Instrument Formats

Format	Read a run	Read a TimeArray	Write
LEMI-424	read_lemi424	load_lemi424	write_lemi424
GEOMAG-02	read_geomag	load_geomag	write_geomag
Metronix ADU	read_metronix	load_metronix	write_metronix

Don't know the format? read_timekeeper and write_timekeeper pick it for you.

Channel names

Every format uses the same names:

Component	Meaning	Units
:bx, :by, :bz	magnetic field, geographic N / E / down	nT
:e1, :e2	electric field, dipole 1 / 2	mV/km
:temperature_e, :temperature_h	electronics / sensor temperature	°C
:battery	supply voltage	V
:elevation	GPS elevation	m

default_components gives the five signal channels (bx, by, bz, e1, e2); components gives every channel in the run.

LEMI-424

using Timekeepers

run = read_lemi424("data/LEMI090.txt")
ta  = load_lemi424("data/LEMI090.txt")     # straight to a TimeArray
write_lemi424("data/LEMI090_copy.txt", ta) # same 24-field layout, nothing lost

• Whitespace-separated ASCII, one line per sample; LEMI424_COLUMNS names the 24 fields.

• Extra columns are ignored; missing trailing columns come back as NaN.

• include_aux = false reads only the five signal channels.

• 7-column .xyz exports (date time Bx By Bz Ex Ey) open in run_tkapp only.

GEOMAG-02

run = read_geomag("data/MS_26_250523000000.TXT")
sampling_rate(run)                     # 10.0 for a 0.10 s interval
run.metadata[:instrument_model]        # "GEOMAG-02"

• ASCII with a ; header (model, interval, position), detected by the GEOMAG token.

• Reads the five signal channels plus both temperatures; write_geomag writes header and data back.

Metronix ADU (ATS)

run = read_metronix("data/RK137/meas_2025-04-01_07-00-05")
components(run)     # [:bx, :by, :bz, :e1, :e2]
sampling_rate(run)  # 128.0

• A run is one .ats file per channel plus an .xml, inside a meas_* directory.

• Pass the run's .xml, one of its .ats files, or a meas_* directory that holds only that run. A directory with several runs gives an error listing them.

• METRONIX_CHANNEL_MAP: Ex → :e1, Ey → :e2, Hx → :bx, Hy → :by, Hz → :bz; unknown types keep their own name.

• write_metronix needs a run read by read_metronix (it reuses its XML).

• To cut masked intervals out of a whole site, see Metronix Sites.

Metadata

In run.metadata, or TimeSeries.meta(ta):

Key	Present for	Meaning
:sample_rate	all	samples per second
:start_time	all	timestamp of the first sample
:instrument_model	GEOMAG, Metronix	instrument identification
:aux_columns	LEMI-424, GEOMAG	auxiliary values, for lossless writes
:site, :n_files	site loads	site name and number of runs joined
:metronix_xml_path	Metronix	XML template for the writer
:metronix_prefix, :metronix_run_token, :metronix_freq_token	Metronix	filename tokens the writer keeps
:mask_intervals, :masked_samples	after a mask	intervals cut and number of samples