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