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.
10 #include <simgear/compiler.h>
11 #include <simgear/math/sg_geodesy.hxx>
12 #include <simgear/math/sg_random.h>
14 #include <Main/fg_props.hxx>
15 #include <Navaids/navlist.hxx>
26 * Start by calculating the radar horizon based on the elevation
27 * difference, then clamp to the maximum, then add a fudge for
28 * borderline reception.
31 adjust_range (double transmitter_elevation_ft, double aircraft_altitude_ft,
35 double delta_elevation_ft =
36 fabs(aircraft_altitude_ft - transmitter_elevation_ft);
37 double range_nm = 1.23 * sqrt(delta_elevation_ft);
38 if (range_nm > max_range_nm)
39 range_nm = max_range_nm;
40 else if (range_nm < 20.0)
42 double rand = sg_random();
43 SG_LOG( SG_INSTR, SG_DEBUG, " tacan range " << range_nm << " max range " << max_range_nm);
44 return range_nm + (range_nm * rand * rand);
48 TACAN::TACAN ( SGPropertyNode *node )
49 : _last_distance_nm(0),
50 _last_frequency_mhz(-1),
51 _time_before_search_sec(0),
52 _carrier_valid(false),
53 _transmitter_valid(false),
54 _transmitter_elevation_ft(0),
55 _transmitter_range_nm(0),
56 _transmitter_bias(0.0),
63 for ( i = 0; i < node->nChildren(); ++i ) {
64 SGPropertyNode *child = node->getChild(i);
65 string cname = child->getName();
66 string cval = child->getStringValue();
67 if ( cname == "name" ) {
69 } else if ( cname == "number" ) {
70 num = child->getIntValue();
72 SG_LOG( SG_INSTR, SG_DEBUG, "Error in TACAN config logic" );
73 if ( name.length() ) {
74 SG_LOG( SG_INSTR, SG_DEBUG, "Section = " << name );
81 : _last_distance_nm(0),
82 _last_frequency_mhz(-1),
83 _time_before_search_sec(0),
84 _carrier_valid(false),
85 _transmitter_valid(false),
86 _transmitter_elevation_ft(0),
87 _transmitter_range_nm(0),
88 _transmitter_bearing_deg(0),
89 _transmitter_bias(0.0),
90 _transmitter_name(""),
103 branch = "/instrumentation/" + name;
105 SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
107 _longitude_node = fgGetNode("/position/longitude-deg", true);
108 _latitude_node = fgGetNode("/position/latitude-deg", true);
109 _altitude_node = fgGetNode("/position/altitude-ft", true);
110 _serviceable_node = node->getChild("serviceable", 0, true);
111 _electrical_node = fgGetNode("/systems/electrical/outputs/tacan", true);
112 SGPropertyNode *fnode = node->getChild("frequencies", 0, true);
113 _source_node = fnode->getChild("source", 0, true);
114 _frequency_node = fnode->getChild("selected-mhz", 0, true);
115 _channel_node = fnode->getChild("selected-channel", 1, true);
116 _channel_node = fnode->getChild("selected-channel", 2, true);
117 _channel_node = fnode->getChild("selected-channel", 3, true);
118 _channel_node = fnode->getChild("selected-channel", 4, true);
119 _in_range_node = node->getChild("in-range", 0, true);
120 _distance_node = node->getChild("indicated-distance-nm", 0, true);
121 _speed_node = node->getChild("indicated-ground-speed-kt", 0, true);
122 _time_node = node->getChild("indicated-time-min", 0, true);
123 _name_node = node->getChild("name", 0, true);
124 _bearing_node = node->getChild("indicated-bearing-true-deg", 0, true);
125 SGPropertyNode *cnode = fgGetNode("/ai/models/carrier", num, true );
126 _carrier_name_node = cnode->getChild("name", 0, true);
131 TACAN::update (double delta_time_sec)
136 double carrier_az2= 0;
137 double carrier_bearing = 0;
138 double carrier_distance = 0;
139 double frequency_mhz = 0;
140 string _channel, _last_channel, _channel_1, _channel_2,_channel_3, _channel_4;
142 // If it's off, don't waste any time.
143 if (!_serviceable_node->getBoolValue() || !_electrical_node->getBoolValue()) {
144 _last_distance_nm = 0;
145 _in_range_node->setBoolValue(false);
146 _distance_node->setDoubleValue(0);
147 _speed_node->setDoubleValue(0);
148 _time_node->setDoubleValue(0);
149 SG_LOG( SG_INSTR, SG_DEBUG, "skip tacan" );
153 // Figure out the source
154 const char * source = _source_node->getStringValue();
156 if (source[0] == '\0') {
158 branch = "/instrumentation/" + name + "/frequencies/selected-channel";
159 _source_node->setStringValue(branch.c_str());
160 source = _source_node->getStringValue();
161 SG_LOG( SG_INSTR, SG_DEBUG, "source " << source );
164 _channel_1 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[1]");
165 _channel_2 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[2]");
166 _channel_3 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[3]");
167 _channel_4 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[4]");
168 SG_LOG( SG_INSTR, SG_DEBUG, "channels " << _channel_1 << _channel_2 << _channel_3 << _channel_4);
169 _channel = _channel_1 + _channel_2 + _channel_3 + _channel_4;
170 SG_LOG( SG_INSTR, SG_DEBUG, "channel " << _channel );
172 // Get the frequecncy
173 if (_channel != _last_channel) {
174 _time_before_search_sec = 0;
175 _last_channel = _channel;
176 frequency_mhz = searchChannel(_channel);
177 SG_LOG( SG_INSTR, SG_DEBUG, "frequency " << frequency_mhz );
178 _frequency_node->setDoubleValue(frequency_mhz);
181 // Get the aircraft position
182 double longitude_deg = _longitude_node->getDoubleValue();
183 double latitude_deg = _latitude_node->getDoubleValue();
184 double altitude_m = _altitude_node->getDoubleValue() * SG_FEET_TO_METER;
185 double longitude_rad = longitude_deg * SGD_DEGREES_TO_RADIANS;
186 double latitude_rad = latitude_deg * SGD_DEGREES_TO_RADIANS;
188 // On timeout, scan again
189 _time_before_search_sec -= delta_time_sec;
190 if (_time_before_search_sec < 0 && frequency_mhz > 0)
191 search(frequency_mhz, longitude_rad, 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) {
267 _in_range_node->setBoolValue(false);
268 _distance_node->setDoubleValue(0);
269 _speed_node->setDoubleValue(0);
270 _time_node->setDoubleValue(0);
271 _bearing_node->setDoubleValue(0);
272 _transmitter_name = "";
273 _name_node->setStringValue(_transmitter_name.c_str());
276 } // end function update
279 TACAN::search (double frequency_mhz, double longitude_rad,
280 double latitude_rad, double altitude_m)
283 SG_LOG( SG_INSTR, SG_DEBUG, "tacan freq " << frequency_mhz );
286 _time_before_search_sec = 1.0;
288 //try any carriers first
289 FGNavRecord *carrier_tacan
290 = globals->get_carrierlist()->findStationByFreq( frequency_mhz );
291 _carrier_valid = (carrier_tacan != NULL);
293 if ( _carrier_valid ) {
294 SG_LOG( SG_INSTR, SG_DEBUG, "carrier transmitter valid " << _carrier_valid );
296 string str1( carrier_tacan->get_name() );
298 SGPropertyNode * branch = fgGetNode("ai/models", true);
299 vector<SGPropertyNode_ptr> carrier = branch->getChildren("carrier");
301 int number = carrier.size();
303 SG_LOG( SG_INSTR, SG_DEBUG, "carrier " << number );
306 for ( i = 0; i < number; ++i ) {
307 string str2 ( carrier[i]->getStringValue("name", ""));
308 // SG_LOG( SG_INSTR, SG_DEBUG, "carrier name " << str2 );
310 SG_LOG( SG_INSTR, SG_DEBUG, "strings 1 " << str1 << " 2 " << str2 );
311 unsigned int loc1= str1.find( str2, 0 );
312 if ( loc1 != string::npos && str2 != "" ) {
313 SG_LOG( SG_INSTR, SG_DEBUG, " string found" );
314 _carrier_lat = carrier[i]->getDoubleValue("position/latitude-deg");
315 _carrier_lon = carrier[i]->getDoubleValue("position/longitude-deg");
316 _carrier_elevation_ft = carrier_tacan->get_elev_ft();
317 _carrier_range_nm = carrier_tacan->get_range();
318 _carrier_bias = carrier_tacan->get_multiuse();
319 _carrier_name = carrier_tacan->get_name();
321 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter valid " << _carrier_valid );
325 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
329 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _carrier_name);
330 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _carrier_lat << "lon " << _carrier_lon);
331 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _carrier_elevation_ft);
334 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
338 // try the TACAN/VORTAC list next
340 = globals->get_tacanlist()->findByFreq( frequency_mhz, longitude_rad,
341 latitude_rad, altitude_m);
343 _transmitter_valid = (tacan != NULL);
345 if ( _transmitter_valid ) {
346 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter valid " << _transmitter_valid );
348 _transmitter_lat = tacan->get_lat();
349 _transmitter_lon = tacan->get_lon();
350 _transmitter_elevation_ft = tacan->get_elev_ft();
351 _transmitter_range_nm = tacan->get_range();
352 _transmitter_bias = tacan->get_multiuse();
353 _transmitter_name = tacan->get_name();
354 _name_node->setStringValue(_transmitter_name.c_str());
356 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _transmitter_name);
357 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _transmitter_lat << "lon " << _transmitter_lon);
358 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _transmitter_elevation_ft);
361 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter invalid " << _transmitter_valid );
366 TACAN::searchChannel (const string& _channel){
368 double frequency_khz = 0;
371 = globals->get_channellist()->findByChannel( _channel );
372 double _freq_valid = (freq != NULL);
373 SG_LOG( SG_INSTR, SG_DEBUG, "freq valid " << _freq_valid );
375 frequency_khz = freq->get_freq();
376 SG_LOG( SG_INSTR, SG_DEBUG, "freq output " << frequency_khz );
378 if (frequency_khz >=9620 && frequency_khz <= 12130)
379 return frequency_khz/100;
381 return frequency_khz = 0;
382 } // end TACAN::searchChannel