Focus on Competition - 2010/12
Technically Speaking ...
Greg Hahn Technical Director [email protected]
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 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 (a large 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 signals that 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 loose nuts and bolts in general can and will cause interference severe enough to result in 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 GHz. 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!
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
