Cellphone interference?

Possible? Definitely. Probable while the plane is at altitude? No.

The frequencies are separated by more than an order of magnitude, and use different modulation methods, but that doesn't prevent poorly designed or poorly shielded electronic gear from picking up cell phone transmissions. I can hear hash from my Nokia GMS phone in computer speakers, and they're not even supposed to be receivers.

Mostly BS. The only way you can get interferance is from IF frequencies and only when the cell phone is very close to the reciever. Both the RC transmitter and the cell phone is about equal in power, but the frequencies are far far apart. The only real issue is a cell phone left on top of a computer transmitter, wiping out its memory.

About the only mechanism I can come up with is if you throw the phone at the plane, it hits the side, and disconnects the power source from the receiver, it may interfere. It's more likley that the signal radiation from the phone caused an ionic disturbance in the pilot's thumbs and induced an involuntary twitch causing the exclamation "I don't have it." And don't EVEN get me started on the woman over at the edge of our field (maybe a half mile away) who used her microwave oven one day and wreaked havoc with a guy flying. It could happen.

Charlie

The power level of the phone is so low he will have more interference from a tower than the phone. Your friend doesn't have a clue what he is talking about.

The cell phone does not interfere with the Rx but can do strange things to computer Tx that are within a 3 feet (1 meter) of the phone. Much depends on the phone system used. There are differences between the euro and US systems and with the two types of system used in the US. Some recent traffic with info:

My 9ZHPS will transmit garbage if my Sprint Samsung phone comes within 6 inches of the RF module.

Fritz

Cellphones are (sporadically) whitnessed to interfere with the

*transmitter* - if it is held *very close*. (cellphone in the pocket, TX held against the pocket).

The mechanism is direct HF - detecting in the -usually cpu driven- electronics. (so freq is somewhat irrelevant)

There were isolated cases of preset programs to be erased. (forgot affected brands at the moment)

The cellphone can (if the dynamic power is set to max due to weak signal from base station) put down a stronger local HF field than the TX itself. Sure the offended sailplane pilot was not carrying a cellphone...?

I've experienced my cell phone intefering with my TX but not my RX. It is easy to duplicate if you want to try it, and I would encourage you to do it to see just how sensitive your TX is (and how strong your phone is).

Turn on your plane and your TX, lay your cell phone down on the table near the TX, and call it from another phone. You will see the control surfaces on the plane twitching and jerking before you even hear the cell phone ring.

Fortunately, when I discovered this, I was sitting down packing my stuff up from the day. I had my cell phone in my pocket and my TX sitting on my lap (and the plane on the ground). Since then I leave my phone in the car when I'm out flying.

Steve

I don't know why this would tell you how strong your phone is. Information on cell phone strength is readily available. The newer digital phones are maxed out at one watt, the older analog phones are stronger. I would think almost any transmitter of any frequency of equal to larger strength would do this when placed right next to the transmitter, as may a large magnet! People need to have some common sense and quit blaming others for their faults.

Listed at

Phone Warnings

British Models Assoc Ban cell Phones =

Canadian & NZ Cellphone warning for R/C phone radiation - headlines Govt. -"Why must I switch off my cellphone in aircraft, hospitals and petrol stations." Groups Discussion - Mobile Phone and Synth TX warning - Mobile Phone - RC Interference... Demand Cell Phone Warnings In past 18 months, our club has experienced 3 odd happenings. One club member has a badly cut arm when a large petrol motor went from idle to full power, stretching the restraining strap, at same time his cell phone rang.

8UAP TX was on bench with Nokia cellphone close by, both well out of reach of anyone and stick could not have been accidentally bumped. Another flyer with 7UAP lost settings when another pilot used a cell phone close by. A 40 MHz synthesised receiver lost settings and had to be reprogrammed to correct TX. This whilst wheeling the model it was in, with .60 engine at idle, past a cell phone which rang and was answered within 2 metres of the model.

I support BFMA SWITCHES, PHONES AND PENNANTS

"Picture the scene - the sun is shining, wind 5 mph, the perfect flying day. Pre-flight checks satisfactory according to BMFA guidance. However, before we rush to be the first into the air some thought is still needed.

You do carry your own peg board don't you? That mobile phone in your top pocket can, according to the evidence that is available, reconfigure the EPROM settings on your PCM set (maybe a problem with PPM as well). Mobile phones should never be operated within 1 metre of any transmitter - turn it off now! You did check the fail-safe settings before take off didn't you? That pennant does display the frequency in use today? (I have been a victim of this one so don't laugh - it happens.) " ===============

OF MOBILE TELEPHONES IN PROXIMITY TO ELECTRONICALLY PROGRAMMED TRANSMITTERS

The JRCUC has reported there may be a problem associated with operating mobile telephones in the close proximity of programmable transmitters causing the memories to be partly or fully erased. This problem has yet to be scientifically substantiated; however, it is generally known that RF radiation can disable or permanently damage some modern electronic devices.

Although the risk may be small, we believe it should be minimised by bringing it to the attention of members and clubs. Pending resolution, we recommend that mobile telephones are not switched on within 10 feet of any programmable transmitter. This may appear to be overkill, but better safe than sorry. Care should be taken during pre-flight checks to ensure that all controls are operating fully and in their correct sense and to ensure that the memory has not been affected by any undetected or unknown transmissions since the last flight.

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

There has not been one single documented case of a cellphone causing a fire at a gas station. What causes the fire is static from the person getting in/out of the car while using a cellphone. Or checkbook. Or drinking a soda. Or whatever. The vast percentage of those fires involved young to middle aged females. They are much more likely to get back into a vehicle which is being fueled up. Least percentage was seniors. They tend to lean on the car at one time or another cancelling the charge differential. Male or female, young or old, those fires also usually happened in cold dry weather.

On Mythbusters they couldnt get a fire started with a cellphone at all till they cheated and made an incindiary device out of the thing.

What is so magically special about EPROMs in computer radios? Do people really think they are completely different from the millions of EPROMs in other devices? Specially manufactured for the huge R/C market with critical requirements, such as vulnerability to cell phones? The computer power in the average computer radio is *nothing* compared to the average laptop, PDA or phone. Yet suprisingly enough, all these vastly more complex computers manage to somehow avoid having their memory corrupted by the huge number of cell phones they are exposed to.

Finally, as for phones at service stations - the most common example of one of these explosions/fires is claimed to have occured in Australia. Last year this was thoroughly investigated and as far as any fire service, police service and oil company in Australia knows, it *never happened*. It is a myth. My belief is that they are banned at service stations to improve throughput - people on phones tend to take longer to fuel their cars and pay, thus slowing the car turnover of the station.

The only cass that have been possibly identified were of a cellphone scrambling a coomputer transmitter at very short range.

Nevertheless, its in the AMA/BMFA that you mustn't operate cellphones near toy planes...

insurance invalidation etc etc.

Towers and phones generate approximatley equal signals. They have to since they both transmit and recieve.

The most radiation you will ever get is froma phone clamped to your ear.

There is enoiugh signal coming out of a ringing phone to disturb almost any electronics at a distance of a foot or two. Beyind that its negligible.

They are attached to a circuit board with a 4 foot antenna sticking out of it?

They are not shielded adequately from 900Mhz?

The brands that are affected have some quirk of layout that renders then totally susceptible to 900Mhz interference?

One can think of so many reasons.

Do people

"Eppur Sui Muove" ;-)

That logic doesn't follow. The tower has a huge antenna (for transmitting and receiving); the phone has a tiny one. What do the relative power levels (ERP) need to be now?

Well of copurse if the tower has a big efficient antenna, it ovbiusly needs less power for the same field strength...

Seriously, both towers and phones are of the order of a watt absolute max.

FWIW, radiated power levels of cell sites is considerably higher than from hand-held phones. See (third paragraph down)-

Bill(oc)

Most people don't.

GSM phones can burst Tx up to 20W (last I read, maybe more now). It's part of their housekeeping routine. The power out depends on how far away from a tower they might be at the moment. If it's laying close to volatile chips, Ram etc, it's possible for the burst to swamp those systems and change the data inside. Maybe a little and maybe a lot. To many variables to predict for sure.

Don't believe me? Contact Motorola or Nokia. They'll tell you.