User's Manual

Table Of Contents

ITCR Wayside User’s Manual

5/16/2013 7

for 10 feet of Times Microwave LMR-195 Ultra Flex coaxial cable. Transmitter power

output limit = 47-2.4+0.6 = 45.2 dBm PEP and therefore the system is compliant with

the 50W ERP limit. The actual ERP in this case is 10^(14.85+2.4-0.6) = 46.2 W. This

installation is not allowed to transmit on FCC channels 196-200 because the

maximum ERP is greater than 2 watts.

Fixed Installation: In a fixed installation, a common single-element exposed folded

dipole antenna without reflector has 0 up to 2.9 dBd (2.1 to 5.0 dBi) azimuthal gain

depending on the design.

Once the allowable ERP is determined by applying all power-restrictive rules from

above and the antenna gain is known, the transmitter peak envelope power output

feeding the transmission line is determined by subtracting the antenna gain in dBd

from the ERP and adding the loss from the antenna feedline and connectors plus the

loss from any external inline power sensors, combiners, filters or lightning arresters.

If the net value is greater than or equal to 44.85 dBm, then the maximum power of

the Wayside transmitter can be used. If the value is less than 44.85 dBm, then the

transmitter output power must be reduced to the net value.

Example for the 50W ERP fixed case: Antenna gain = 2.9 dBd and feedline loss is at

least 0.5 dB for 25 feet of Times Microwave LMR-400 coax plus 0.4 dB for inline

lightning arrester and three connectors. Assuming no other losses, the transmitter

power output limit = 47-2.9+0.9 = 45 dBm PEP. In this case, the actual Wayside ERP

is 44.85+2.9-0.9 dBm = 46.85 dBm = 48.4 W PEP and therefore the system is

compliant with the 50W ERP limit. This installation is not allowed to transmit on FCC

channels 196-200 because the maximum ERP is greater than 2 watts.

4. Setup and Configuration for the Wayside Radio

Set up physical connections with the following:

• DC Power

• Ethernet

RF output termination

The sections below identify each of the physical connections.