1 // navradio.cxx -- class to manage a nav radio instance
3 // Written by Curtis Olson, started April 2000.
5 // Copyright (C) 2000 - 2002 Curtis L. Olson - http://www.flightgear.org/~curt
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
28 #include "navradio.hxx"
32 #include <simgear/sg_inlines.h>
33 #include <simgear/timing/sg_time.hxx>
34 #include <simgear/math/vector.hxx>
35 #include <simgear/math/sg_random.h>
36 #include <simgear/misc/sg_path.hxx>
37 #include <simgear/math/sg_geodesy.hxx>
38 #include <simgear/structure/exception.hxx>
39 #include <simgear/math/interpolater.hxx>
41 #include <Navaids/navrecord.hxx>
43 #include <Airports/runways.hxx>
44 #include <Navaids/navlist.hxx>
45 #include <Main/util.hxx>
50 // General-purpose sawtooth function. Graph looks like this:
53 // Odd symmetry, inversion symmetry about the origin.
54 // Unit slope at the origin.
55 // Max 1, min -1, period 4.
56 // Two zero-crossings per period, one with + slope, one with - slope.
57 // Useful for false localizer courses.
58 static double sawtooth(double xx)
60 return 4.0 * fabs(xx/4.0 + 0.25 - floor(xx/4.0 + 0.75)) - 1.0;
63 // Calculate a unit vector in the horizontal tangent plane
64 // starting at the given "tail" of the vector and going off
65 // with the given heading.
66 static SGVec3d tangentVector(const SGGeod& tail, const SGVec3d& tail_xyz,
69 // The fudge factor here is presumably intended to improve
70 // numerical stability. I don't know if it is necessary.
71 // It gets divided out later.
74 double az2; // ignored
75 SGGeodesy::direct(tail, heading, fudge, head, az2);
76 head.setElevationM(tail.getElevationM());
77 SGVec3d head_xyz = SGVec3d::fromGeod(head);
78 return (head_xyz - tail_xyz) * (1.0/fudge);
81 // Create a "serviceable" node with a default value of "true"
82 SGPropertyNode_ptr createServiceableProp(SGPropertyNode* aParent, const char* aName)
84 SGPropertyNode_ptr n = (aParent->getChild(aName, 0, true)->getChild("serviceable", 0, true));
85 simgear::props::Type typ = n->getType();
86 if ((typ == simgear::props::NONE) || (typ == simgear::props::UNSPECIFIED)) {
87 n->setBoolValue(true);
93 FGNavRadio::FGNavRadio(SGPropertyNode *node) :
94 lon_node(fgGetNode("/position/longitude-deg", true)),
95 lat_node(fgGetNode("/position/latitude-deg", true)),
96 alt_node(fgGetNode("/position/altitude-ft", true)),
101 sel_radial_node(NULL),
103 ident_btn_node(NULL),
104 audio_btn_node(NULL),
105 backcourse_node(NULL),
106 nav_serviceable_node(NULL),
107 cdi_serviceable_node(NULL),
108 gs_serviceable_node(NULL),
109 tofrom_serviceable_node(NULL),
110 dme_serviceable_node(NULL),
112 fmt_alt_freq_node(NULL),
115 recip_radial_node(NULL),
116 target_radial_true_node(NULL),
117 target_auto_hdg_node(NULL),
118 time_to_intercept(NULL),
120 from_flag_node(NULL),
122 signal_quality_norm_node(NULL),
123 cdi_deflection_node(NULL),
124 cdi_deflection_norm_node(NULL),
125 cdi_xtrack_error_node(NULL),
126 cdi_xtrack_hdg_err_node(NULL),
130 gs_deflection_node(NULL),
131 gs_deflection_deg_node(NULL),
132 gs_deflection_norm_node(NULL),
133 gs_rate_of_climb_node(NULL),
135 gs_inrange_node(NULL),
141 nav_slaved_to_gps_node(NULL),
142 gps_cdi_deflection_node(NULL),
143 gps_to_flag_node(NULL),
144 gps_from_flag_node(NULL),
145 gps_has_gs_node(NULL),
152 last_xtrack_error(0.0),
154 _localizerWidth(5.0),
155 _name(node->getStringValue("name", "nav")),
156 _num(node->getIntValue("number", 0)),
157 _time_before_search_sec(-1.0),
158 _falseCoursesEnabled(true)
160 SGPath path( globals->get_fg_root() );
162 term.append( "Navaids/range.term" );
164 low.append( "Navaids/range.low" );
166 high.append( "Navaids/range.high" );
168 term_tbl = new SGInterpTable( term.str() );
169 low_tbl = new SGInterpTable( low.str() );
170 high_tbl = new SGInterpTable( high.str() );
175 FGNavRadio::~FGNavRadio()
189 branch = "/instrumentation/" + _name;
191 SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
194 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
197 is_valid_node = node->getChild("data-is-valid", 0, true);
198 power_btn_node = node->getChild("power-btn", 0, true);
199 power_btn_node->setBoolValue( true );
200 vol_btn_node = node->getChild("volume", 0, true);
201 ident_btn_node = node->getChild("ident", 0, true);
202 ident_btn_node->setBoolValue( true );
203 audio_btn_node = node->getChild("audio-btn", 0, true);
204 audio_btn_node->setBoolValue( true );
205 backcourse_node = node->getChild("back-course-btn", 0, true);
206 backcourse_node->setBoolValue( false );
208 nav_serviceable_node = node->getChild("serviceable", 0, true);
209 cdi_serviceable_node = createServiceableProp(node, "cdi");
210 gs_serviceable_node = createServiceableProp(node, "gs");
211 tofrom_serviceable_node = createServiceableProp(node, "to-from");
212 dme_serviceable_node = createServiceableProp(node, "dme");
214 globals->get_props()->tie("sim/realism/false-radio-courses-enabled",
215 SGRawValuePointer<bool>(&_falseCoursesEnabled));
218 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
219 freq_node = subnode->getChild("selected-mhz", 0, true);
220 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
221 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
222 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
225 subnode = node->getChild("radials", 0, true);
226 sel_radial_node = subnode->getChild("selected-deg", 0, true);
227 radial_node = subnode->getChild("actual-deg", 0, true);
228 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
229 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
230 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
233 heading_node = node->getChild("heading-deg", 0, true);
234 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
235 to_flag_node = node->getChild("to-flag", 0, true);
236 from_flag_node = node->getChild("from-flag", 0, true);
237 inrange_node = node->getChild("in-range", 0, true);
238 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
239 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
240 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
241 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
242 cdi_xtrack_hdg_err_node
243 = node->getChild("crosstrack-heading-error-deg", 0, true);
244 has_gs_node = node->getChild("has-gs", 0, true);
245 loc_node = node->getChild("nav-loc", 0, true);
246 loc_dist_node = node->getChild("nav-distance", 0, true);
247 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
248 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
249 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
250 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
251 gs_dist_node = node->getChild("gs-distance", 0, true);
252 gs_inrange_node = node->getChild("gs-in-range", 0, true);
254 nav_id_node = node->getChild("nav-id", 0, true);
255 id_c1_node = node->getChild("nav-id_asc1", 0, true);
256 id_c2_node = node->getChild("nav-id_asc2", 0, true);
257 id_c3_node = node->getChild("nav-id_asc3", 0, true);
258 id_c4_node = node->getChild("nav-id_asc4", 0, true);
260 node->tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
262 // gps slaving support
263 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
264 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
265 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
266 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
267 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
269 std::ostringstream temp;
270 temp << _name << "nav-ident" << _num;
271 nav_fx_name = temp.str();
272 temp << _name << "dme-ident" << _num;
273 dme_fx_name = temp.str();
284 FGNavRadio::unbind ()
289 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
290 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
291 double nominalRange )
293 if (nominalRange <= 0.0) {
294 nominalRange = FG_NAV_DEFAULT_RANGE;
297 // extend out actual usable range to be 1.3x the published safe range
298 const double usability_factor = 1.3;
300 // assumptions we model the standard service volume, plus
301 // ... rather than specifying a cylinder, we model a cone that
302 // contains the cylinder. Then we put an upside down cone on top
303 // to model diminishing returns at too-high altitudes.
305 // altitude difference
306 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
307 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
308 // << " station elev = " << stationElev << endl;
310 if ( nominalRange < 25.0 + SG_EPSILON ) {
311 // Standard Terminal Service Volume
312 return term_tbl->interpolate( alt ) * usability_factor;
313 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
314 // Standard Low Altitude Service Volume
315 // table is based on range of 40, scale to actual range
316 return low_tbl->interpolate( alt ) * nominalRange / 40.0
319 // Standard High Altitude Service Volume
320 // table is based on range of 130, scale to actual range
321 return high_tbl->interpolate( alt ) * nominalRange / 130.0
327 // model standard ILS service volumes as per AIM 1-1-9
328 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
329 double offsetDegrees, double distance )
331 // assumptions we model the standard service volume, plus
333 // altitude difference
334 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
335 // double offset = fabs( offsetDegrees );
337 // if ( offset < 10 ) {
338 // return FG_ILS_DEFAULT_RANGE;
339 // } else if ( offset < 35 ) {
340 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
341 // } else if ( offset < 45 ) {
342 // return (45 - offset);
343 // } else if ( offset > 170 ) {
344 // return FG_ILS_DEFAULT_RANGE;
345 // } else if ( offset > 145 ) {
346 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
347 // } else if ( offset > 135 ) {
348 // return (offset - 135);
352 return FG_LOC_DEFAULT_RANGE;
356 //////////////////////////////////////////////////////////////////////////
357 // Update the various nav values based on position and valid tuned in navs
358 //////////////////////////////////////////////////////////////////////////
360 FGNavRadio::update(double dt)
366 // Create "formatted" versions of the nav frequencies for
367 // instrument displays.
369 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
370 fmt_freq_node->setStringValue(tmp);
371 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
372 fmt_alt_freq_node->setStringValue(tmp);
374 if (power_btn_node->getBoolValue()
375 && (bus_power_node->getDoubleValue() > 1.0)
376 && nav_serviceable_node->getBoolValue() )
378 if (nav_slaved_to_gps_node->getBoolValue()) {
392 void FGNavRadio::clearOutputs()
394 inrange_node->setBoolValue( false );
395 cdi_deflection_node->setDoubleValue( 0.0 );
396 cdi_deflection_norm_node->setDoubleValue( 0.0 );
397 cdi_xtrack_error_node->setDoubleValue( 0.0 );
398 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
399 time_to_intercept->setDoubleValue( 0.0 );
400 gs_deflection_node->setDoubleValue( 0.0 );
401 gs_deflection_deg_node->setDoubleValue(0.0);
402 gs_deflection_norm_node->setDoubleValue(0.0);
403 gs_inrange_node->setBoolValue( false );
405 to_flag_node->setBoolValue( false );
406 from_flag_node->setBoolValue( false );
411 void FGNavRadio::updateReceiver(double dt)
413 // Do a nav station search only once a second to reduce
414 // unnecessary work. (Also, make sure to do this before caching
416 _time_before_search_sec -= dt;
417 if ( _time_before_search_sec < 0 ) {
422 _cdiDeflection = 0.0;
423 _cdiCrossTrackErrorM = 0.0;
424 _toFlag = _fromFlag = false;
425 _gsNeedleDeflection = 0.0;
426 _gsNeedleDeflectionNorm = 0.0;
427 inrange_node->setBoolValue(false);
431 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
432 lat_node->getDoubleValue(),
433 alt_node->getDoubleValue());
435 double nav_elev = _navaid->get_elev_ft();
436 SGVec3d aircraft = SGVec3d::fromGeod(pos);
437 double loc_dist = dist(aircraft, _navaid->cart());
438 loc_dist_node->setDoubleValue( loc_dist );
439 bool is_loc = loc_node->getBoolValue();
440 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
443 //////////////////////////////////////////////////////////
444 // compute forward and reverse wgs84 headings to localizer
445 //////////////////////////////////////////////////////////
447 SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s);
448 heading_node->setDoubleValue(hdg);
449 double radial = az2 - twist;
450 double recip = radial + 180.0;
451 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
452 radial_node->setDoubleValue( radial );
453 recip_radial_node->setDoubleValue( recip );
455 //////////////////////////////////////////////////////////
456 // compute the target/selected radial in "true" heading
457 //////////////////////////////////////////////////////////
459 target_radial = sel_radial_node->getDoubleValue();
462 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
463 double trtrue = target_radial + twist;
464 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
465 target_radial_true_node->setDoubleValue( trtrue );
467 //////////////////////////////////////////////////////////
468 // adjust reception range for altitude
469 // FIXME: make sure we are using the navdata range now that
470 // it is valid in the data file
471 //////////////////////////////////////////////////////////
473 double offset = radial - target_radial;
474 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
476 = adjustILSRange( nav_elev, pos.getElevationM(), offset,
477 loc_dist * SG_METER_TO_NM );
480 = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() );
483 double effective_range_m = effective_range * SG_NM_TO_METER;
485 //////////////////////////////////////////////////////////
486 // compute signal quality
487 // 100% within effective_range
488 // decreases 1/x^2 further out
489 //////////////////////////////////////////////////////////
490 double last_signal_quality_norm = signal_quality_norm;
492 if ( loc_dist < effective_range_m ) {
493 signal_quality_norm = 1.0;
495 double range_exceed_norm = loc_dist/effective_range_m;
496 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
499 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
500 signal_quality_norm, dt );
502 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
503 bool inrange = signal_quality_norm > 0.2;
504 inrange_node->setBoolValue( inrange );
506 //////////////////////////////////////////////////////////
507 // compute to/from flag status
508 //////////////////////////////////////////////////////////
513 double offset = fabs(radial - target_radial);
514 _toFlag = (offset > 90.0 && offset < 270.0);
516 _fromFlag = !_toFlag;
518 _toFlag = _fromFlag = false;
522 double r = target_radial - radial;
523 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
526 if (_falseCoursesEnabled) {
527 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
528 // zeros i.e. six courses: one front course, one back course, and four
529 // false courses. Three of the six are reverse sensing.
530 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
532 // no false courses, but we do need to create a back course
533 if (fabs(r) > 90.0) { // front course
534 _cdiDeflection = r - copysign(180.0, r);
536 _cdiDeflection = r; // back course
539 _cdiDeflection = -_cdiDeflection; // reverse for outbound radial
540 } // of false courses disabled
542 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
543 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
545 if (backcourse_node->getBoolValue()) {
546 _cdiDeflection = -_cdiDeflection;
549 // handle the TO side of the VOR
550 if (fabs(r) > 90.0) {
551 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
554 } // of non-localiser case
556 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
557 _cdiDeflection *= signal_quality_norm;
559 // cross-track error (in metres)
560 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
562 updateGlideSlope(dt, aircraft, signal_quality_norm);
565 last_loc_dist = loc_dist;
568 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
570 _gsNeedleDeflection = 0.0;
571 if (!_gs || !inrange_node->getBoolValue()) {
572 gs_dist_node->setDoubleValue( 0.0 );
573 gs_inrange_node->setBoolValue(false);
577 double gsDist = dist(aircraft, _gsCart);
578 gs_dist_node->setDoubleValue(gsDist);
579 bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
580 gs_inrange_node->setBoolValue(gsInRange);
586 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
587 // The positive GS axis points along the runway in the landing direction,
588 // toward the far end, not toward the approach area, so we need a - sign here:
589 double dot_h = -dot(pos, _gsAxis);
590 double dot_v = dot(pos, _gsVertical);
591 double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES;
592 double deflectionAngle = target_gs - angle;
594 if (_falseCoursesEnabled) {
595 // Construct false glideslopes. The scale factor of 1.5
596 // in the sawtooth gives a period of 6 degrees.
597 // There will be zeros at 3, 6r, 9, 12r et cetera
598 // where "r" indicates reverse sensing.
599 // This is is consistent with conventional pilot lore
600 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
601 // but inconsistent with
602 // http://www.freepatentsonline.com/3757338.html
604 // It may be that some of each exist.
605 if (deflectionAngle < 0) {
606 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
608 // no false GS below the true GS
612 _gsNeedleDeflection = deflectionAngle * 5.0;
613 _gsNeedleDeflection *= signal_quality_norm;
615 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
616 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
618 //////////////////////////////////////////////////////////
619 // Calculate desired rate of climb for intercepting the GS
620 //////////////////////////////////////////////////////////
621 double gs_diff = target_gs - angle;
622 // convert desired vertical path angle into a climb rate
623 double des_angle = angle - 10 * gs_diff;
625 // estimate horizontal speed towards ILS in meters per minute
626 double elapsedDistance = last_x - gsDist;
629 double new_vel = ( elapsedDistance / dt );
630 horiz_vel = 0.75 * horiz_vel + 0.25 * new_vel;
632 gs_rate_of_climb_node
633 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
634 * horiz_vel * SG_METER_TO_FEET );
637 void FGNavRadio::updateDME(const SGVec3d& aircraft)
639 if (!_dme || !dme_serviceable_node->getBoolValue()) {
644 double dme_distance = dist(aircraft, _dme->cart());
645 _dmeInRange = (dme_distance < _dme->get_range() * SG_NM_TO_METER);
648 void FGNavRadio::updateGPSSlaved()
650 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
652 _toFlag = gps_to_flag_node->getBoolValue();
653 _fromFlag = gps_from_flag_node->getBoolValue();
655 inrange_node->setBoolValue(_toFlag | _fromFlag);
657 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
658 // clmap to some range (+/- 10 degrees) as the regular deflection
659 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
661 _cdiCrossTrackErrorM = 0.0; // FIXME, supply this
662 _gsNeedleDeflection = 0.0; // FIXME, supply this
665 void FGNavRadio::updateCDI(double dt)
667 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
668 bool inrange = inrange_node->getBoolValue();
670 if (tofrom_serviceable_node->getBoolValue()) {
671 to_flag_node->setBoolValue(_toFlag);
672 from_flag_node->setBoolValue(_fromFlag);
674 to_flag_node->setBoolValue(false);
675 from_flag_node->setBoolValue(false);
678 if (!cdi_serviceable) {
679 _cdiDeflection = 0.0;
680 _cdiCrossTrackErrorM = 0.0;
683 cdi_deflection_node->setDoubleValue(_cdiDeflection);
684 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
685 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
687 //////////////////////////////////////////////////////////
688 // compute an approximate ground track heading error
689 //////////////////////////////////////////////////////////
690 double hdg_error = 0.0;
691 if ( inrange && cdi_serviceable ) {
692 double vn = fgGetDouble( "/velocities/speed-north-fps" );
693 double ve = fgGetDouble( "/velocities/speed-east-fps" );
694 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
695 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
697 SGPropertyNode *true_hdg
698 = fgGetNode("/orientation/heading-deg", true);
699 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
701 // cout << "ground track = " << gnd_trk_true
702 // << " orientation = " << true_hdg->getDoubleValue() << endl;
704 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
706 //////////////////////////////////////////////////////////
707 // Calculate a suggested target heading to smoothly intercept
709 //////////////////////////////////////////////////////////
711 // Now that we have cross track heading adjustment built in,
712 // we shouldn't need to overdrive the heading angle within 8km
715 // The cdi deflection should be +/-10 for a full range of deflection
716 // so multiplying this by 3 gives us +/- 30 degrees heading
718 double adjustment = _cdiDeflection * 3.0;
719 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
721 // determine the target heading to fly to intercept the
722 // tgt_radial = target radial (true) + cdi offset adjustmest -
723 // xtrack heading error adjustment
725 double trtrue = target_radial_true_node->getDoubleValue();
726 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
727 // tuned to a localizer and backcourse mode activated
728 trtrue += 180.0; // reverse the target localizer heading
729 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
730 nta_hdg = trtrue - adjustment - hdg_error;
732 nta_hdg = trtrue + adjustment - hdg_error;
735 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
736 target_auto_hdg_node->setDoubleValue( nta_hdg );
738 //////////////////////////////////////////////////////////
739 // compute the time to intercept selected radial (based on
740 // current and last cross track errors and dt
741 //////////////////////////////////////////////////////////
743 if ( inrange && cdi_serviceable ) {
744 double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
745 xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate;
746 if ( fabs(xrate_ms) > 0.00001 ) {
747 t = _cdiCrossTrackErrorM / xrate_ms;
752 time_to_intercept->setDoubleValue( t );
754 if (!gs_serviceable_node->getBoolValue() ) {
755 _gsNeedleDeflection = 0.0;
756 _gsNeedleDeflectionNorm = 0.0;
758 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
759 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
760 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
762 last_xtrack_error = _cdiCrossTrackErrorM;
765 void FGNavRadio::updateAudio()
767 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
771 // play station ident via audio system if on + ident,
772 // otherwise turn it off
773 if (!power_btn_node->getBoolValue()
774 || !(bus_power_node->getDoubleValue() > 1.0)
775 || !ident_btn_node->getBoolValue()
776 || !audio_btn_node->getBoolValue() ) {
777 globals->get_soundmgr()->stop( nav_fx_name );
778 globals->get_soundmgr()->stop( dme_fx_name );
782 SGSoundSample *sound = globals->get_soundmgr()->find( nav_fx_name );
783 double vol = vol_btn_node->getDoubleValue();
784 SG_CLAMP_RANGE(vol, 0.0, 1.0);
786 if ( sound != NULL ) {
787 sound->set_volume( vol );
789 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" );
792 sound = globals->get_soundmgr()->find( dme_fx_name );
793 if ( sound != NULL ) {
794 sound->set_volume( vol );
796 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" );
799 const int NUM_IDENT_SLOTS = 5;
800 const time_t SLOT_LENGTH = 5; // seconds
802 // There are N slots numbered 0 through (NUM_IDENT_SLOTS-1) inclusive.
803 // Each slot is 5 seconds long.
804 // Slots 0 is for DME
805 // the rest are for azimuth.
806 time_t now = globals->get_time_params()->get_cur_time();
807 if ((now >= last_time) && (now < last_time + SLOT_LENGTH)) {
808 return; // wait longer
812 play_count = ++play_count % NUM_IDENT_SLOTS;
814 // Previous ident is out of time; if still playing, cut it off:
815 globals->get_soundmgr()->stop( nav_fx_name );
816 globals->get_soundmgr()->stop( dme_fx_name );
817 if (play_count == 0) { // the DME slot
818 if (_dmeInRange && dme_serviceable_node->getBoolValue()) {
820 globals->get_soundmgr()->play_once( dme_fx_name );
823 if (inrange_node->getBoolValue() && nav_serviceable_node->getBoolValue()) {
824 globals->get_soundmgr()->play_once(nav_fx_name);
829 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
831 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
836 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
839 // Update current nav/adf radio stations based on current postition
840 void FGNavRadio::search()
842 _time_before_search_sec = 1.0;
843 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
844 lat_node->getDoubleValue(), alt_node->getDoubleValue());
845 double freq = freq_node->getDoubleValue();
847 FGNavRecord* nav = findPrimaryNavaid(pos, freq);
848 if (nav == _navaid) {
849 return; // found the same as last search, we're done
853 char identBuffer[5] = " ";
855 _dme = globals->get_dmelist()->findByFreq(freq, pos);
857 nav_id_node->setStringValue(nav->get_ident());
858 strncpy(identBuffer, nav->ident().c_str(), 5);
860 effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range());
861 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
862 twist = nav->get_multiuse();
864 if (nav->type() == FGPositioned::VOR) {
865 target_radial = sel_radial_node->getDoubleValue();
867 has_gs_node->setBoolValue(false);
868 } else { // ILS or LOC
869 _gs = globals->get_gslist()->findByFreq(freq, pos);
870 has_gs_node->setBoolValue(_gs != NULL);
871 _localizerWidth = localizerWidth(nav);
873 effective_range = nav->get_range();
875 target_radial = nav->get_multiuse();
876 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
879 int tmp = (int)(_gs->get_multiuse() / 1000.0);
880 target_gs = (double)tmp / 100.0;
882 // until penaltyForNav goes away, we cannot assume we always pick
883 // paired LOC/GS trasmsitters. As we pass over a runway threshold, we
884 // often end up picking the 'wrong' LOC, but the correct GS. To avoid
885 // breaking the basis computation, ensure we use the GS radial and not
886 // the (potentially reversed) LOC radial.
887 double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
888 SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
890 // GS axis unit tangent vector
891 // (along the runway)
892 _gsCart = _gs->cart();
893 _gsAxis = tangentVector(_gs->geod(), _gsCart, gs_radial);
895 // GS baseline unit tangent vector
896 // (perpendicular to the runay along the ground)
897 SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, gs_radial + 90.0);
898 _gsVertical = cross(baseline, _gsAxis);
899 } // of have glideslope
900 } // of found LOC or ILS
903 } else { // found nothing
906 nav_id_node->setStringValue("");
907 globals->get_soundmgr()->remove( nav_fx_name );
908 globals->get_soundmgr()->remove( dme_fx_name );
911 is_valid_node->setBoolValue(nav != NULL);
912 id_c1_node->setIntValue( (int)identBuffer[0] );
913 id_c2_node->setIntValue( (int)identBuffer[1] );
914 id_c3_node->setIntValue( (int)identBuffer[2] );
915 id_c4_node->setIntValue( (int)identBuffer[3] );
918 double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
920 FGRunway* rwy = aLOC->runway();
923 SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold()));
924 double axisLength = dist(aLOC->cart(), thresholdCart);
925 double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end()));
927 // Reference: http://dcaa.slv.dk:8000/icaodocs/
928 // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet.
929 // ICAO 3.1.1 half course = DDM = 0.0775
930 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold
931 // implies peg-to-peg of 214 m ... we will stick with 210.
932 // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees."
934 // Very short runway: less than 1200 m (4000 ft) landing length:
935 if (landingLength < 1200.0) {
936 // ICAO fudges localizer sensitivity for very short runways.
937 // This produces a non-monotonic sensitivity-versus length relation.
938 axisLength += 1050.0;
941 // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R
942 // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6
943 // Example: very long: Denver KDEN (Denver) ILS RWY 16R
944 double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES;
945 return raw_width < 6.0? raw_width : 6.0;
948 void FGNavRadio::audioNavidChanged()
950 if ( globals->get_soundmgr()->exists(nav_fx_name)) {
951 globals->get_soundmgr()->remove(nav_fx_name);
955 string trans_ident(_navaid->get_trans_ident());
956 SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY);
957 sound->set_volume( 0.3 );
958 if (!globals->get_soundmgr()->add( sound, nav_fx_name )) {
959 SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound");
962 if ( globals->get_soundmgr()->exists( dme_fx_name ) ) {
963 globals->get_soundmgr()->remove( dme_fx_name );
966 sound = morse.make_ident( trans_ident, HI_FREQUENCY );
967 sound->set_volume( 0.3 );
968 globals->get_soundmgr()->add( sound, dme_fx_name );
970 int offset = (int)(sg_random() * 30.0);
971 play_count = offset / 4;
972 last_time = globals->get_time_params()->get_cur_time() - offset;
973 } catch (sg_io_exception& e) {
974 SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage());