ZyXEL Communications MSC1000G Series, Руководство пользователя

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Chapter 9 Subscriber Port Setup Screens
Management Switch Card User’s Guide
229
RFI Band RFI is induced noise on the lines by surrounding radio sources such as AM and HAM radio
stations. To avoid performance degradation due to RFI, set the switch to not transmit VDSL
signals in the RFI band plans defined by the regulatory bodies. You can also configure your
own RFI band plans on the system.
Select ansi to use the RFI band plan settings defined by ANSI.
Select etsi to use the RFI band plan settings defined by ETSI.
Select disable to deactivate this function.
Select custom to configure RFI settings in the fields below.
Limit Mask To reduce the impact of interference and attenuation, ITU-T 993.2 specifies a PSD mask to
limit the Power Spectral Density at both downstream and upstream. Select the correct PSD
mask for your region and line conditions. Selecting multiple PSD masks for a single DSL line
or line bundle may increase interference.
See Table 102 on page 234 for a list of Limit Mask profiles available in this screen.
Min INP Sudden spikes in the line’s noise level (external noise) can cause errors and result in lost
packets. Set the impulse noise protection minimum to have a buffer to protect the ADSL
physical layer against impulse noise. This buffering causes a delay that reduces transfer
speeds. It is recommended you use a non-zero setting for real-time traffic that has no error
correction (such as video-conferencing).
Type DMT (Discrete Multi-Tone) values in the Up Stream and Down Stream fields
provided to specify the level of impulse noise (burst) protection (INP) for a slow (or
interleaved) channel.
INP is defined in this screen as a multiple (between 0.5~160) of 0.1 DMT symbols. The
number of DMT symbols specifies the time in which errors can be completely corrected. A
higher symbol value provides higher error correction capability, but it causes overhead and
higher delay which may increase error rates in received multimedia data.
UPBO UPBO (Upstream Power Back Off) allows the switch to provide better service in a network
environment with telephone wiring of varying lengths.
Select Enable to activate this feature.
Select Disable to deactivate this feature.
Type the UPBOSEL (Upstream Power Back-off Exchange-Side Electrical Length) to specify
the electrical length of the cable between CPE and CO.
Set this to 0~127 (in 0.1 dB) to force CPE devices to use the Device's electrical length value
for UPBO adjustment.
Set this to -1 to use a dynamic electrical length based on the result of the negotiation
between the Device and CPE devices.
For Bands 1~3 specify 4000~8095 (0.01 dBm/Hz) for parameter A which defines the
original band shape. Specify 0~4095 (0.01 dBm/Hz) for parameter B which defines the
power back-off degree. Parameter A and B are used for UPBO PSD mask calculations.
Table 100
VDSL Port Setup: Advanced
LABEL DESCRIPTION