Remove hard-coded values wherever possible;

Make most of the station parameters configurable outside
the attenuation functions with the ultimate goal of exposing
them via the property tree

diff --git a/src/Radio/radio.cxx b/src/Radio/radio.cxx
index 994f3aee950138b62bed3333efd56dcbd68d8603..4f2772e4ed04eb430f80a9aac3ff8f6e1f2714e1 100644 (file)
--- a/src/Radio/radio.cxx
+++ b/src/Radio/radio.cxx
@@ -23,8 +23,7 @@
 #endif
 
 #include <math.h>
-#define NDEBUG
-#include <assert.h>
+
 #include <stdlib.h>
 #include <deque>
 #include "radio.hxx"
@@ -37,15 +36,10 @@
 
 FGRadioTransmission::FGRadioTransmission() {
        
-       /** radio parameters (which should probably be set for each radio) */
        
        _receiver_sensitivity = -110.0; // typical AM receiver sensitivity seems to be 0.8 microVolt at 12dB SINAD
        
        /** AM transmitter power in dBm.
-       *       Note this value is calculated from the typical final transistor stage output
-       *       small aircraft have portable transmitters which operate at 36 dBm output (4 Watts) others operate in the range 10-20 W
-       *       later possibly store this value in aircraft description
-       *       ATC comms usually operate high power equipment, thus making the link asymetrical; this is taken care of in propagation routines
        *       Typical output powers for ATC ground equipment, VHF-UHF:
        *       40 dBm - 10 W (ground, clearance)
        *       44 dBm - 20 W (tower)
@@ -59,18 +53,14 @@ FGRadioTransmission::FGRadioTransmission() {
        
        _rx_antenna_height = 2.0; // RX antenna height above ground level
        
-       /** pilot plane's antenna gain + AI aircraft antenna gain
-       *       real-life gain for conventional monopole/dipole antenna
-       **/
-       _antenna_gain = 2.0;
        
-       _rx_antenna_gain = 1.0;
+       _rx_antenna_gain = 1.0; // gain expressed in dBi
        _tx_antenna_gain = 1.0;
        
        _rx_line_losses = 2.0;  // to be configured for each station
        _tx_line_losses = 2.0;
        
-       _propagation_model = 2; //  choose between models via option: realistic radio on/off
+       _propagation_model = 2; 
        _terrain_sampling_distance = fgGetDouble("/sim/radio/sampling-distance", 90.0); // regular SRTM is 90 meters
 }
 
@@ -124,10 +114,16 @@ double FGRadioTransmission::receiveNav(SGGeod tx_pos, double freq, int transmiss
 void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_air) {
 
        
+       if(ground_to_air == 1) {
+               _transmitter_power += 6.0;
+               _tx_antenna_height += 30.0;
+               _tx_antenna_gain += 3.0; 
+       }
+       
+       
        double comm1 = getFrequency(1);
        double comm2 = getFrequency(2);
        if ( !(fabs(freq - comm1) <= 0.0001) &&  !(fabs(freq - comm2) <= 0.0001) ) {
-               //cerr << "Frequency not tuned: " << freq << " Radio1: " << comm1 << " Radio2: " << comm2 << endl;
                return;
        }
        else {
@@ -139,13 +135,10 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
                        // TODO: free space, round earth
                        double signal = LOS_calculate_attenuation(tx_pos, freq, ground_to_air);
                        if (signal <= 0.0) {
-                               SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
-                               //cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
                                return;
                        }
                        else {
-                               SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
-                               //cerr << "Signal completely readable: " << signal << endl;
+                               
                                fgSetString("/sim/messages/atc", text.c_str());
                                /** write signal strength above threshold to the property tree
                                *       to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
@@ -157,8 +150,6 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
                        // Use ITM propagation model
                        double signal = ITM_calculate_attenuation(tx_pos, freq, ground_to_air);
                        if (signal <= 0.0) {
-                               SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
-                               //cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
                                return;
                        }
                        if ((signal > 0.0) && (signal < 12.0)) {
@@ -188,8 +179,6 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
                                fgSetDouble("/sim/sound/voices/voice/volume", old_volume);
                        }
                        else {
-                               SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
-                               //cerr << "Signal completely readable: " << signal << endl;
                                fgSetString("/sim/messages/atc", text.c_str());
                                /** write signal strength above threshold to the property tree
                                *       to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
@@ -233,16 +222,11 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
        
        double clutter_loss = 0.0;      // loss due to vegetation and urban
        double tx_pow = _transmitter_power;
-       double ant_gain = _antenna_gain;
+       double ant_gain = _rx_antenna_gain + _tx_antenna_gain;
        double signal = 0.0;
        
-       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;     
 
        FGScenery * scenery = globals->get_scenery();
        
@@ -259,11 +243,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
        SGGeoc center = SGGeoc::fromGeod( max_own_pos );
        SGGeoc own_pos_c = SGGeoc::fromGeod( own_pos );
        
-       /**     position of sender radio antenna (HAAT)
-                       sender can be aircraft or ground station
-       **/
-       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;
@@ -302,7 +282,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
 
        double elevation_under_pilot = 0.0;
        if (scenery->get_elevation_m( max_own_pos, elevation_under_pilot, NULL )) {
-               receiver_height = own_alt - elevation_under_pilot + 3; //assume antenna located 3 meters above ground
+               receiver_height = own_alt - elevation_under_pilot; 
        }
 
        double elevation_under_sender = 0.0;
@@ -313,10 +293,10 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
                transmitter_height = sender_alt;
        }
        
-       if(transmission_type == 1) 
-               transmitter_height += ATC_HAAT;
-       else
-               transmitter_height += Aircraft_HAAT;
+       
+       transmitter_height += _tx_antenna_height;
+       receiver_height += _rx_antenna_height;
+       
        
        SG_LOG(SG_GENERAL, SG_BULK,
                        "ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters");
@@ -383,7 +363,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
        }
        
        double num_points= (double)_elevations.size();
-       //cerr << "ITM:: Max alt between: " << max_alt_between << ", num points:" << num_points << endl;
+
        _elevations.push_front(point_distance);
        _elevations.push_front(num_points -1);
        int size = _elevations.size();
@@ -442,7 +422,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                        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) );
-                       assert(frs_rad > 0);
                        
                        //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 );    // K=4/3
                        
@@ -494,7 +473,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                                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) );
-                               assert(frs_rad > 0);
                                
                                //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 );    // K=4/3
                                
@@ -539,7 +517,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                                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) );
-                               assert(frs_rad > 0);
                                
                                //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 );    // K=4/3
                                
@@ -592,7 +569,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                                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) );
-                               assert(frs_rad > 0);
                                
                                //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 );    // K=4/3
                                
@@ -637,7 +613,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                                // 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) );
                                
-                               assert(frs_rad > 0);
                                //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);
@@ -682,7 +657,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
                                // 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) );
                                
-                               assert(frs_rad > 0);
                                
                                //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 );    // K=4/3
                                
@@ -847,10 +821,9 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
                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;
@@ -859,13 +832,8 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
        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;
        
@@ -881,10 +849,10 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
        
        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);

diff --git a/src/Radio/radio.hxx b/src/Radio/radio.hxx
index 4c2bb7f64c7e0707986824b142a5ff0d443738c1..1261b7c5109aa9e0c585c2feef5fbb466cfa464a 100644 (file)
--- a/src/Radio/radio.hxx
+++ b/src/Radio/radio.hxx
@@ -44,7 +44,6 @@ private:
        double _transmitter_power;
        double _tx_antenna_height;
        double _rx_antenna_height;
-       double _antenna_gain;
        double _rx_antenna_gain;
        double _tx_antenna_gain;
        double _rx_line_losses;
@@ -72,6 +71,10 @@ public:
     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);