Accelerometer calibration

I am new to RaceChrono but after searching around could not find any option to calibrate the device. How the acceleration is calculated if switch from portrait to landscape? How accurate acceleration value is?


  • The "Longitudinal acceleration" and "Lateral acceleration" channels are calculated from GPS data, so they are not "real" accelerometer values, although with a good GPS they are pretty close.

    You can enable "Internal sensors" in settings, which will record the raw X/Y/Z value from the internal accelerometer, as well as raw values from magnetometer and gyroscope. The values are in no way calibrated or rotated.
  • for an accurate acceleration value is iPhone internal gps enough or need to have external GPS?
  • I did a comparison between the acceleration values between Race Chrono and vehicle sensors. Noticed the Race Chrono is ~ 30% higher. Is it possible to get more precise acceleration values from app?
  • edited August 2020
    The lateral/longitudinal acceleration, that are calculated from GPS, might have very unrealistic minimum and maximum peak values, as they solely rely on the GPS data quality. You can improve the calculated values' accuracy by getting a better external Bluetooth GPS.
  • got it. I just tested 5Hz external GPS and noticed the acceleration values were much closer to vehicle data. is there an optimal frequency rate should target for?
  • The higher the frequency the better generally. But of course reception quality is important too, a fast rate of incoming bad data makes no one happy.

    Dual, Garmin and so on run at 10Hz

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