Merge branch 'radio-clutter' into attenuation
This commit is contained in:
adrian
commit
8184c290cc
4 changed files with 550 additions and 93 deletions
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@ -746,7 +746,7 @@ void FGATCController::transmit(FGTrafficRecord * rec, FGAirportDynamics *parent,
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if( fgGetBool( "/sim/radio/use-itm-attenuation", false ) ) {
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//cerr << "Using ITM radio propagation" << endl;
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FGRadio* radio = new FGRadio();
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FGRadioTransmission* radio = new FGRadioTransmission();
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SGGeod sender_pos;
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double sender_alt_ft, sender_alt;
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if(ground_to_air) {
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@ -1519,6 +1519,8 @@ void point_to_point(double elev[],
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double rel, // 0.01 .. .99, Fractions of time
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double &dbloss,
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char *strmode,
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int &p_mode, // propagation mode selector
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double (&horizons)[2], // horizon distances
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int &errnum)
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{
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// radio_climate: 1-Equatorial, 2-Continental Subtropical, 3-Maritime Tropical,
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@ -1568,22 +1570,38 @@ void point_to_point(double elev[],
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fs = 32.45 + 20.0 * log10(frq_mhz) + 20.0 * log10(prop.d / 1000.0);
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q = prop.d - prop.d_L;
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horizons[0] = 0.0;
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horizons[1] = 0.0;
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if (int(q) < 0.0) {
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strcpy(strmode, "Line-Of-Sight Mode");
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p_mode = 0;
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} else {
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if (int(q) == 0.0)
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if (int(q) == 0.0) {
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strcpy(strmode, "Single Horizon");
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horizons[0] = prop.d_Lj[0];
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p_mode = 1;
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}
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else
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if (int(q) > 0.0)
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else {
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if (int(q) > 0.0) {
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strcpy(strmode, "Double Horizon");
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horizons[0] = prop.d_Lj[0];
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horizons[1] = prop.d_Lj[1];
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p_mode = 1;
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}
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}
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if (prop.d <= prop.d_Ls || prop.d <= prop.dx)
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if (prop.d <= prop.d_Ls || prop.d <= prop.dx) {
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strcat(strmode, ", Diffraction Dominant");
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p_mode = 1;
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}
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else
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if (prop.d > prop.dx)
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strcat(strmode, ", Troposcatter Dominant");
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else {
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if (prop.d > prop.dx) {
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strcat(strmode, ", Troposcatter Dominant");
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p_mode = 2;
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}
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}
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}
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dbloss = avar(zr, 0.0, zc, prop, propv) + fs;
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@ -23,26 +23,23 @@
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#endif
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#include <math.h>
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#include <stdlib.h>
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#include <deque>
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#include "radio.hxx"
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#include <simgear/scene/material/mat.hxx>
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#include <Scenery/scenery.hxx>
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#define WITH_POINT_TO_POINT 1
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#include "itm.cpp"
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FGRadio::FGRadio() {
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FGRadioTransmission::FGRadioTransmission() {
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/** radio parameters (which should probably be set for each radio) */
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_receiver_sensitivity = -110.0; // typical AM receiver sensitivity seems to be 0.8 microVolt at 12dB SINAD
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/** AM transmitter power in dBm.
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* Note this value is calculated from the typical final transistor stage output
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* small aircraft have portable transmitters which operate at 36 dBm output (4 Watts) others operate in the range 10-20 W
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* later possibly store this value in aircraft description
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* ATC comms usually operate high power equipment, thus making the link asymetrical; this is taken care of in propagation routines
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* Typical output powers for ATC ground equipment, VHF-UHF:
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* 40 dBm - 10 W (ground, clearance)
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* 44 dBm - 20 W (tower)
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@ -52,20 +49,27 @@ FGRadio::FGRadio() {
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**/
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_transmitter_power = 43.0;
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/** pilot plane's antenna gain + AI aircraft antenna gain
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* real-life gain for conventional monopole/dipole antenna
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**/
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_antenna_gain = 2.0;
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_propagation_model = 2; // choose between models via option: realistic radio on/off
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_tx_antenna_height = 2.0; // TX antenna height above ground level
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_rx_antenna_height = 2.0; // RX antenna height above ground level
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_rx_antenna_gain = 1.0; // gain expressed in dBi
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_tx_antenna_gain = 1.0;
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_rx_line_losses = 2.0; // to be configured for each station
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_tx_line_losses = 2.0;
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_propagation_model = 2;
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_terrain_sampling_distance = fgGetDouble("/sim/radio/sampling-distance", 90.0); // regular SRTM is 90 meters
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}
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FGRadio::~FGRadio()
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FGRadioTransmission::~FGRadioTransmission()
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{
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}
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double FGRadio::getFrequency(int radio) {
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double FGRadioTransmission::getFrequency(int radio) {
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double freq = 118.0;
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switch (radio) {
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case 1:
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@ -83,13 +87,13 @@ double FGRadio::getFrequency(int radio) {
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/*** TODO: receive multiplayer chat message and voice
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***/
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void FGRadio::receiveChat(SGGeod tx_pos, double freq, string text, int ground_to_air) {
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void FGRadioTransmission::receiveChat(SGGeod tx_pos, double freq, string text, int ground_to_air) {
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}
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/*** TODO: receive navaid
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***/
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double FGRadio::receiveNav(SGGeod tx_pos, double freq, int transmission_type) {
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double FGRadioTransmission::receiveNav(SGGeod tx_pos, double freq, int transmission_type) {
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// typical VOR/LOC transmitter power appears to be 200 Watt ~ 53 dBm
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// vor/loc typical sensitivity between -107 and -101 dBm
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@ -107,13 +111,19 @@ double FGRadio::receiveNav(SGGeod tx_pos, double freq, int transmission_type) {
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/*** Receive ATC radio communication as text
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***/
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void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_air) {
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void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_air) {
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if(ground_to_air == 1) {
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_transmitter_power += 6.0;
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_tx_antenna_height += 30.0;
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_tx_antenna_gain += 3.0;
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}
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double comm1 = getFrequency(1);
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double comm2 = getFrequency(2);
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if ( !(fabs(freq - comm1) <= 0.0001) && !(fabs(freq - comm2) <= 0.0001) ) {
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//cerr << "Frequency not tuned: " << freq << " Radio1: " << comm1 << " Radio2: " << comm2 << endl;
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return;
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}
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else {
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@ -125,13 +135,10 @@ void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_
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// TODO: free space, round earth
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double signal = LOS_calculate_attenuation(tx_pos, freq, ground_to_air);
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if (signal <= 0.0) {
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SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
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//cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
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return;
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}
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else {
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SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
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//cerr << "Signal completely readable: " << signal << endl;
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fgSetString("/sim/messages/atc", text.c_str());
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/** write signal strength above threshold to the property tree
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* to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
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@ -143,8 +150,6 @@ void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_
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// Use ITM propagation model
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double signal = ITM_calculate_attenuation(tx_pos, freq, ground_to_air);
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if (signal <= 0.0) {
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SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
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//cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
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return;
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}
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if ((signal > 0.0) && (signal < 12.0)) {
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@ -174,8 +179,6 @@ void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_
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fgSetDouble("/sim/sound/voices/voice/volume", old_volume);
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}
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else {
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SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
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//cerr << "Signal completely readable: " << signal << endl;
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fgSetString("/sim/messages/atc", text.c_str());
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/** write signal strength above threshold to the property tree
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* to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
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@ -192,7 +195,7 @@ void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_
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/*** Implement radio attenuation
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based on the Longley-Rice propagation model
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***/
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double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmission_type) {
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double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, int transmission_type) {
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@ -213,19 +216,17 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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double rel = 0.90;
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double dbloss;
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char strmode[150];
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int p_mode = 0; // propgation mode selector: 0 LOS, 1 diffraction dominant, 2 troposcatter
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double horizons[2];
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int errnum;
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double clutter_loss = 0.0; // loss due to vegetation and urban
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double tx_pow = _transmitter_power;
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double ant_gain = _antenna_gain;
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double ant_gain = _rx_antenna_gain + _tx_antenna_gain;
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double signal = 0.0;
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if(transmission_type == 1)
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tx_pow = _transmitter_power + 6.0;
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if((transmission_type == 1) || (transmission_type == 3))
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ant_gain = _antenna_gain + 3.0; //pilot plane's antenna gain + ground station antenna gain
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double link_budget = tx_pow - _receiver_sensitivity + ant_gain;
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double link_budget = tx_pow - _receiver_sensitivity - _rx_line_losses - _tx_line_losses + ant_gain;
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FGScenery * scenery = globals->get_scenery();
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@ -242,11 +243,7 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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SGGeoc center = SGGeoc::fromGeod( max_own_pos );
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SGGeoc own_pos_c = SGGeoc::fromGeod( own_pos );
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/** position of sender radio antenna (HAAT)
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sender can be aircraft or ground station
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**/
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double ATC_HAAT = 30.0;
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double Aircraft_HAAT = 5.0;
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double sender_alt_ft,sender_alt;
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double transmitter_height=0.0;
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double receiver_height=0.0;
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@ -258,7 +255,7 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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SGGeoc sender_pos_c = SGGeoc::fromGeod( sender_pos );
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//cerr << "ITM:: sender Lat: " << parent->getLatitude() << ", Lon: " << parent->getLongitude() << ", Alt: " << sender_alt << endl;
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double point_distance= 90.0; // regular SRTM is 90 meters
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double point_distance= _terrain_sampling_distance;
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double course = SGGeodesy::courseRad(own_pos_c, sender_pos_c);
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double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
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double probe_distance = 0.0;
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@ -276,12 +273,16 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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}
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double max_points = distance_m / point_distance;
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int max_points = (int)floor(distance_m / point_distance);
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double delta_last = fmod(distance_m, point_distance);
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deque<double> _elevations;
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deque<string> materials;
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double elevation_under_pilot = 0.0;
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if (scenery->get_elevation_m( max_own_pos, elevation_under_pilot, NULL )) {
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receiver_height = own_alt - elevation_under_pilot + 3; //assume antenna located 3 meters above ground
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receiver_height = own_alt - elevation_under_pilot;
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}
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double elevation_under_sender = 0.0;
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@ -292,47 +293,65 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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transmitter_height = sender_alt;
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}
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if(transmission_type == 1)
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transmitter_height += ATC_HAAT;
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else
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transmitter_height += Aircraft_HAAT;
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transmitter_height += _tx_antenna_height;
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receiver_height += _rx_antenna_height;
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SG_LOG(SG_GENERAL, SG_BULK,
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"ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters");
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//cerr << "ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters" << endl;
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cerr << "ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters" << endl;
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unsigned int e_size = (deque<unsigned>::size_type)max_points;
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while (_elevations.size() <= e_size) {
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probe_distance += point_distance;
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SGGeod probe = SGGeod::fromGeoc(center.advanceRadM( course, probe_distance ));
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const SGMaterial *mat = 0;
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double elevation_m = 0.0;
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if (scenery->get_elevation_m( probe, elevation_m, NULL )) {
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if (scenery->get_elevation_m( probe, elevation_m, &mat )) {
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if((transmission_type == 3) || (transmission_type == 4)) {
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_elevations.push_back(elevation_m);
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if(mat) {
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const std::vector<string> mat_names = mat->get_names();
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materials.push_back(mat_names[0]);
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}
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else {
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materials.push_back("None");
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}
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}
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else {
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_elevations.push_front(elevation_m);
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if(mat) {
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const std::vector<string> mat_names = mat->get_names();
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materials.push_front(mat_names[0]);
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}
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else {
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materials.push_front("None");
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}
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}
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}
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else {
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if((transmission_type == 3) || (transmission_type == 4)) {
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_elevations.push_back(elevation_m);
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_elevations.push_back(0.0);
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materials.push_back("None");
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}
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else {
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_elevations.push_front(0.0);
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_elevations.push_front(0.0);
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materials.push_front("None");
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}
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}
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}
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if((transmission_type == 3) || (transmission_type == 4)) {
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_elevations.push_front(elevation_under_pilot);
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_elevations.push_back(elevation_under_sender);
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if (delta_last > (point_distance / 2) ) // only add last point if it's farther than half point_distance
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_elevations.push_back(elevation_under_sender);
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}
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else {
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_elevations.push_back(elevation_under_pilot);
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_elevations.push_front(elevation_under_sender);
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if (delta_last > (point_distance / 2) )
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_elevations.push_front(elevation_under_sender);
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}
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@ -344,7 +363,7 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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}
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double num_points= (double)_elevations.size();
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//cerr << "ITM:: Max alt between: " << max_alt_between << ", num points:" << num_points << endl;
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_elevations.push_front(point_distance);
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_elevations.push_front(num_points -1);
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int size = _elevations.size();
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@ -354,41 +373,447 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq, int transmiss
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//cerr << "ITM:: itm_elev: " << _elevations[i] << endl;
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}
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/** first Fresnel zone radius
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frequency in the middle of the bandplan, more accuracy is not necessary
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*/
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double fz_clr= 8.657 * sqrt(distance_m / 0.125);
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// TODO: If we clear the first Fresnel zone, we are into line of sight territory
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// else we need to calculate point to point link loss
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if((transmission_type == 3) || (transmission_type == 4)) {
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// the sender and receiver roles are switched
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point_to_point(itm_elev, receiver_height, transmitter_height,
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eps_dielect, sgm_conductivity, eno, frq_mhz, radio_climate,
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pol, conf, rel, dbloss, strmode, errnum);
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pol, conf, rel, dbloss, strmode, p_mode, horizons, errnum);
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if( fgGetBool( "/sim/radio/use-clutter-attenuation", false ) )
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clutterLoss(frq_mhz, distance_m, itm_elev, materials, receiver_height, transmitter_height, p_mode, horizons, clutter_loss);
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}
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else {
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point_to_point(itm_elev, transmitter_height, receiver_height,
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eps_dielect, sgm_conductivity, eno, frq_mhz, radio_climate,
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pol, conf, rel, dbloss, strmode, errnum);
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pol, conf, rel, dbloss, strmode, p_mode, horizons, errnum);
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if( fgGetBool( "/sim/radio/use-clutter-attenuation", false ) )
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clutterLoss(frq_mhz, distance_m, itm_elev, materials, transmitter_height, receiver_height, p_mode, horizons, clutter_loss);
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}
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SG_LOG(SG_GENERAL, SG_BULK,
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"ITM:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, " << strmode << ", Error: " << errnum);
|
||||
cerr << "ITM:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, " << strmode << ", Error: " << errnum << endl;
|
||||
|
||||
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 FGRadioTransmission::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) {
|
||||
|
||||
distance_m = itm_elev[0] * itm_elev[1]; // only consider elevation points
|
||||
|
||||
if (p_mode == 0) { // LOS: take each point and see how clutter height affects first Fresnel zone
|
||||
int mat = 0;
|
||||
int j=1;
|
||||
for (int k=3;k < (int)(itm_elev[0]) + 2;k++) {
|
||||
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
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) );
|
||||
|
||||
//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 ((itm_elev[2] + transmitter_height) > ( itm_elev[(int)itm_elev[0] + 2] + receiver_height) ) {
|
||||
d1 = (itm_elev[0] - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
mat++;
|
||||
}
|
||||
|
||||
}
|
||||
else if (p_mode == 1) { // diffraction
|
||||
|
||||
if (horizons[1] == 0.0) { // single horizon: same as above, except pass twice using the highest point
|
||||
int num_points_1st = (int)floor( horizons[0] * itm_elev[0]/ distance_m );
|
||||
int num_points_2nd = (int)ceil( (distance_m - horizons[0]) * itm_elev[0] / distance_m );
|
||||
//cerr << "Diffraction 1 horizon:: points1: " << num_points_1st << " points2: " << num_points_2nd << endl;
|
||||
int last = 1;
|
||||
/** perform the first pass */
|
||||
int mat = 0;
|
||||
int j=1;
|
||||
for (int k=3;k < num_points_1st + 2;k++) {
|
||||
if (num_points_1st < 1)
|
||||
break;
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m;
|
||||
// First Fresnel radius
|
||||
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) );
|
||||
|
||||
//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[num_points_1st + 2] + clutter_height);
|
||||
double d1 = j * itm_elev[1];
|
||||
if ( (itm_elev[2] + transmitter_height) > (itm_elev[num_points_1st + 2] + clutter_height) ) {
|
||||
d1 = (num_points_1st - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
mat++;
|
||||
last = k;
|
||||
}
|
||||
|
||||
/** and the second pass */
|
||||
mat +=1;
|
||||
j =1; // first point is diffraction edge, 2nd the RX elevation
|
||||
for (int k=last+2;k < (int)(itm_elev[0]) + 2;k++) {
|
||||
if (num_points_2nd < 1)
|
||||
break;
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
double grad = fabs(itm_elev[last+1] + clutter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m;
|
||||
// First Fresnel radius
|
||||
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) );
|
||||
|
||||
//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[last+1] + clutter_height, itm_elev[(int)itm_elev[0] + 2] + receiver_height);
|
||||
double d1 = j * itm_elev[1];
|
||||
if ( (itm_elev[last+1] + clutter_height) > (itm_elev[(int)itm_elev[0] + 2] + receiver_height) ) {
|
||||
d1 = (num_points_2nd - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
mat++;
|
||||
}
|
||||
|
||||
}
|
||||
else { // double horizon: same as single horizon, except there are 3 segments
|
||||
|
||||
int num_points_1st = (int)floor( horizons[0] * itm_elev[0] / distance_m );
|
||||
int num_points_2nd = (int)floor(horizons[1] * itm_elev[0] / distance_m );
|
||||
int num_points_3rd = (int)itm_elev[0] - num_points_1st - num_points_2nd;
|
||||
//cerr << "Double horizon:: horizon1: " << horizons[0] << " horizon2: " << horizons[1] << " distance: " << distance_m << endl;
|
||||
//cerr << "Double horizon:: points1: " << num_points_1st << " points2: " << num_points_2nd << " points3: " << num_points_3rd << endl;
|
||||
int last = 1;
|
||||
/** perform the first pass */
|
||||
int mat = 0;
|
||||
int j=1; // first point is TX elevation, 2nd is obstruction elevation
|
||||
for (int k=3;k < num_points_1st +2;k++) {
|
||||
if (num_points_1st < 1)
|
||||
break;
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m;
|
||||
// First Fresnel radius
|
||||
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) );
|
||||
|
||||
//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[num_points_1st + 2] + clutter_height);
|
||||
double d1 = j * itm_elev[1];
|
||||
if ( (itm_elev[2] + transmitter_height) > (itm_elev[num_points_1st + 2] + clutter_height) ) {
|
||||
d1 = (num_points_1st - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
last = k;
|
||||
}
|
||||
mat +=1;
|
||||
/** and the second pass */
|
||||
int last2=1;
|
||||
j =1; // first point is 1st obstruction elevation, 2nd is 2nd obstruction elevation
|
||||
for (int k=last+2;k < num_points_1st + num_points_2nd +2;k++) {
|
||||
if (num_points_2nd < 1)
|
||||
break;
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
double grad = fabs(itm_elev[last+1] + clutter_height - itm_elev[num_points_1st + num_points_2nd + 2] + clutter_height) / distance_m;
|
||||
// First Fresnel radius
|
||||
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) );
|
||||
|
||||
//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[last+1] + clutter_height, itm_elev[num_points_1st + num_points_2nd +2] + clutter_height);
|
||||
double d1 = j * itm_elev[1];
|
||||
if ( (itm_elev[last+1] + clutter_height) > (itm_elev[num_points_1st + num_points_2nd + 2] + clutter_height) ) {
|
||||
d1 = (num_points_2nd - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
mat++;
|
||||
last2 = k;
|
||||
}
|
||||
|
||||
/** third and final pass */
|
||||
mat +=1;
|
||||
j =1; // first point is 2nd obstruction elevation, 3rd is RX elevation
|
||||
for (int k=last2+2;k < (int)itm_elev[0] + 2;k++) {
|
||||
if (num_points_3rd < 1)
|
||||
break;
|
||||
double clutter_height = 0.0; // mean clutter height for a certain terrain type
|
||||
double clutter_density = 0.0; // percent of reflected wave
|
||||
get_material_properties(materials[mat], clutter_height, clutter_density);
|
||||
|
||||
double grad = fabs(itm_elev[last2+1] + clutter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m;
|
||||
// First Fresnel radius
|
||||
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_3rd - j) * itm_elev[1] / 1000000) / ( num_points_3rd * itm_elev[1] * freq / 1000) );
|
||||
|
||||
|
||||
//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[last2+1] + clutter_height, itm_elev[(int)itm_elev[0] + 2] + receiver_height);
|
||||
double d1 = j * itm_elev[1];
|
||||
if ( (itm_elev[last2+1] + clutter_height) > (itm_elev[(int)itm_elev[0] + 2] + receiver_height) ) {
|
||||
d1 = (num_points_3rd - j) * itm_elev[1];
|
||||
}
|
||||
double ray_height = (grad * d1) + min_elev;
|
||||
|
||||
double clearance = ray_height - (itm_elev[k] + clutter_height) - frs_rad * 8/10;
|
||||
double intrusion = fabs(clearance);
|
||||
|
||||
if (clearance >= 0) {
|
||||
// no losses
|
||||
}
|
||||
else if (clearance < 0 && (intrusion < clutter_height)) {
|
||||
|
||||
clutter_loss += clutter_density * (intrusion / (frs_rad * 2) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else if (clearance < 0 && (intrusion > clutter_height)) {
|
||||
clutter_loss += clutter_density * (clutter_height / (frs_rad * 2 ) ) * (freq/100) * (itm_elev[1]/100);
|
||||
}
|
||||
else {
|
||||
// no losses
|
||||
}
|
||||
j++;
|
||||
mat++;
|
||||
|
||||
}
|
||||
|
||||
}
|
||||
}
|
||||
else if (p_mode == 2) { // troposcatter: ignore ground clutter for now...
|
||||
clutter_loss = 0.0;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
/*** Temporary material properties database
|
||||
* height: median clutter height
|
||||
* density: radiowave attenuation factor
|
||||
***/
|
||||
void FGRadioTransmission::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) {
|
||||
double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, int transmission_type) {
|
||||
double frq_mhz;
|
||||
if( (freq < 118.0) || (freq > 137.0) )
|
||||
frq_mhz = 125.0; // sane value, middle of bandplan
|
||||
|
|
@ -396,10 +821,9 @@ double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmiss
|
|||
frq_mhz = freq;
|
||||
double dbloss;
|
||||
double tx_pow = _transmitter_power;
|
||||
double ant_gain = _antenna_gain;
|
||||
double ant_gain = _rx_antenna_gain + _tx_antenna_gain;
|
||||
double signal = 0.0;
|
||||
double ATC_HAAT = 30.0;
|
||||
double Aircraft_HAAT = 5.0;
|
||||
|
||||
double sender_alt_ft,sender_alt;
|
||||
double transmitter_height=0.0;
|
||||
double receiver_height=0.0;
|
||||
|
|
@ -408,13 +832,8 @@ double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmiss
|
|||
double own_alt_ft = fgGetDouble("/position/altitude-ft");
|
||||
double own_alt= own_alt_ft * SG_FEET_TO_METER;
|
||||
|
||||
if(transmission_type == 1)
|
||||
tx_pow = _transmitter_power + 6.0;
|
||||
|
||||
if((transmission_type == 1) || (transmission_type == 3))
|
||||
ant_gain = _antenna_gain + 3.0; //pilot plane's antenna gain + ground station antenna gain
|
||||
|
||||
double link_budget = tx_pow - _receiver_sensitivity + ant_gain;
|
||||
double link_budget = tx_pow - _receiver_sensitivity - _rx_line_losses - _tx_line_losses + ant_gain;
|
||||
|
||||
//cerr << "ITM:: pilot Lat: " << own_lat << ", Lon: " << own_lon << ", Alt: " << own_alt << endl;
|
||||
|
||||
|
|
@ -430,10 +849,10 @@ double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmiss
|
|||
|
||||
double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
|
||||
|
||||
if(transmission_type == 1)
|
||||
transmitter_height += ATC_HAAT;
|
||||
else
|
||||
transmitter_height += Aircraft_HAAT;
|
||||
|
||||
transmitter_height += _tx_antenna_height;
|
||||
receiver_height += _rx_antenna_height;
|
||||
|
||||
|
||||
/** radio horizon calculation with wave bending k=4/3 */
|
||||
double receiver_horizon = 4.12 * sqrt(receiver_height);
|
||||
|
|
@ -453,3 +872,5 @@ double FGRadio::LOS_calculate_attenuation(SGGeod pos, double freq, int transmiss
|
|||
return signal;
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -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>
|
||||
|
|
@ -33,7 +33,7 @@
|
|||
using std::string;
|
||||
|
||||
|
||||
class FGRadio
|
||||
class FGRadioTransmission
|
||||
{
|
||||
private:
|
||||
bool isOperable() const
|
||||
|
|
@ -42,21 +42,39 @@ private:
|
|||
|
||||
double _receiver_sensitivity;
|
||||
double _transmitter_power;
|
||||
double _antenna_gain;
|
||||
double _tx_antenna_height;
|
||||
double _rx_antenna_height;
|
||||
double _rx_antenna_gain;
|
||||
double _tx_antenna_gain;
|
||||
double _rx_line_losses;
|
||||
double _tx_line_losses;
|
||||
double _terrain_sampling_distance;
|
||||
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 get_material_properties(string mat_name, double &height, double &density);
|
||||
|
||||
public:
|
||||
|
||||
FGRadio();
|
||||
~FGRadio();
|
||||
FGRadioTransmission();
|
||||
~FGRadioTransmission();
|
||||
|
||||
|
||||
void setFrequency(double freq, int radio);
|
||||
double getFrequency(int radio);
|
||||
void setTxPower(double txpower) { _transmitter_power = txpower; };
|
||||
void setRxSensitivity(double sensitivity) { _receiver_sensitivity = sensitivity; };
|
||||
void setTxAntennaHeight(double tx_antenna_height) { _tx_antenna_height = tx_antenna_height; };
|
||||
void setRxAntennaHeight(double rx_antenna_height) { _rx_antenna_height = rx_antenna_height; };
|
||||
void setTxAntennaGain(double tx_antenna_gain) { _tx_antenna_gain = tx_antenna_gain; };
|
||||
void setRxAntennaGain(double rx_antenna_gain) { _rx_antenna_gain = rx_antenna_gain; };
|
||||
void setTxLineLosses(double tx_line_losses) { _tx_line_losses = tx_line_losses; };
|
||||
void setRxLineLosses(double rx_line_losses) { _rx_line_losses = rx_line_losses; };
|
||||
void setPropagationModel(int model) { _propagation_model = model; };
|
||||
// transmission_type: 0 for air to ground 1 for ground to air, 2 for air to air, 3 for pilot to ground, 4 for pilot to air
|
||||
void receiveATC(SGGeod tx_pos, double freq, string text, int transmission_type);
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue