Altitude Discrepancy

[Top Hat]

Took off from a local urban park @ ground level and took the MP out and up @ 75 ft high.
The park is wide open and no one was around so I was flying all over it a varying altitude.
Noticed that the batt is getting low I took it back closer and lower. This is when I noticed the discrepancy on altitude. I lowered the MP to 3 ft but to my estimation the actual alt of the MP is about 10' to 12'.
To make it more precise I brought it even closer and lower and dropped the alt further down to -11' but actually only a foot from the ground where it was hovering. What is wrong here and how can I correct this. Besides this issue I have no other problem to date.

 

[dragos28]

mine does the opposite, it takes off from 0 on the ground. then when i bring it down to land it shows -14' or even up to -24 at ground level.

weird.

 

[Raptor63]

could it be a calibration issue?

 

[Mr. Salty]

The barometric sensor for measuring altitude isn't all that accurate.

 

[msinger]

What is wrong here and how can I correct this.

If you're able to repeat that consistently, then calibrate the IMU to see if it resolves the issue.

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[Raptor63]

Thanks for the support guys

 

[Gotcha]

I have the same issues:
Strange altitude reading (deviation)
My theory is that the barometric pressure sensor is not temperature compensated. But to be on the save side, they rather give a altitude reading that is to low than vice versa

 

[mavicn00b]

I get this occasionally. Landing at -10m from original takeoff point etc. No biggie as the vps kicks in plus I bring it in visually, but makes you wonder what height the craft is really at up there and are we getting bogus telemetry

 

[gnirtS]

Fairly common for me to "land" at -8ft or so. As above its not a very accurate altimeter and i dont think its temperature compensated so as the drone warms up from the electronics and being in the sun it drifts.
Its not an issue really.
Mine always goes negative - ie it ends up thinking its a bit higher than it actually is.

 

[SeaComms]

Hmm.. an old thread but I have the opposite problem with a student on the weekend. After flying around at about 1m for 5 minutes it was reporting he was 6 metres up.