Manual of VDSL2 Mini MEG101AE-R4
Page #6
http://www.black-box.eu
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What does SNRM mean?
This means the Signal to Noise ratio. Any xDSL device puts a signal on a cable which
degrades with every meter and kilometre of cable. The degradation comes from noise
produced by other signals on nearby cables, by high power devices (elevators), by
smartphones (EMI) and other wireless devices.
At the end the signal of the xDSL device has a certain strength in comparison to the noise.
You can compare this with two people talking being in an empty room talking (no noise) or
two people talking in a disco (high noise).
Many xDSL devices adopt themselves in term of bandwidth and modulation. The better
the signal in comparison to the noise comes through, the higher the bandwidth can be.
Setting the MEG101AE-R4 to a higher SNRM of 9db means that the modem will
synchronize the line with a spare of 9db budget. If you experience high EMI at your
installation a higher spare budget means more stability but less bandwidth.
What does DIP Switch #2 do?
The factory default setting is to have DIP Switch #2 to OFF position. This is good for
long/bad cables (and for short/good cables too). A different frequency spectrum is used
whether you have DIP Switch #2 to ON or OFF position.
DIP Switch #2 ON
for short/good cables
500kHz to 30MHz
DIP Switch #2 OFF
for long/bad cables
25kHz to 30MHz
In mode “for long/bad cables” the modem completely autodetects cable length. The
complete frequency spectrum can be used. In mode “for short/good cables” just a part of
the frequency spectrum is used. That mode also allows maximum bandwidth, but the
frequencies from ISDN/telephony nearby cables are not touched and used. That reduces
EMI interferences.
