User's Manual

Chapter 2: Hardware and Pinouts
LIM0001AA Rev E
Cable Loss and Transmit Power Settings
The Transmit Power parameter is the output power of the transceiver. The transceiver output power level
must be set to satisfy maximum Equivalent Isotropically Radiated Power (EIRP) requirements in the country
in which the installation exists.
When setting up the network, consider the power gain that an antenna may add, and the power loss through
cabling. Adjust the Transmit Power on the transceiver to ensure that you do not exceed the maximum EIRP
for the regulating body where the installation exists. Use the tables below to determine the correct Transmit
Power parameter setting for each transceiver in the network.
Important: The information in this section discusses FCC and ETSI maximum EIRP
regulations. Ensure your installation meets the maximum EIRP requirements for the
country in which you are installing transceivers. It remains the installer's responsibility
to ensure that an installation is within EIRP emission limits.
The FCC permits 1 Watt output power at the transceiver and 36 dBm (4 Watts) at the antenna. When
calculating the power gain, use the following equation to determine the total output power at the antenna. Loss
calculations should include cable, connectors, surge protectors, etc.
Transceiver Output – Losses + Antenna Gain = Output Antenna Power
For example, 30 dBm – 2 dB + 6 dBi = 34 dBm (or 2.5 Watts). 34 dBm is within the FCC limits. However, 30
dBm – 2 dB + 10 dBi = 38 dBm (or 6.3 Watts) exceeds the FCC limits.
Cable
Type
Attenuation
(db/100 ft) Run Length (ft) Total Run Attenuation (dB)
LMR400 3.93 25 1.0
LMR500 3.154 25 0.8
LMR600 2.518 25 0.6
LMR900 1.709 25 0.4
Shielding
FreeWave OEM transceivers are shielded to prevent any unintended emission. Additional shielding may be
required to prevent the OEM equipment from interfering with the FreeWave transceiver. This is unlikely but it
depends on the equipment and components in the OEM application.
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