I have installed a helm x650 which has a great screen 1000nits. Runs on windows embedded. Works great in every respect but refuses to show altitude or height. Tried all the usual switching on and off, turning instruments off and on etc. any ideas?

Had another go today. Deleted program, reinstalled. No joy. Did it again. Didn't work. Went flying - not working. Went to the cafe in disgust, returned switched on and hey presto it works. Let's see how stable it proves.

If SkyDemon isn't showing altitude it's because the source device either isn't giving an altitude reading, or its altitude reading is not of sufficient quality and is being discarded.

Was using SD on my last EasyJet flight (as passenger, not pilot!) and playing with the Altimeter feature.
Are the coloured triangles in the top left of the tab (which change from blue to green to red etc.) basically an indication of how many GPS satellites are being received?
I understand that multiple GPS satellite signals (more than 3) are needed for an accurate altitude figure?
Tony Nowak

From the user guide:

Yes, I saw that as well in the user manual!
What improves height accuracy????

Tony

Generally the available satellites and their geometry compared to you. It should be noted that even these values are typically guessed at by the receiving equipment, and they are only "likely" accuracy.

After all, if we knew exactly what the error was, there would be no error.

Good answer.
And don't forget no satellite system can tell you 'precisly' your altitude, it is all based on averages. (especially when shield inside a tin can - sorry Easyjet!
The two main systems, the European and the American, then use Glasnost (forgive the spelling) as a moderator. All of which is also referenced to your geographic location and any known terrain elevations, giving you height above the ground.
 

Further to that posted earlier;
GPS altitude displayed is the World Geodetic System 1984 (WGS–84) height above the ellipsoid (geoid height + height above MSL). The GPS altitude is not relative to pressure altitude but is referenced to an earth–centered earth–fixed (ECEF) coordinate system. Pressure altitude is not relative to the same reference frame, but relative to the standard pressure or local pressure settings. Therefore, significant differences can be seen between GPS altitude and pressure altitude.
The system also suffers from at least two factors - vertical dilution of precision (VDOP), and horizontal dilution of precision (HDOP).

The GPS altitude displayed in SkyDemon is relative to local mean sea level.