RE: Cellular phone and glitching
 

Yes, exactly what I was saying.

As for noise, I know my microwave makes my home cordless phone sound scratchy too. Not going to take it to the field to see if it screws up the planes though. :)

At any rate, I just wanted to make sure he plays with it some more to figure out the real reason it was glitching, instead of blaming the cell phone and then wondering later why the plane crashed.

RE: Cellular phone and glitching
 

Myself and 3 of my closest flying buddys all have cellphones on us at all times and we have never had a single problem. Phones ring on the flightline all the time with planes in the air and in the pits, turned on and running, no problems. I have always felt some of the clubs around that have rules against cell phones on the flightline were to keep people from being distracted, not interferred with, but who knows. By the way, we have JR, Futaba and Hi-tec systems with and without synthesized modules.

RE: Cellular phone and glitching
 

Did anyone else but me catch this dangerous statement [X(] Or am I reading it wrong and hopefully someone else had control of the plane and radio

RE: Cellular phone and glitching
 

Man, sure would be hard to hear anything on a cell with an engine running right there.

RE: Cellular phone and glitching
 

Flyboy,

I thought of that too...:D Just wondering

RE: Cellular phone and glitching
 

This is likely to be due to the TX overloading the front end of the RX, I am guessing that the TX aerial was fully extended? although it would probably also happen with the antenna collapsed as well.

RE: Cellular phone and glitching
 

We used to refer to it as swamping and thats exactly what it is.

RE: Cellular phone and glitching
 

Greetings, all.
Another 2 cents, maybe 4..... I am the Freq. coordinator and membership sec. for one of the clubs I belong to.
Due to unverified rumors, "No Cell" signs were posted at our field as well..
I and some other members questioned the rule, and My investigation has thus far come up with NO hard evidence that the issues exist.
I have a quote from Steve Kaluf at AMA, as mentioned above, they were never able to duplicate the Programmable Tx Issue.

Now, as for interference, being an RF technician, I want everyone to be aware that it's more than the specific frequencies that can cause issues.
Yes, cell phones, CB's ham radios etc and etc are on totally different bands. However it is possible, even commonplace, for multiple RF signals to mix. Your receivers also use an Intermediate frequency, usually 10.7 MHz, in the process of extracting the servo commands from the RF signal.

I don't want this to be too long and drawn out, but if there is a pager tx nearby, that happens to transmit on 167.38 MHz, take the first sub harmonic, 83.69MHz, subtract the 10.7 MHz IF, and voila, I have interferance on 72.99 MHz which is channel 60.
Now, for every RC freq. there is a 1st harmonic (twice the freq) a 1st plus IF, and a 1st minus IF where it is EASY to create interferance!!!! If there happen to be a few transmitters in the area, they can mix signals that would otherwise not be an issue and cause interferance.

For the record, I am building a directional antenna for the 72 MHz band, because a fellow member and I were both shot down on 60 the same day. On BOTH occasions, we turned off our Tx's and turned on a scanner and found a STRONG signal, definately RC, on channel 60!! This is Seconds after the crash!!!!!!
This is an AMA club site, with a few farm houses in the area. My suspicion is that someone was testing a radio system in the area without either knowledge or regard that there is a field nearby.

Lastly, another club I belong to has a cell tower ON THE FIELD!!!!!!!!!!
Thus far, (Several years) there have been no apparent issues with the tower or cell phones on the field.
Again, to err on the side of safety is my preference, but I think INFORMED fliers can have MORE fun!!!!!!

RE: Cellular phone and glitching
 

Does a cell phone interfer with flying MOST DEFFINATLY also with eating out at dinner, fishing and many other times. My cell phone spends alot of time in the truck by itself.

RE: Cellular phone and glitching
 

I got my new RC Report yesterday, and read the Tony Stillman "Radio Ramblings" article.

He has 2 reports of repeatable, testable reaction of Futaba 14Z and 9Z systems (with the synthesized RF module) to nearby cellphone operation, acting as barracudahockey described. Incoming calls cause the phone to issue a lot of signal, just before ringing, which produces a response from the synthesized system.

They tried to reproduce with Polk and HiTec synthesized systems, and could not get a reaction.

Interesting article, before I read it I was just dismissing the cell phone interference thing. Maybe I'll pay more attention now.

Good luck,
Dave Olson

RE: Cellular phone and glitching
 

Well, then I better not get that new [link=http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=SPM2030]2.4 gHz DSM Spectrum System[/link] for my RC truck. :eek:[&:]

RE: Cellular phone and glitching
 

We have a no-cell phone on the flight line rule at our club but I occasionally forget it's there. It has not caused a problem.

RE: Cellular phone and glitching
 

Hate to bring up old news, but at the field today, one of our new pilots was doing a great job flying a 4-star 60 around, and his cellphone rang. he dutifully handed the Tx to his instructor and answered his phone, then took the radio back and finished his flight. Us 'hangar flyers' who were watching got to talking about what we'd heard, read, etc about cellphone interference, and I brought up this article I read in R/C REPORT magazine, the July 2005 issue. There is an article by Tony Stillman (Radio Ramblings) that is a 'should read' regarding rf interference between cellphones and out Tx's.

Experiments done by the School of Mechanical and Aerospace Engineering at Oklahoma State University showed a definite interference problem with synthesized frequency transmitters, specifically the Futaba 9Z Tx using synthesized frequency modules. Interesting reading.

RE: Cellular phone and glitching
 

Isnt it possible for the Rx filter at times to just have too much RF to filter out and in turn cause jittering or other output problems ? such as the Rx too close to the servos and maybe the Rx antena too close to the servo leads . and maybe its not acting up till someone comes too close to it with a Say ringing cell phone ! And then the blane gets thrown to the cell phone when the real blame should be at the builder of the aircraft . In my shop I can set a Rx and servos all on my bench conect them up to see if all is working. And if I have the Rx ant laying with the servos they will jitter. And yet if the Tx is too close with its ant colapsed they jitter. Also if I have the Rx ant laying off the end of my bench. This happens to be in parallel to the florecent lights in my shop they seem to again jitter. But move the Rx ant just a little bit then it all works fine . I know it must be Rf thats causing this in my shop because if i just shut off my lights all is well again ! just my 2 cents worth .

RE: Cellular phone and glitching
 

Well I can tell you for a fact it has happened to me twice now.

Flying my helicopter in a remote farm field. Flew straight down the runway and the bird glitched. Nothing big just a jump up and down. Landed and checked everything over on the ground and everything seemed fine. Heard a beep and noticed that my cell phone, which was on my belt at the time had recieved a text message. I didn't think too much of it but 2 days later it happened again, after I landed I noticed I had recieved a call while I was flying. In both cases I was the only one at the field with a transmitter. It wasn't enough to cause a crash but it was definately due to rf interference from the cell phone being in close proximity to the transmitter.

This was with 2 different heli's, 2 different recievers but both use the same 9C transmitter with a crystal module.

Before anyone says I have no idea what I'm talking about, I was a radio communications operator on a P-3 as well as an avionics and radio technician in the Navy working on everything from HF to microwave and satilite communicatons systems, radio teletype, encrypted com's etc for 12 years.

RE: Cellular phone and glitching
 

Phew!!! I thought this thread died! In any event, the only problem I have is with Hitec Electron 6 channel rx's. I use a Futaba 9C radio on channel 36. If I have my Verizon cell phone clipped to my belt, the rx glitches. If I leave cell phone in truck, I get no glitches.
My other rx's (Berg, FMA M5, Hitec 555 and Futaba 7 channel rx's) also have no problems with cell phone. Only the Electron rx. So,
it must be on the rx's circuit board or something.
My opinion, cell phones shouldn't be on or worn on the flight line anyways. Too much distraction if your setting needle valves etc.

Dave...

RE: Cellular phone and glitching
 

Dude, this has been hacked on and off for at least ten years. To date there has been NO evedence that suggests that cell phones do anything to interfere with models. I'm flying electric now and you would think that the possibilities would be greater however I have never suffered a glitch due to a cell phone.

RE: Cellular phone and glitching
 

There is a logical explanation for this and after thinking about it I have a theory. Cell phones work on different bands, but you gotta remember that a cell phone will produce a lot of noise that is not on it's band. It's the same with a tv or a blender. It's going to make noise, even though it wasn't designed to transmit, how much noise depends on the device and how much shielding was put into it.

I would say that past a couple of feet a cell phone isn't going to make enough noise to matter, but when the phone is close to the rx or tx, then you could have interference. How much interference completely depends on the shielding in the phone or rx/tx. If you have a well engineered phone and tx there shouldn't be a problem, but if you have a poorly engineered phone and tx then interference is certainly possible.

My current phone doesn't interfere with the radio in my truck, but my old phone broadcasted so much noise that you could hear the toaster buzz when it was about to ring.

So I think it all depends on the phone and radio.

RE: Cellular phone and glitching
 

OK,my 2 cents-All radio transmitters emit a signal on their assigned frequency,ie 72 mhz-but they also emit harmonics which are usually in relation to their assigned freq.
In other words,a transmitter on 72 mhz will emit a harmonic signal at double that,triple,half ect.If the cell phone signal is at or close to a multiplier of 72mhz then interference is POSSIBLE.
Just my opinion as a former cb radio enthusiast

RE: Cellular phone and glitching
 

What Akschu said is completely correct. It depends on the phone, transmitter and reciever. Same phone, same transmitter, but a different heli on a pcm reciever I haven't seen a problem. But I know for certain, that with my particular setup, on those 2 particular days I got hit because of the phone recieving a text message once and a call once. I haven't tried to duplicate it, but I may do so one night this week after work, set everything up in the driveway with the motor off and give it a shot.

If I still had access to all the cool toys I got to play with in the Navy I could conduct some serious testing on the issue.

But the point I am trying to make, is while it may not bother most of the people most of the time, you cannot dismiss it out of hand as impossible.