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<DIV><SPAN class=275233917-03052003><FONT size=2>This information fits what I
know about field, being first educated as an RF engineer.</FONT></SPAN></DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2>There should not be any problem
between a properly designed and operating cell phone, and a properly designed
and operating R/C transmitter. They operate on widely different
frequencies.</FONT></SPAN></DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2>Will we find a very
few cases where they interfere-- yes. Either the cell phone or R/C
transmitter can have either tuning system or active
component problems (e.g. a defective RF protective diode or final stage
transistor) such that they spew out interference. How many times have
I dropped my cell phone??? Did that knock the RF deck out of alignment, or knock
loose a solder junction? In a synthesized RF module (cell phone is full of
them), there are many more mixing frequencies and phase-locking loop signals to
be interfered with if something is not right.</FONT></SPAN></DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2>Its also possible, with 800+
cell frequencies and our 50+ frequencies where the right combination 3rd or 5th
order harmonics could mix in the R/C transmitter's final output stage where it
could be amplified enough to cause trouble. I used to have a computer program
around here that would predict this. Maybe an interesting
exercise.</FONT></SPAN></DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2>Its not going to be a every
cell phone interfers with every transmitter thing. Are we talking a 1 in 100
combinations or 1 in 100,000? There seems to be enough anecdotal
occurances that suggest its more prevelent than 1-100,000, but not enough to
suggest its as low as 1-100.</FONT></SPAN></DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=275233917-03052003><FONT size=2>Well, that's my analysis for
what it is worth. Whether to ban them or not, depends on an individual or club's
risk adversion.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org]<B>On Behalf Of </B>Don
Ramsey<BR><B>Sent:</B> Saturday, May 03, 2003 4:48 AM<BR><B>To:</B>
discussion@nsrca.org<BR><B>Subject:</B> Re: Cell Phone<BR><BR></FONT></DIV>
<DIV><FONT size=2>I just got this info about some testing on cell
phones.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Don</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>
<DIV><FONT face=Arial>Hi Don,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I am following the NSRCA mailing list but am not a
member. Because of this I cannot mail on the list without censors reading it
first, so I decided to reply to you directly.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>The use of cell phones with R/C equipment has been
discussed on the the list in August last year, I do not remember the
consensus. </FONT></DIV>
<DIV><FONT face=Arial>A couple of years ago I found a test report on the
Internet, in German. That page does not exist anymore but the story goes like
this:</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>An R/C helicopter crashed when the pilots cell phone
rang. The phone was on the belt. The insurance company and DMFV (Deutscher
Modellflieger Verband, German "AMA") got interested. A radio specialist (MSc
in RF) and an R/C pilot himself carried out the tests.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Results:</FONT></DIV>
<DIV><FONT face=Arial>- Robbe Futaba FC-28 (exactly the same technology
as Futaba 9Z) with synthesized RF module lost control when a cell phone was
very close to it, less than 40 cm distance. It turned out that it was not
interference, but the transmitter was was not able to hold the right
frequency, IOW it was sending with a false frequency. </FONT></DIV>
<DIV><FONT face=Arial>- Same transmitter with a non-synthesized RF
module was totally unaffected by a cell phone</FONT></DIV>
<DIV><FONT face=Arial>- Several other JR and Futaba (probably also
Multiplex) transmitters were tested. No effect at all !</FONT></DIV>
<DIV><FONT face=Arial>- Various brands and types of receivers and servos
were also tested. No effect at all !</FONT></DIV>
<DIV><FONT face=Arial>- Receivers were tested at the flying
distance</FONT></DIV>
<DIV><FONT face=Arial>- In these tests the R/C equipment was 35 MHz and
cell phones 900 and 1800 MHz. In the USA teh frequencies are different but
basic rules against interference applie the same.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>So the Futaba synth module may be affected by
cell phone. It is also important to avoid close proximity of cell phone
at the pits, because the transmitting frequency is possibly altered. You may
shoot someone else down ! </FONT></DIV>
<DIV><FONT face=Arial>The sensitivity of other brands i do not know, but why
take a chance.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>On the other hand what is the benefit of having a phone
close to you while flying, since you cannot answer it anyway. If you have a
hands free, you still have to concentrate on flying.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Best regards,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Iiro Nikkila</FONT></DIV>
<DIV><FONT face=Arial>Finland</FONT></DIV>
<DIV><FONT face=Arial>F3A, Futaba 9ZAP with TK-FSS module</FONT></DIV>
<DIV><FONT face=Arial
size=2></FONT> </DIV></DIV></BLOCKQUOTE></BODY></HTML>