SkyRadar DX Altitude and Speed Method

[Gaston]

Does SkyRadar DX use GPS or Pitot/Static Pressure for Airspeed and Altitude?

[SkyRADARSupport]

It uses GPS. No pressure tubes needed.

[tinker]

Caution:  GPS cannot determine airspeed.  What you are getting is ground speed.  Airspeed does need pitot/static.

Along those same lines, GPS altitude is NOT MSL altitude.  It is altitude above a theoretical ellipsoid that approximates the earth, WGS84.  Again, for MSL altitude you need a static port connection and a barometer value.

(New here, just ordered a DX, and happened to see this post.)

[SkyRADARSupport]

Yes that's correct, but SkyRadar-DX is Attitude-Heading system not airspeed/altimeter system.
GPS allows for more accurate determination of inertial forces acting on the airplane than airspeed systems.

[Russgrif]

Greetings!  I understand that SkyRadar is a Heading/Attitude device, not an Altitude system.  However, I was surprised that, using the SkyRadar's GPS, the altitude reading is normally off by 200 feet.  When using my iPad's GPS, it is within 50 feet.  I do realize that these comparisons are coincidental and have no basis or correlation to one another. My question is, can the difference in altitude offset be re-calibrated or should I just ignore it? 

By the way, I love my SkRadar DX!  I'm very happy with it!  I think that this sparsely populated forum simply proves that the system works incredibly well.  Otherwise, there would be far more posts containing "issues" that the SkyRadar DX appears not to have.

[Forum Administrator]

If you have ADS-B out and use our SkyRadar software on iPad you can tell SkyRadar software your own tail number, it will use your own ADS-B output as true basis for altitude and will track quick short changes in altitude using internal SkyRadarDX GPS.

GPS only altitude is not super accurate, WAAS corrections help a little, but i sill would not rely on non-certified GPS altitude.

Different GPS receivers use different computation engines as well as earth ellipsoid models and they can be off quite a bit when compared between each other.