3.10 More tests and 360 min_west fix

models/soil.cc

@@ -0,0 +1,33 @@
+/*****************************************************************************
+*  Soil Path Loss model for Signal Server by Alex Farrant                    *
+*  21 February 2018                                                          *
+*                                                                            *
+*  This program is free software; you can redistribute it and/or modify it   *
+*  under the terms of the GNU General Public License as published by the     *
+*  Free Software Foundation; either version 2 of the License or any later    *
+*  version.                                                                  *
+*                                                                            *
+*  This program is distributed in the hope that it will useful, but WITHOUT  *
+*  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or     *
+*  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License     *
+*  for more details.                                                         *
+*
+* Frequency: Any MHz
+* Distance: Any Km
+* Terrain permittivity: 1 - 15 (Bad to Good)
+*/
+
+#include <math.h>
+
+// use call with log/ln as this may be faster
+// use constant of value 20.0/log(10.0)
+static __inline float _20log10f(float x)
+{
+  return(8.685889f*logf(x));
+}
+
+double SoilPathLoss(float f, float d, float terdic)
+{
+  float soil = (120/terdic);
+  return(6.4 + _20log10f(d) + _20log10f(f)+(8.69*soil));
+}