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calculation.c
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calculation.c
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#include <math.h>
#include <stdio.h>
#include <gtk/gtk.h>
//#define DEBUG
double fog_attenuation(double frequency, double T0, double visibility, double distance){
double M; // water content /[g/m³]
double theta;
double f_s;
double f_p;
double epsilon_0, epsilon_1,epsilon_2;
double epsilon_1_strich, epsilon_2_strich;
double eta;
double k_l;
double attenuation_fog; //Total fog attenuation
double f_f_p_square;
double f_f_s_square;
if (visibility < 0.01) {
visibility = 0.01;
}
M = pow( (0.024/visibility), 1.54);
#ifdef DEBUG
g_print("\n\rFog water content %3.3f g/m³\n\r",M);
#endif
theta = 300 / (273.15+T0);
f_p = 20.09 - 142 * (theta -1) + 294 * (theta - 1) * (theta - 1);
f_s = 590 - 1500 * (theta - 1);
epsilon_2 = 3.51;
epsilon_1 = 5.48;
epsilon_0 = 77.6 + 103.3 * (theta - 1);
f_f_p_square = pow((frequency/f_p),2);
f_f_s_square = pow((frequency/f_s),2);
epsilon_2_strich = ( frequency * ( epsilon_0-epsilon_1) / f_p / (1 + f_f_p_square ) ) + ( frequency * ( epsilon_1-epsilon_2) / f_s / (1 + f_f_s_square) );
epsilon_1_strich = ( ( epsilon_0-epsilon_1) / (1 + f_f_p_square ) ) + ( ( epsilon_1-epsilon_2) / (1 + f_f_s_square ) ) + epsilon_2;
eta = (2 + epsilon_1_strich) / epsilon_2_strich;
k_l = 0.819 * frequency / epsilon_2_strich / (1 + eta * eta);
#ifdef DEBUG
g_print("Specific fog attenuation %3.3f g/m³\n\r",k_l);
#endif
attenuation_fog = k_l * M * distance;
return attenuation_fog;
}
double rain_attenuation(double frequency, double rainfall, double distance){
double k_h_a[4] = {-5.33980,-0.35351,-0.23789,-0.94158};
double k_h_b[4] = {-0.10008,1.26970,0.86036,0.64552};
double k_h_c[4] = {1.13098,0.45400,0.15354,0.16817};
double k_h_m_k = -0.18961;
double k_h_c_k = 0.71147;
double a_h_a[5] ={-0.14318,0.29591,0.32177,-5.37610,16.1721};
double a_h_b[5] ={1.82442,0.77564,0.63773,-0.96230,-3.29980};
double a_h_c[5] ={-0.55187,0.19822,0.13164,1.47828,3.43990};
double a_h_m_a = 0.67849;
double a_h_c_a = -1.95537;
double k = 0;
double log_k = 0;
double alpha = 0;
double con1;
double con2;
double con3;
double attenuation_rain;
int j;
for (j = 0; j < 4;j ++){
con1 = (log10(frequency)-k_h_b[j]) / k_h_c[j];
con2 = -1.0 * pow(con1 ,2);
con3 = k_h_a[j] * exp (con2);
log_k = log_k + con3;
}
log_k = log_k + k_h_m_k * log10(frequency) + k_h_c_k;
k = pow(10,log_k);
for (j = 0; j < 5;j ++){
con1 = (log10(frequency)-a_h_b[j]) / a_h_c[j];
con2 = -1.0 * pow(con1 ,2);
con3 = a_h_a[j] * exp (con2);
alpha = alpha + con3;
}
alpha = alpha + a_h_m_a* log10(frequency) + a_h_c_a;
attenuation_rain = k * pow(rainfall,alpha) * distance;
return (attenuation_rain);
}
double oxygen_attenuation(double frequency, double distance){
double con1;
double con2;
double con3;
double gamma_0;
double attenuation_oxygen;
if( frequency < 53) {
con1 = 6.09 / ( frequency * frequency +0.277);
con2 = 4.81 / ( pow((frequency - 57),2) + 1.5 );
con3 = 0.00719 + con1 + con2;
gamma_0 = con3 * frequency * frequency * 0.001;
}
else
if( frequency > 63) {
con1 = 0.625 / ( pow((frequency - 63),2) + 1.59 );
con2 = 0.028 / ( pow((frequency - 118),2) + 1.47 );
con3 = 0.000000379 * frequency + con1 + con2;
gamma_0 = con3 * pow((frequency+198),2) * 0.001;
}
else {
gamma_0 = 14.9;
}
attenuation_oxygen = gamma_0 * distance;
return attenuation_oxygen;
}
double vapour_attenuation(double frequency, double temperature, double rel_humidity, double distance){
double con1;
double con2;
double con3;
double gamma_0;
double attenuation_vapour;
double W; //weight of water in saturted air[g/m³]
W = 4.85 + 0.33 * temperature + 0.01 * pow(temperature,2) + 0.00023 * pow(temperature,3);
W = W * rel_humidity/100.0;
con1 = 3.6 / ( pow((frequency - 22.2),2) + 8.5 );
con2 = 10.6 / ( pow((frequency - 183.3),2) + 9.0 );
con3 = 8.9 / ( pow((frequency - 325.4),2) + 26.3 );
gamma_0 = (0.05 + 0.0021 * W + con1 + con2 + con3) * W * frequency * frequency * 0.0001;
attenuation_vapour = gamma_0 * distance;
#ifdef DEBUG
g_print("Vapour attenuation %3.3f dB\n\r",attenuation_vapour);
#endif
return attenuation_vapour;
}