From dd6588d4f03f1a6bc365c92000427642731cfaa5 Mon Sep 17 00:00:00 2001
From: adrian <adrian@localhost.com>
Date: Sat, 26 Nov 2011 18:51:33 +0200
Subject: [PATCH] Use landcover to determine ground clutter path loss for LOS
modified: src/Radio/itm.cpp modified: src/Radio/radio.cxx
modified: src/Radio/radio.hxx
---
src/Radio/itm.cpp | 32 +++++--
src/Radio/radio.cxx | 223 ++++++++++++++++++++++++++++++++++++++++++--
src/Radio/radio.hxx | 8 +-
3 files changed, 248 insertions(+), 15 deletions(-)
diff --git a/src/Radio/itm.cpp b/src/Radio/itm.cpp
index 9c2f010fc..79360a201 100644
--- a/src/Radio/itm.cpp
+++ b/src/Radio/itm.cpp
@@ -1519,6 +1519,8 @@ void point_to_point(double elev[],
double rel, // 0.01 .. .99, Fractions of time
double &dbloss,
char *strmode,
+ int &p_mode, // propagation mode selector
+ double (&horizons)[2], // horizon distances
int &errnum)
{
// radio_climate: 1-Equatorial, 2-Continental Subtropical, 3-Maritime Tropical,
@@ -1568,22 +1570,38 @@ void point_to_point(double elev[],
fs = 32.45 + 20.0 * log10(frq_mhz) + 20.0 * log10(prop.d / 1000.0);
q = prop.d - prop.d_L;
+ horizons[0] = 0.0;
+ horizons[1] = 0.0;
if (int(q) < 0.0) {
strcpy(strmode, "Line-Of-Sight Mode");
+ p_mode = 0;
} else {
- if (int(q) == 0.0)
+ if (int(q) == 0.0) {
strcpy(strmode, "Single Horizon");
+ horizons[0] = prop.d_Lj[0];
+ p_mode = 1;
+ }
- else
- if (int(q) > 0.0)
+ else {
+ if (int(q) > 0.0) {
strcpy(strmode, "Double Horizon");
+ horizons[0] = prop.d_Lj[0];
+ horizons[1] = prop.d_Lj[1];
+ p_mode = 1;
+ }
+ }
- if (prop.d <= prop.d_Ls || prop.d <= prop.dx)
+ if (prop.d <= prop.d_Ls || prop.d <= prop.dx) {
strcat(strmode, ", Diffraction Dominant");
+ p_mode = 1;
+ }
- else
- if (prop.d > prop.dx)
- strcat(strmode, ", Troposcatter Dominant");
+ else {
+ if (prop.d > prop.dx) {
+ strcat(strmode, ", Troposcatter Dominant");
+ p_mode = 2;
+ }
+ }
}
dbloss = avar(zr, 0.0, zc, prop, propv) + fs;
diff --git a/src/Radio/radio.cxx b/src/Radio/radio.cxx
index fb73dffed..72fdb15d8 100644
--- a/src/Radio/radio.cxx
+++ b/src/Radio/radio.cxx
@@ -26,6 +26,7 @@
#include <stdlib.h>
#include <deque>
#include "radio.hxx"
+#include <simgear/scene/material/mat.hxx>
#include <Scenery/scenery.hxx>
#define WITH_POINT_TO_POINT 1
@@ -213,8 +214,11 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
double rel = 0.90;
double dbloss;
char strmode[150];
+ int p_mode = 0; // propgation mode selector: 0 LOS, 1 diffraction dominant, 2 troposcatter
+ double horizons[2];
int errnum;
+ double clutter_loss; // loss due to vegetation and urban
double tx_pow = _transmitter_power;
double ant_gain = _antenna_gain;
double signal = 0.0;
@@ -278,6 +282,8 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
double max_points = distance_m / point_distance;
deque<double> _elevations;
+ deque<string> materials;
+
double elevation_under_pilot = 0.0;
if (scenery->get_elevation_m( max_own_pos, elevation_under_pilot, NULL )) {
@@ -306,23 +312,39 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
while (_elevations.size() <= e_size) {
probe_distance += point_distance;
SGGeod probe = SGGeod::fromGeoc(center.advanceRadM( course, probe_distance ));
-
+ const SGMaterial *mat = 0;
double elevation_m = 0.0;
- if (scenery->get_elevation_m( probe, elevation_m, NULL )) {
+ if (scenery->get_elevation_m( probe, elevation_m, &mat )) {
if((transmission_type == 3) || (transmission_type == 4)) {
_elevations.push_back(elevation_m);
+ if(mat) {
+ const std::vector<string> mat_names = mat->get_names();
+ materials.push_back(mat_names[0]);
+ }
+ else {
+ materials.push_back("None");
+ }
}
else {
_elevations.push_front(elevation_m);
+ if(mat) {
+ const std::vector<string> mat_names = mat->get_names();
+ materials.push_front(mat_names[0]);
+ }
+ else {
+ materials.push_front("None");
+ }
}
}
else {
if((transmission_type == 3) || (transmission_type == 4)) {
- _elevations.push_back(elevation_m);
+ _elevations.push_back(0.0);
+ materials.push_back("None");
}
else {
- _elevations.push_front(0.0);
+ _elevations.push_front(0.0);
+ materials.push_front("None");
}
}
}
@@ -367,25 +389,205 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
// the sender and receiver roles are switched
point_to_point(itm_elev, receiver_height, transmitter_height,
eps_dielect, sgm_conductivity, eno, frq_mhz, radio_climate,
- pol, conf, rel, dbloss, strmode, errnum);
+ pol, conf, rel, dbloss, strmode, p_mode, horizons, errnum);
}
else {
point_to_point(itm_elev, transmitter_height, receiver_height,
eps_dielect, sgm_conductivity, eno, frq_mhz, radio_climate,
- pol, conf, rel, dbloss, strmode, errnum);
+ pol, conf, rel, dbloss, strmode, p_mode, horizons, errnum);
}
SG_LOG(SG_GENERAL, SG_BULK,
"ITM:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, " << strmode << ", Error: " << errnum);
cerr << "ITM:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, " << strmode << ", Error: " << errnum << endl;
+ clutterLoss(frq_mhz, distance_m, itm_elev, materials, transmitter_height, receiver_height, p_mode, horizons, clutter_loss);
+ cerr << "Clutter loss: " << clutter_loss << endl;
//if (errnum == 4) // if parameters are outside sane values for lrprop, the alternative method is used
// return -1;
- signal = link_budget - dbloss;
+ signal = link_budget - dbloss - clutter_loss;
return signal;
}
+/*** Calculate losses due to vegetation and urban clutter (WIP)
+* We are only worried about clutter loss, terrain influence
+* on the first Fresnel zone is calculated in the ITM functions
+***/
+void FGRadio::clutterLoss(double freq, double distance_m, double itm_elev[], deque<string> materials,
+ double transmitter_height, double receiver_height, int p_mode,
+ double horizons[], double &clutter_loss) {
+
+ if (p_mode == 0) { // LOS: take each point and see how clutter height affects first Fresnel zone
+ int j=1; // first point is TX elevation, last is RX elevation
+ for (int k=3;k < (int)itm_elev[0];k++) {
+
+ double clutter_height = 0.0; // clutter height hard-coded to 15 for now
+ double clutter_density = 0.0; // percent of reflected wave
+ get_material_properties(materials[j-1], clutter_height, clutter_density);
+ //cerr << "Clutter:: material: " << materials[j-1] << " height: " << clutter_height << ", density: " << clutter_density << endl;
+ double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m;
+ // First Fresnel radius
+ double frs_rad = 548 * sqrt( (j * itm_elev[1] * (itm_elev[0] - j) * itm_elev[1] / 1000000) / ( distance_m * freq / 1000) );
+ //cerr << "Clutter:: fresnel radius: " << frs_rad << endl;
+ //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
+
+ double min_elev = SGMiscd::min(itm_elev[2] + transmitter_height, itm_elev[(int)itm_elev[0] + 2] + receiver_height);
+ double d1 = j * itm_elev[1];
+ if (fabs(min_elev - itm_elev[2]) <= 0.0001)
+ d1 = (itm_elev[0] - j) * itm_elev[1];
+ double ray_height = (grad * d1) + min_elev;
+ //cerr << "Clutter:: ray height: " << ray_height << " ground height:" << itm_elev[k] << endl;
+ double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad;
+ double intrusion = fabs(clearance);
+ //cerr << "Clutter:: clearance: " << clearance << endl;
+ if (clearance >= 0) {
+ clutter_loss +=0.0;
+ }
+ else if (clearance < 0 && (intrusion < clutter_height)) {
+
+ clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * freq/100;
+ }
+ else if (clearance < 0 && (intrusion > clutter_height)) {
+ clutter_loss += clutter_density * (clutter_height / (frs_rad *2 ) ) * freq/100;
+ }
+ else {
+ clutter_loss += 0.0;
+ }
+ j++;
+ }
+
+ }
+ else if (p_mode == 1) { // diffraction
+
+ if (horizons[1] == 0.0) { // single horizon: same as above, except pass twice using the highest point
+
+ }
+ else { // double horizon: same as single horizon, except there are 3 segments
+
+ }
+ }
+ else if (p_mode == 2) { // troposcatter: use the first smooth earth horizon as mid point
+
+ }
+
+}
+
+/*** Material properties database
+* height: median clutter height
+* density: radiowave attenuation factor
+***/
+void FGRadio::get_material_properties(string mat_name, double &height, double &density) {
+
+ if(mat_name == "Landmass") {
+ height = 15.0;
+ density = 0.2;
+ }
+
+ else if(mat_name == "SomeSort") {
+ height = 15.0;
+ density = 0.2;
+ }
+
+ else if(mat_name == "Island") {
+ height = 15.0;
+ density = 0.2;
+ }
+ else if(mat_name == "Default") {
+ height = 15.0;
+ density = 0.2;
+ }
+ else if(mat_name == "EvergreenBroadCover") {
+ height = 20.0;
+ density = 0.2;
+ }
+ else if(mat_name == "EvergreenForest") {
+ height = 20.0;
+ density = 0.2;
+ }
+ else if(mat_name == "DeciduousBroadCover") {
+ height = 15.0;
+ density = 0.3;
+ }
+ else if(mat_name == "DeciduousForest") {
+ height = 15.0;
+ density = 0.3;
+ }
+ else if(mat_name == "MixedForestCover") {
+ height = 20.0;
+ density = 0.25;
+ }
+ else if(mat_name == "MixedForest") {
+ height = 15.0;
+ density = 0.25;
+ }
+ else if(mat_name == "RainForest") {
+ height = 25.0;
+ density = 0.55;
+ }
+ else if(mat_name == "EvergreenNeedleCover") {
+ height = 15.0;
+ density = 0.2;
+ }
+ else if(mat_name == "WoodedTundraCover") {
+ height = 5.0;
+ density = 0.15;
+ }
+ else if(mat_name == "DeciduousNeedleCover") {
+ height = 5.0;
+ density = 0.2;
+ }
+ else if(mat_name == "ScrubCover") {
+ height = 3.0;
+ density = 0.15;
+ }
+ else if(mat_name == "BuiltUpCover") {
+ height = 30.0;
+ density = 0.7;
+ }
+ else if(mat_name == "Urban") {
+ height = 30.0;
+ density = 0.7;
+ }
+ else if(mat_name == "Construction") {
+ height = 30.0;
+ density = 0.7;
+ }
+ else if(mat_name == "Industrial") {
+ height = 30.0;
+ density = 0.7;
+ }
+ else if(mat_name == "Port") {
+ height = 30.0;
+ density = 0.7;
+ }
+ else if(mat_name == "Town") {
+ height = 10.0;
+ density = 0.5;
+ }
+ else if(mat_name == "SubUrban") {
+ height = 10.0;
+ density = 0.5;
+ }
+ else if(mat_name == "CropWoodCover") {
+ height = 10.0;
+ density = 0.1;
+ }
+ else if(mat_name == "CropWood") {
+ height = 10.0;
+ density = 0.1;
+ }
+ else if(mat_name == "AgroForest") {
+ height = 10.0;
+ density = 0.1;
+ }
+ else {
+ height = 0.0;
+ density = 0.0;
+ }
+
+}
+
/*** implement simple LOS propagation model (WIP)
***/
double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmission_type) {
@@ -453,3 +655,10 @@ double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmiss
return signal;
}
+
+/*** Material properties database
+***/
+void FGRadio::set_material_properties() {
+
+
+}
diff --git a/src/Radio/radio.hxx b/src/Radio/radio.hxx
index 6f37a5201..d6cc77e82 100644
--- a/src/Radio/radio.hxx
+++ b/src/Radio/radio.hxx
@@ -23,7 +23,7 @@
#include <simgear/compiler.h>
#include <simgear/structure/subsystem_mgr.hxx>
-
+#include <deque>
#include <Main/fg_props.hxx>
#include <simgear/math/sg_geodesy.hxx>
@@ -43,10 +43,16 @@ private:
double _receiver_sensitivity;
double _transmitter_power;
double _antenna_gain;
+ std::map<string, double[2]> _mat_database;
int _propagation_model; /// 0 none, 1 round Earth, 2 ITM
double ITM_calculate_attenuation(SGGeod tx_pos, double freq, int ground_to_air);
double LOS_calculate_attenuation(SGGeod tx_pos, double freq, int ground_to_air);
+ void clutterLoss(double freq, double distance_m, double itm_elev[], std::deque<string> materials,
+ double transmitter_height, double receiver_height, int p_mode,
+ double horizons[], double &clutter_loss);
+ void set_material_properties();
+ void get_material_properties(string mat_name, double &height, double &density);
public: