TK119-3g altitude
What protocol are you using? Many devices don't report altitude value at all.
eelink
There are two different message types in "eelink" protocol. One with altitude and the other one is without altitude. I guess your device sends the latter one.
Doh!
By the way thank you for your time and effort on this project!
Recently got one of these devices and setup a server, I don't seem to be getting altitude data, anyone else come across this?