Was at the field yesterday and when I powered up my Tiger 2, got servos glitching. Not real bad but noticeable. Started engine anyways and gave it full throttle. Backed down throttle on the tx but, the engine was stuck on full throttle. Luckily, we use those plane stands at the field. Didn't have any servo control either as the FMA rx wouldn't accept any input. Shut engine down by pulling fuel tube out from needle valve. Took the wing off and moved the rx away from the servos. I also noticed that I had my cell phone on in its holder which clips to your pocket or belt. I shut it off and put it in the truck. After putting the wing back on I turned on planes system and didn't notice any glitching. Flew the plane for 5 flights without nary a problem. So, would having a cell phone on within a few feet of your tx and rx cause radio problems? I use a Futaba 9C transmitter and hitec/futaba/fma rx's. When I was getting no input from the rx the first time, it was like someone else on your channel. But it couldn't have been that because I was the only one at the field.

Dave...

I've been flying for 9 years and I always have me cell phone on my belt, never had a problem yet.

I had a cell phone for the last year and it hasn't seemed to bother the airplane that I can tell?

Enjoy,

Jim

I don't think it does. Because today while trying to get my engine tuned correctly i was on the phone and no problems arised.

I know it has been said that cell phones don't make a difference but......its the only explainable thing that I can come up with.
For the better sake of safety, I'm shutting mine off when I'm at the field. I don't need a 6 pound airplane doing 60 mph to fly into
the pit or parking lot area with no control. My luck, it would hit a cadillac escalade and go right thru the windshield.

Dave...

lucky,

i to have used my cell phone at the field and never had any problems.

in your first post you said you MOVED the RX away from the servos, did you move it back after shutting down the cell phone ? if not that could have been the problem. also was there anyone else there on the same channel that accidently turned on there radio then shut it off right away at the time you were running up the engine ?


bassman

Cell phones emit quite a bit of RF energy right before they ring. They go through a step down handshake with the tower to see the lowest power that they can negotiate a reliable connection with. During this handshake they can and will interfere with nearby rf signals but in RC it seems to only affect synthesized transmitters.

There have been some tests done in a controlled environment and crystal based transmitters dont seem effected while synthesized ones seem susceptable.

Cell phone do not operate in the same frequency ranges that our radios do. I know that it may seem like your cell phone is the cause of your interference, but it's more than likely something else.

[link]http://www.spectrum.ieee.org/publicfeature/aug00/prad.html[/link]
Over the years there have been a lot of things that have been tagged to cause interference with our radios, that never actually did. People get it set in their mind that these things are interfering and refuse to think otherwise even in the face of hard evidence to the contrary. Go figure.

Hope this helps.

My club is looking into this problem, Futaba told out club that cell phones can effect the transmition, the AMA didn't have a comment about it. The man who i fly with was flying with another man. The mans cell Phone started ringing all of a sudden both planes go to the ground and are totalled. Now we shut out cell phones off. It doesn't seem to efect if when it is not ringing. that's just our expereince.

Bass, I did have the rx right beside the servo tray. No one else was at the field. The phone wasn't ringing when the glitches etc. happened. I moved the rx away from the servo tray and then shut off the phone and put it in the truck. So, coulda been that glitching occurred because I was stupid and put the rx beside the servos. After being moved, I had no problems. My TX is a Futaba 9C that has the module in the back.
I'm going to the field today to maiden my Space Walker using the same RX. Servos glitching and buzzing don't really concern me that much when I got my smaller electrics out and I fly them on my farm. Glow planes are a different story. You just hate to see
a pile of sticks if you have system problems or, an errant aircraft on its way towards the pits.

Dave...

hey lucky armpit, why dident you do a test? I dont understand. If you notice the glitching with your cell phone next to you and when you put away your cell phone and moved the rx you dident notice a glitch. So, Why dident you bring back the cell phone turn it on and see if it happens again? There's ur answer. Assuming that your doing this while the plane is on the ground hehe.

I was going to break in a newbies engine for him. I had just started the engine and got the needle valve adjusted. The engine was running at a nice idle. Suddenly the throttle was jumping up and down. I looked at the transmitter in my hand and was wonndering if my fingers had gone crazy without me noticing. No problems there but the throttle was still revving the engine up and down. I started to look around and there was another guy I had never seen before standing beside us. I noticed he had a cell phone and I asked him if it was on. He said yes. I asked him to turn it off. As soon as he did the throttle settled down and there were no more problems. Obviously the cell phone was wrecking havic with the new guys plane. Good thing it was tied down. Now there is a policy at our field, no active cell phone within 5 meters of our planes. [8D]

this looks like a case for mythbusters

Here's an instance where testing was done under controlled conditions.

Depending on the power output and proximity to the transmitter or reciever, the cell phone doesn't have to be on or even near our freqencies.

http://www.runryder.com/helicopter/t171865p1

Lucky, you better figure out where your radio problem is and don't just write it off to the cell phone caused it our you will crash your plane. The cell phone is not your problem. I am guessing it is your RX placement. You moved it and the problem went away.

Look for the real cause and save yourself a crash. Don't just blame something that has no affect to have an easy out or you will crash. I have been flying with the cell on my belt, and have even answered the thing (someone standing next to me answered it guys) while flying and never saw a glitch. They don't opperate on the same freq and are not even that close. Anyone that tells you that the cell was your problem is not doing you any favors. If you had glitching, you have another problem. Find it before you crash.

the new GSM phones seem to interfere with everything. radio speakers is where i am getting this. i would agree with an ealier post get a GSM standard phone have you radio on and dial the phone out and recieve phone calls and text messages. try it at different distances. it maybe that you have to be real close.

In the case I mentioned the cell phone was just on standby and the radio was a new Airtronics 4 channel radio. Before I asked the guy with the cell phone to switch it off I did have him back up a few feet first and the servos stopped twitching. The problem was when the cellphone was within about 3-5 feet. If the power goes up when the phone is about to ring, this will probably compound the problem. The phone obviously doesn't have to be on the same frequency to cause interference. It may a 4th or 5th harmonic causing the problem or the phone may just be putting out more power than the recevier can filter out but from my personal experience its something to be concerned with.[8D]

I think your problem was more that it was an airtronics. I have used many, and every single one had intermittent glitches that the facotry couldn't figure out, and that was before cell phones were thought about.

Might have been anything. Who knows. Could have been the cell, could have been the guys keys in his pocket, could have been the plate in his head.

Tough call on that one. Wasn't there, would sure do more tesing before I flew it if it were my plane though.

Flyboy,
Thank you for stepping up here. As I have said earlier, some things get wrongly blamed for causing interference and then everybody runs around blaming crashes on it. Cell phones aren't even close to our frequency. If you want some really mind numbing research check out the FCC frequency distribution;

[link]http://www.ntia.doc.gov/osmhome/allochrt.pdf[/link]

Now with that being said, I just hung up the phone with Steve Kaluf who is the technical director at the AMA. The conversation boiled down to him saying that the AMA did do research on this when cell phones first came out and they found that cell phones don't cause interference for our planes while they are on. He did mention that there is a slight chance of a cell phone close to a micro-processor controlled transmitter that is TURNED OFF and the cell phone rings there is a small chance it could damage your chip in your transmitter, but today's transmitters have shielding for the chip to help prevent this and he also said that this WON'T happen if the radio is on. Steve was very helpful in his conversation and I don't want to misquote him. He said he would be more than happy to talk to anybody out there that still thinks cell phones can cause interference. His email address is [email protected] or you can call him at (765)287-1256.

My conversation with Steve was to back up what I already know, cell phone WILL NOT cause interference in our radios. Our radios work in the 72 MHz frequency ranges. Some older cell phones work in the 900 MHz & 1400 MHz range, but most modern phones are actually pushing the 2.4 Ghz range (that is 2400 MHZ to keep units the same). No matter what others say the have "found" or "seen" it's just not possible to for them to interfere. I for one have no fear of hanging my phone on my belt while I fly. My phone rings all the time while I fly (no, I don't answer it until I land) and it has NEVER caused any problems.

Thanks Ken, I fully expected to get slammed for the key and metal plate comment.

Flyboy,
Yeah, I know what you mean. I've already got my asbestos suit on getting ready for the answers to come in!!

flyboy

hehe i know the titanium plate in my neck doesnt cause any problems been flying with it for awhile now and no crashes LOL


bassman

Dont get me wrong guys. Im not saying that a cell phone can or will cause a crash. The testing I linked was done using synthesized transmitters but it was done under controlled conditions.

Cell phones do emit quite a bit of RF engery before they ring. Need proof? Mine will drown out the radio in my car with buzzing before it rings. The new one isn't as bad, my old Nextel I thought was going to blow a speaker.

But what I am saying is don't dismiss it out of hand. Like Fastsky says, it could be a harmonic. TV stations aren't on or near our freqencies either but harmonics from them have made certain channels in certain area's useless.

All that being said, most radio problems that get blamed on "getting hit" are usually caused by poor installation or older equipment or mixing and matching crystals trying to save 3 bucks. Nearly all of which could be prevented by proper installation and proper maintence.

It's not your radio picking up the interference, it's the speakers buzzing when your phone rings. Same thing will happen with any speaker you are near when the phone rings

Look at the chart posted earlier. Actually TV frequencies are very very close to our radio's frequencys. In fact, broadcast channels 2-4 broadcast on 53 MHz to 72 MHz and our radios are just above the 72 MHz line. Broadcast TV channel 4 does cause some interference with our lower channels in some areas. Here's the link to the spectrun chart again.

[link]http://www.ntia.doc.gov/osmhome/allochrt.pdf[/link]


I couldn't agree more on this one. It seems some people will blame everything else for a crash instead of poor installation or "dumb thumbs".

I'd tend to agree that most TX/RX communication issues are probably due to malfunctioning equipment, improper setup, etc. In general, I'd agree that cell phones should not interfere with our communications. But this does not mean they will not interfere.

RCKen, you cannot rule out any electrical device in close proximity just because it's useful or intended frequency is not close to our RC bands. Pretty much all electrical devices splatter out RF all over the spectrum, which is unintentional. This varies by device, maker and even model. Both of my parents worked for FCC field offices and did enforcement work. You'd be surprised at the wide range of seeming opposite devices that can interfere with each other, regardless of their intended operating bands.

I once produced a repeatable glitch by simply holding my TX near the RX. It only happened with one make/model of RX, but was interesting none the less. As soon as I backed off to about 5 feet, the Tx/RX worked perfectly. Both the TX and RX were operating properly otherwise as per the service center. I pushed the service center for an answer, and I got it. Long winded and technical, but in short, while everything was still within operating "specs", it was possible under the right conditions for my specific TX to interfere with my specifc RX at very close range.

Cheers!