Nice app! Congratulations!
I have some questions.. What is the reason to add fixed height of geoid in GGA string? And whether it makes sense to transfer GLL, VTG and ZDA strings? I tested a similar program for several weeks with some client applications (SAS Planet, OziExplorer, gpsVP, Navitel ets.) and decided not to use that elements. On my N900 the attribute of MagneticVariation always comes without validity confirmation. Is it a bug of pr.1.2?