From dd6588d4f03f1a6bc365c92000427642731cfaa5 Mon Sep 17 00:00:00 2001 From: adrian 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 #include #include "radio.hxx" +#include #include #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 _elevations; + deque 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 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 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 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 #include - +#include #include
#include @@ -43,10 +43,16 @@ private: double _receiver_sensitivity; double _transmitter_power; double _antenna_gain; + std::map _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 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: -- 2.39.5