itur package

Package contents

ITU-RPy is a python implementation of the ITU-P R Recommendations.

ITU-Rpy can be used to compute atmospheric attenuation for Earth-to-space and horizontal paths, for frequencies in the GHz range.

The propagation loss on an Earth-space path and a horizontal-path, relative to the free-space loss, is the sum of different contributions, namely:

  • attenuation by atmospheric gases;
  • attenuation by rain, other precipitation and clouds;
  • scintillation and multipath effects;
  • attenuation by sand and dust storms.

Each of these contributions has its own characteristics as a function of frequency, geographic location and elevation angle. ITU-Rpy allows for fast, vectorial computation of the different contributions to the atmospheric attenuation.

itur.atmospheric_attenuation_slant_path(lat, lon, f, el, p, D, hs=None, rho=None, R001=None, eta=0.5, T=None, H=None, P=None, hL=1000.0, Ls=None, tau=45, V_t=None, mode='approx', return_contributions=False, include_rain=True, include_gas=True, include_scintillation=True, include_clouds=True)[source]

Calculate long-term atmospheric attenuation statistics for slant paths.

This function provides estimates of the long-term statistics of the slant-path atmospheric attenuation at a given location, for frequencies up to 55 GHz and percentages of time 0.001% < p < 50%.

The model used is based on the guidelines provided in Section 2 of ITU-R P.618. If optional values are not provided they will be automatically computed using the procedures described in other ITU-R P. recommendations.

Parameters:
  • lat (number, sequence, or numpy.ndarray) – Latitudes of the receiver points
  • lon (number, sequence, or numpy.ndarray) – Longitudes of the receiver points
  • f (number or Quantity) – Frequency (GHz)
  • el (sequence, number or Quantity) – Elevation angle (degrees)
  • p (number) – Percentage of the time the rain attenuation value is exceeded.
  • D (number or Quantity) – Physical diameter of the earth-station antenna (m)
  • hs (number, sequence, or numpy.ndarray, optional) – Height above mean sea level of the earth station (km). If local data for the earth station height above mean sea level is not available, an estimate is obtained from the maps of topographic altitude given in Recommendation ITU-R P.1511.
  • rho (number or Quantity, optional) – Water vapor density (g/m3). If not provided, an estimate is obtained from Recommendation Recommendation ITU-R P.836.
  • R001 (number or Quantity, optional) –

    Point rainfall rate for the location for 0.01% of an average year (mm/h). If not provided, an estimate is obtained from Recommendation ITU-R P.837. Some useful values:

    • 0.25 mm/h : Drizzle
    • 2.5 mm/h : Light rain
    • 12.5 mm/h : Medium rain
    • 25.0 mm/h : Heavy rain
    • 50.0 mm/h : Downpour
    • 100 mm/h : Tropical
    • 150 mm/h : Monsoon
  • eta (number, optional) – Antenna efficiency. Default value 0.5 (conservative estimate)
  • T (number, sequence, or numpy.ndarray, optional) – Average surface ambient temperature (°C) at the site. If None, uses the ITU-R P.1510 to estimate the surface ambient temperature.
  • H (number, sequence, or numpy.ndarray, optional) – Average surface relative humidity (%) at the site. If None, uses the ITU-R P.836 to estimate the wet term of the surface relative humidity.
  • P (number, sequence, or numpy.ndarray, optional) – Average surface pressure (hPa) at the site. If None, uses the ITU-R P.835 to estimate the average surface pressure.
  • hL (number, optional) – Height of the turbulent layer (m). Default value 1000 m
  • Ls (number, optional) – Slant path length (km). If not provided, it will be computed using the rain height and the elevation angle. The ITU model does not require this parameter as an input.
  • tau (number, optional) – Polarization tilt angle relative to the horizontal (degrees) (tau = 45 deg for circular polarization). Default value is 45
  • V_t (number or Quantity, optional) – Integrated water vapour content along the path (kg/m2 or mm). If not provided this value is estimated using Recommendation ITU-R P.836. Default value None
  • mode (string, optional) – Mode for the calculation of gaseous attenuation. Valid values are ‘approx’, ‘exact’. If ‘approx’ Uses the method in Annex 2 of Recommendation ITU-R P.676, else uses the method described in Section 1. Default, ‘approx’
  • return_contributions (bool, optional) – Determines whether individual contributions from gases, rain, clouds and scintillation are returned in addition to the total attenuation (True), or just the total atmospheric attenuation (False). Default is False
  • include_rain (bool, optional) – Determines whether to include the rain contribution in the total atmospheric attenuation calculation or not. Default is True
  • include_gas (bool, optional) – Determines whether to include the gaseous contribution in the total atmospheric attenuation calculation or not. Default is True
  • include_scintillation (bool, optional) – Determines whether to include the scintillation contribution in the total atmospheric attenuation calculation or not. Default is True
  • include_clouds (bool, optional) – Determines whether to include the clouds contribution in the total atmospheric attenuation calculation or not. Default is True
Returns:

  • A (Quantity) – Total atmospheric attenuation (dB)
  • Ag, Ac, Ar, As, A (tuple) – Gaseous, Cloud, Rain, Scintillation contributions to total attenuation, and total attenuation (dB)

References

[1] Propagation data and prediction methods required for the design of Earth-space telecommunication systems: https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.618-12-201507-I!!PDF-E.pdf