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>
22 * Start by calculating the radar horizon based on the elevation
23 * difference, then clamp to the maximum, then add a fudge for
24 * borderline reception.
27 adjust_range (double transmitter_elevation_ft, double aircraft_altitude_ft,
31 double delta_elevation_ft =
32 fabs(aircraft_altitude_ft - transmitter_elevation_ft);
33 double range_nm = 1.23 * sqrt(delta_elevation_ft);
34 if (range_nm > max_range_nm)
35 range_nm = max_range_nm;
36 else if (range_nm < 20.0)
38 double rand = sg_random();
39 SG_LOG( SG_INSTR, SG_DEBUG, " tacan range " << range_nm << " max range " << max_range_nm);
40 return range_nm + (range_nm * rand * rand);
44 TACAN::TACAN ( SGPropertyNode *node )
45 : _last_distance_nm(0),
46 _last_frequency_mhz(-1),
47 _time_before_search_sec(0),
48 _carrier_valid(false),
49 _transmitter_valid(false),
50 _transmitter_elevation_ft(0),
51 _transmitter_range_nm(0),
52 _transmitter_bias(0.0),
59 for ( i = 0; i < node->nChildren(); ++i ) {
60 SGPropertyNode *child = node->getChild(i);
61 string cname = child->getName();
62 string cval = child->getStringValue();
63 if ( cname == "name" ) {
65 } else if ( cname == "number" ) {
66 num = child->getIntValue();
68 SG_LOG( SG_INSTR, SG_DEBUG, "Error in TACAN config logic" );
69 if ( name.length() ) {
70 SG_LOG( SG_INSTR, SG_DEBUG, "Section = " << name );
77 : _last_distance_nm(0),
78 _last_frequency_mhz(-1),
79 _time_before_search_sec(0),
80 _carrier_valid(false),
81 _transmitter_valid(false),
82 _transmitter_elevation_ft(0),
83 _transmitter_range_nm(0),
84 _transmitter_bearing_deg(0),
85 _transmitter_bias(0.0),
86 _transmitter_name(""),
99 branch = "/instrumentation/" + name;
101 SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
103 _longitude_node = fgGetNode("/position/longitude-deg", true);
104 _latitude_node = fgGetNode("/position/latitude-deg", true);
105 _altitude_node = fgGetNode("/position/altitude-ft", true);
106 _serviceable_node = node->getChild("serviceable", 0, true);
107 _electrical_node = fgGetNode("/systems/electrical/outputs/tacan", true);
108 SGPropertyNode *fnode = node->getChild("frequencies", 0, true);
109 _source_node = fnode->getChild("source", 0, true);
110 _frequency_node = fnode->getChild("selected-mhz", 0, true);
111 _channel_node = fnode->getChild("selected-channel", 1, true);
112 _channel_node = fnode->getChild("selected-channel", 2, true);
113 _channel_node = fnode->getChild("selected-channel", 3, true);
114 _channel_node = fnode->getChild("selected-channel", 4, true);
115 _in_range_node = node->getChild("in-range", 0, true);
116 _distance_node = node->getChild("indicated-distance-nm", 0, true);
117 _speed_node = node->getChild("indicated-ground-speed-kt", 0, true);
118 _time_node = node->getChild("indicated-time-min", 0, true);
119 _name_node = node->getChild("name", 0, true);
120 _bearing_node = node->getChild("indicated-bearing-true-deg", 0, true);
121 SGPropertyNode *cnode = fgGetNode("/ai/models/carrier", num, true );
122 _carrier_name_node = cnode->getChild("name", 0, true);
127 TACAN::update (double delta_time_sec)
132 double carrier_az2= 0;
133 double carrier_bearing = 0;
134 double carrier_distance = 0;
135 double frequency_mhz = 0;
136 string _channel, _last_channel, _channel_1, _channel_2,_channel_3, _channel_4;
138 // If it's off, don't waste any time.
139 if (!_serviceable_node->getBoolValue() || !_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" );
149 // Figure out the source
150 const char * source = _source_node->getStringValue();
152 if (source[0] == '\0') {
154 branch = "/instrumentation/" + name + "/frequencies/selected-channel";
155 _source_node->setStringValue(branch.c_str());
156 source = _source_node->getStringValue();
157 SG_LOG( SG_INSTR, SG_DEBUG, "source " << source );
160 _channel_1 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[1]");
161 _channel_2 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[2]");
162 _channel_3 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[3]");
163 _channel_4 = fgGetString("/instrumentation/tacan/frequencies/selected-channel[4]");
164 SG_LOG( SG_INSTR, SG_DEBUG, "channels " << _channel_1 << _channel_2 << _channel_3 << _channel_4);
165 _channel = _channel_1 + _channel_2 + _channel_3 + _channel_4;
166 SG_LOG( SG_INSTR, SG_DEBUG, "channel " << _channel );
168 // Get the frequecncy
169 if (_channel != _last_channel) {
170 _time_before_search_sec = 0;
171 _last_channel = _channel;
172 frequency_mhz = searchChannel(_channel);
173 SG_LOG( SG_INSTR, SG_DEBUG, "frequency " << frequency_mhz );
174 _frequency_node->setDoubleValue(frequency_mhz);
177 // Get the aircraft position
178 double longitude_deg = _longitude_node->getDoubleValue();
179 double latitude_deg = _latitude_node->getDoubleValue();
180 double altitude_m = _altitude_node->getDoubleValue() * SG_FEET_TO_METER;
181 double longitude_rad = longitude_deg * SGD_DEGREES_TO_RADIANS;
182 double latitude_rad = latitude_deg * SGD_DEGREES_TO_RADIANS;
184 // On timeout, scan again
185 _time_before_search_sec -= delta_time_sec;
186 if (_time_before_search_sec < 0 && frequency_mhz > 0)
187 search(frequency_mhz, longitude_rad, latitude_rad, altitude_m);
189 // Calculate the distance to the transmitter
191 //calculate the bearing and range of the carrier from the aircraft
192 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_lat " << _carrier_lat);
193 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_lon " << _carrier_lon);
194 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_name " << _carrier_name);
195 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_valid " << _carrier_valid);
196 geo_inverse_wgs_84(altitude_m,
201 &carrier_bearing, &carrier_az2, &carrier_distance);
204 //calculate the bearing and range of the station from the aircraft
205 geo_inverse_wgs_84(altitude_m,
210 &bearing, &az2, &distance);
214 if ( carrier_distance <= distance && _carrier_valid) {
215 SG_LOG( SG_INSTR, SG_DEBUG, "carrier_distance_nm " << carrier_distance);
216 SG_LOG( SG_INSTR, SG_DEBUG, "distance_nm " << distance);
217 bearing = carrier_bearing;
218 distance = carrier_distance;
219 _transmitter_elevation_ft = _carrier_elevation_ft;
220 _transmitter_range_nm = _carrier_range_nm;
221 _transmitter_bias = _carrier_bias;
222 _transmitter_name = _carrier_name;
223 _name_node->setStringValue(_transmitter_name.c_str());
226 double distance_nm = distance * SG_METER_TO_NM;
227 SG_LOG( SG_INSTR, SG_DEBUG, "distance_nm " << distance_nm << " bearing " << bearing);
230 sgGeodToCart(Point3D(longitude_rad, latitude_rad, altitude_m));
231 double distance_nm = _transmitter.distance3D(location) * SG_METER_TO_NM;*/
233 double range_nm = adjust_range(_transmitter_elevation_ft,
234 altitude_m * SG_METER_TO_FEET,
235 _transmitter_range_nm);
237 if (distance_nm <= range_nm) {
238 double speed_kt = (fabs(distance_nm - _last_distance_nm) *
239 ((1 / delta_time_sec) * 3600.0));
240 _last_distance_nm = distance_nm;
242 _in_range_node->setBoolValue(true);
243 double tmp_dist = distance_nm - _transmitter_bias;
244 if ( tmp_dist < 0.0 ) {
247 _distance_node->setDoubleValue( tmp_dist );
248 _speed_node->setDoubleValue(speed_kt);
249 _time_node->setDoubleValue(distance_nm/speed_kt*60.0);
250 _bearing_node->setDoubleValue(bearing);
253 _last_distance_nm = 0;
254 _in_range_node->setBoolValue(false);
255 _distance_node->setDoubleValue(0);
256 _speed_node->setDoubleValue(0);
257 _time_node->setDoubleValue(0);
258 _bearing_node->setDoubleValue(0);
261 // If we can't find a valid station set everything to zero
262 if (!_transmitter_valid && !_carrier_valid) {
263 _in_range_node->setBoolValue(false);
264 _distance_node->setDoubleValue(0);
265 _speed_node->setDoubleValue(0);
266 _time_node->setDoubleValue(0);
267 _bearing_node->setDoubleValue(0);
268 _transmitter_name = "";
269 _name_node->setStringValue(_transmitter_name.c_str());
272 } // end function update
275 TACAN::search (double frequency_mhz, double longitude_rad,
276 double latitude_rad, double altitude_m)
279 SG_LOG( SG_INSTR, SG_DEBUG, "tacan freq " << frequency_mhz );
282 _time_before_search_sec = 1.0;
284 //try any carriers first
285 FGNavRecord *carrier_tacan
286 = globals->get_carrierlist()->findStationByFreq( frequency_mhz );
287 _carrier_valid = (carrier_tacan != NULL);
289 if ( _carrier_valid ) {
290 SG_LOG( SG_INSTR, SG_DEBUG, "carrier transmitter valid " << _carrier_valid );
292 string str1( carrier_tacan->get_name() );
294 SGPropertyNode * branch = fgGetNode("ai/models", true);
295 vector<SGPropertyNode_ptr> carrier = branch->getChildren("carrier");
297 int number = carrier.size();
299 SG_LOG( SG_INSTR, SG_DEBUG, "carrier " << number );
302 for ( i = 0; i < number; ++i ) {
303 string str2 ( carrier[i]->getStringValue("name", ""));
304 // SG_LOG( SG_INSTR, SG_DEBUG, "carrier name " << str2 );
306 SG_LOG( SG_INSTR, SG_DEBUG, "strings 1 " << str1 << " 2 " << str2 );
307 unsigned int loc1= str1.find( str2, 0 );
308 if ( loc1 != string::npos && str2 != "" ) {
309 SG_LOG( SG_INSTR, SG_DEBUG, " string found" );
310 _carrier_lat = carrier[i]->getDoubleValue("position/latitude-deg");
311 _carrier_lon = carrier[i]->getDoubleValue("position/longitude-deg");
312 _carrier_elevation_ft = carrier_tacan->get_elev_ft();
313 _carrier_range_nm = carrier_tacan->get_range();
314 _carrier_bias = carrier_tacan->get_multiuse();
315 _carrier_name = carrier_tacan->get_name();
317 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter valid " << _carrier_valid );
321 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
325 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _carrier_name);
326 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _carrier_lat << "lon " << _carrier_lon);
327 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _carrier_elevation_ft);
330 SG_LOG( SG_INSTR, SG_DEBUG, " carrier transmitter invalid " << _carrier_valid );
334 // try the TACAN/VORTAC list next
336 = globals->get_tacanlist()->findByFreq( frequency_mhz, longitude_rad,
337 latitude_rad, altitude_m);
339 _transmitter_valid = (tacan != NULL);
341 if ( _transmitter_valid ) {
342 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter valid " << _transmitter_valid );
344 _transmitter_lat = tacan->get_lat();
345 _transmitter_lon = tacan->get_lon();
346 _transmitter_elevation_ft = tacan->get_elev_ft();
347 _transmitter_range_nm = tacan->get_range();
348 _transmitter_bias = tacan->get_multiuse();
349 _transmitter_name = tacan->get_name();
350 _name_node->setStringValue(_transmitter_name.c_str());
352 SG_LOG( SG_INSTR, SG_DEBUG, "name " << _transmitter_name);
353 SG_LOG( SG_INSTR, SG_DEBUG, "lat " << _transmitter_lat << "lon " << _transmitter_lon);
354 SG_LOG( SG_INSTR, SG_DEBUG, "elev " << _transmitter_elevation_ft);
357 SG_LOG( SG_INSTR, SG_DEBUG, "transmitter invalid " << _transmitter_valid );
362 TACAN::searchChannel (const string& _channel){
364 double frequency_khz = 0;
367 = globals->get_channellist()->findByChannel( _channel );
368 double _freq_valid = (freq != NULL);
369 SG_LOG( SG_INSTR, SG_DEBUG, "freq valid " << _freq_valid );
371 frequency_khz = freq->get_freq();
372 SG_LOG( SG_INSTR, SG_DEBUG, "freq output " << frequency_khz );
374 if (frequency_khz >9620 && frequency_khz <= 12130)
375 return frequency_khz/100;
377 return frequency_khz = 0;
378 } // end TACAN::searchChannel