satkit.events.gnd_access

Module for ground-based accesses and passes.

Classes

GroundPassList(search_interval, gnd_pos, ...)

Parameters associated with a list of "passes" (line-of-sight availability) over a ground location.
class GroundPassList(search_interval, gnd_pos, elev_mask, propagator, planet=None, refraction_model=None, az_el_timestep=<Quantity(60, 'second')>)[source]

Parameters associated with a list of “passes” (line-of-sight availability) over a ground location.

The constructor computes the pass properties given the search interval. A “pass” could be a satellite communications pass over a ground station or an observation opportunity for a ground observation station. The object then holds information such as pass duration, peak elevation time and value as well as azimuth-elevation-range list for multiple such passes or GroundPass objects.

This method is not limited to a ground location on Earth (as defined by the planet parameter). It uses the Orekit ElevationDetector to find the “elevation equal to elevation mask” events. However, the cases with “no events in the search interval” are handled correctly. The output is a TimeIntervalList which can then be intersected with another interval list, for example “ground location illuminated intervals”.

The method accepts both a fixed elevation mask or an ElevationMask with a complex mask shape.

The planet parameter can be any OneAxisEllipsoid with its own fixed frame. For example, Earth can be generated as follows:

itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, True)
earth = OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
                         Constants.WGS84_EARTH_FLATTENING,
                         itrf)

If the gnd_pos parameter is defined as a TopocentricFrame, then the optional planet parameter is ignored. Otherwise, it is set to Earth as given above.

Atmospheric Refraction Model should be set to None for communications applications. It can be set to EarthITU453AtmosphereRefraction or EarthStandardAtmosphereRefraction (provided by Orekit) for visual or optical applications.

Parameters

  • search_interval (TimeInterval) – Search interval for the “elevation events”

  • gnd_pos (org.orekit.bodies.GeodeticPoint | org.orekit.frames.TopocentricFrame) – Ground position in geodetic coordinates (or the topocentric frame associated with it)

  • elev_mask (float | pint.registry.Quantity | org.orekit.utils.ElevationMask) – Elevation mask, either a fixed value or a complex mask shape

  • propagator (Propagator) – Propagator to generate the trajectory of the satellite (or any other object)

  • planet (OneAxisEllipsoid) – The planet where the ground location is located. Defaults to WGS84 Earth.

  • refraction_model (AtmosphericRefractionModel) – Atmospheric Refraction Model, defaults to None

  • az_el_timestep – Stepsize for the azimuth-elevation-range list