gnssr4water.fresnel.fresnelzone module#

To compute and show the first Fresnel Zone.

@author: Lubin Roineau, ENSG-Geomatics (internship at UT-ITC Enschede), Aug 26, 2022 Modified/rewritten R.Rietbroek, March-June 2024

gnssr4water.fresnel.fresnelzone.elev_from_radius(radius, antennaHeight, wavelength=0.19029367279836487)#

Retrieve the elevation angles associated with the radial distances of the centroids of the first Fresnel ellipses

gnssr4water.fresnel.fresnelzone.firstFresnelZone(GNSSlambda, h, elev)#

This function gets the size and center of the First Fresnel Zone ellipse. (based on a code by Kristine Larson and Carolyn Roesler).

Parameters:

  • GNSSlambda (float) – wavelength of the GNSS signal

  • h (float) – Hight of the receiver in meters.

  • elev (float array_like) – Satellite elevation angle in degrees.

Returns:

  • a (float) – Semi-major axis, aligned with the satellite azimuth (meters).

  • b (float) – Semi-minor axis (meters).

  • R (float) – Locates the center of the ellispe on the satellite azimuth direction and R meters away from the base of the Antenna.

  • area (float) – Area of the elliptical first Fresnel zone

gnssr4water.fresnel.fresnelzone.fresnelZones(elev, azim, lon, lat, orthoHeight, antennaHeight, GNSSWavelength=0.19029367279836487, npoints=100)#

Compute Fresnel zones (center, and ellipses from satellite positions, geographical location, antenna height, and GNSS wavelength returns a geopandas dataframe Fresnel zones and properties

gnssr4water.fresnel.fresnelzone.generate_enu_ellipses(a, b, R, azim, npoints=100)#
gnssr4water.fresnel.fresnelzone.plotEllipse(a, b, R, lon, lat, h, azim)#

Create an ellipse of a Fresnel zone.

Parameters:

  • a (float) – Semi-major axis, aligned with the satellite azimuth (meters).

  • b (float) – Semi-minor axis (meters).

  • R (float) – Locates the center of the ellispe on the satellite azimuth direction and R meters away from the base of the Antenna.

  • lon (float) – Position of the receiver in geographical coordinates (degrees).

  • lat (float) – Position of the receiver in geographical coordinates (degrees).

  • h (float) – Hight of the receiver in meters.

  • azim (float) – Given azimut of ellipse in degrees.

Returns:

  • p (Polygon) – Polygon of the ellipse.

  • area (float) – Area of the Polygon in square meter.

gnssr4water.fresnel.fresnelzone.specularPoint(a, b, R, azim, color=None)#

This function just return the center of an ellipse, i.e the reflection point.

Parameters:

  • a (float) – Semi-major axis, aligned with the satellite azimuth (meters).

  • b (float) – Semi-minor axis (meters).

  • R (float) – Locates the center of the ellispe on the satellite azimuth direction and R meters away from the base of the Antenna.

  • azim (list) – List of azimuths

  • color (String (optional)) – Color of center points.

Return type:

Plot of center of ellipses.