1 // antenna.cxx -- implementation of FGRadioAntenna
2 // Class to represent a virtual radio antenna properties
3 // Written by Adrian Musceac, started December 2011.
5 // This program is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU General Public License as
7 // published by the Free Software Foundation; either version 2 of the
8 // License, or (at your option) any later version.
10 // This program is distributed in the hope that it will be useful, but
11 // WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // General Public License for more details.
15 // You should have received a copy of the GNU General Public License
16 // along with this program; if not, write to the Free Software
17 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
28 #include <Scenery/scenery.hxx>
29 #include "antenna.hxx"
33 FGRadioAntenna::FGRadioAntenna(string type) {
35 _mirror_y = 1; // normally we want to mirror these axis because the pattern is simetric
38 load_antenna_pattern(type);
41 FGRadioAntenna::~FGRadioAntenna() {
46 double FGRadioAntenna::calculate_gain(double bearing, double angle) {
48 // TODO: what if the pattern is assimetric?
49 bearing = fabs(bearing);
51 bearing = 360 - bearing;
52 // for plots with 2 degrees resolution:
53 int azimuth = (int)floor(bearing);
54 azimuth += azimuth % 2;
55 int elevation = (int)floor(angle);
56 elevation += elevation % 2;
58 for (unsigned int i =0; i < _pattern.size(); i++) {
59 AntennaGain point_gain = _pattern[i];
61 if ( (azimuth == point_gain.azimuth) && (elevation == point_gain.elevation)) {
62 return point_gain.gain;
71 /*** load external plot file generated by NEC4
73 void FGRadioAntenna::load_antenna_pattern(string type) {
75 SGPath pattern_file(fgGetString("/sim/fg-home"));
76 pattern_file.append("antennas");
77 pattern_file.append(type + ".txt");
78 if (!pattern_file.exists()) {
81 ifstream file_in(pattern_file.c_str());
82 int heading, elevation;
84 while(!file_in.eof()) {
85 file_in >> heading >> elevation >> gain;
86 if( (_mirror_y == 1) && (heading > 180) ) {
89 if ( (_mirror_z == 1) && (elevation < 0) ) {
92 //cerr << "head: " << heading << " elev: " << elevation << " gain: " << gain << endl;
93 AntennaGain datapoint;
94 datapoint.azimuth = heading;
95 datapoint.elevation = 90.0 - fabs(elevation);
96 datapoint.gain = gain;
97 _pattern.push_back(datapoint);