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airspy_calibrate

airspy_calibrate help

Specify either read or write option.
Usage:
        -r: Read and display calibration data.
        -w <calibration in ppb>: Erase and Write calibration in ppb.

See code https://github.com/airspy/airspyone_host/blob/master/airspy-tools/src/airspy_calibrate.c

Frequency correction to ppb algorithm

• ppb = ((actual_freq_MHz - observed_freq_MHz) / actual_freq_MHz) * 1e9

Example usage:

The airspy_calibrate tool will erase previous calibration and write the new one with your provided ppb value (+ or - accepted of course)

Actual Frequency 1544.500MHz vs Observed Frequency 1544.503 MHz

• ((1544.500-1544.503)/1544.500)*1e9 = -1942 ppb

1. To be sure of your new correction you shall first erase calibration using 0 ppb with airspy_calibrate -w 0
2. PowerOff / PowerON AirSpy (as Calibration is read/applied during boot)
3. Do the measurement with your tool and check the Frequency vs Frequency Expected like you have done then do again the computation (using https://www.sitime.com/ppm-hz-calculator ...) to find ppm & ppb (the important is to use ppb rounded to nearest)
4. Apply the new ppb computed (example -1942) with airspy_calibrate -w -1942
5. PowerOff / PowerON AirSpy (as Calibration is read/applied during boot)
6. Check with your software all is fine now