Installation Guide

9 / 16 HONG KONG KONING INDUSTRIAL LIMITED
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W400/200 SERIES INSTALLATION GUIDE
3) Signal Booster Oscillation Avoidance
Signal booster is two-way (full duplexer) amplifier.so donor antenna and sever antenna should be
adequate isolation to prevent any feedback “oscillations”. We take MIC and speaker for example to
clear understanding, when we put MIC near speaker, the speaker produces sharp scream. In order to
ensure signal booster work normally, the isolation between donor antenna and sever antenna is
bigger 10-15dB than signal booster gain. Suppose signal booster gain is 70dB, then the isolation
between donor antenna and sever antenna is 80-85dB.
As figure show: signal booster amplify the signal “R” from cell tower, if inadequate isolation
between donor antenna and sever antenna, the amplified signal “R” will broadcast back to
donor antenna by sever antenna, and then the signal booster will amplify the “R” again , “R”
flow back to donor antenna through sever antenna, be amplified again. After several circle,
signal ‘R” will be stronger and stronger gradually up to signal booster limits and start
oscillation. In inadequate isolation coverage area, the signa wave obviously, bad signal
quality at the border of coverage area, easy drop words and break off
When Wisdom signal booster detect oscillation, the system will attenuate internal gain to
remove oscillation. but low gain will affect coverage area.
we can take some simple ways to get “safe separation distance “
a) Vertical distance: the donor antenna and sever antenna are two floors apart from