Merge pull request #13 from NTIA/issue_11

Issue 11

dotnet/ITS.Propagation.EHata/IntermediateValues.cs

@@ -10,7 +10,7 @@ public static partial class EHata
         /// <summary>
         /// Intermediate values from EHata
         /// </summary>
-        public class IntermediateValues
+        public struct IntermediateValues
         {
             /// <summary>
             /// Breakpoint distance, in km

dotnet/ITS.Propagation.EHata/Properties/AssemblyInfo.cs

@@ -32,5 +32,5 @@
 // You can specify all the values or you can default the Build and Revision Numbers
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("3.1.0.0")]
-[assembly: AssemblyFileVersion("3.1.0.0")]
+[assembly: AssemblyVersion("3.2.0.0")]
+[assembly: AssemblyFileVersion("3.2.0.0")]

dotnet/nuget/ExtendedHata.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>ExtendedHata</id>
-    <version>3.1.0</version>
+    <version>3.2.0</version>
     <authors>The Institute for Telecommunication Sciences</authors>
     <owners>The Institute for Telecommunication Sciences</owners>
     <license type="file">LICENSE.md</license>

src/IsolatedRidgeCorrectionFactor.cpp

@@ -16,25 +16,48 @@ double IsolatedRidgeCorrectionFactor(double d1_hzn__km, double d2_hzn__km, doubl
     double d_1__km[3] = { 15.0, 30.0, 60.0 };
     double d_2__km[9] = { 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
 
-    // points from Figure 31, Okumura
+    // points from Figure 31, Okumura, at corresponding d2 distances
     double curve_data[3][9] =
             { {  4.0, -13.0, -17.5, -17.5, -15.0, -12.5, -10.0, -8.0, -6.0 },   // C curve : d1 <= 15 km
               { 12.0,  -8.5, -13.0, -12.0, -10.0,  -8.0,  -6.5, -5.0, -4.0 },   // B curve : d1 <= 30 km
               { 20.0,  -4.0,  -6.5,  -6.0,  -4.5,  -3.5,  -2.5, -2.0, -1.0 } }; // A curve : d1 <= 60 km
 
     // normalized ridge height factor
-    double alpha = sqrt(h_edge__meter / 200.0); // Eq 1, Okumura, alpha = 0.07 * sqrt(h)
+    // Eq 1, Okumura, alpha = 0.07 * sqrt(h)
+    //   Note: 0.07 is approx sqrt (1/ 200), with 200 being the normalization height
+    double alpha = sqrt(h_edge__meter / 200.0);
 
+    // identify the d1 curve set to use
     int id1 = 0;
     if (d1_hzn__km >= d_1__km[1])
         id1 = 1;
-    int id2 = 0;
 
+    // select the first d2 curve distance that is <= to actual path d2 distance
+    int id2 = 0;
     while (id2 < 7 && d2_hzn__km > d_2__km[id2 + 1])
         id2 = id2 + 1;
 
+    // c1 is value on "lower" curve in Figure 31, Okumura, relative to d1 - either curve B or C
+    // c2 is value on "upper" curve in Figure 31, Okumura, relative to d1 - either curve A or B
     double c1 = curve_data[id1][id2] + (curve_data[id1][id2 + 1] - curve_data[id1][id2]) * (d2_hzn__km - d_2__km[id2]) / (d_2__km[id2 + 1] - d_2__km[id2]);
     double c2 = curve_data[id1 + 1][id2] + (curve_data[id1 + 1][id2 + 1] - curve_data[id1 + 1][id2]) * (d2_hzn__km - d_2__km[id2]) / (d_2__km[id2 + 1] - d_2__km[id2]);
 
-    return alpha * (c1 + (c2 - c1) * (d1_hzn__km - d_1__km[id1]) / (d_1__km[id1 + 1] - d_1__km[id1]));
+    // compute isolated ridge correction factor, K_im, from Figure 31, Okumura
+    double K_im;
+    if (d1_hzn__km <= 15)       // clamp to curve C
+        K_im = c1;
+    else if (d1_hzn__km >= 60)  // clamp to curve A
+        K_im = c2;
+    else                        // interpolate between curves
+        K_im = (c1 + (c2 - c1) * (d1_hzn__km - d_1__km[id1]) / (d_1__km[id1 + 1] - d_1__km[id1]));
+
+    // clamp K_im asymptote value to 0 dB (to avoid causing a non-physical gain from occuring)
+    // allow the gain to occur for portion of the curve with d2 distances close to or equal to 0 km
+    if (d2_hzn__km > 2)
+        K_im = MIN(K_im, 0);
+
+    // apply conversion factor to account for ridge height, Figure 32, Okumura
+    double L_iso__db = alpha * K_im;
+
+    return L_iso__db;
 }

win32/ehata/ehata.rc

@@ -51,8 +51,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 3,1,0,0
- PRODUCTVERSION 3,1,0,0
+ FILEVERSION 3,2,0,0
+ PRODUCTVERSION 3,2,0,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -69,11 +69,11 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "The Institute for Telecommunication Sciences"
             VALUE "FileDescription", "Extended Hata Urban Propagation Model (EHata)"
-            VALUE "FileVersion", "3.1.0.0"
+            VALUE "FileVersion", "3.2.0.0"
             VALUE "InternalName", "ehata.dll"
             VALUE "OriginalFilename", "ehata.dll"
             VALUE "ProductName", "Extended Hata Urban Propagation Model (EHata)"
-            VALUE "ProductVersion", "3.1.0.0"
+            VALUE "ProductVersion", "3.2.0.0"
         END
     END
     BLOCK "VarFileInfo"