Re: [Paparazzi-devel] Long Range Flying Wing

[Chris]

Well i have flown to a point where the ground station with its 8db patch 
could not receive well
the planes data but i was still able to give a command to the plane and 
return it home which indicates
good airborne reception.
I use as stated the polling mode with no confirmation and retries are 
set to 0.
I have set the addresses somewhere in the top range, FFF0-FFF1 i think 
and changed the channel
to 9 (different hopping frequencies).
One day i had a problem communicating with the plane (the downlink was 
fine)
and it proved to be the video tx.
Since then i have fitted filters to the video tx (high pass) and the 
modem (low pass)
and all problems were solved.
The antenna and the modem have to be in a straight line otherwise SWR 
will rise,
RF will flow through the wires all over the airplane causing havoc and 
the antenna
radiation pattern will be greatly distorted.
The same goes for the video tx.
Chris

Hi Stephen

We configured our 9XTends according to your recommendation
(Acknowledged Polling Mode):

http://paparazzi.enac.fr/wiki/Modems#Configuration

As we are sending lots of telemetry and not using datalink joystick
control we chose the air module as the base. It gets pretty warm in
operation. In the workshop everything works fine.

On the field we experience a very asymmetrical link: The telemetry
data from the aircraft gets well to the ground station, also at range.
But the commands from the ground station only get to the aircraft at
very close range. At range we don't get any commands from the ground
station to the aircraft anymore.

Can you explain this behaviour? How do you achieve a symmetrical data link?

We still have a 90 degree bend between the modem body and the antenna
on the airplane. On the ground station we have them in a straight
line. Could this explain the asymmetrical link?

Regards, Reto

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