Airspeed sensor calibration sensitivity

Hi,

I am working on a fixed-wing UAV and my airspeed sensor is digital MATEK 4525DO. I have calibrated the sensor with the AUTO_CAL parameter and the ARSPD_RATIO value fell around smaller than 2. This looks normal. But on the ground when I power the pixhawk, the airspeed value is changing around 7 m/s. I think this is too much. When we blow the pitot tube, the airspeed value increases to around 20 m/s. Is there any mistake? Or is the sensitivity of the speed sensor normal as well? Has anyone had a problem like this before?

Thanks for helping.

Make sure you loosely cover the pitot tube when you boot up the plane. It will calibrate during it’s startup and if there’s a wind or breeze when it’s booting it will offset the calibration.

If you forget you can also cover the pitot tube once it’s booted up and use MP to do a pre-flight calibration.

First of all thanks for your reply. When I was booting the pixhawk, I covered the pitot tube loosely. After the calibration, the airspeed value came as I mentioned first. So after that, I wanted to do a preflight calibration. But when I clicked the button, MP got an error like “The command failed to execute”. Why I got this error? Where am I mistaking I do not know?

Is there any other idea or suggestion ? Thanks

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