QNH source in MP

[Adam_Borowski]

I was wondering what is the source of QNH for MP? Is that something measured by flight controller somehow?

I have really strange readings.

Highest I have seen so far was about 4000, but today… damn… 10bars?

[Eosbandi (Andras Schaffer)]

In Mp the QNH is a construct, calculated from baro scaled pressure and altitude(amsl) coming from the autopilot.

QNH = pressure / Exp(Log(1.0 - alt_amsl / (153.8462 * temp)) / 0.190259);
Where temp is 15Celsius in Farenheit.