The airspeed sensor's zero was measured
What ArduPilot says:
- Airspeed N calibrated, offset = N.N
- AUAV AIRSPEED[N]: Found bus N addr 0x0x…
- MS5525[N]: Found on bus N addr 0x0x…
- Airspeed: skipping cal
- SDP3?[N]: Found bus N addr 0x0x… scale=N
- Airspeed N calibrated
Also explained here: 2 more
- Airspeed N calibration started
- MS4525[N]: Found bus N addr 0x0x…
At each start the plane measures what the airspeed sensor reads with no air moving and stores it as the zero, ARSPD_OFFSET. From “calibration started” to “calibrated” takes a little over 1 s. Any wind into the pitot tube during that second becomes an error for the whole flight, so cover the tube loosely before power-on and uncover it before take-off. “Airspeed: skipping cal” appears after a watchdog restart: the old zero is kept, so a restart in the air does not zero the sensor at flying speed. “Found bus … addr …” means the sensor was detected.
With ARSPD_SKIP_CAL 1 there is no calibration at start-up and the saved zero is used.
Parameters to look at
| Parameter | What it is |
|---|---|
ARSPD_OFFSET | Airspeed offset |
ARSPD_SKIP_CAL | Skip airspeed offset calibration on startup |
ARSPD_OPTIONS | Airspeed options bitmask |
The code that sends it
Airspeed N calibrated, offset = N.N
libraries/AP_Airspeed/AP_Airspeed.cpp AP_Airspeed::update_calibration() · Open in ArduPilot Copter-4.7.1
AUAV AIRSPEED[N]: Found bus N addr 0x0x…
libraries/AP_Airspeed/AP_Airspeed_AUAV.cpp AP_Airspeed_AUAV::init() · Open in ArduPilot Copter-4.7.1
MS5525[N]: Found on bus N addr 0x0x…
libraries/AP_Airspeed/AP_Airspeed_MS5525.cpp AP_Airspeed_MS5525::init() · Open in ArduPilot Copter-4.7.1
Airspeed: skipping cal
libraries/AP_Airspeed/AP_Airspeed.cpp AP_Airspeed::calibrate() · Open in ArduPilot Copter-4.7.1
And 4 more messages, sent from the same places.