1 // tacan.cxx - Tactical Navigation Beacon.
2 // Written by Vivian Meazaa, started 2005.
4 // This file is in the Public Domain and comes with no warranty.
6 #include <simgear/compiler.h>
7 #include <simgear/math/sg_geodesy.hxx>
8 #include <simgear/math/sg_random.h>
10 #include <Main/fg_props.hxx>
11 #include <Navaids/navlist.hxx>
19 * Start by calculating the radar horizon based on the elevation
20 * difference, then clamp to the maximum, then add a fudge for
21 * borderline reception.
24 adjust_range (double transmitter_elevation_ft, double aircraft_altitude_ft,
28 double delta_elevation_ft =
29 fabs(aircraft_altitude_ft - transmitter_elevation_ft);
30 double range_nm = 1.23 * sqrt(delta_elevation_ft);
31 if (range_nm > max_range_nm)
32 range_nm = max_range_nm;
33 else if (range_nm < 20.0)
35 double rand = sg_random();
36 SG_LOG( SG_INSTR, SG_DEBUG, " tacan range " << range_nm << " max range " << max_range_nm);
37 return range_nm + (range_nm * rand * rand);
41 TACAN::TACAN ( SGPropertyNode *node )
42 : _last_distance_nm(0),
43 _last_frequency_mhz(-1),
44 _time_before_search_sec(0),
45 _carrier_valid(false),
46 _transmitter_valid(false),
47 _transmitter_elevation_ft(0),
48 _transmitter_range_nm(0),
49 _transmitter_bias(0.0),
56 for ( i = 0; i < node->nChildren(); ++i ) {
57 SGPropertyNode *child = node->getChild(i);
58 string cname = child->getName();
59 string cval = child->getStringValue();
60 if ( cname == "name" ) {
62 } else if ( cname == "number" ) {
63 num = child->getIntValue();
65 SG_LOG( SG_INSTR, SG_DEBUG, "Error in TACAN config logic" );
66 if ( name.length() ) {
67 SG_LOG( SG_INSTR, SG_DEBUG, "Section = " << name );
74 : _last_distance_nm(0),
75 _last_frequency_mhz(-1),
76 _time_before_search_sec(0),
77 _carrier_valid(false),
78 _transmitter_valid(false),
79 _transmitter_elevation_ft(0),
80 _transmitter_range_nm(0),
81 _transmitter_bearing_deg(0),
82 _transmitter_bias(0.0),
83 _transmitter_name(""),
96 branch = "/instrumentation/" + name;
98 SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
100 _longitude_node = fgGetNode("/position/longitude-deg", true);
101 _latitude_node = fgGetNode("/position/latitude-deg", true);
102 _altitude_node = fgGetNode("/position/altitude-ft", true);
103 _serviceable_node = node->getChild("serviceable", 0, true);
104 _electrical_node = fgGetNode("/systems/electrical/outputs/tacan", true);
105 SGPropertyNode *fnode = node->getChild("frequencies", 0, true);
106 _source_node = fnode->getChild("source", 0, true);
107 _frequency_node = fnode->getChild("selected-mhz", 0, true);
108 _channel_node = fnode->getChild("selected-channel", 1, true);
109 _channel_node = fnode->getChild("selected-channel", 2, true);
110 _channel_node = fnode->getChild("selected-channel", 3, true);
111 _channel_node = fnode->getChild("selected-channel", 4, true);
112 _in_range_node = node->getChild("in-range", 0, true);
113 _distance_node = node->getChild("indicated-distance-nm", 0, true);
114 _speed_node = node->getChild("indicated-ground-speed-kt", 0, true);
115 _time_node = node->getChild("indicated-time-min", 0, true);
116 _name_node = node->getChild("name", 0, true);
117 _bearing_node = node->getChild("indicated-bearing-true-deg", 0, true);
118 _carrier_lat_node = fgGetNode("/ai/models/carrier/position/latitude-deg", true);
119 _carrier_lon_node = fgGetNode("/ai/models/carrier/position/longitude-deg", true);
120 _carrier_name_node = fgGetNode("/ai/models/carrier/name", true);
125 TACAN::update (double delta_time_sec)
130 double carrier_az2= 0;
131 double carrier_bearing = 0;
132 double carrier_distance = 0;
133 double frequency_mhz = 0;
134 string _channel, _last_channel, _channel_1, _channel_2,_channel_3, _channel_4;
136 // If it's off, don't waste any time.
137 if (!_serviceable_node->getBoolValue() ||
138 !_electrical_node->getBoolValue()
140 _last_distance_nm = 0;
141 _in_range_node->setBoolValue(false);
142 _distance_node->setDoubleValue(0);
143 _speed_node->setDoubleValue(0);
144 _time_node->setDoubleValue(0);
145 SG_LOG( SG_INSTR, SG_DEBUG, "skip tacan " );
148 //SG_LOG( SG_INSTR, SG_DEBUG, "run tacan " );
151 // Figure out the source
152 const char * source = _source_node->getStringValue();
154 if (source[0] == '\0') {
156 branch = "/instrumentation/" + name + "/frequencies/selected-channel";
157 // branch = "/instrumentation/" + _name + "/frequencies/selected-mhz";
158 _source_node->setStringValue(branch.c_str());
159 source = _source_node->getStringValue();
160 SG_LOG( SG_INSTR, SG_DEBUG, "source " << source );
163 _channel_1 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[1]");
164 _channel_2 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[2]");
165 _channel_3 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[3]");
166 _channel_4 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[4]");
167 SG_LOG( SG_INSTR, SG_DEBUG, "channels " << _channel_1 << _channel_2 << _channel_3 << _channel_4);
168 _channel = _channel_1 + _channel_2 + _channel_3 + _channel_4;
169 SG_LOG( SG_INSTR, SG_DEBUG, "channel " << _channel );
171 // Get the frequecncy
172 if (_channel != _last_channel) {
173 _time_before_search_sec = 0;
174 _last_channel = _channel;
175 frequency_mhz = searchChannel(_channel);
176 SG_LOG( SG_INSTR, SG_DEBUG, "frequency " << frequency_mhz );
177 _frequency_node->setDoubleValue(frequency_mhz);
180 // Get the aircraft position
181 double longitude_deg = _longitude_node->getDoubleValue();
182 double latitude_deg = _latitude_node->getDoubleValue();
183 double altitude_m = _altitude_node->getDoubleValue() * SG_FEET_TO_METER;
184 double longitude_rad = longitude_deg * SGD_DEGREES_TO_RADIANS;
185 double latitude_rad = latitude_deg * SGD_DEGREES_TO_RADIANS;
187 // On timeout, scan again
188 _time_before_search_sec -= delta_time_sec;
189 if (_time_before_search_sec < 0 && frequency_mhz > 0)
190 search(frequency_mhz, longitude_rad,
191 latitude_rad, altitude_m);
193 // Calculate the distance to the transmitter
195 //calculate the bearing and range of the carrier from the aircraft
196 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_lat " << _carrier_lat);
197 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_lon " << _carrier_lon);
198 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_name " << _carrier_name);
199 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_valid " << _carrier_valid);
200 geo_inverse_wgs_84(altitude_m,
205 &carrier_bearing, &carrier_az2, &carrier_distance);
208 //calculate the bearing and range of the station from the aircraft
209 geo_inverse_wgs_84(altitude_m,
214 &bearing, &az2, &distance);
218 if ( carrier_distance <= distance && _carrier_valid) {
219 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_distance_nm " << carrier_distance);
220 SG_LOG( SG_INSTR, SG_DEBUG, "distance_nm " << distance);
221 bearing = carrier_bearing;
222 distance = carrier_distance;
223 _transmitter_elevation_ft = _carrier_elevation_ft;
224 _transmitter_range_nm = _carrier_range_nm;
225 _transmitter_bias = _carrier_bias;
226 _transmitter_name = _carrier_name;
227 _name_node->setStringValue(_transmitter_name.c_str());
230 double distance_nm = distance * SG_METER_TO_NM;
231 SG_LOG( SG_INSTR, SG_DEBUG, "distance_nm " << distance_nm << " bearing " << bearing);
234 sgGeodToCart(Point3D(longitude_rad, latitude_rad, altitude_m));
235 double distance_nm = _transmitter.distance3D(location) * SG_METER_TO_NM;*/
237 double range_nm = adjust_range(_transmitter_elevation_ft,
238 altitude_m * SG_METER_TO_FEET,
239 _transmitter_range_nm);
241 if (distance_nm <= range_nm) {
242 double speed_kt = (fabs(distance_nm - _last_distance_nm) *
243 ((1 / delta_time_sec) * 3600.0));
244 _last_distance_nm = distance_nm;
246 _in_range_node->setBoolValue(true);
247 double tmp_dist = distance_nm - _transmitter_bias;
248 if ( tmp_dist < 0.0 ) {
251 _distance_node->setDoubleValue( tmp_dist );
252 _speed_node->setDoubleValue(speed_kt);
253 _time_node->setDoubleValue(distance_nm/speed_kt*60.0);
254 _bearing_node->setDoubleValue(bearing);
257 _last_distance_nm = 0;
258 _in_range_node->setBoolValue(false);
259 _distance_node->setDoubleValue(0);
260 _speed_node->setDoubleValue(0);
261 _time_node->setDoubleValue(0);
262 _bearing_node->setDoubleValue(0);
265 // If we can't find a valid station set everything to zero
266 if (!_transmitter_valid && !_carrier_valid)
268 _in_range_node->setBoolValue(false);
269 _distance_node->setDoubleValue(0);
270 _speed_node->setDoubleValue(0);
271 _time_node->setDoubleValue(0);
272 _bearing_node->setDoubleValue(0);
273 _transmitter_name = "";
274 _name_node->setStringValue(_transmitter_name.c_str());
277 } // end function update
280 TACAN::search (double frequency_mhz, double longitude_rad,
281 double latitude_rad, double altitude_m)
284 SG_LOG( SG_INSTR, SG_DEBUG, "tacan freq " << frequency_mhz );
287 _time_before_search_sec = 1.0;
289 //try any carriers first
290 FGNavRecord *carrier_tacan
291 = globals->get_carrierlist()->findStationByFreq( frequency_mhz );
292 _carrier_valid = (carrier_tacan != NULL);
294 if ( _carrier_valid ) {
295 SG_LOG( SG_INSTR, SG_DEBUG, "carrier transmitter valid " << _carrier_valid );
297 string str1( carrier_tacan->get_name() );
298 string str2 ( _carrier_name_node->getStringValue());
299 SG_LOG( SG_INSTR, SG_DEBUG, "strings 1 " << str1 << " 2 " << str2 );
300 unsigned int loc1= str1.find( str2, 0 );
301 if( loc1 != string::npos && str2 != "" ){
302 SG_LOG( SG_INSTR, SG_DEBUG, " string found" );
303 _carrier_lat = _carrier_lat_node->getDoubleValue();
304 _carrier_lon = _carrier_lon_node->getDoubleValue();
305 _carrier_elevation_ft = carrier_tacan->get_elev_ft();
306 _carrier_range_nm = carrier_tacan->get_range();
307 _carrier_bias = carrier_tacan->get_multiuse();
308 _carrier_name = carrier_tacan->get_name();
312 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
316 //_name_node->setStringValue(_transmitter_name.c_str());
318 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _carrier_lat << "lon " << _carrier_lon);
319 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _carrier_elevation_ft);
320 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _carrier_name);
323 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
327 // try the TACAN/VORTAC list next
329 = globals->get_tacanlist()->findByFreq( frequency_mhz, longitude_rad,
330 latitude_rad, altitude_m);
332 _transmitter_valid = (tacan != NULL);
334 if ( _transmitter_valid ) {
335 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter valid " << _transmitter_valid );
337 _transmitter_lat = tacan->get_lat();
338 _transmitter_lon = tacan->get_lon();
339 _transmitter_elevation_ft = tacan->get_elev_ft();
340 _transmitter_range_nm = tacan->get_range();
341 _transmitter_bias = tacan->get_multiuse();
342 _transmitter_name = tacan->get_name();
343 _name_node->setStringValue(_transmitter_name.c_str());
345 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _transmitter_lat << "lon " << _transmitter_lon);
346 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _transmitter_elevation_ft);
347 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _transmitter_name);
350 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter invalid " << _transmitter_valid );
356 TACAN::searchChannel (const string& _channel){
358 double frequency_khz = 0;
361 = globals->get_channellist()->findByChannel( _channel );
362 double _freq_valid = (freq != NULL);
363 SG_LOG( SG_INSTR, SG_DEBUG, "freq valid " << _freq_valid );
365 frequency_khz = freq->get_freq();
366 SG_LOG( SG_INSTR, SG_DEBUG, "freq output " << frequency_khz );
368 if (frequency_khz >9620 && frequency_khz <= 12130)return frequency_khz/100;
370 return frequency_khz = 0;
371 } // end TACAN::searchChannel