MDS 05-2806A01, Rev. A MDS iNET 900 User’s Guide 103
5. If constant interference is present in a particular frequency zone
(collection of 8 RF channels), it may be necessary to “skip” that
zone from the radio’s hopping pattern. The radio includes built-in
software to help users identify and remove blocked frequency zones
from its hopping pattern. (See “Skip Zone Options Menu” on
Page 31 for more information.)
6. If interference problems persist even after skipping some zones, try
reducing the length of data streams. Groups of short data streams
have a better chance of getting through in the presence of interfer-
ence than do long streams.
7. The power output of all radios in a system should be set for the low-
est level necessary for reliable communications. This lessens the
chance of causing unnecessary interference to nearby systems.
If you are not familiar with these interference-control techniques, con-
tact your MDS sales or Technical Support Department for more infor-
mation.
5.1.7 How Much Output Power Can be Used?
The iNET 900 is normally supplied from the factory set for a nominal
+30 dBm (1 Watt) RF power output setting; this is the maximum trans-
mitter output power allowed under FCC rules. The power must be
decreased from this level if the antenna system gain exceeds 6 dBi. The
allowable level is dependent on the antenna gain, feedline loss, and the
transmitter output power setting.
NOTE: In some countries, the maximum allowable RF output may be
limited to less than 1 watt (For example, 100 mW /+20 dBm).
Be sure to check for and comply with the requirements for
your area.
Calculating System Gain
To determine the maximum allowable power setting of the radio, per-
form the following steps:
1. Determine the antenna system gain by subtracting the feedline loss
(in dB) from the antenna gain (in dBi). For example, if the antenna
gain is 9.5 dBi, and the feedline loss is 1.5 dB, the antenna system
gain would be 8 dB. (If the antenna system gain is 6 dB or less, no
power adjustment is required.)
2. Subtract the antenna system gain from 36 dBm (the maximum
allowable EIRP). The result indicates the maximum transmitter
power (in dBm) allowed under the rules. In the example above, this
is 28 dBm.
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