Source code for itmlogic.preparatory_subroutines.qlra

import math
import numpy as np

def qlra(kst, prop):
    """
    Preparatory subroutine for area prediction mode, as described in equations (3.1)-(3.4)
    of "The ITS Irregular Terrain Model, version 1.2.2: The Algorithm" and as a function of
    the siting criteria for the transmit and receive terminals described using 2 element
    array KST (0=random, 1= "with care", 2= "with great care").

    Parameters
    ----------
    kst : list
        Siting criteria for the transmitter and receiver.
    prop : dict
        Contains all input propagation parameters.

    Returns
    -------
    prop : dict
        Contains all input and output propagation parameters.

    """
    prop['he'] = [0, 0]
    prop['dl'] = [0, 0]
    prop['the'] = [0, 0]

    for j in range(0, 2):

        if kst[j] <= 0:

            prop['he'][j] = prop['hg'][j]
        else:
            q = 4

            if kst[j] != 1:
                q = 9

            if prop['hg'][j] < 5:
                q = q * math.sin(0.3141593 * prop['hg'][j])

            prop['he'][j] = (
                prop['hg'][j] + (1 + q) *
                math.exp(-min(20, 2 * prop['hg'][j] / max(1e-3, prop['dh'])))
                )

        q = np.sqrt(2 * prop['he'][j] / prop['gme'])

        prop['dl'][j] = (
            q * math.exp(-0.07 * np.sqrt(prop['dh'] /
            max(prop['he'][j], 5)))
            )

        prop['the'][j] = (
            (0.65 * prop['dh'] * (q / prop['dl'][j] - 1) -
            2 * prop['he'][j]) / q
            )

    prop['mdp'] = 1
    prop['lvar'] = max(prop['lvar'], 3)

    if prop['mdvarx'] >= 0:
        prop['mdvar'] = prop['mdvarx']
        prop['lvar'] = max(prop['lvar'], 4)

    if prop['klimx'] > 0:
        prop['klim'] = prop['klimx']
        prop['lvar'] = 5

    return prop