
-Minimum – Configures the minimum acceptable signal-to-noise
margin. (Range: 0-62, in units of 0.5 dB; Default: 10 dB)
This parameter sets the minimum noise margin the receiver can
tolerate. If the noise margin falls below this level, the receiver will ask
the sender to increase its transmit power. If it is not possible to
increase the transmit power, a loss-of-margin defect occurs, the link
will fail and the receiver will attempt to re-initialize.
When rate adaptation is enabled, the signal-to-noise ratio (SNR) is an
indicator of link quality. The switch itself has no internal functions to
ensure link quality. To ensure a stable link, you should add a margin
to the theoretical minimum signal-to-noise ratio (SNR).
•Rate Adaption –
See “Configuring Global Settings for VDSL Ports” on page 10-1.