Mobile phones & computer Tx?

Yes. There was some discussion on ezone

a while ago. Try searching on 'phone'.

IIRC thgere have been at least two, possibly three instances of

programming going wild, one just before the phone started to ring,

another when the phone was tossed with the transmitter, in the flight

box, in the car, on the way to the field.

Those are the only two that seemed to be genuine 'it happened to me' but of course everybody had *heard* of someone who knew someone...

And zillions of people, myself inclded, who had kept a phone in their breast pocket whle flying, and taken a call, although I have to admit that was NOT a computerised transmitter....

A couople of points emerged from teh discussions - again this is memoy, so check out yourself waht was said. The first is that the signal strength of a mobile is increased if it is far away from a base station. The second is that the transmitter is LARGELY inactive apart from the 'I am here base station, if anyone wants me' periodic registrtion call, unless the phone is actually in use for a call, the thiird is that the frequency of a mobile is up ariund a Ghz, way different from teh 30-80 Mhz region used by the model avionics, and teh fourth was that I *think* no one had a tx go wild except in teh sense of broken programming, but my memory is hazy here, and teh fifth was that teh tx wasn;t switched ON in teh case where it was in teh back of teh car, but it screwed the NVRAM/EEPROM whatever anyway. Allegedly.

I think the consesnus was that the BMFA rules are way over cautious, and beyind a few inches it wouldn't be an issue. Its very very rare, but has happened at least twice, and no one is really sure of the mechanism.

See the Futaba FAQ at

Also search Google for "cell phone". Tons of opinions there, scant proof. Cheers, Fred McClellan The House Of Balsa Dust

Personally, I consider this another one of those 'urban legends'. I use a JR 8103 radio and have never had a problem even though people have taken cell phone calls while I was flying.

And that is the problem. It really does seem to have happened once or twice, but by and large people take calls while flying with absolutely no effect.

I think there is just enough evidence to suggest it CAN happen.

The REAL urban legend IMHO is cellphones and exploding gas stations.

But cellphones are still banned from use in all UK gas filling stations.

I looked into this with a friend of mine experienced in both telephone and R/C. He said he'd heard the stories too but could not nail anything definitive down. However, one thing he did glean from his research was that the phones in question were of the GSM type.

Of note are the facts that the GSM phone does change it's TX power dependant on range to the nearest cell. Up to 20 watts has been mentioned but I don't know how true this is. And the phone does periodically send out short bursts to maintain it's "knowledge" of the local cells.

At the time of the reported problems they were quite popular in Europe and almost non-existent in the US. However, they have become more prevalent in the US. But like with everything else, technology has improved considerably since then and it is possible the reported problems have been engineered out. Intentionally or not!

Chuck

I'll differ with that opinion. To say that it "seems" to have happened once or twice leads to suggest that it CAN happen is how misinformation and then Urban Legends get started and take on a life of their own. What is the statistical ratio for "once or twice" in how many flights and cell phone uses over a give period of time? Infinitesable (sp?) at best. I'll bet that more people crash from accidentally dropping their transmitters while flying that do those who "think" a problem occured due to cell phone use. What is being reported is technically "anecdotal" evidence which carries no weight at all for proving, or even suggesting, the link between cell phones and TX's. MY anecdotal evidence is that I have used my cell phone WHILE FLYING (hands free ear bud) as well as to use it while others have been flying and have NEVER seen a glitch of any sort. Since you won't accept that as proof that cell phones don't affect TX operation, why then would I accept YOUR anecdotal "evidence" as being proof that cell phones DO affect TX operations? Personally, I'm waiting for some Expert class Ham type guy who knows what he's talking about to do some actual tests with his high-dollar Ham radio equipment and publish a report complete with notated test results and at various frequencies. I would MOST like to see the AMA do this kind of comprehensive testing because it would be to their benefit to find out if a problem "may" exist that could affect a future personal injury pay-out. Until then, all we have is a bunch of old ladies making things up as they go along.

MJC

"The Natural Philosopher" wrote in message news: snipped-for-privacy@b.c...

First of all, it is certainly possible to affect computer circuits and RAM with high signal strength radio fields.

So it is not that this is impossible according to the laws of physics as we know them.

The fact that it is so rare implies either

(i) that its total bollocks as you suggest (ii) that the conditions for it to occur require two or three unlikely things to happen all at once.

Now I am a fully qualified electronic engineer, and believe me, the latter is in my opinion the most likley.

It probably needs a combination of a particular frequency, very close proximity, a particular orientation of a particular phone to a partiucular transmitter and an incoming phone call from a distant base station to do it.

However the conicindence of someone receiving a call while flying and exactly the half second before it rang (consistent with strong exchange between phone and station) and subsequent discovery post werck, of scrambled model memories, seems a little too precise to be discounted out of hand.

Its rare, its very unlikley, but I believe it has happened as many as two or three times.

You may think its so rare as to be completely not worth bothering with. Frankly I would not disagree. However the BMFA at least have felt tht it is sufficiently strong a possibility to recommend a ban on carrying transmitters and mobile phones together while flying.

I take no position on this, other than to insist that it is certainly possible. I've seen computers reboot under the impact of a strong police band transmitter. Field strengths from a couple of watts or more of microwave energy at very close wuarters - a few cm or so - are extremely high. Enough to induce a few volts into otherwise robust circuits, and DRAM and NVRAM and EEPROM are not THAT robust.

Thanks for all the input guys. Reason for the ? I had words with committee members at one of the clubs I belong, as they have introduced the rule no mobiles in flight area. I will of course obey but said I don't agree. Another club I am a member of has no such rule and pilots are just careful when using phones near trannys. Fact is many flyers are on call when out and this stops them flying. It seems the jury will be out for a long time over this ? However I do think that many have taken this inc' the UK's BMFA far to far. Regards John

----- Original Message ----- From: "C.O.Jones" Newsgroups: rec.models.rc.air Sent: Wednesday, January 07, 2004 10:56 AM Subject: Re: Mobile phones & computer Tx?

considerably

Well all of my phones were always of the CDMA variety, not GSM. I have since gotten a GSM phone but have not done much flying with it on hand. I'll remember to keep it away from my tranny when flying, just in case.

considerably

We've had two cases where computer tx's have had problem immediatly before a call arrives.

Put your mobile next to a speaker and turn it on or off and you get buzzing interference, thats the problem, not the actual conversation. It des away within 1m, but if you fly with the phone in front pocket it within a few 10's of CM and can be a problem with some TX (ff9 in the two cases, maybe others are better shielded)

Sounds like a good rule to me.

Not because of any mythical interference issues, but because cell phones are a known distraction.

How many times in the average work day do you see some dolt yakking away on the cell phone while screaming down the interstate doing 80 or better ?

How many times have you had to _avoid_ that same dolt because he was paying more attention to his conference call than to traffic around him ?

Many states are busily enacting legislation to prohibit cell phone use when the vehicle is in motion, and for very good reason.

I don't worry about a cell phone changing the programming in my transmitters.

I _do_ worry about the idiot who answers a phone call while flying his DA 150 powered 30-odd percent aerobatic ship.

Flying models isn't the most difficult task in the world, but it is more difficult than driving the family bus down the road.

If talking on a cell phone while driving can be dangerous (and it has been so demonstrated countless times), then certainly yakking on a cell phone in the pits (or worse, when flying) is a really bad idea.

Doesn't matter if you've "got away with it before", it's still a really bad idea.

I think on-call folks ( and I am in that category every third week) need to put the cell phone in the car when they've got a transmitter in their hands, because there is no good reason to put the other folks at the field in jeopardy simply because the cell phone addicts are too busy being busy to pay attention to basic safety : keep your mind on what you're doing. Cheers, Fred McClellan The House Of Balsa Dust

Coincidence? perhaps, but a club member recently had an arm in bandages. His large 30cc motor was idling with TX (40Mhz) and Nokia Cellphone on bench close to model. Friend reached across top of model toward bench, just as cellphone rang, motor went to full throttle and model lurched forward against restraint. Movement against restraint at full throttle was enough to cut several slices into his forearm. He had not touched TX nor moved throttle lever from the idle position. Enough for our large club to continue to ban cellphones from flight line.

regards

Alan T. Alan's Hobby, Model & RC Links

I'll chime in with my own experience with the RINGER on a phone (an old fashoned one with an electromagneticly driven bell). I had a floppy disk lying next to the phone when it rang and it scrambled the data on the disk. Now I know the Eeprom storage mechanism is totaly different from that used on a floppy; nevertheless, I would suspect that the vibrator or similar electrfo-mechanical device on a cell phone would be more likely to create a field that would be strong enough to affect storage media than the RF signals from the cell tower or the phone's transmitter. I don't have the equipment to test the field strength generated by the ringer, but it wouldn't be difficult to meaasure.

The ringer on an old conventional phone has nothing to do with RF. It's the magnetism that zapped your disk; there wasn't a single RF blip in the area. Comparing the two situations is like comparing, well, apples to oranges.

MJC

What I was suggesting was that the electro-magnetic field from a ringer is much stronger than the RF field from a cell. I pointed out that the two media are quite different. Having had some experience in VLF and the difficulty in shielding in that spectra, I think the field from a ringer/vibrator is much more _likely_ to couple to the internal circuitry of a transmitter than a Ghz signal. A relative assignation, easy enough to check: did the event happen before, after or during the ringing?

I wonder what has to happen within the memory circuitry for parameters to be altered- noise on the supply bus, switch interface, strobe lines? Perhaps in combination with marginal battery charge? It ought to be reproducible, and as potentially harmful as the proported incidents are, I would think it should be investigated beyond the modestly informed speculation I'm offering.

Well I for one and I am sure many others would like to see an in depth study done if there is a real problem. We are talking safety here. John

I will give $1000.00 to the first person to prove that a cell phone at the field was responsible for am R/C crash do to electrical interference from said cell phone. (USA only as I am unfamiliar with the world model freqs.)

That being said, don't mistake lawyering up with fact. The Futaba web site is an example of that, gas stations are another.

I suspect the same guy that crashed when the cell phone rang would have crashed do some other imagined "glitch" in the absence of a cell phone.

Right after a crash you more often than not hear those famous words "who turned on their transmitter", to give them an additional excuse is unconscionable.

Is it worth the risk? We had some issues with cellphones at work affecting kit (making a press that could deliver 100psi judder, even when in standby, and would you want to put your fingers near that just in case!!), and the NHS have done a really comprehensive study (but it cost's £125 a copy so I'm quoting from memory as it's not here with me here!)

Cellphone radiation is at it's highes when it's trying to establish contact with a cell mast, be that at the start or end of a call or when it checks in periodically to report it's still in the cell.

At the start of a call the phone is paged and it responds, saying I'm here, this signal is a higher strength than the signal during the conversation as it does not know how far it is from the mast, similarly the checkin call every so often is a stronger pulse as the phone doesn't know what cell it is in.

Getting back to the NHS thing, most equipment is not affected by a phone more than 3m away, (it's an inverse square law rule) but as you don't know where the sensative equipment is they ban them totall, (might be other side of the wall your leaning against).

That signal pulse WILL affect equiment the question is will your equiment accept it (it should) and will it be affected (it should not), but getting back th the point is it worth the risk.

Make a rule no cellphones on the flight line, and be aware that iot may present a problem in the pits maybe even moving out and away from the pits if you get a call. It might be a bit OTT but it's no more than not standing in front of a prop, yes there is a risk, but why tempt fate and follow bad practice.

I liked Futabas opinion on interference. Interference is no problem, the FCC makes sure that the frequencies don't interfere with one onother. But still, keep a mobile phone 1000 ft. away ?! Geez... Its a shame that they can't say what they want without disclaiming for legal reasons. What is this world coming to?

*disclaimer* I accept no responsibility for any eye-damage or mouse-itis you may get from reading/scrolling this. Neither incidental nor consequential. Futaba is a registered trademark of Futaba Inc. FCC had no part in writing this message I love lawyers (sarcasm not intentional)

-- Wood floats... We can make it fly...

Stefan Pettersen

| > > > MJC | > > What I was suggesting was that the electro-magnetic field from a | > > ringer is much stronger than the RF field from a cell. I pointed out | > > that the two media are quite different. Having had some experience in | > > VLF and the difficulty in shielding in that spectra, I think the field | > > from a ringer/vibrator is much more _likely_ to couple to the internal | > > circuitry of a transmitter than a Ghz signal. A relative assignation, | > > easy enough to check: did the event happen before, after or during the | > > ringing? | > >

| > > I wonder what has to happen within the memory circuitry for parameters | > > to be altered- noise on the supply bus, switch interface, strobe | > > lines? Perhaps in combination with marginal battery charge? It ought | > > to be reproducible, and as potentially harmful as the proported | > > incidents are, I would think it should be investigated beyond the | > > modestly informed speculation I'm offering. | >

| > Well I for one and I am sure many others would like to see an in depth | > study done if there is a real problem. We are talking safety here. | > John | >

| >

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