ZyXEL Communications VES-1616F-44, User Manual

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VES-1616F/1624F-44 User’s Guide
74 Chapter 6 Basic Setting
The switch determines line quality using the Signal-to-Noise Ratio (SNR). SNR is the ratio of
the amplitude of the actual signal to the amplitude of noise signals at a given point in time. A
low SNR indicates poor line quality.
Select Fixed Rate to disable transmission rate adjustment. If the attainable speeds cannot
match configured speeds, then the VDSL link may go down or link communications may be
sporadic due to line errors and consequent retransmissions
Select Rate Adaptive Decrease Mode to enable the switch to adjust to a new lower rate when
the line quality deteriorates until the connection is broken. The switch will re-establish the line
connection when the line quality improves. However, the new line rate might be lower that the
configured line rate.
6.8.7 RFI (Radio Frequency Interference)
RFI is induced noise on the lines by surrounding radio frequency electromagnetic radiation
from sources such as AM and HAM radio stations. Since the VDSL uses a much larger
frequency range that overlaps with other radio frequency systems, signals from VDSL lines
and other radio systems interfere with each other. To avoid performance degradation due to
RFI, set the switch to not transmit VDSL signals in the RFI band.
6.9 VDSL Common Setup
To configure general VDSL port settings, click Basic Setting and VDSL Common Setup to
display the screen as shown next.
Refer to Section 6.8 on page 72 for more information.
Figure 27 VDSL Common Setup
The following table describes the labels in this screen.
Table 15 VDSL Common Setup
LABEL DESCRIPTION
Band Plan Select a band plan from the drop-down list box.
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 function. Otherwise, select Disable to deactivate this
function.