chcal reads different calibration formats and converts them into others.

The most common usage is

chcal -outdir /home/newcal -old_to_new -tojson *.txt

This converts old metronix calibration files into the new JSON format.

For a magnetic sensor the .json should contain:

"units_frequency": "Hz",
"units_amplitude": "mV/nT",
"units_phase": "degrees"

For a MFS-06xx chopper on you typically have f, a, p: 0.1, 20.0, 89.0

chcal -help gives you more options you don’t need.

An old metronix file MFS06022.TXT is split into MFS-06_0022_chopper_off.json and MFS-06_0022_chopper_on.json.