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Read antenna radiation pattern from file

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This commit is contained in:
adrian 2011-12-04 21:59:38 +02:00
parent 6d816823db
commit 500086adec
4 changed files with 61 additions and 14 deletions
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36
src/Radio/antenna.cxx
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@ -32,17 +32,37 @@ using namespace std;
FGRadioAntenna::FGRadioAntenna(string type) {
_mirror_y = 1;
_mirror_y = 1; // normally we want to mirror these axis because the pattern is simetric
_mirror_z = 1;
_invert_ground = 0;
_invert_ground = 0;
load_antenna_pattern(type);
}
FGRadioAntenna::~FGRadioAntenna() {
_pattern.clear();
}
double FGRadioAntenna::calculate_gain(double azimuth, double elevation) {
double FGRadioAntenna::calculate_gain(double bearing, double angle) {
// TODO: what if the pattern is assimetric?
bearing = fabs(bearing);
if (bearing > 180)
bearing = 360 - bearing;
// for plots with 2 degrees resolution:
int azimuth = (int)floor(bearing);
azimuth += azimuth % 2;
int elevation = (int)floor(angle);
elevation += elevation % 2;
for (unsigned int i =0; i < _pattern.size(); i++) {
AntennaGain point_gain = _pattern[i];
if ( (azimuth == point_gain.azimuth) && (elevation == point_gain.elevation)) {
return point_gain.gain;
}
}
return 0;
}
@ -63,10 +83,16 @@ void FGRadioAntenna::load_antenna_pattern(string type) {
double gain;
while(!file_in.eof()) {
file_in >> heading >> elevation >> gain;
cerr << "head: " << heading << " elev: " << elevation << " gain: " << gain << endl;
if( (_mirror_y == 1) && (heading > 180) ) {
continue;
}
if ( (_mirror_z == 1) && (elevation < 0) ) {
continue;
}
//cerr << "head: " << heading << " elev: " << elevation << " gain: " << gain << endl;
AntennaGain datapoint;
datapoint.azimuth = heading;
datapoint.elevation = elevation;
datapoint.elevation = 90.0 - fabs(elevation);
datapoint.gain = gain;
_pattern.push_back(datapoint);
}

6
src/Radio/antenna.hxx
View file

@ -51,7 +51,7 @@ public:
FGRadioAntenna(string type);
~FGRadioAntenna();
double calculate_gain(double azimuth, double elevation);
double calculate_gain(double bearing, double angle);
void set_heading(double heading_deg) {_heading_deg = heading_deg ;};
void set_elevation_angle(double elevation_angle_deg) {_elevation_angle_deg = elevation_angle_deg ;};
};

29
src/Radio/radio.cxx
View file

@ -66,6 +66,8 @@ FGRadioTransmission::FGRadioTransmission() {
_root_node = fgGetNode("sim/radio", true);
_terrain_sampling_distance = _root_node->getDoubleValue("sampling-distance", 90.0); // regular SRTM is 90 meters
}
FGRadioTransmission::~FGRadioTransmission()
@ -202,11 +204,8 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
double eps_dielect=15.0;
double sgm_conductivity = 0.005;
double eno = 301.0;
double frq_mhz;
if( (freq < 118.0) || (freq > 137.0) )
frq_mhz = 125.0; // sane value, middle of bandplan
else
frq_mhz = freq;
double frq_mhz = freq;
int radio_climate = 5; // continental temperate
int pol= _polarization;
double conf = 0.90; // 90% of situations and time, take into account speed
@ -233,6 +232,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
double own_lat = fgGetDouble("/position/latitude-deg");
double own_lon = fgGetDouble("/position/longitude-deg");
double own_alt_ft = fgGetDouble("/position/altitude-ft");
double own_heading = fgGetDouble("/orientation/heading-deg");
double own_alt= own_alt_ft * SG_FEET_TO_METER;
@ -257,6 +257,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
double point_distance= _terrain_sampling_distance;
double course = SGGeodesy::courseRad(own_pos_c, sender_pos_c);
double reverse_course = SGGeodesy::courseRad(sender_pos_c, own_pos_c);
double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
double probe_distance = 0.0;
/** If distance larger than this value (300 km), assume reception imposssible */
@ -400,6 +401,22 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
//cerr << "Clutter loss: " << clutter_loss << endl;
//if (errnum == 4) // if parameters are outside sane values for lrprop, the alternative method is used
// return -1;
double sender_heading = 270.0; // due West
double tx_antenna_bearing = sender_heading - reverse_course;
double rx_antenna_bearing = own_heading - course;
double rx_elev_angle = atan((itm_elev[2] + transmitter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m) * SGD_RADIANS_TO_DEGREES;
double tx_elev_angle = 0.0 - rx_elev_angle;
_TX_antenna = new FGRadioAntenna("Plot2");
_TX_antenna->set_heading(sender_heading);
_TX_antenna->set_elevation_angle(0);
double tx_pattern_gain = _TX_antenna->calculate_gain(tx_antenna_bearing, tx_elev_angle);
_RX_antenna = new FGRadioAntenna("Plot2");
_RX_antenna->set_heading(own_heading);
_RX_antenna->set_elevation_angle(fgGetDouble("/orientation/pitch-deg"));
double rx_pattern_gain = _RX_antenna->calculate_gain(rx_antenna_bearing, rx_elev_angle);
delete _TX_antenna;
delete _RX_antenna;
signal = link_budget - dbloss - clutter_loss + pol_loss;
double signal_strength_dbm = signal_strength - dbloss - clutter_loss + pol_loss;
double field_strength_uV = dbm_to_microvolt(signal_strength_dbm);
@ -407,6 +424,8 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
_root_node->setDoubleValue("station[0]/field-strength-uV", field_strength_uV);
_root_node->setDoubleValue("station[0]/signal", signal);
_root_node->setDoubleValue("station[0]/tx-erp", tx_erp);
_root_node->setDoubleValue("station[0]/tx-pattern-gain", tx_pattern_gain);
_root_node->setDoubleValue("station[0]/rx-pattern-gain", rx_pattern_gain);
return signal;
}

4
src/Radio/radio.hxx
View file

@ -28,7 +28,7 @@
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/debug/logstream.hxx>
#include "antenna.hxx"
using std::string;
@ -48,6 +48,8 @@ private:
double _tx_antenna_gain;
double _rx_line_losses;
double _tx_line_losses;
FGRadioAntenna* _TX_antenna;
FGRadioAntenna* _RX_antenna;
double _terrain_sampling_distance;
int _polarization;
std::map<string, double[2]> _mat_database;