User's Manual

ITCR Locomotive Radio User Guide
© 2013 Meteorcomm LLC. All Rights Reserved. Proprietary and Confidential
6 Do Not Distribute 4/30/2013
Please refer to Part 90 Subpart T and SRSP-512 for additional frequency use
restrictions in Canadian and Mexican border areas.
3.3 Locomotive radiated power limits
It is the responsibility of the licensee to comply with the effective
radiated power limits based on operating frequency, geographic location,
and effective antenna height set out in 47CFR Parts 80 and 90 or Industry
Canada SRSP-512 §6.3, as applicable.
Important: The following supplementary antenna system information discusses
means for the licensee to calculate effective radiated power (ERP) and how to
comply with regulatory power limits.
Licensees should note that mobile radios operating in the 220-222 MHz frequency
range including Locomotive radios must limit effective radiated power (ERP) to 50W
or 10*log(50) + 30 = 47dBm PEP referenced to the 2.15 dBi gain of a dipole unless
operating under a waiver of FCC rule §90.729(b) or IC SRSP512 §6.3.1.4 as
applicable. The EIRP for this case is 49.15 dBm. Also note that the maximum ERP on
FCC/IC channels 196-200 at 220.975 to 221.000 MHz is 2 watts.
Antennas designed for locomotives at 220 MHz generally use a rugged cast
aluminum body and are top-loaded vertically polarized requiring a metal cab roof for
a ground plane. They are necessarily electrically shorter than one fourth wavelength
due to vertical space limitations. Maximum practical antenna gain when installed
properly on a locomotive cab roof is expected to be 0 dBd = 2.15 dBi.
Assuming no other losses between transmitter and antenna, the maximum allowed
transmitter output for 0 dBd gain antenna is (47-0) = 47 dBm PEP = 50W PEP. In this
case, if the measured transmitter output power exceeds 50W PEP, its power must
be adjusted down to 50W PEP. Locomotive radio output power can be adjusted as
described later in the manual.
The Locomotive transmitter should not be adjusted to greater than 50W PEP output.
In a practical installation, the feedline and filter losses between transmitter and
antenna are taken into account. If the Locomotive transmitter output is 50W PEP =