1 // radiostack.cxx -- class to manage an instance of the radio stack
3 // Written by Curtis Olson, started April 2000.
5 // Copyright (C) 2000 Curtis L. Olson - curt@flightgear.org
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include <simgear/math/sg_random.h>
26 #include <Aircraft/aircraft.hxx>
27 #include <Main/bfi.hxx>
28 #include <Navaids/ilslist.hxx>
29 #include <Navaids/navlist.hxx>
30 #include <Time/event.hxx>
32 #include "radiostack.hxx"
34 static int nav1_play_count = 0;
35 static time_t nav1_last_time = 0;
39 * Boy, this is ugly! Make the VOR range vary by altitude difference.
42 kludgeRange (double stationElev, double aircraftElev, double nominalRange)
44 // Assume that the nominal range (usually
45 // 50nm) applies at a 5,000 ft difference.
47 double factor = ((aircraftElev*METER_TO_FEET) - stationElev) / 1000.0;
48 double range = fabs(nominalRange * factor);
50 // Clamp the range to keep it sane; for
51 // now, never less than 25% or more than
52 // 500% of nominal range.
53 if (range < nominalRange/4.0) {
54 range = nominalRange/4.0;
55 } else if (range > nominalRange*5.0) {
56 range = nominalRange*5.0;
63 FGRadioStack *current_radiostack;
66 // periodic radio station search wrapper
67 static void fgRadioSearch( void ) {
68 current_radiostack->search();
72 FGRadioStack::FGRadioStack() {
78 longitudeVal = fgGetValue("/position/longitude");
79 latitudeVal = fgGetValue("/position/latitude");
80 altitudeVal = fgGetValue("/position/altitude");
85 FGRadioStack::~FGRadioStack()
87 unbind(); // FIXME: should be called externally
99 // Search radio database once per second
100 global_events.Register( "fgRadioSearch()", fgRadioSearch,
101 fgEVENT::FG_EVENT_READY, 1000);
105 FGRadioStack::bind ()
108 fgTie("/radios/nav1/frequencies/selected", this,
109 &FGRadioStack::get_nav1_freq, &FGRadioStack::set_nav1_freq);
110 fgTie("/radios/nav1/frequencies/standby", this,
111 &FGRadioStack::get_nav1_alt_freq, &FGRadioStack::set_nav1_alt_freq);
112 fgTie("/radios/nav1/radials/selected", this,
113 &FGRadioStack::get_nav1_sel_radial,
114 &FGRadioStack::set_nav1_sel_radial);
115 fgTie("/radios/nav1/on", this,
116 &FGRadioStack::get_nav1_on_btn,
117 &FGRadioStack::set_nav1_on_btn);
118 fgTie("/radios/nav1/ident", this,
119 &FGRadioStack::get_nav1_ident_btn,
120 &FGRadioStack::set_nav1_ident_btn);
123 fgTie("/radios/nav1/radials/actual", this, &FGRadioStack::get_nav1_radial);
124 fgTie("/radios/nav1/to-flag", this, &FGRadioStack::get_nav1_to_flag);
125 fgTie("/radios/nav1/from-flag", this, &FGRadioStack::get_nav1_from_flag);
126 fgTie("/radios/nav1/in-range", this, &FGRadioStack::get_nav1_inrange);
127 fgTie("/radios/nav1/dme/distance", this, &FGRadioStack::get_nav1_dme_dist);
128 fgTie("/radios/nav1/dme/in-range", this,
129 &FGRadioStack::get_nav1_dme_inrange);
130 fgTie("/radios/nav1/heading-needle-deflection", this,
131 &FGRadioStack::get_nav1_heading_needle_deflection);
132 fgTie("/radios/nav1/gs-needle-deflection", this,
133 &FGRadioStack::get_nav1_gs_needle_deflection);
136 fgTie("/radios/nav2/frequencies/selected", this,
137 &FGRadioStack::get_nav2_freq, &FGRadioStack::set_nav2_freq);
138 fgTie("/radios/nav2/frequencies/standby", this,
139 &FGRadioStack::get_nav2_alt_freq, &FGRadioStack::set_nav2_alt_freq);
140 fgTie("/radios/nav2/radials/selected", this,
141 &FGRadioStack::get_nav2_sel_radial,
142 &FGRadioStack::set_nav2_sel_radial);
143 fgTie("/radios/nav2/on", this,
144 &FGRadioStack::get_nav2_on_btn,
145 &FGRadioStack::set_nav2_on_btn);
146 fgTie("/radios/nav2/ident", this,
147 &FGRadioStack::get_nav2_ident_btn,
148 &FGRadioStack::set_nav2_ident_btn);
151 fgTie("/radios/nav2/radials/actual", this, &FGRadioStack::get_nav2_radial);
152 fgTie("/radios/nav2/to-flag", this, &FGRadioStack::get_nav2_to_flag);
153 fgTie("/radios/nav2/from-flag", this, &FGRadioStack::get_nav2_from_flag);
154 fgTie("/radios/nav2/in-range", this, &FGRadioStack::get_nav2_inrange);
155 fgTie("/radios/nav2/dme/distance", this, &FGRadioStack::get_nav2_dme_dist);
156 fgTie("/radios/nav2/dme/in-range", this,
157 &FGRadioStack::get_nav2_dme_inrange);
158 fgTie("/radios/nav2/heading-needle-deflection", this,
159 &FGRadioStack::get_nav2_heading_needle_deflection);
160 fgTie("/radios/nav2/gs-needle-deflection", this,
161 &FGRadioStack::get_nav2_gs_needle_deflection);
164 fgTie("/radios/adf/frequencies/selected", this,
165 &FGRadioStack::get_adf_freq, &FGRadioStack::set_adf_freq);
166 fgTie("/radios/adf/frequencies/standby", this,
167 &FGRadioStack::get_adf_alt_freq, &FGRadioStack::set_adf_alt_freq);
168 fgTie("/radios/adf/rotation", this,
169 &FGRadioStack::get_adf_rotation, &FGRadioStack::set_adf_rotation);
173 FGRadioStack::unbind ()
175 fgUntie("/radios/nav1/frequencies/selected");
176 fgUntie("/radios/nav1/frequencies/standby");
177 fgUntie("/radios/nav1/radials/actual");
178 fgUntie("/radios/nav1/radials/selected");
179 fgUntie("/radios/nav1/on");
180 fgUntie("/radios/nav1/ident");
181 fgUntie("/radios/nav1/to-flag");
182 fgUntie("/radios/nav1/from-flag");
183 fgUntie("/radios/nav1/in-range");
184 fgUntie("/radios/nav1/dme/distance");
185 fgUntie("/radios/nav1/dme/in-range");
186 fgUntie("/radios/nav1/heading-needle-deflection");
187 fgUntie("/radios/nav1/gs-needle-deflection");
189 fgUntie("/radios/nav2/frequencies/selected");
190 fgUntie("/radios/nav2/frequencies/standby");
191 fgUntie("/radios/nav2/radials/actual");
192 fgUntie("/radios/nav2/radials/selected");
193 fgUntie("/radios/nav2/on");
194 fgUntie("/radios/nav2/ident");
195 fgUntie("/radios/nav2/to-flag");
196 fgUntie("/radios/nav2/from-flag");
197 fgUntie("/radios/nav2/in-range");
198 fgUntie("/radios/nav2/dme/distance");
199 fgUntie("/radios/nav2/dme/in-range");
200 fgUntie("/radios/nav2/heading-needle-deflection");
201 fgUntie("/radios/nav2/gs-needle-deflection");
203 fgUntie("/radios/adf/frequencies/selected");
204 fgUntie("/radios/adf/frequencies/standby");
205 fgUntie("/radios/adf/rotation");
208 // Update the various nav values based on position and valid tuned in navs
210 FGRadioStack::update()
212 double lon = longitudeVal->getDoubleValue() * DEG_TO_RAD;
213 double lat = latitudeVal->getDoubleValue() * DEG_TO_RAD;
214 double elev = altitudeVal->getDoubleValue() * FEET_TO_METER;
218 Point3D aircraft = sgGeodToCart( Point3D( lon, lat, elev ) );
223 station = Point3D( nav1_x, nav1_y, nav1_z );
224 nav1_loc_dist = aircraft.distance3D( station );
226 if ( nav1_has_dme ) {
227 // staightline distance
228 station = Point3D( nav1_dme_x, nav1_dme_y, nav1_dme_z );
229 nav1_dme_dist = aircraft.distance3D( station );
235 station = Point3D( nav1_gs_x, nav1_gs_y, nav1_gs_z );
236 nav1_gs_dist = aircraft.distance3D( station );
241 nav1_effective_range = kludgeRange(nav1_elev, elev, nav1_range);
242 if ( nav1_loc_dist < nav1_effective_range * NM_TO_METER ) {
246 geo_inverse_wgs_84( elev, lat * RAD_TO_DEG, lon * RAD_TO_DEG,
247 nav1_loclat, nav1_loclon,
249 // cout << "az1 = " << az1 << " magvar = " << nav1_magvar << endl;
250 nav1_heading = az1 - nav1_magvar;
251 // Alex: nav1_heading = - (az1 - FGBFI::getMagVar() / RAD_TO_DEG);
253 // cout << " heading = " << nav1_heading
254 // << " dist = " << nav1_dist << endl;
256 nav1_inrange = false;
261 nav1_radial = nav1_sel_radial;
264 nav1_inrange = false;
266 // cout << "not picking up vor. :-(" << endl;
269 if ( nav1_valid && nav1_inrange ) {
270 // play station ident via audio system if on + ident,
271 // otherwise turn it off
272 if ( nav1_on_btn && nav1_ident_btn ) {
273 if ( nav1_last_time <
274 globals->get_time_params()->get_cur_time() - 30 ) {
275 nav1_last_time = globals->get_time_params()->get_cur_time();
278 if ( nav1_play_count < 4 ) {
280 if ( !globals->get_soundmgr()->is_playing("nav1-vor-ident") ) {
281 globals->get_soundmgr()->play_once( "nav1-vor-ident" );
284 } else if ( nav1_play_count < 5 && nav1_has_dme ) {
286 if ( !globals->get_soundmgr()->is_playing("nav1-vor-ident") &&
287 !globals->get_soundmgr()->is_playing("nav1-dme-ident") ) {
288 globals->get_soundmgr()->play_once( "nav1-dme-ident" );
293 globals->get_soundmgr()->stop( "nav1-vor-ident" );
294 globals->get_soundmgr()->stop( "nav1-dme-ident" );
299 station = Point3D( nav2_x, nav2_y, nav2_z );
300 nav2_loc_dist = aircraft.distance3D( station );
302 if ( nav2_has_dme ) {
303 // staightline distance
304 station = Point3D( nav2_dme_x, nav2_dme_y, nav2_dme_z );
305 nav2_dme_dist = aircraft.distance3D( station );
311 station = Point3D( nav2_gs_x, nav2_gs_y, nav2_gs_z );
312 nav2_gs_dist = aircraft.distance3D( station );
317 nav2_effective_range = kludgeRange(nav2_elev, elev, nav2_range);
318 if ( nav2_loc_dist < nav2_effective_range * NM_TO_METER ) {
322 geo_inverse_wgs_84( elev, lat * RAD_TO_DEG, lon * RAD_TO_DEG,
323 nav2_loclat, nav2_loclon,
325 nav2_heading = az1 - nav2_magvar;
326 // Alex: nav2_heading = - (az1 - FGBFI::getMagVar() / RAD_TO_DEG);
328 // cout << " heading = " << nav2_heading
329 // << " dist = " << nav2_dist << endl;
331 nav2_inrange = false;
335 nav2_radial = nav2_sel_radial;
338 nav2_inrange = false;
339 // cout << "not picking up vor. :-(" << endl;
344 // staightline distance
345 station = Point3D( adf_x, adf_y, adf_z );
346 adf_dist = aircraft.distance3D( station );
348 adf_effective_range = kludgeRange(adf_elev, elev, adf_range);
349 if ( adf_dist < adf_effective_range * NM_TO_METER ) {
353 geo_inverse_wgs_84( elev, lat * RAD_TO_DEG, lon * RAD_TO_DEG,
358 // cout << " heading = " << nav2_heading
359 // << " dist = " << nav2_dist << endl;
369 // Update current nav/adf radio stations based on current postition
370 void FGRadioStack::search()
372 double lon = longitudeVal->getDoubleValue() * DEG_TO_RAD;
373 double lat = latitudeVal->getDoubleValue() * DEG_TO_RAD;
374 double elev = altitudeVal->getDoubleValue() * FEET_TO_METER;
380 static string last_nav1_ident = "";
381 static string last_nav2_ident = "";
382 static bool last_nav1_vor = false;
383 static bool last_nav2_vor = false;
384 if ( current_ilslist->query( lon, lat, elev, nav1_freq, &ils ) ) {
385 nav1_ident = ils.get_locident();
386 if ( last_nav1_ident != nav1_ident || last_nav1_vor ) {
387 nav1_trans_ident = ils.get_trans_ident();
388 last_nav1_ident = nav1_ident;
389 last_nav1_vor = false;
392 nav1_has_dme = ils.get_has_dme();
393 nav1_has_gs = ils.get_has_gs();
395 nav1_loclon = ils.get_loclon();
396 nav1_loclat = ils.get_loclat();
397 nav1_gslon = ils.get_gslon();
398 nav1_gslat = ils.get_gslat();
399 nav1_dmelon = ils.get_dmelon();
400 nav1_dmelat = ils.get_dmelat();
401 nav1_elev = ils.get_gselev();
403 nav1_range = FG_ILS_DEFAULT_RANGE;
404 nav1_effective_range = nav1_range;
405 nav1_target_gs = ils.get_gsangle();
406 nav1_radial = ils.get_locheading();
407 while ( nav1_radial < 0.0 ) { nav1_radial += 360.0; }
408 while ( nav1_radial > 360.0 ) { nav1_radial -= 360.0; }
409 nav1_x = ils.get_x();
410 nav1_y = ils.get_y();
411 nav1_z = ils.get_z();
412 nav1_gs_x = ils.get_gs_x();
413 nav1_gs_y = ils.get_gs_y();
414 nav1_gs_z = ils.get_gs_z();
415 nav1_dme_x = ils.get_dme_x();
416 nav1_dme_y = ils.get_dme_y();
417 nav1_dme_z = ils.get_dme_z();
419 if ( globals->get_soundmgr()->exists( "nav1-vor-ident" ) ) {
420 globals->get_soundmgr()->remove( "nav1-vor-ident" );
422 FGSimpleSound *sound;
423 sound = morse.make_ident( nav1_trans_ident, LO_FREQUENCY );
424 sound->set_volume( 0.3 );
425 globals->get_soundmgr()->add( sound, "nav1-vor-ident" );
427 if ( globals->get_soundmgr()->exists( "nav1-dme-ident" ) ) {
428 globals->get_soundmgr()->remove( "nav1-dme-ident" );
430 sound = morse.make_ident( nav1_trans_ident, HI_FREQUENCY );
431 sound->set_volume( 0.3 );
432 globals->get_soundmgr()->add( sound, "nav1-dme-ident" );
434 int offset = (int)(sg_random() * 30.0);
435 nav1_play_count = offset / 4;
436 nav1_last_time = globals->get_time_params()->get_cur_time() -
438 cout << "offset = " << offset << " play_count = " << nav1_play_count
439 << " nav1_last_time = " << nav1_last_time << " current time = "
440 << globals->get_time_params()->get_cur_time() << endl;
442 cout << "Found an ils station in range" << endl;
443 cout << " id = " << ils.get_locident() << endl;
445 } else if ( current_navlist->query( lon, lat, elev, nav1_freq, &nav ) ) {
446 nav1_ident = nav.get_ident();
447 if ( last_nav1_ident != nav1_ident || !last_nav1_vor ) {
448 last_nav1_ident = nav1_ident;
449 last_nav1_vor = true;
450 nav1_trans_ident = nav.get_trans_ident();
453 nav1_has_dme = nav.get_has_dme();
455 nav1_loclon = nav.get_lon();
456 nav1_loclat = nav.get_lat();
457 nav1_elev = nav.get_elev();
458 nav1_magvar = nav.get_magvar();
459 nav1_range = nav.get_range();
460 nav1_effective_range = kludgeRange(nav1_elev, elev, nav1_range);
461 nav1_target_gs = 0.0;
462 nav1_radial = nav1_sel_radial;
463 nav1_x = nav1_dme_x = nav.get_x();
464 nav1_y = nav1_dme_y = nav.get_y();
465 nav1_z = nav1_dme_z = nav.get_z();
467 if ( globals->get_soundmgr()->exists( "nav1-vor-ident" ) ) {
468 globals->get_soundmgr()->remove( "nav1-vor-ident" );
470 FGSimpleSound *sound;
471 sound = morse.make_ident( nav1_trans_ident, LO_FREQUENCY );
472 sound->set_volume( 0.3 );
473 globals->get_soundmgr()->add( sound, "nav1-vor-ident" );
475 if ( globals->get_soundmgr()->exists( "nav1-dme-ident" ) ) {
476 globals->get_soundmgr()->remove( "nav1-dme-ident" );
478 sound = morse.make_ident( nav1_trans_ident, HI_FREQUENCY );
479 sound->set_volume( 0.3 );
480 globals->get_soundmgr()->add( sound, "nav1-dme-ident" );
482 int offset = (int)(sg_random() * 30.0);
483 nav1_play_count = offset / 4;
484 nav1_last_time = globals->get_time_params()->get_cur_time() -
486 cout << "offset = " << offset << " play_count = " << nav1_play_count
487 << " nav1_last_time = " << nav1_last_time << " current time = "
488 << globals->get_time_params()->get_cur_time() << endl;
490 cout << "Found a vor station in range" << endl;
491 cout << " id = " << nav.get_ident() << endl;
498 globals->get_soundmgr()->remove( "nav1-vor-ident" );
499 globals->get_soundmgr()->remove( "nav1-dme-ident" );
500 cout << "not picking up vor1. :-(" << endl;
503 if ( current_ilslist->query( lon, lat, elev, nav2_freq, &ils ) ) {
504 nav2_ident = ils.get_locident();
505 if ( last_nav2_ident != nav2_ident || last_nav2_vor ) {
506 last_nav2_ident = nav2_ident;
507 last_nav2_vor = false;
508 nav2_trans_ident = ils.get_trans_ident();
511 nav2_has_dme = ils.get_has_dme();
512 nav2_has_gs = ils.get_has_gs();
514 nav2_loclon = ils.get_loclon();
515 nav2_loclat = ils.get_loclat();
516 nav2_elev = ils.get_gselev();
518 nav2_range = FG_ILS_DEFAULT_RANGE;
519 nav2_effective_range = nav2_range;
520 nav2_target_gs = ils.get_gsangle();
521 nav2_radial = ils.get_locheading();
522 while ( nav2_radial < 0.0 ) { nav2_radial += 360.0; }
523 while ( nav2_radial > 360.0 ) { nav2_radial -= 360.0; }
524 nav2_x = ils.get_x();
525 nav2_y = ils.get_y();
526 nav2_z = ils.get_z();
527 nav2_gs_x = ils.get_gs_x();
528 nav2_gs_y = ils.get_gs_y();
529 nav2_gs_z = ils.get_gs_z();
530 nav2_dme_x = ils.get_dme_x();
531 nav2_dme_y = ils.get_dme_y();
532 nav2_dme_z = ils.get_dme_z();
533 // cout << "Found an ils station in range" << endl;
534 // cout << " id = " << ils.get_locident() << endl;
536 } else if ( current_navlist->query( lon, lat, elev, nav2_freq, &nav ) ) {
537 nav2_ident = nav.get_ident();
538 if ( last_nav2_ident != nav2_ident || !last_nav2_vor ) {
539 last_nav2_ident = nav2_ident;
540 last_nav2_vor = true;
541 nav2_trans_ident = nav.get_trans_ident();
544 nav2_has_dme = nav.get_has_dme();
545 nav2_has_dme = false;
546 nav2_loclon = nav.get_lon();
547 nav2_loclat = nav.get_lat();
548 nav2_elev = nav.get_elev();
549 nav2_magvar = nav.get_magvar();
550 nav2_range = nav.get_range();
551 nav2_effective_range = kludgeRange(nav2_elev, elev, nav2_range);
552 nav2_target_gs = 0.0;
553 nav2_radial = nav2_sel_radial;
554 nav2_x = nav2_dme_x = nav.get_x();
555 nav2_y = nav2_dme_y = nav.get_y();
556 nav2_z = nav2_dme_z = nav.get_z();
557 // cout << "Found a vor station in range" << endl;
558 // cout << " id = " << nav.get_ident() << endl;
565 // cout << "not picking up vor2. :-(" << endl;
569 if ( current_navlist->query( lon, lat, elev, adf_freq, &nav ) ) {
572 adf_lon = nav.get_lon();
573 adf_lat = nav.get_lat();
574 adf_elev = nav.get_elev();
575 adf_range = nav.get_range();
576 adf_effective_range = kludgeRange(adf_elev, elev, adf_range);
580 // cout << "Found an adf station in range" << endl;
581 // cout << " id = " << nav.get_ident() << endl;
584 // cout << "not picking up adf. :-(" << endl;
589 // return the amount of heading needle deflection, returns a value
590 // clamped to the range of ( -10 , 10 )
591 double FGRadioStack::get_nav1_heading_needle_deflection() const {
594 if ( nav1_inrange ) {
595 r = nav1_heading - nav1_radial;
596 // cout << "Radial = " << nav1_radial
597 // << " Bearing = " << nav1_heading << endl;
599 while ( r > 180.0 ) { r -= 360.0;}
600 while ( r < -180.0 ) { r += 360.0;}
601 if ( fabs(r) > 90.0 ) {
602 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
608 // According to Robin Peel, the ILS is 4x more sensitive than a vor
609 if ( nav1_loc ) { r *= 4.0; }
610 if ( r < -10.0 ) { r = -10.0; }
611 if ( r > 10.0 ) { r = 10.0; }
619 // return the amount of heading needle deflection, returns a value
620 // clamped to the range of ( -10 , 10 )
621 double FGRadioStack::get_nav2_heading_needle_deflection() const {
624 if ( nav2_inrange ) {
625 r = nav2_heading - nav2_radial;
626 // cout << "Radial = " << nav2_radial
627 // << " Bearing = " << nav2_heading << endl;
629 while (r> 180.0) r-=360.0;
630 while (r<-180.0) r+=360.0;
631 if ( fabs(r) > 90.0 )
632 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
633 // According to Robin Peel, the ILS is 4x more sensitive than a vor
634 if ( nav2_loc ) r *= 4.0;
635 if ( r < -10.0 ) r = -10.0;
636 if ( r > 10.0 ) r = 10.0;
644 // return the amount of glide slope needle deflection (.i.e. the
645 // number of degrees we are off the glide slope * 5.0
646 double FGRadioStack::get_nav1_gs_needle_deflection() const {
647 if ( nav1_inrange && nav1_has_gs ) {
648 double x = nav1_gs_dist;
649 double y = (FGBFI::getAltitude() - nav1_elev) * FEET_TO_METER;
650 double angle = atan2( y, x ) * RAD_TO_DEG;
651 return (nav1_target_gs - angle) * 5.0;
658 // return the amount of glide slope needle deflection (.i.e. the
659 // number of degrees we are off the glide slope * 5.0
660 double FGRadioStack::get_nav2_gs_needle_deflection() const {
661 if ( nav2_inrange && nav2_has_gs ) {
662 double x = nav2_gs_dist;
663 double y = (FGBFI::getAltitude() - nav2_elev) * FEET_TO_METER;
664 double angle = atan2( y, x ) * RAD_TO_DEG;
665 return (nav2_target_gs - angle) * 5.0;
673 * Return true if the NAV1 TO flag should be active.
676 FGRadioStack::get_nav1_to_flag () const
679 double offset = fabs(nav1_heading - nav1_radial);
683 return (offset <= 90.0 || offset >= 270.0);
691 * Return true if the NAV1 FROM flag should be active.
694 FGRadioStack::get_nav1_from_flag () const
697 double offset = fabs(nav1_heading - nav1_radial);
701 return (offset > 90.0 && offset < 270.0);
709 * Return true if the NAV2 TO flag should be active.
712 FGRadioStack::get_nav2_to_flag () const
715 double offset = fabs(nav2_heading - nav2_radial);
719 return (offset <= 90.0 || offset >= 270.0);
727 * Return true if the NAV2 FROM flag should be active.
730 FGRadioStack::get_nav2_from_flag () const
733 double offset = fabs(nav2_heading - nav2_radial);
737 return (offset > 90.0 && offset < 270.0);