User Manual

110 MDS entraNET 900 System Guide (Preliminary) MDS 05-4055A01, Rev. A
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 transceiver 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.
3. If the maximum transmitter power allowed is less than 30 dBm, set
the power to the desired level using the entraNET Management Sys-
tem.
(
Main Menu>Radio Configuration>RF Output Power Setpoint)
For convenience, Table 5-3 lists several antenna system gains and
shows the maximum allowable power setting of the radio. Note that a
gain of 6 dB or less entitles you to operate the radio at full power output
–30 dBm (1 Watt).