Cell Phone

[Don Ramsey]

I just got this info about some testing on cell phones.

Don

Hi Don,

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.

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. 
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:

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.

Results:
-  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. 
-  Same transmitter with a non-synthesized RF module was totally unaffected by a cell phone
-  Several other JR and Futaba (probably also Multiplex) transmitters were tested. No effect at all !
-  Various brands and types of receivers and servos were also tested. No effect at all !
-  Receivers were tested at the flying distance
-  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.

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 !  
The sensitivity of other brands i do not know, but why take a chance.

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.

Best regards,

Iiro Nikkila
Finland
F3A, Futaba 9ZAP with TK-FSS module
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