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refactor receiveATC(), implement simple LOS routine, set comm1-signal property

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adrian 2011-11-24 17:25:49 +02:00
parent f023c3bc0a
commit 2c6946c3e8
3 changed files with 103 additions and 11 deletions
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2
src/ATC/trafficcontrol.cxx
View file

@ -762,7 +762,7 @@ void FGATCController::transmit(FGTrafficRecord * rec, FGAirportDynamics *parent,
rec->getLatitude(), sender_alt );
}
double frequency = ((double)stationFreq) / 100;
radio->receiveText(sender_pos, frequency, text, ground_to_air);
radio->receiveATC(sender_pos, frequency, text, ground_to_air);
delete radio;
}
else {

106
src/Radio/radio.cxx
View file

@ -34,14 +34,15 @@
FGRadio::FGRadio() {
/** radio parameters (which should probably be set for each radio via constructor) */
/** 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)
* later store this value in aircraft description
* ATC comms usually operate high power equipment, thus making the link asymetrical; this is ignored for now
* 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
**/
_transmitter_power = 43.0;
@ -74,10 +75,16 @@ double FGRadio::getFrequency(int radio) {
return freq;
}
/*** TODO: receive multiplayer chat message and voice
***/
void FGRadio::receiveChat(SGGeod tx_pos, double freq, string text,
int ground_to_air) {
}
void FGRadio::receiveText(SGGeod tx_pos, double freq, string text,
/*** Receive ATC radio communication as text
***/
void FGRadio::receiveATC(SGGeod tx_pos, double freq, string text,
int ground_to_air) {
/*
@ -93,7 +100,19 @@ void FGRadio::receiveText(SGGeod tx_pos, double freq, string text,
fgSetString("/sim/messages/atc", text.c_str());
}
else if ( _propagation_model == 1 ) {
// free space, round earth
// 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());
fgSetDouble("/sim/radio/comm1-signal", signal);
}
}
else if ( _propagation_model == 2 ) {
// Use ITM propagation model
@ -126,12 +145,14 @@ void FGRadio::receiveText(SGGeod tx_pos, double freq, string text,
//cerr << "Usable signal at limit: " << signal << endl;
fgSetDouble("/sim/sound/voices/voice/volume", volume);
fgSetString("/sim/messages/atc", text.c_str());
fgSetDouble("/sim/radio/comm1-signal", signal);
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());
fgSetDouble("/sim/radio/comm1-signal", signal);
}
}
@ -221,8 +242,8 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq,
if (own_alt > 8000) {
dbloss = 20 * log10(distance_m) +20 * log10(frq_mhz) -27.55;
SG_LOG(SG_GENERAL, SG_BULK,
"LOS-mode:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, free-space attenuation");
//cerr << "LOS-mode:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, free-space attenuation" << endl;
"ITM Free-space mode:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, free-space attenuation");
//cerr << "ITM Free-space mode:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm, free-space attenuation" << endl;
signal = link_budget - dbloss;
return signal;
}
@ -338,3 +359,72 @@ double FGRadio::ITM_calculate_attenuation(SGGeod pos, double freq,
return signal;
}
/*** implement simple LOS propagation model (WIP)
***/
double FGRadio::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
else
frq_mhz = freq;
double dbloss;
double tx_pow = _transmitter_power;
double ant_gain = _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;
double own_lat = fgGetDouble("/position/latitude-deg");
double own_lon = fgGetDouble("/position/longitude-deg");
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;
//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 sender_pos = pos;
sender_alt_ft = sender_pos.getElevationFt();
sender_alt = sender_alt_ft * SG_FEET_TO_METER;
receiver_height = own_alt;
transmitter_height = sender_alt;
double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
if(transmission_type == 1)
transmitter_height += ATC_HAAT;
else
transmitter_height += Aircraft_HAAT;
/** radio horizon calculation with wave bending k=4/3 */
double receiver_horizon = 4.12 * sqrt(receiver_height);
double transmitter_horizon = 4.12 * sqrt(transmitter_height);
double total_horizon = receiver_horizon + transmitter_horizon;
if (distance_m > total_horizon) {
return -1;
}
// free-space loss (distance calculation should be changed)
dbloss = 20 * log10(distance_m) +20 * log10(frq_mhz) -27.55;
signal = link_budget - dbloss;
SG_LOG(SG_GENERAL, SG_BULK,
"LOS:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm ");
cerr << "LOS:: Link budget: " << link_budget << ", Attenuation: " << dbloss << " dBm " << endl;
return signal;
}

6
src/Radio/radio.hxx
View file

@ -46,6 +46,7 @@ private:
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);
public:
@ -56,8 +57,9 @@ public:
void setFrequency(double freq, int radio);
double getFrequency(int radio);
void setTxPower(double txpower) { _transmitter_power = txpower; };
// transmission_type: 1 for ground to air, 2 for air to air, 3 for pilot to ground, 4 for pilot to air
void receiveText(SGGeod tx_pos, double freq, string text, int transmission_type);
// 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);
void receiveChat(SGGeod tx_pos, double freq, string text, int transmission_type);
void setPropagationModel(int model) { _propagation_model = model; };
};