ZyXEL Communications MSC1000G Series, Руководство пользователя

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Chapter 30 profile Commands
Management Switch Card User’s Guide
897
[refvnds <tone_index> <vn_psd>
[...]]
[refvnus <tone_index> <vn_psd>
[...]]
= Adds virtual noise levels on downstream (ds) or
upstream (us) tones where actual noise may occur.
If there is too much noise on a line, the allowed line
speed may be reduced or the line may not initialized.
Virtual noise is the noise allowed before adjustment
occurs. Switch then uses lower data rate on tones
which you added a noise level for the line
initialization. Lower data rate increases a line’s
stability and avoid the line to be easily dropped when
actual noise occurs. The Switch adds pre-configured
virtual noise on specified set of breakpoints. used to
avoid a VDSL line assigning an overly optimistic
number of bits to a sub-carrier. When the actual
noise increased, the actual SNR margin is enough to
maintain the bit-loading, and not leads to line drop.
That is, the virtual noise adding can increase the
line’s stability.
<tone_Index>
: 1~4096 in units of 4.3125 kHz, 0
means not used
<vn_psd>
: 0~200 (representing a PSD of -140+psd/
2 dBm/Hz)
[dpbotype < dpbotype >]
= Sets the DPBO type.
dpbotype
: 0=G.997.1 or 1=t-com
[dpboescma <escma>]
[dpboescmb <escmb>]
[dpboescmc <escmc>]
= These parameters define a cable model that is used
to describe the frequency dependent loss of
exchange-side cables.
<escma>
: DPBO A parameter, 0~640 represent -
1~1.5 in step of 1/256
<escmb>
: DPBO B parameter, 0~640 represent -
1~1.5 in step of 1/256
<escmc>
: DPBO C parameter, 0~640 represent -
1~1.5 in step of 1/256
[dpboesel <esel>]
= Specify the electrical length of the cable between the
system and CPE devices.
<esel>
: Electrical length of DPBO, 0~511 (in units of
0.5dB)
See Section 9.2.9 on page 208 .
[dpboesel <eselmin>]
= Specify the minimum electrical length of the cable
between the system and CPE devices.
<eselmin>
: Minimum electrical length of DPBO,
0~511 (in units of 0.5dB)
[dpbomus <mus>]
= Set the assumed minimum usable received PSD mask
(in dBm/Hz) for exchange based services, used to
modify parameter DPBOFMAX defined below. Enter
from 0 to 255 to set the PSD to 0~-127.5 dBm/Hz in
steps of -0.5 dBm.
[dpbofmax <fmax>]
= This defines the maximum frequency at which DPBO
may be applied.
<fmax>
: 32~6956 (units of 4.3125kHz)
[dpbofmin <fmin>]]
= This defines the minimum frequency from which the
DPBO shall be applied.
<fmin>
: 0~2048 (units of 4.3125kHz)