Sidereon.GNSS.PreciseEphemeris (Sidereon v0.29.1)

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A precise-ephemeris source built directly from samples, with no SP3 text in the loop.

This is the Elixir surface over sidereon-core's sample-backed precise-ephemeris source. The canonical intermediate representation of a precise orbit/clock product is a set of per-satellite ECEF position (+ optional clock) samples on a time axis (Sidereon.GNSS.PreciseEphemerisSample); this module builds an interpolatable source from those samples directly. It drives the exact same interpolation substrate the SP3-parsed source uses, so Sidereon.GNSS.Observables.predict_ranges/3 accepts either kind of source.

A built source is held as a resource handle by the BEAM; evaluation operates on that handle.

Round trip

{:ok, sp3} = Sidereon.GNSS.SP3.load("igs.sp3")
samples = Sidereon.GNSS.SP3.precise_ephemeris_samples(sp3)
{:ok, source} = Sidereon.GNSS.PreciseEphemeris.from_samples(samples)

For samples that are the faithful image of the interpolation fit nodes (the round-trip case above), the rebuilt source interpolates and predicts ranges byte-identically to the SP3-parsed source. Samples carrying lower precision interpolate at that precision.

Summary

Types

t()

Functions

from_samples(samples)

Build a precise-ephemeris source from a list of Sidereon.GNSS.PreciseEphemerisSample structs.

observable_states_at_j2000_s(source, satellites, epochs_j2000_s)

Evaluate states for parallel satellite and J2000-second arrays.

observable_states_at_shared_j2000_s(source, satellites, epoch_j2000_s)

Evaluate states for many satellites at one shared J2000-second epoch.

satellites(source)

Return the satellite ids available in this sample-backed precise source.

Types

t()

@type t() :: %Sidereon.GNSS.PreciseEphemeris{
  handle: reference(),
  time_scale: String.t() | nil
}

Functions

from_samples(samples)

@spec from_samples([Sidereon.GNSS.PreciseEphemerisSample.t()]) ::
  {:ok, t()} | {:error, term()}

Build a precise-ephemeris source from a list of Sidereon.GNSS.PreciseEphemerisSample structs.

Samples are grouped by satellite. Each satellite's series must be strictly increasing in epoch and carry at least two samples, and every sample must share one time scale. Returns {:ok, %Sidereon.GNSS.PreciseEphemeris{}}, or {:error, reason} where reason is one of the structural validation atoms:

  • :empty - no samples supplied
  • :single_sample_satellite - a satellite has only one sample
  • :non_monotonic - a satellite's epochs are not strictly increasing
  • :mixed_timescale - samples carry more than one time scale
  • :non_finite - a sample position or clock value was not finite
  • :out_of_range - a sample epoch is not representable as J2000 seconds

A malformed satellite token or time scale in a sample is returned verbatim as {:error, reason} without raising.

observable_states_at_j2000_s(source, satellites, epochs_j2000_s)

@spec observable_states_at_j2000_s(t(), [String.t()], [number()]) ::
  {:ok, Sidereon.GNSS.PreciseEphemeris.StateBatch.t()} | {:error, term()}

Evaluate states for parallel satellite and J2000-second arrays.

observable_states_at_shared_j2000_s(source, satellites, epoch_j2000_s)

@spec observable_states_at_shared_j2000_s(t(), [String.t()], number()) ::
  {:ok, Sidereon.GNSS.PreciseEphemeris.StateBatch.t()} | {:error, term()}

Evaluate states for many satellites at one shared J2000-second epoch.

satellites(source)

@spec satellites(t()) :: [String.t()] | {:error, term()}

Return the satellite ids available in this sample-backed precise source.