sp3 0.0.3

Download and interpolate precise satellite ephemeris (SP3)

sp3

Download and interpolate precise ephemeris (SP3).

CDDIS registration

http://urs.earthdata.nasa.gov

Caveats

• Norad / PRN correlation may change over time (especially for GNSS satellites).
• All user-facing functions use UTC timestamps for compatibility with TLE data. Unlike UTC, the GPS / TAI clocks used by some SP3 files do not have leap seconds (https://en.wikipedia.org/wiki/Leap_second). This difference can cause interpolation issues under the rare condition of satellite observation over a leap second.
• SP3 files from GNSS providers (BeiDou, Galileo, GPS, IRNSS, and GLONASS) sometimes contain data for only parts of a constellation. This library's interpolation function will automatically try different providers until it finds the expected satellite.
• Ultra-rapid products (esu, igu, igv...), which include predicted positions, are not listed in the providers.

Format documentation

SP3-c https://files.igs.org/pub/data/format/sp3c.txt SP3-d https://gssc.esa.int/wp-content/uploads/2018/07/sp3d.pdf

Sources for satellites names, SP3 ids (PRN), and NORAD ids

BeiDou:

• http://www.csno-tarc.cn/en/system/constellation

Galileo:

• https://en.wikipedia.org/wiki/List_of_Galileo_satellites
• http://www.celestrak.com/Norad/elements/table.php?tleFile=galileo&title=Galileo%20Satellites

GPS:

• https://celestrak.com/NORAD/elements/table.php?tleFile=gps-ops&title=GPS%20Operational%20Satellites
• https://www.pulsesat.com/satellites

IRNSS:

• https://en.wikipedia.org/wiki/Indian_Regional_Navigation_Satellite_System

GLONASS:

• http://www.csno-tarc.cn/en/glonass/constellation
• https://celestrak.com/NORAD/elements/table.php?tleFile=glo-ops&title=GLONASS%20Operational%20Satellites

Tests and figures

• python3 test.py runs parsing tests.
• python3 plot_interpolation.py generates decimated polynomial interpolations graphs with errors (position only).
• python3 plot_velocities.py generates position and velocity graphs. Velocity is interpolated when velocity samples are available and is calculated from the position otherwise.
• python3 plot_window_to_error calculates the error on decimated samples for different polynomial window / polynomial degree combinations.

The output of plot scripts is saved to renders.

Contribute

Run black . to format the source code (see https://github.com/psf/black).

Run pyright . to check types (see https://github.com/microsoft/pyright).

Run python3 test.py to run unit tests.

Publish

rm -rf dist
python3 setup.py sdist
python3 -m twine upload dist/*