Mobile phones & computer Tx?

Just to clear the air a bit, in the cases I have heard about the R/C TX was turned off when in close proximity to the cell phone. Assuming for a moment that the phone did cause the problem, one would then have to surmise that the means of the problem was the RF energy off the phone doing something at the chip level of the TX programming. Like zeroing out memory that isn't being sustained by a signal or something like that. I am told such things can and do happen in other devices. And one example can be simulated by simply driving under power lines with the car radio on an AM station. Granted, it doesn't change settings but, it does demonstrate what interference can do. As for RF, check out how a microwave oven cooks! IMO it's impossible for anyone to even suggest it can't possibly happen!

Chuck

Reply to
C.O.Jones
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I have already thrown down the gauntlet as regards to this particular nonsense. Feel free to pick it up.

assignation,

Reply to
w4jle

It may be nonsense to you but it did happen to me. I had a std cellphone by Cingular and a 8UHP futaba Tx. On two occasions the Tx reversed the settings on a servo channel and once disabled a P-Mix. This occurred after I set my cellphone next to / on top of the Tx on the way to the flying field. After I separated the phone from the tx by a foot it never happened again. No, I did not mess with the Tx settings. I flew my glider, shut it off, shut the Tx off and packed up. Next day the V-Tail did not work and both aileron servos moved in the same direction. On my heli the P-Mix controlling the Governor turned itself off. The menus are several layers deep so an accidental button push is very unlikely. Somehow the cellular RF changes the EEPROM settings in the futaba Tx. I never heard of a JR tx being affected but they use a different EEPROM whose memory is kept alive by a lithium battery. The same is in the futaba 9Z which has no trouble reports either.

'Fritz the Cat' Blackburn VP-94 Techrep NAS New Orleans

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I have already thrown down the gauntlet as regards to this particular

Reply to
Fritz Blackburn

No one can prove it. No one can prove anything.

At best one might say that is was a coincidnce with a very very low chance of happening. But it might stiill be a coincidence.

You can't prove smoking gives you cancer either. In fact it doesn't. However the staitsical evidence that smokes die younger and more often from cabncer is sufficiently strong to deduce some kind of link.

Reply to
The Natural Philosopher

Exactly. However txes that have been on have also been affected.

Just bring a cellphone near to ANY electronic device and you can hear it/see it cause interference. The questin is not whether it does, but whether it does enough to cause danger.

The BMFA decision was, I am sure, as much about being seen to not be in vilation of insurance policy, as having any real effect.

How manty things are done today so that some smarty lawyer cannot stand up in court and say 'but you recognised and were aware of the possibility that...and so no, your are to blame, not my client'

Reply to
The Natural Philosopher

I think the original post had to do with transmitter memory issues, not crashes. Be that as it may, if I can demonstrate an interaction between an external electro-magnetic field and an R/C transmitter's operation, you'll give me, or anyone else for that matter, $1,000? Keep an eye on that gauntlet.

Reply to
TexMex

Go back and re-read the challange, I was very specific.

I anticipated the "as my plane flew by slowly I threw my cell phone at it. It hit the prop causing the plane to crash, send my money" nonsense.

Reply to
w4jle

I lack the technical experience and knowledge for such a challenge. And I freely admit it! I suspect however that you also lack the expertise but unlike me, are unwilling to admit it! There in lies the difference. I have an open mind to any number of possibilities. Doesn't mean I'll believe or accept them but I will entertain the ideas. But I suspect you have less of a clue on the matter than I do!

Fact is, enough RF energy will mess with any number of things. The AM car radio is one example. Exactly what and how depends on a number of variables. Ever heard of the navigation system called LORAN? The Transmitters have antennas ranging from 400 to 625 feet tall. When on you can take a florescent bulb/tube and approach the antenna. The bulb will light up, in your hand, without being plugged in to anything. In the demo I saw the bulb was some fifty yards or so from the antenna. And BTW, LORAN transmits at 100 KHz.

Fact is your microwave oven uses RF energy to do the cooking.

Fact is, power lines with bad insulators have been identified as causing interference with R/C Models to include crashing planes.

Fact is, flying an R/C plane through the beam of a microwave communications shot can indeed cause a hit on the plane.

Fact is, there are too many variables for any one individual to check and confirm without the help of a good test lab. So your challenge is nothing more than your own way of blowing smoke at everyone else. Screw caution and screw being safe. Just stay away from my flying field!

Reply to
C.O.Jones

With all due respect, your facts don't link together to prove anything about the problem at hand.

Let me give you a few facts that do:

  1. Our Receivers are FM, the information is varied by phase or pulse width rather than amplitude.

  1. FM receivers lock on to the strongest signal (called capture effect) The output of the normal handheld cell phone is in the order of 300 milliwatts. The harmonics of any radiated signal would be considerable less. Your transmitter exceeds the 300 milliwatt level.

As far as your other comments questioning my expertise, let me reply using your own example. I was involved in the design and installation of the Loran "C" system .

. That has little to do with the problem. I have been a ham for almost 50 years (extra class), the knowledge gained there gives me a leg up on interference problems.

I have also conducted a number of tests using various cell phones laying next to a receiver prior to flinging the gauntlet.

Simply because you lack the specific knowledge, in no way means that others do not. To further postulate that it makes me dangerous, and unsafe, and unwelcome at your flying field is ludicrous.

communications

Reply to
w4jle

I am curious, have you tried the same experiment with the cell phone next to a typical R/C transmitter?? That's the experiment I would like to see done (but not next to my Tx)

73.....

milliwatts.

Reply to
Jim P.

I have not tried that yet. I will try the futaba stuff that I have and see if I can see anything.

Reply to
w4jle

Perhaps you missed my post several days ago 8 Jan. = "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

Reply to
A.T.

Let e suggest that you try it with the motor not running (to avoid further arm damage) and simply watch the reaction of the servo. I suspect that as a function of leaning for the phone the throttle lever was moved by contact with some part of his body.

Let me know what you observe under controlled conditions. I have no idea what freqs your on in New Zealand with either your transmitters or cell phones. Sans this information I am reluctant to make any definitive statement.

Reply to
w4jle

I'd say your money is pretty much safe. Nobody's going to *prove*, after the fact, that a crash that happened under non-controlled conditions was caused by direct interference with the transmitter's operation by a cell phone.

The only way to do this is to provoke the crash, under controlled conditions, several times, which isn't going to happen, of course.

Cutting to the chase, though, it's a well-known, non-disputed fact that cell phones can interfere with various electronic equipment, including microprocessors and their surrounding circuitry. This happens when the cell phone transmits at high power, very close to the circuitry in question. (There is, of course, an inverse square relationship, so the phone has to be close.)

Because of this, I will never keep a cell phone in my breast pocket while operating my computer transmitter. I'd feel reasonably safe with the phone in a back pocket -- but why take the chance? I'll leave it back in the pits, safely stashed where it's a few feet from my transmitter and planes while I'm starting them up there.

-tih

Reply to
Tom Ivar Helbekkmo

The issue is not radio interference at the rx end it's the radiated RF affecting the TX computer before the siganl leaves the aerial

Reply to
gavin

Neither do yours.

So? This is nothing to do with the issue in hand.

Apart from the fact that the second point is not really true in the case of NBFM.

The mechanism that is suggested is not that the cellphone intereferes with the receiver,

but that its exceptionally strong (peaks greater than 5W sometimes) and very high

(typically 1 -2Ghz) frequency are enough to scramble the digital electronics of your TRANSMITTER. ESPECIALLY its memory.

Non digital trannies should be completely immune.

Reply to
The Natural Philosopher

Wasn't trying to link anything, just provide some examples to demonstrate that the possibility is there.

I see! So FM makes them JAM proof? Funny! I'm sure the military would like to know that.

milliwatts.

This locking has to happen while the TX is turned ON. If you read my posts, you'll see where I said the reports I heard about were ALL while the TX was turned OFF. Besides, what's a TX doing locking on a signal? That is after all, where the problem lies!

So? That makes you an expert who can do or say no wrong?

Then you should know that enough energy under the right condition can mess with various chips even when there is no power to them. If not, you haven't learned much. And that I got from a good friend in the upper echelons of Motorola.

Were any of them of the GSM variety? As I said before, the reports I'vew heard about involved the GSM variety. And that was a couple of years ago so you may want to scrounge up some of the older GSM style phones. The new ones may have cleared the problem be it intentional or not.

Not your knowledge makes you unwelcome. It's your know it all, pompous ass, do no wrong attitude that did it. You'r not even reading the posts on this matter because you ignore key facts in order to spout your crap.

Now you prove to me that RF energy will not change the programming of the programable chips in the computer radios that are turned off and I'll pay you $10,000.00 I know you can't as well as you do!

Chuck

Reply to
C.O.Jones

Here's an interesting site I found. Not conclusive to this particular subject but, it does raise the possibility!

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Chuck

Reply to
C.O.Jones

I've had Motorola V-60t (personal) and a Nextel i30sx (company) cell phones for several years.

That Nextel is well and truly nasty . . . puts a herringbone pattern on the flat panel computer monitor and on both TVs when keyed; nothing when idle.

Zilch from the Motorola.

Neither has had any effect whatsoever on my Futaba 9ZAS WC II, and I've done everything except actually lay the phones on the Tx - _way_ too many switches sticking outta that Tx to lay something on it.

FWIW. Cheers, Fred McClellan The House Of Balsa Dust

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Reply to
Fred McClellan

Is that a GSM phone, perchance ? Cheers, Fred McClellan The House Of Balsa Dust

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Reply to
Fred McClellan

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