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Advanced Settings

These settings are for fine-tuning. The defaults work well for most installations.

AHRS Algorithm

OnSpeed supports two attitude estimation algorithms:

Algorithm Setting Characteristics
Madgwick 0 (default) Complementary filter, quaternion-based. Well-proven, lower CPU cost. Good for most installations.
EKF6 1 6-state Extended Kalman Filter. Estimates pitch, roll, AOA, and 3 gyro biases. More sophisticated, better long-term stability.

Algorithm differences

Both algorithms compute Derived AOA slightly differently, but switching between them does not require recalibration. Your existing calibration curves will work with either algorithm.

AOA Smoothing

Controls the Exponential Moving Average (EMA) filter applied to the AOA signal.

  • Default: 20 (samples)
  • Lower values: More responsive but noisier — the tone will fluctuate more in turbulence
  • Higher values: Smoother but slower response — the tone may lag behind rapid AOA changes

For most aircraft, the default of 20 provides a good balance.

Pressure Smoothing

Controls EMA filtering on the pitot, AOA, and static pressure readings.

  • Default: 15 (samples)
  • Lower values: Faster response, more noise
  • Higher values: Smoother, more lag

CAS Curve (Calibrated Airspeed)

If your aircraft has a known airspeed calibration curve (correcting IAS to CAS), you can enter polynomial coefficients here:

  • Type: 1 (polynomial)
  • Coefficients: X3, X2, X1, X0 (cubic polynomial)
  • Enabled: false by default

Most aircraft don't need this — the default is a pass-through (X1=1.0, all others=0.0).

Only enable this if you have a measured position error correction curve for your pitot/static system. An incorrect CAS curve is worse than no curve at all.

Serial Output Format

Controls the format of data sent on the display serial output (GPIO 10):

  • ONSPEED — OnSpeed native format
  • G3X — Garmin G3X-compatible format

Use G3X if you're feeding data to a Garmin display. Otherwise, leave as ONSPEED.

Data Source

Controls where the AOA data comes from:

Source Use
SENSORS Normal operation — live sensor data
TESTPOT Test mode — AOA from a test potentiometer
RANGESWEEP Test mode — automatic AOA sweep 0–20°
REPLAYLOGFILE Replay a recorded log file through the system

For normal flight operations, this should always be set to SENSORS.

Calibration Source

Controls which IAS source the calibration wizard uses:

  • ONSPEED — use OnSpeed's own pitot/IAS
  • EFIS — use the EFIS-provided IAS

If you have an EFIS connected with accurate IAS, using EFIS may give better calibration results.