GPS fails in height

[AlpVir]

My code is wrong a few tens of meters to measure the height, probably because they consider the geoid or ellipsoid (not sure which one).
I use a external GPS (connected via Bluetooth).
Here is some code snippet :

GPS1.Initialize("GPS")
StartActivity(GPS1.LocationSettingsIntent)
Sub GPS_LocationChanged (Location1 As Location)
H=Location1.Altitude
lblQuotaX.Text = H
End Sub

Thanks in advance

 

[AlpVir]

Certainly!
I checked and it is Version 1.20

 

[Erel]

Can you upload your project (File - Export as zip)?

 

[AlpVir]

The attached project is virtually identical to your tutorial on the GPS.
I tried reinstalling B4A (version 3.0).
In the folder C:\Program Files\Anywhere Software\Basic4android\AdditionalLibrerie there were two old files (GPS.jar and GPS.xml) of 2012. I deleted them.
In the folder C:\Program Files\Anywhere Software\Basic4android\Libraries there were two files relating to GPS :
02/07/2013 15:39 9,803 GPS.jar
02/09/2013 13:06 10,856 GPS.xml
2 File 20,659 bytes
The IDE of B4a (tab "Libs") signals "GPS: (version 1.20)", even after the refresh.
Tanks Erel.

 

[Erel]

Which device are you using? Seems like there are known issues related to the listener (addNmeaListener) and some devices.

 

[AlpVir]

I use a Motorola Defy Plus MB526.
It receives 7-8-9 satellites.
Latitude and Longitude is absolutely OK
The height is greater than 50-55 meters, always !!!

With the app TwoNav the height is wrong from 1 to 5 meters, at most 10.

 

[Erel]

Google for Motorola Defy and NMEA. Seems like Motorola didn't implement this feature.

 

[AlpVir]

I would never have assumed that a smartphone with integrated GPS could NOT receive NMEA sentence that are the basis of the GPS communication !
I also read that the Motorola Defy has problems in this regard.
At this cue I installed the app "NMEA recorder" and I found that actually is not recorded anything.
Then I tried the app "Ultra GPS Logger" but that creates the NMEA sentences, do not read from the satellite, and the values are also wrong here of about 50 meters.

At this point the question is : how does TwoNav for Android (https://play.google.com/store/apps/details?id=com.compegps.twonav) to read the exact height above sea level (error 2-5-10 meters at most)?
With the same device, same hardware ?

Erel Thanks for the patience with which you have followed me this far.

EDIT :
I believe that we must take into account the geoid (http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html)
There is a FORTRAN program that reads a file of 9 MB.
All very very simple ;-)