Re: [Paparazzi-devel] Encryption of PPM frame

[Felix Ruess]

Hi Achim,

sorry for the late response...
That is a pretty nice idea. But IMHO for most cases it doesn't really
make sense. RC is mainly used because it is convienient, people
already have a transmitter lying around. If you need to start
modifying it, I think it would be simpler to just make the switch and
use something more capable like zigbee right away.
It would be nice to have sometimes (I also had some problem with
spurious fake rc frames) but not worth the effort in my opinion. (I
would not be able to use my RC for my normal planes anymore).

Cheers, Felix

On Thu, Feb 11, 2010 at 9:07 PM, Achim Walther <address@hidden> wrote:
> Hello everyone,
>
> while I was working on a new version of my PPM decoder for the 35 MHz
> system the idea of encrypting the PPM signal crossed my mind. The basic
> principle is once you have control over the signal in the RC transmitter
> you can manipulate it in any way you want. Of course within the
> bandwidth limitations. No more need for a 6 ms sync pulse etc. This way
> one could protect a UAV from being hi-jacked when flying farther away.
> It might not be sufficient to protect from jamming however.
>
> Even though 2.4 GHz systems are not concerned with the problem of double
> channel allocation there are still some 35 MHz users around.
>
> I described the principle at the end of this page:
> http://www.voidpointer.de/ppmswitch/index_en.html . One challenge is the
> voltage of the signal in the transmitter having 9 Volts or higher. This
> could be met using a special uC like the ATmega16HVB.
>
> What do you think? Is R/C still a subject and would this be a valuable
> feature? Or is dealing with PPM outdated now we have Zigbee etc.?
>
> Regards, Achim.
>
>
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