Focus on Competition - 2010/12

180 MODEL AVIATION
Cell Towers, Factories, and Cell
Phones: Questions often come in groups, and
lately I’ve fielded several calls asking about
the possible interference from different types
of towers and manufacturing facilities. I can
understand the worry, and getting a straight
answer from anyone can be frustrating. I
have found that not getting a good answer is
seldom because someone is hiding
something, but rather because few people
Technically Speaking ...
Greg Hahn
Technical Director
[email protected]
Focus on Competition
really know what or how to answer the
questions.
Back in the day, any trucker with a good
CB radio running a linear could end our
flying day in a real hurry. Thank goodness
that was just a fad, and now we’re on to
bigger and better things like cell phones and
Wi-Fi.
To keep this as simple as possible (I’m not
an electronics engineer either), most of the
outside interference we deal with today on
our “old” 72 MHz sets has to do with
shadowing or the effects of power output.
The interferer is not actually operating on
one of our direct frequencies but is
transmitting on an adjacent frequency with
enough power output to cause a problem
(big footprint).
This issue doesn’t usually come from
towers but often from manufacturing
facilities using radio control for their
overhead cranes and other automated
systems in the factory. Hospitals can also be
a problem sometimes, as we saw recently
with a club in Minnesota.
Most of the problems with 72 MHz
actually come from within our own
equipment or the airframe it’s operating in.
Any metal-to-metal contact added to
vibration will often create the frequencies to
interfere with our receivers, and the filtering
process is not strong enough to cancel out
this interference.
Things such as bad engine bearings,
metal clevises, loose motor mounts, and
nuts and bolts in general can and will cause
problems to the point of causing a crash.
I know that many of you had a feeling of
“Now that I’m on 2.4 GHz, I’ll never crash
again.” Well, not so fast.
Besides the venerable dumb thumb
(what’s that?), we still live in an era where
the air is a very busy place. Our use of the
2.4 GHz band has given us some good
perks, such as no frequency pins, no need
for impound, and better resolution, but the
air is still busy and that radio traffic does
and can cause problems.
Just in the past 10 years or so, think of
all the other gadgets and widgets that have
been invented that also operate on 2.4. All
these new things add to the radio traffic,
making the link between you and your
beloved model more difficult to hang onto.
Granted, our receivers and equipment have
become so good as to be almost
bulletproof, but they’re still not perfect.
The point of all this is to make you aware
of what is out there and to make you aware
that problems still exist, and most of it is a
traffic issue. Very rarely does something
such as one cell tower or one building
cause a problem. It’s usually a group of
things all coming together to cause you
grief.
Be safe and have fun! MAThe
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