CHCNAV CHC i83 - Best Practices for Extending UHF Radio Range; Multiple Users on same Radio Frequency; Base Output Power Setting

CHC i83 User Manual 14
Emission Designator
9K75F1D
Best Practices for Extending UHF Radio Range
The UHF radio in the receiver has excellent range. However, range is greatly reduced by other users on the same
frequency, damaged antennas, damaged cables and configuration issues.
The most common range issues are listed below. If you need to dependably operate at more than 3-miles from your
Base, consider purchasing an iGR 35-watt base radio:
Multiple Users on Same Radio Frequency
If someone or something else is utilizing the same frequency for voice or data, it will greatly reduce the distance you can
move from your base. This is the most common cause of bad radio range.
Use a Handheld UHF radio to check if the frequency is unused before you start your base. Carry the Handheld radio with
you all day so that you can check if someone sets up on your frequency after your session begins.
If you think someone else may have begun to use the same frequency, turn off your base while listening to the
frequency.
The ‘BaoFeng UV-5R’ is available from Amazon for less than $20 and is a ‘good-enough’ choice for monitoring
frequencies:
Become familiar with what it sounds like if you are the only user on a frequency and what it sounds like if there are
more than one user on the same frequency.
Sources of interference include:
other surveyors and engineers
voice users (truckers, businesses, railroads, schools, service companies)
wireless microphones
SCADA equipment (like water or oil pipeline infrastructure)
control backhauls on com links
nearby AM or FM radio transmitters
nearby radar systems
The radio frequencies that are usually assigned (by the FCC in conjunction with frequency coordination) are not
exclusive and are assigned to many users in the same area.
Unlicensed voice transmissions have a higher priority than licensed data transmissions. Your radio (the radio built into
your Base) will wait for other users before it transmits (this is called CSMA: collision sense multiple avoidance.)
If you find that the frequency that you were going to transmit is busy, you can change the channel/frequency of your
Base and Rover to an alternate frequency.
Base Output Power Setting
You probably will want the radio in your Base to output as high of power as possible.
If 2-watts with an elevated antenna is not sufficient, we recommend purchasing a high-power repeater.