ITM (Irregular Terrain Model) propagation model

This directory holds a Python extension module of the ITS Irregular Terrain Model.

The ITM model is described in details in the documentation found in subfolder its/original/docs.

The its/ folder contains the C++ implementation (itself derived from the reference Fortran implementation), with only minimal modifications.

A simple python wrapper itm.py is provided for defining the model interface.

Interface

The entry point is the routine point_to_point(). See the python wrapper itm.py for a complete description of input/output parameters.

There are only a few changes compared to the original ITM code:

the core implementation has been extended with a new point_to_point_rels() routine, which takes an array of reliabilities and returns an array of path losses. This is useful for efficient computation of the mean and inverse CDF.
point_to_point() routine takes the extra mdvar parameter as to allow for specializing this parameter in WinnForum. This parameter is by default set to 12 which is the default value in the original ITM code. Value 13 shall be used for the WinnForum implementation.
point_to_point() routine also takes the extra eno_is_final boolean parameter, which is by default set to False. When set to True, the code dealing with refractivity calculation replicates the logic found in the original Fortran code, which has been lost during the Fortran->C++ port (namely to allow specifying a final refractivity 'eno' with no compensation by altitude). In particular this allows to run the original ITS test set as originally intended.

To run the original ITS test set, first compile le python extension module, then run the itm_test.py module:

`python itm_test.py`

Warning: The ITS ITM implementation is not thread-safe as it extensively uses global variables. Do not try to run several calculation in parallel.