propagation_model

propagation_model … end_propagation_model
propagation_model <derived-name> <base-name>
   ... Input for the propagation model ...
end_propagation_model

Overview

propagation_model is used to create configured propagations models that can be referenced in the propagation_model block in a transmitter definition.

<derived-name> is the name you wish your configured propagation model to be assigned. <derived-name> is the name by which the user wishes to refer to the configured propagation model. <base-name> is one of the Available Propagation Models:

Effective Use Of Propagation Models

A propagation model definition may be embedded directly in the definition of a radar. For example, assume you have a file called ‘ex_radar.txt’:

sensor EX_RADAR WSF_RADAR_SENSOR
   transmitter
      ... transmitter commands ...
      propagation_model fast_multipath
         ... fast_multipath model commands ...
      end_propagation_model
   end_transmitter
   receiver
      ... receiver commands ...
   end_receiver
end_sensor

The problem with this method is that one must modify the radar definition to change or eliminate the propagation model. In many production uses this is undesirable or infeasible. What would be more desirable is to provide a ‘default’ propagation model definition that can be overridden.

The new ‘ex_radar.txt’ would now contain:

# Define the 'default' propagation model
propagation_model EX_RADAR_PROPAGATION fast_multipath
   ... fast_multipath model commands ...
end_propagation_model

sensor EX_RADAR WSF_RADAR_SENSOR
   transmitter
      ... transmitter commands ...
      propagation_model EX_RADAR_PROPAGATION # References the propagation model symbolically
   end_transmitter
   receiver
      ... receiver commands ...
   end_receiver
end_sensor

Then to override the propagation model:

#include ex_radar.txt

# Provide a new definition that overrides the existing definition.
# This example now uses the none propagation model.

propagation_model EX_RADAR_PROPAGATION none
end_propagation_model

The radar model will use the last definition of EX_RADAR_PROPAGATION when it finally creates instances of the radar in the simulation.

Available Propagation Models

none

A ‘dummy’ propagation model that results in no effect.

propagation_model <derived-name> none end_propagation_model

fast_multipath

The ‘fast_multipath’ model is an implementation of the method defined in ‘Radar Range Performance Analysis, Lamont V. Blake, 1986, Artech House, Inc.’. It computes the effects of constructive or destructive interference due to the specular reflection of the signal off of a round, rough Earth. Two factors can be supplied to define the properties of the surface at the reflection point.

propagation_model <derived-name> fast_multipath
   soil_moisture_fraction ...
   surface_roughness ...
end_propagation_model
soil_moisture_fraction [ 0.0 .. 1.0 ]

Define the moisture content of the soil.

Default 0.15

surface_roughness <length-value>

Define the standard deviation of the variation in the height of the surface.

Default 3.0 meters

alarm

The alarm propagation model high-fidelity model from the ALARM radar model. It is available only in the non-exportable release. See ALARM Propagation Model Documentation (only present in the non-exportable release).

ground_wave_propagation

This is a special model that should only be used with WSF_SURFACE_WAVE_RADAR_SENSOR. Please refer to it for documentation.