RINEXParser.jl

Streaming writer for RINEX 3.05 GNSS files: observation files (pseudorange, carrier phase, Doppler, signal strength) and navigation files (broadcast ephemerides plus ionosphere and time-system corrections).

The package is receiver-agnostic: it consumes plain record types and knows nothing about how the measurements were made. It follows the design of RTKLIB's rinex.c (a standalone format library) combined with GNSS-SDR's runtime model (headers are written lazily on the first record, observation epochs stream as they happen, ephemerides are written event-driven and deduplicated). Output has been cross-validated against RTKLIB's RINEX reader.

Currently GPS is implemented; the record types carry the satellite-system character throughout, so other constellations can be added without breaking the API.

Observation files

using RINEXParser, Dates

header = RinexObsHeader(
    marker_name = "ROOF-1",
    receiver_type = "GNSSReceiver.jl",
    antenna_type = "UNKNOWN",
    approx_position = (4141446.0, 604023.0, 4796597.6),  # ECEF, meters
    obs_types = ['G' => ["C1C", "L1C", "D1C", "S1C"]],
    interval = 1.0,
    leap_seconds = 18,
)

RinexObsWriter("data.obs", header) do writer
    write_epoch!(writer, ObsEpoch(
        DateTime(2020, 1, 1, 0, 0, 30),                   # GPS time
        [
            SatObs('G', 2, [
                ObsValue(21234567.890),                   # pseudorange [m]
                ObsValue(111583948.752, lli = 0, ssi = 7),# carrier [cycles]
                ObsValue(-1234.567),                      # Doppler [Hz]
                ObsValue(45.2),                           # C/N0 [dB-Hz]
            ]),
        ],
        clock_offset = -1.2e-4,                           # receiver clock [s]
    ))
end

Each satellite's observation vector is aligned with the header's obs_types for its system; use nothing for missing observations. The header is written when the first epoch arrives, so time_of_first_obs is filled in automatically.

Navigation files

header = RinexNavHeader(
    ionospheric_corrections = [
        IonosphericCorrection("GPSA", (α0, α1, α2, α3)),  # Klobuchar
        IonosphericCorrection("GPSB", (β0, β1, β2, β3)),
    ],
    time_system_corrections = [
        TimeSystemCorrection("GPUT", a0, a1, t_ot, week),
    ],
    leap_seconds = 18,
)

RinexNavWriter("data.nav", header) do writer
    write_ephemeris!(writer, GPSEphemeris(
        prn = 13, toc = DateTime(2020, 1, 1, 2, 0, 0),
        af0 = ..., af1 = ..., af2 = ...,
        iode = ..., crs = ..., deltan = ..., m0 = ...,
        # ... remaining Keplerian elements, see ?GPSEphemeris
    ))
end

write_ephemeris! skips ephemerides it has already written (same PRN, IODC, and time of ephemeris), so it is safe to forward every decoded navigation frame. The nav header is also written lazily, and writer.header may be updated until the first ephemeris is written — useful when ionosphere/UTC parameters decode later than the first ephemeris.

Epoch timing conventions

RINEX itself does not mandate an observation rate or epoch alignment, but processing tools and the IGS conventions expect epochs at "round" GPS times (integer multiples of the interval) with the receiver clock error kept small (conventionally below 1 ms). A software receiver does not need hardware clock steering for this: once a PVT solution provides the clock offset, schedule the measurement epochs at the sample instants corresponding to integer GPS seconds and propagate code and carrier phase to that instant. Any residual offset can be reported per epoch via clock_offset.