#include <algorithm>
#include <math.h>
+#include <stdlib.h>
#include <deque>
#include <osg/Geode>
double snr = calculate_attenuation(rec, parent, ground_to_air);
if (snr <= 0)
return;
- if (snr > 0 && snr < 10) {
- //for low snr values implement a way to make the conversation
- //hard to understand (perhaps eliminate letters from words or such
- return;
+ if (snr > 0 && snr < 12) {
+ //for low SNR values implement a way to make the conversation
+ //hard to understand but audible
+ string hash_noise = " ";
+ int reps = fabs((int)snr - 11);
+ int t_size = text.size();
+ for (int n=1;n<=reps * 2;n++) {
+ int pos = rand() % t_size -1;
+ text.replace(pos,1, hash_noise);
+ }
+
}
if (rec->allowTransmissions()) {
}
}
-int FGATCController::calculate_attenuation(FGTrafficRecord * rec, FGAirportDynamics *parent,
+double FGATCController::calculate_attenuation(FGTrafficRecord * rec, FGAirportDynamics *parent,
int ground_to_air) {
- /////////////////////////////////////////////////
- /// Implement radio attenuation
- /// based on the Longley-Rice propagation model
- /////////////////////////////////////////////////
+ //////////////////////////////////////////////////
+ /// Implement radio attenuation //
+ /// based on the Longley-Rice propagation model//
+ //////////////////////////////////////////////////
FGScenery * scenery = globals->get_scenery();
// player aircraft position
double own_alt_ft = fgGetDouble("/position/altitude-ft");
double own_alt= own_alt_ft * SG_FEET_TO_METER;
+ cerr << "ITM:: pilot Lat: " << own_lat << ", Lon: " << own_lon << ", Alt: " << own_alt << endl;
+
SGGeod own_pos = SGGeod::fromDegM( own_lon, own_lat, own_alt );
SGGeod max_own_pos = SGGeod::fromDegM( own_lon, own_lat, SG_MAX_ELEVATION_M );
SGGeoc center = SGGeoc::fromGeod( max_own_pos );
+ SGGeoc own_pos_c = SGGeoc::fromGeod( own_pos );
- // position of sender
+ // position of sender radio antenna (HAAT)
// sender can be aircraft or ground station
+ double ATC_HAAT = 30.0;
+ double Aircraft_HAAT = 7.0;
double sender_alt_ft,sender_alt;
+ double transceiver_height=0.0;
+ double receiver_height=0.0;
SGGeod sender_pos;
if(ground_to_air) {
sender_alt_ft = parent->getElevation();
- sender_alt = sender_alt_ft * SG_FEET_TO_METER;
+ sender_alt = sender_alt_ft * SG_FEET_TO_METER + ATC_HAAT;
sender_pos= SGGeod::fromDegM( parent->getLongitude(),
parent->getLatitude(), sender_alt );
}
else {
sender_alt_ft = rec->getAltitude();
- sender_alt = sender_alt_ft * SG_FEET_TO_METER;
+ sender_alt = sender_alt_ft * SG_FEET_TO_METER + Aircraft_HAAT;
sender_pos= SGGeod::fromDegM( rec->getLongitude(),
rec->getLatitude(), sender_alt );
}
- double point_distance= 100.0; // regular SRTM is 90 meters
- double course = SGGeodesy::courseDeg(own_pos, sender_pos);
+ SGGeoc sender_pos_c = SGGeoc::fromGeod( sender_pos );
+ cerr << "ITM:: sender Lat: " << parent->getLatitude() << ", Lon: " << parent->getLongitude() << ", Alt: " << sender_alt << endl;
+
+ double point_distance= 90.0; // regular SRTM is 90 meters
+ double course = SGGeodesy::courseRad(own_pos_c, sender_pos_c);
double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
+ double probe_distance = 0.0;
+
+ cerr << "ITM:: Distance: " << distance_m << endl;
+
double max_points = distance_m / point_distance;
deque<double> _elevations;
+ SGGeod probe_pilot = SGGeod::fromGeoc(center.advanceRadM( course, 0 ));
+ double elevation_under_pilot = 0.0;
+ if (scenery->get_elevation_m( probe_pilot, elevation_under_pilot, NULL )) {
+ receiver_height = own_alt - elevation_under_pilot;
+ }
+ _elevations.push_front(receiver_height);
+
+ SGGeod probe_sender = SGGeod::fromGeoc(center.advanceRadM( course, distance_m ));
+ double elevation_under_sender = 0.0;
+ if (scenery->get_elevation_m( probe_sender, elevation_under_sender, NULL )) {
+ transceiver_height = sender_alt - elevation_under_sender;
+ }
+
// If distance larger than this value (400 km), assume reception imposssible
// technically 400 km is no problem if LOS conditions exist,
// but we do this to spare resources
if (distance_m > 400000)
- return -1;
+ return -1.0;
- while (_elevations.size() < (deque<double>::size_type)max_points) {
- SGGeod probe = SGGeod::fromGeoc(center.advanceRadM( course, point_distance ));
+ int e_size = (deque<unsigned>::size_type)max_points;
+
+ while (_elevations.size() < e_size) {
+ probe_distance += point_distance;
+ SGGeod probe = SGGeod::fromGeoc(center.advanceRadM( course, probe_distance ));
double elevation_m = 0.0;
if (scenery->get_elevation_m( probe, elevation_m, NULL )) {
_elevations.push_front(elevation_m);
+ //cerr << "ITM:: Probe elev: " << elevation_m << endl;
}
}
- /*
+ _elevations.push_front(transceiver_height);
double max_alt_between=0.0;
for( deque<double>::size_type i = 0; i < _elevations.size(); i++ ) {
if (_elevations[i] > max_alt_between) {
max_alt_between = _elevations[i];
}
}
- */
- double num_points= (int)_elevations.size();
- _elevations.push_front(distance_m);
+ 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();
+ int size = _elevations.size();
double itm_elev[size];
for(int i=0;i<size;i++) {
itm_elev[i]=_elevations[i];
+ //cerr << "ITM:: itm_elev: " << _elevations[i] << endl;
}
////////////// ITM default parameters //////////////
double frq_mhz = 125.0; // middle of bandplan
int radio_climate = 5; // continental temperate
int pol=1; // assuming vertical polarization
- double conf = 0.70; // my own tests in Radiomobile have worked best with these values
- double rel = 0.70; // ^^
+ double conf = 0.90; // my own tests in Radiomobile have worked best with these values
+ double rel = 0.80; // ^^
double dbloss;
char strmode[150];
int errnum;
// !!! small aircraft have portable transmitters which operate at 36 dBm output (4 Watts)
// later store this value in aircraft description
// ATC comms usually operate high power equipment, thus making the link asymetrical; this is ignored for now
- double transmitter_power = 43.0;
- double link_budget = transmitter_power - receiver_sensitivity;
+ if(ground_to_air)
+ double transmitter_power = 49.0;
+ else
+ double transmitter_power = 43.0;
+ if(ground_to_air)
+ double antenna_gain = 5.0; //pilot plane's antenna gain + Controller antenna gain
+ else
+ double antenna_gain = 2.0; //pilot plane's antenna gain + AI aircraft antenna gain
+ double link_budget = transmitter_power - receiver_sensitivity + antenna_gain;
+
// first Fresnel zone radius
// frequency in the middle of the bandplan, more accuracy is not necessary
eps_dielect, sgm_conductivity, eno, frq_mhz, radio_climate,
pol, conf, rel, dbloss, strmode, errnum);
- cerr << "Attenuation: " << dbloss << ", Mode: " << strmode << ", Error: " << errnum << endl;
+ cerr << "ITM:: Attenuation: " << dbloss << " dBm, " << strmode << ", Error: " << errnum << endl;
- if (errnum !=0 && errnum !=1)
- return -1;
+ //if (errnum !=0 && errnum !=1)
+ // return -1;
double snr = link_budget - dbloss;
return snr;
projects / flightgear.git / commitdiff