>> -I'm still considering pressure sensors but the idea was to stay as close as
>> possible to the popular TWOG. Maybe I could put these on the end of the PCB
>> that can be cut off if not needed?
You are quite right that the heat will affect the humidity sensor.
It is a good idea to leave it off. I think that a pressure sensor is very useful in any case
but i think i can live with out it also. It can be positioned in a place that can be cut off as you said.
>> -What about 10 $$ extra for a 4-layer design with improved EMC/IMU robustness
>> what kind of GPS/IMU/Thermopile/Modem do you think about?
I think that the current GPS works well (Ublox) and the IMU i will try after my experiments will be either
the Xsens MtiG or the Vector-Nav VN-100.
I have to say that other than the proven Xsens MtiG all other choices are a guess to me.
>From now on the only modem i will use is the 9xtend 1W 900 Mhz.
It is so reliable for long range....
Going to a solution with Xbee + 1W amplifier is also doable.