ItuRPropagation (ITU-R Propagation v0.6.1)

Copy Markdown View Source

Pure Elixir implementation of ITU-R atmospheric propagation models for satellite link budget calculations.

This library implements the following ITU-R P-series recommendations:

  • P.676 - Gaseous attenuation (oxygen and water vapor absorption)
  • P.838 - Specific rain attenuation (power-law coefficients)
  • P.618 - Earth-space path rain attenuation
  • P.839 - Rain height model

These models are the international standard for predicting atmospheric propagation effects on satellite communication links.

Quick Start

For most link budget calculations, use total_atmospheric_attenuation/2:

ItuRPropagation.total_atmospheric_attenuation(
  frequency_ghz: 12.0,
  elevation_deg: 30.0,
  latitude_deg: 40.0,
  longitude_deg: -100.0,
  rain_rate_mmh: 25.0
)

This returns the total atmospheric attenuation in dB along with a breakdown by component (gaseous, rain, cloud, scintillation).

Individual Models

Each ITU-R recommendation is also available as a standalone module:

Summary

Types

attenuation_result()

Functions

total_atmospheric_attenuation(opts)

Compute total atmospheric attenuation for a satellite link.

Types

attenuation_result()

@type attenuation_result() :: %{
  total_db: float(),
  gaseous_db: float(),
  rain_db: float(),
  cloud_db: float(),
  scintillation_db: float()
}

Functions

total_atmospheric_attenuation(opts)

@spec total_atmospheric_attenuation(keyword()) :: attenuation_result()

Compute total atmospheric attenuation for a satellite link.

This is the primary entry point for link budget calculations. It combines gaseous attenuation (P.676), rain attenuation (P.618), and simplified cloud and scintillation models.

Options

  • :frequency_ghz - Frequency in GHz (required)
  • :elevation_deg - Elevation angle in degrees (required)
  • :latitude_deg - Earth station latitude in degrees (required)
  • :longitude_deg - Earth station longitude in degrees (required)
  • :rain_rate_mmh - Rain rate in mm/h for the desired exceedance probability (required)
  • :station_altitude_km - Earth station altitude above mean sea level in km (default: 0.0)
  • :water_vapor_density - Water vapor density in g/m^3 (default: 7.5)
  • :polarization - Polarization type: :horizontal, :vertical, or :circular (default: :circular)
  • :cloud_liquid_water - Integrated cloud liquid water content in kg/m^2 (default: 0.3)

Returns

A map with the following keys:

  • :total_db - Total atmospheric attenuation in dB
  • :gaseous_db - Gaseous attenuation component in dB
  • :rain_db - Rain attenuation component in dB
  • :cloud_db - Cloud attenuation component in dB
  • :scintillation_db - Scintillation component in dB

Examples

iex> result = ItuRPropagation.total_atmospheric_attenuation(
...>   frequency_ghz: 12.0,
...>   elevation_deg: 30.0,
...>   latitude_deg: 40.0,
...>   longitude_deg: -100.0,
...>   rain_rate_mmh: 25.0
...> )
iex> result.total_db > 0.0
true