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Aerial Photography and Video > Cell Site Transmitters - Hazard?
 
 
Flyingeye
Senior Heliman
Location: San Diego, CA, USA

My biggest discomfort about this process is the possibility of losing control of the helicopter. Every time I see one of these cell site transmitters, it gives me pause for thought:



...and they are EVEREYWHERE. Does anyone know how close you can get to one without experiencing radio problems? Do they transmit watts or 100's of watts?

I think I'm going to find one and just fly my cheap foam flying wing around it to see how close I can get without problems. There is a mountain top near me with a gaggle of various radio transmitter antennas and I did this kind of test last week. I could get within about 0.1 mile. As I got my plane farther than about 200 feet away from me, it would get hit really bad, flutter down and then I would regain control as it got closer to me.

I wonder if the different service providers are on substantially different frequencies?

Any thoughts would be appreciated.

Mark
04-11-2003 Over year old.
 
 
Jagboy69
Key Veteran
Location: Lake Mary, Florida (20 mins East of Orlando)

I think the water presents a bigger hazard than the cell phone tower.. I flew recently SERIOUSLY close to very high power overhead power lines.. the heli had no problems.. but now I have developed a strange twitch in my left eye... hehhe././ Jason

Jason /// Sceadu50/9chp WWW.Jagboy69.com
04-12-2003 Over year old.
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HeliDude24
Senior Heliman
Location: USA

Mark,

From a technical perspective these towers can transmit up to 700Watts on a range of frequencies in the 800Mhz/1200Mhz band.

I've read online somewhere where a fella was using a scanner to check for interference on his channel. He also mentioned a technique one of his instructors uses. When one RC flyer lost control of his heli he informed everyone on the field that he was going on the field. He then ran towards the heli and got as close as possible to get a better signal.
He then regained control over the heli. The interference was off field interference.
04-13-2003 Over year old.
 
 
MCSalot
Heliman
Location: Murrieta, CA

For What It Is Worth…..

If you are using a load base antenna system on your receiver or transmitter you are asking for problems regarding lost of control. They might look cool and save time on your installation but electronically it changes the angle of radiation pattern and is not as efficient as the factory supplied antenna. The best set up would be to use the factory supplied receiver antenna and Ni-Rod, plastic tubing, and space the antenna wire away from the helicopter metal or carbon fiber frame about ¼ to ½ inch away. The full length of the receiver antenna wire should be run horizontally and do not coil up any part of the antenna wire. Were the wire antenna comes out of the receiver be sure to also space it away from the frame. The transmitter antenna should also be the factory supplied antenna and pulled out completely, if it is damaged in any way you should stop flying and replace it with a factory supplied antenna for your model. It is also a great idea to invest in a small frequency analyzer and check the location before you fly. Over the years I have heard many stories about close calls were there were spikes on the helicopter receiver frequency. Checking the frequency should be as common practices as fueling and battery voltage checking before each flight.

One last note, if you are what I call a “Golfer RC Flyer“, one who holds the transmitter downwards so the antenna is pointed towards the ground…STOP IT! The antenna is designed to be held upwards for maximum RF performance.

Monte C Salot
04-13-2003 Over year old.
 
 
Twobeers
Key Veteran
Location: Toronto, Canada

Cellular repeater antenna's can be a real hazard to any type of R/C craft if you run into it. So keep far away from them.

I lost my infamous tag line.
04-13-2003 Over year old.
 
 
Jetter
Heliman
Location: Cincinnati, Ohio

Cell Tower

There is a cell tower on my companies property. It is less than 40 yards from where we fly all sorts of rc aircraft from park flyers to helis. We have never had an interference problem, or even a glitch. I always use my frequency scanner to check for potential problems before flying...so far, so good.
04-13-2003 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

Assuming you're in the US the cell frequencies are around 865 MHz for CELLULAR band and 1930-1960MHz for the PCS band. Your transmitter/receiver work at 72 MHz.

Receivers have built-in filters that attenuate the signal coming into your receiver by about 60 dB. The only time you would have a problem is if you came so close to the cellular trasmitt antenna (about a few feet away) that even with the 60dB attenuation the total power into your receiver's input low noise amplifier would be more than it could take so it would go first stage saturation. Once into saturation the response across the RC band gets wiped out as a consequence.

If you're flying about 100 fet away or so you shouldn't have any problems.

Augusto.

Avant Aurora Ultimate
04-14-2003 Over year old.
 
 
cyhyamSenior Heliman - Location: So. California -
They have never given me a problem.




Walt
04-17-2003 Over year old.
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flyboy
Elite Veteran
Location: California

Nice shot. Picture is worth a thousand words.
04-17-2003 Over year old.
 
 
Smithprod
Veteran
Location: Oklahoma

I've never had any problems, but I recently purchased a Icom IC-R2 scanner for peace of mind. The thing is tiny and was only a hundred bucks. Well worth it in my opinion.

Brad
04-17-2003 Over year old.
HOMEPAGE  
 
 
Flyingeye
Senior Heliman
Location: San Diego, CA, USA

Hi Everyone,

Thanks for your input. I did find a cell tower near my home so I flew my Zagi style flying wing around it to within about 50' and had no symptoms of interference.

Thanks again for your responses.

Mark
04-20-2003 Over year old.
 
 
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Aerial Photography and Video > Cell Site Transmitters - Hazard?
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