Mobile phones & computer Tx?

I am in the process of looking at this, so far I have not been able to duplicate any of the anecdotal information.

The statement in no way implies what you have infured.

I have no idea what causes you to make these leaps, I have an opinion based on experience as does anyone else.

Wher do you think I implied I can say no wrong? My wife proves otherwise on a daily basis, just not in my chosen field of electronics.

A little less emotional outbursts, and a little more controlled experimentation will go further to serve the modeling community.

I simply find stories based on old wives tales lacking in usefulness. Tell me that a motorola model xxx causes the Futaba yyy to loose it's memory under z conditions.

With these facts others can duplicate the problem. This will lead to a solution or the fact that a particular transmitter and no others has a problem.

No.

" a maximum transmitted peak power of mobile phones of 1 Watt (W) at

1800 MHz and 2 W at 900 MHz respectively"

From

( a test on radiated power on stiff inserted into people)

Other sources I could find suggested +33dBm at 900 Mhz, which is 2W also.

This source

suggests up to 8W is allowable on GSM.

This site

again gives 2W as peak power from GSM phone with 350mW being average.

I am pretty sure GSM at 950 and 1900 Mhz is teh US cellphone standard. Europe is definitelty GSM at 900 and 1800 Mhz.

Fred,

Are these GSM type phones? And if so, do you know if they were transmitting at max power when next to you radio? And was your radio turned off?

All,

The thing all our local experts seem to forget is, there are a great number of variables in this issue. There are a great variety of phones out there and we should try each and every type. In addition, phones like the GSM style which can change their output power need to be set somehow at max power. Also, every make and model of computer radio needs to be involved and for all of this. And every version of firmware for both phone and radio needs to be present.

Until someone tests all the possible variations from the above (and anything else I might have missed), the only thing any of you can prove is that you are unable to duplicate the reported problems. But that does not mean the problems do not exist. Some of you understand this. Some of you prefer to try to throw your expertise around and pose as some kind of know it all (not you Fred). Makes me wonder what other kinds of idiocy occur at the fields frequented by these individuals?

Chuck

From the Motorola web site FAQ's:

output power of the Accompli A009 is 200mW average, 1-7 watt peak.

And that is just the one type of phone. What possibilities are present with the others?

Chuck

Hear hear. Mind you most of us can crash our planes without recourse to a mobile phone.

Its very hard to duplicate conditions. If you DID set up a rig transmittkmg 2W ERP at 900Mhz, and managed to scramble one set under one set of conditions, there would still be those who would aver that its a different setup from what they have in the field, and they would be right.

My conclusion restated again, is yes, its happened a couple of times. Its very rare, probably needs a very particular combination of circumstances, but is JUST probable enough for me to put the mobile a few feet away from my tranny.

When you take the tranmsitter out of the flight box, put the cell phone IN the flight box.

If it rings, land and answer it, or let it ring...

Similar actually.

the bateries inside dictate what the peak design power will be. The distance from teh GSM cell dictates what the real power will be.

| 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.

When keyed? Is this like a walkie-talkie rather than a cell phone? In that case, they usually use different frequencies and more power.

| 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.

If you really wanted to interfere with the control of your plane, you'd lay the cell phone on the plane rather than the transmitter, and move the transmitter far far away (making the signal weaker.)

This `gauntlet' is very specific, and he's unlikely to ever pay out because it's going to be almost impossible to `prove' anything. And since he said `from the cell phone' he nicely shot down the (more likely) possibility of flying over near the cell phone *tower*, and being shot down by the many watts being emitted by that, drowning out the signal from your much weaker, distant transmitter (desensitization is the technical term.) Of course, it may not be you that's using the cell phone, or indeed not anybody at the field at all, but still ...)

Still, it seems *much* more likely that the way that a cell phone would cause a crash is that the pilot forgets to keep flying, or bumps his sticks reaching for the phone, or is startled by the ringer or something like that.

| And since he said `from the cell phone' he nicely shot down the | (more likely) possibility of flying over near the cell phone | *tower*, and being shot down by the many watts being emitted by | that, drowning out the signal from your much weaker, distant | transmitter (desensitization is the technical term.) Of course, it | may not be you that's using the cell phone, or indeed not anybody at | the field at all, but still ...)

Actually, to expand on that, what's even more likely is that it's not a cell phone signal at all, but instead a pager signal, since many pagers work right in the middle of our 72 mhz band (in the US, anyways.) If your plane is a 1/4 mile away from you, but only 50 yards from a pager tower, and that pager tower is pumping out 700 watts at only 20 khz away from your signal, guess what your plane is gonna do? :)

Of course, eventually what will happen is that people who fly there will learn where the dangerous spots and frequencies are, and avoid them.

Not that this is really related to cell phones -- but this is a much more likely scenario for experiencing interference.

As for a cell phone scrambling your computer transmitter's memory, I don't buy it. The thing transmits a watt of RF energy whenever it's turned on, and that signal starts inside the unit. Cell phones generally work at higher frequencies and less power, and so the effect would be much less. Now, putting the transmitter right into the beam of a microwave dish -- I can see where that would cause problems (it'll also warm up your hands nicely.)

Still, I don't yak on the phone while I fly. Probably for the same reasons I don't do it when I drive -- it tends to reduce my concentration. That, and I don't have a cell phone ...

Thats not how it happens.

The cellphone scrambles the digital part of the transmitter.

So few people have flown with cellphones starpped to their planes that there isn't even an anecdotal report ofthem affecting receivers.

No argument there.

It's a multi-function gizmoid. Cell, radio, pager, younameit. 600 mW 800 - 900 MHz. Nothing which would obliviously interfere with a telly or monitor. I think it's just a nasty signal with lots of splatter coming off the base-loaded antenna.

Maybe, but the 72 Hz Rx can't hear 800-900 MHz, and 600 MW isn't likely to swap the Rx front end. Wasn't planning on giving my cell phone an airplane ride, anyway.

While there may indeed be a very few Txs that can be reprogrammed by a cell (one way or t'other), it doesn't seem the case in general.

I agree that the 'danger' of cell phones vis a vis models (or anything else for that matter) is operator head-space.

Forgetting what one is doing while focusing on a teleconference is not good. Yakking on the phone while : driving down the interstate, starting the mower, slicing cucumbers, lighting the fireplace, running a table saw, >or< just gawking in the pits or on the flight line, are not compatible activities for most folks.

A G-62 swinging a 22" or a .61 swinging an 11.75" have the nasty habit of biting hell outta someone who is wandering around the pits with their head fully inserted, paying more attention to the little voice inside their head than to the snarling buzz saws snapping at their ankles.

I'm a safe driver. I'm a safe flyer. I survived a really bad heart attack in '91 'cuz I was only two blocks from a hospital at the time.

I'm not going to die from another heart attack, I'm going to die when some dipshit center punches the driver's door on my car because they were too intent on listening to their damn cell phone while running a red light.

I simply do not see a pressing need for model aviators to use (or even carry) cell phones when they are in the pits or on the flight line. IMHO cell phones (and pagers) need to stay in the car if the car is at the flying site. I'm on call every third week, and must carry the company cel/pager/radio/Nextel whatsit. I leave it in the car when I'm at the field, period. Overtime service calls (folks who just can't wait to pay me time-and-a-half) can leave a message - I check the phone every half-hour or so.

Cheers, Fred McClellan The House Of Balsa Dust

The output of an average power station? Not swa(m?)p it?

More like it will incinerate it in a flash ;-)

I disagree. that's been the case in the two or three cases that seem to be 'it happened to me' not 'i heard abouyt it happening'

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