Pixhawk incorrect altitude

Barometric altitude works seamlessly with disconnected GPS! After connecting the GPS displays incorrect altitude, sometimes even negative! what it can be ? I’m a beginner…

You can change the GPS_GAIN parameter on the Mission Planner. Reduce it to reduce the influence of gps correcting the altitude.
You have to find it on the full parameter list at config/tuning part.

You shouldn’t have to change anything. Can you provide a dataflash log when the issue is occurring and we will try to have a look.
Thanks, Grant.

Sir I have same problem that my APM 2.8 showing wrong altitude as like -26, -46 , -56, 23 etc. Altitude continuesly changing, I tested my copter, copter rockets automatically in position hold mode.

I am new with Mission planner, I downloaded Mav link log file, I wish to send you that file for study, but when I see Mission Planner log folder, than Quadkopter folder, I found many files, I am confuse that which file I should send to you for study.

Please guide Sir

Did anyone find the answer to this issue. I tested it with 6 different UBlock GPS system and they all do exactly the same thing. On startup before Ardupilot reads GPS config Altitude is accurate a 0 - 2 ft. Once Ardupilot reads the GPS configuration and identifies it as ublock the altitude reading goes to -56 ft, after a gps lock altitude went to 976 ft - 229876 ft roughly. If I leave GPS unplugged the Altitude is correct. I believe this is clearly a configuration issue which is affecting the EKF calculation of Altitude when the GPS is detected. I need help figuring out how to correct this as the system is not capable of holding altitude or navigating this way.

Hi, did you find a solution to this problem? I am also facing the exact issue (Pixhawk Cube 2.1 hardware).