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Cell Phones and R/C

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Old 04-30-2003, 03:12 PM
  #26  
BillHarris
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Cell phones are the spawn of satan and should not be inflicted upon bystanders. They may or may not cause rf interference, but are a distraction.
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Old 04-30-2003, 03:21 PM
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Originally posted by RCadmin
Problem is once cellphones are banned from the field then what/who do you blame when you punch in your favorite plane?
Solar Flares!!!! They're the worst!

Mike
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Old 04-30-2003, 05:24 PM
  #28  
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Rick 9D, The problem is, our radios are designed to work with other R/C gear in close proximity and therefore rarely interfere. Intermodulation/Mixing from other sources is a total unknown and may end up directly on your frequency. If the spurious signal is stronger than your signal, it wins and you have a problem. The problem I'm looking at is that they are building a new cell tower about 200 yds behind our flight line. (We don't normally fly behind us in that area.) We already have some large antennas of unkown use about 1 mile down the road from us so we are now sandwiched in between 2 higher powered transmitters. We have no idea what mixing products will occur. Needless to say we are a little concerned.
Bill Harris, I agree 100%.
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Old 04-30-2003, 05:54 PM
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Cell phones dont bother r/c, I have mine ring all the time while I fly with it on my hip.

I think they banned them at that field because the flyers are poor and crashed alot and had nothing else to blame it on.
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Old 04-30-2003, 11:17 PM
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Originally posted by FLYBOY
... I answer it if it rings when I am flying all the time.
!!! I hope you have three hands!
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Old 04-30-2003, 11:20 PM
  #31  
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P51B, you're too funny.

(I was thinking the same...how does he do that?)
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Old 05-01-2003, 12:11 AM
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Originally posted by MikeL
There were some concerns about cell phones causing the non-volitile memory in our computer radios to be wiped out a few years ago. There were write-ups in the AMA mag about it, as well as a healthy online debate.
I don't know how this is true, since they use cellular modems in laptops, which use the same frequencies as the cell phones. Never heard of a laptop getting wiped out.
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Old 05-01-2003, 12:58 AM
  #33  
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Laptops use volatile memory, which is different than the non-volatile storage memory in our radios. I can't find any source that verifies the claim, but I do recall it being an issue a few years ago. I've never heard anything about actual radio interference.
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Old 05-01-2003, 03:55 AM
  #34  
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When I get to go to the field, everyone I wish to talk to is within a few yards of me.

While working, I have no choice but to tolerate the thing, but, when Im playing, I have no desire to talk on the phone.
I do leave my personal cell on, (in my truck) so, I can check occasionally, to see if my wife needed something though she rarely distracts me during flying time.

Its gotten so that you cant have a conversation with anyone these days without a damned cell phone interrupting every few mins.
When Im talking with someone and the phone rings, I normally look to see who it is and return the call when were through, same with call waiting, whoever called first is who I will speak with, without interruption.
Seems to me a very basic courtesy.
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Old 05-01-2003, 01:10 PM
  #35  
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When I get to go to the field, everyone I wish to talk to is within a few yards of me.

While working, I have no choice but to tolerate the thing, but, when Im playing, I have no desire to talk on the phone.
That is the truth! A recent trend is that you will occasionally see the "phonies" wandering about in malls and airports with hands-free headsets talking continuously on the phone.

I don't get the fascination some folks have with these devices. But then, we do play with toy aeroplanes.... so who's to talk?
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Old 05-01-2003, 01:53 PM
  #36  
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Originally posted by P-51B
!!! I hope you have three hands!
Always!

Actually, I use a neck strap and its usually my boss wanting me to fly him somewhere so I can't keep flying models. What the heck, then I get to go fly big ones.
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Old 05-02-2003, 02:24 AM
  #37  
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Originally posted by MikeL
Laptops use volatile memory, which is different than the non-volatile storage memory in our radios. I can't find any source that verifies the claim, but I do recall it being an issue a few years ago. I've never heard anything about actual radio interference.
Actually, they use both. I know that some (not all) bios chips in laptops use
non-volatle memory. If that radio really did have it's memory erased from interference, then that would indicate a design flaw. I dont beleve that story is true.
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Old 05-02-2003, 02:47 AM
  #38  
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Nitrowoman, the only thing you need to fear is hitting the tower itself, and not radio interference from the tower's transmissions, and you stated that you don't fly in its vicinity. Without going into radio theory, it's a no-brainer... you have nothing to worry about presuming it is a cell tower.

Rick - AE9D
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Old 05-02-2003, 11:59 AM
  #39  
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the biggest thing I would worry about with cell phones and CBs is splatter.

a TX doesnt just transmit on its own frequency but a range.

if you look at a graph you will see what appears to be a spike in the middle of a "hill" on the frequency chart. the center of that spike is the frequency its tuned to but the hill is on other channels, just weak so it doenst make much diffrence,

the problem comes when that "hill" is too strong.

this usually happens when a RX is real close to the TX,

hold a cell phone next to a FM radio and make a call, you can here the interference coming over the line.

now if someone modifies a CB or such and thay "hill" becomes really great then you have real problems, there are people that put amplifiers on CBs to get more range (against FCC regulations) this causes the entire band to be amplified (including the "hill")

one time when driving on the road I heard a trucker that keyed in his mike and I heard it through my radio.... and I was listening to the CD player.

if he goes anywere near a RC field I KNOW someone will have trouble.
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Old 05-02-2003, 10:41 PM
  #40  
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Default Cell Phones and R/C

Regarding cell phone towers, be careful if the tower is fed from another location via a digital radio system. Fiber optics is usually used, but sometimes a radio system is used, using a physically narrow signal possibly in the 2 gHz range. If you fly your plane through this signal, your receiver may momentarily get screwed up. If you have a PCM, it will go into standby. Look for dish antennas on the tower, see where they are pointing.
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Old 05-03-2003, 12:12 AM
  #41  
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redrocker, there is truth in what you said.

A cellular relay station, not connected by land lines but microwave, could be a problem for R/C.

Rural cell sites that cannot be connected by land-lines can be linked by microwave. There are not many of these in North America.

Transmit power from the originating cell site is limited to .5-10 watts (4-10GHz), but the huge antenna gain translates this into perhaps a .5 kilowatt signal.

Flying through it would probably swamp our receivers, an RF curtain, if you will.

Beam width is in the order or only 2-3 degrees, so loss of control at normal flying speeds would be 1-2 seconds.

Microwave transmission, especially telephone, occurs at various, but few locations in North America.

Even though few and far between, it is, in fact, a true hazard for us......much more than secondary cellular communication.

I guess what I'm saying is that if you see a high tower with dish antennas on it...stay away....

...or fly very fast. LOL
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Old 05-03-2003, 01:12 PM
  #42  
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Actually the problem of digital microwave interfering with our RC activities is more than just possibly from cell phone towers. Starting in the mid 80's and through the 90's it seemed that a lot of business were buying point to point microwave systems for data and voice connectivity around a metro area. For many years we flew RC on the campus of a community college in Scottsdale, AZ. One day a microwave dish showed up mounted on one of the building roofs, and its beam shot across one end of our field. We quickly found out that if your landing approach from the west was a bit high, you would go through this beam and your receiver would be momentarily swamped. I believe this was in the late 80's and there were still a lot of AM radios out there and they fared the worst. Correct- if you flew this beam fast and had an FM radio it was not too bad, but if it was a landing approach with an AM radio, it was hard to recover.

After a while AM radios faded away and most of us flying at this field just unconsciously compensated for this problem.
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