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);
82 FGNavRadio::FGNavRadio(SGPropertyNode *node) :
83 lon_node(fgGetNode("/position/longitude-deg", true)),
84 lat_node(fgGetNode("/position/latitude-deg", true)),
85 alt_node(fgGetNode("/position/altitude-ft", true)),
90 sel_radial_node(NULL),
94 backcourse_node(NULL),
95 nav_serviceable_node(NULL),
96 cdi_serviceable_node(NULL),
97 gs_serviceable_node(NULL),
98 tofrom_serviceable_node(NULL),
100 fmt_alt_freq_node(NULL),
103 recip_radial_node(NULL),
104 target_radial_true_node(NULL),
105 target_auto_hdg_node(NULL),
106 time_to_intercept(NULL),
108 from_flag_node(NULL),
110 signal_quality_norm_node(NULL),
111 cdi_deflection_node(NULL),
112 cdi_deflection_norm_node(NULL),
113 cdi_xtrack_error_node(NULL),
114 cdi_xtrack_hdg_err_node(NULL),
118 gs_deflection_node(NULL),
119 gs_deflection_deg_node(NULL),
120 gs_deflection_norm_node(NULL),
121 gs_rate_of_climb_node(NULL),
128 nav_slaved_to_gps_node(NULL),
129 gps_cdi_deflection_node(NULL),
130 gps_to_flag_node(NULL),
131 gps_from_flag_node(NULL),
132 gps_has_gs_node(NULL),
139 last_xtrack_error(0.0),
140 _localizerWidth(5.0),
141 _name(node->getStringValue("name", "nav")),
142 _num(node->getIntValue("number", 0)),
143 _time_before_search_sec(-1.0)
145 SGPath path( globals->get_fg_root() );
147 term.append( "Navaids/range.term" );
149 low.append( "Navaids/range.low" );
151 high.append( "Navaids/range.high" );
153 term_tbl = new SGInterpTable( term.str() );
154 low_tbl = new SGInterpTable( low.str() );
155 high_tbl = new SGInterpTable( high.str() );
160 FGNavRadio::~FGNavRadio()
174 branch = "/instrumentation/" + _name;
176 SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
179 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
182 is_valid_node = node->getChild("data-is-valid", 0, true);
183 power_btn_node = node->getChild("power-btn", 0, true);
184 power_btn_node->setBoolValue( true );
185 vol_btn_node = node->getChild("volume", 0, true);
186 ident_btn_node = node->getChild("ident", 0, true);
187 ident_btn_node->setBoolValue( true );
188 audio_btn_node = node->getChild("audio-btn", 0, true);
189 audio_btn_node->setBoolValue( true );
190 backcourse_node = node->getChild("back-course-btn", 0, true);
191 backcourse_node->setBoolValue( false );
192 nav_serviceable_node = node->getChild("serviceable", 0, true);
193 cdi_serviceable_node = (node->getChild("cdi", 0, true))
194 ->getChild("serviceable", 0, true);
195 gs_serviceable_node = (node->getChild("gs", 0, true))
196 ->getChild("serviceable");
197 tofrom_serviceable_node = (node->getChild("to-from", 0, true))
198 ->getChild("serviceable", 0, true);
201 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
202 freq_node = subnode->getChild("selected-mhz", 0, true);
203 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
204 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
205 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
208 subnode = node->getChild("radials", 0, true);
209 sel_radial_node = subnode->getChild("selected-deg", 0, true);
210 radial_node = subnode->getChild("actual-deg", 0, true);
211 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
212 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
213 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
216 heading_node = node->getChild("heading-deg", 0, true);
217 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
218 to_flag_node = node->getChild("to-flag", 0, true);
219 from_flag_node = node->getChild("from-flag", 0, true);
220 inrange_node = node->getChild("in-range", 0, true);
221 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
222 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
223 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
224 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
225 cdi_xtrack_hdg_err_node
226 = node->getChild("crosstrack-heading-error-deg", 0, true);
227 has_gs_node = node->getChild("has-gs", 0, true);
228 loc_node = node->getChild("nav-loc", 0, true);
229 loc_dist_node = node->getChild("nav-distance", 0, true);
230 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
231 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
232 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
233 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
234 gs_dist_node = node->getChild("gs-distance", 0, true);
235 nav_id_node = node->getChild("nav-id", 0, true);
236 id_c1_node = node->getChild("nav-id_asc1", 0, true);
237 id_c2_node = node->getChild("nav-id_asc2", 0, true);
238 id_c3_node = node->getChild("nav-id_asc3", 0, true);
239 id_c4_node = node->getChild("nav-id_asc4", 0, true);
241 // gps slaving support
242 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
243 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
244 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
245 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
246 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
247 gps_course_node = fgGetNode("/instrumentation/gps/selected-course-deg", true);
249 std::ostringstream temp;
250 temp << _name << "nav-ident" << _num;
251 nav_fx_name = temp.str();
252 temp << _name << "dme-ident" << _num;
253 dme_fx_name = temp.str();
259 std::ostringstream temp;
262 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
267 FGNavRadio::unbind ()
269 std::ostringstream temp;
272 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
276 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
277 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
278 double nominalRange )
280 // extend out actual usable range to be 1.3x the published safe range
281 const double usability_factor = 1.3;
283 // assumptions we model the standard service volume, plus
284 // ... rather than specifying a cylinder, we model a cone that
285 // contains the cylinder. Then we put an upside down cone on top
286 // to model diminishing returns at too-high altitudes.
288 // altitude difference
289 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
290 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
291 // << " station elev = " << stationElev << endl;
293 if ( nominalRange < 25.0 + SG_EPSILON ) {
294 // Standard Terminal Service Volume
295 return term_tbl->interpolate( alt ) * usability_factor;
296 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
297 // Standard Low Altitude Service Volume
298 // table is based on range of 40, scale to actual range
299 return low_tbl->interpolate( alt ) * nominalRange / 40.0
302 // Standard High Altitude Service Volume
303 // table is based on range of 130, scale to actual range
304 return high_tbl->interpolate( alt ) * nominalRange / 130.0
310 // model standard ILS service volumes as per AIM 1-1-9
311 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
312 double offsetDegrees, double distance )
314 // assumptions we model the standard service volume, plus
316 // altitude difference
317 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
318 // double offset = fabs( offsetDegrees );
320 // if ( offset < 10 ) {
321 // return FG_ILS_DEFAULT_RANGE;
322 // } else if ( offset < 35 ) {
323 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
324 // } else if ( offset < 45 ) {
325 // return (45 - offset);
326 // } else if ( offset > 170 ) {
327 // return FG_ILS_DEFAULT_RANGE;
328 // } else if ( offset > 145 ) {
329 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
330 // } else if ( offset > 135 ) {
331 // return (offset - 135);
335 return FG_LOC_DEFAULT_RANGE;
339 //////////////////////////////////////////////////////////////////////////
340 // Update the various nav values based on position and valid tuned in navs
341 //////////////////////////////////////////////////////////////////////////
343 FGNavRadio::update(double dt)
349 // Create "formatted" versions of the nav frequencies for
350 // instrument displays.
352 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
353 fmt_freq_node->setStringValue(tmp);
354 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
355 fmt_alt_freq_node->setStringValue(tmp);
357 if (power_btn_node->getBoolValue()
358 && (bus_power_node->getDoubleValue() > 1.0)
359 && nav_serviceable_node->getBoolValue() )
361 if (nav_slaved_to_gps_node->getBoolValue()) {
375 void FGNavRadio::clearOutputs()
377 inrange_node->setBoolValue( false );
378 cdi_deflection_node->setDoubleValue( 0.0 );
379 cdi_deflection_norm_node->setDoubleValue( 0.0 );
380 cdi_xtrack_error_node->setDoubleValue( 0.0 );
381 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
382 time_to_intercept->setDoubleValue( 0.0 );
383 gs_deflection_node->setDoubleValue( 0.0 );
384 gs_deflection_deg_node->setDoubleValue(0.0);
385 gs_deflection_norm_node->setDoubleValue(0.0);
387 to_flag_node->setBoolValue( false );
388 from_flag_node->setBoolValue( false );
391 void FGNavRadio::updateReceiver(double dt)
393 // Do a nav station search only once a second to reduce
394 // unnecessary work. (Also, make sure to do this before caching
396 _time_before_search_sec -= dt;
397 if ( _time_before_search_sec < 0 ) {
402 _cdiDeflection = 0.0;
403 _cdiCrossTrackErrorM = 0.0;
404 _toFlag = _fromFlag = false;
405 _gsNeedleDeflection = 0.0;
406 _gsNeedleDeflectionNorm = 0.0;
407 inrange_node->setBoolValue(false);
411 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
412 lat_node->getDoubleValue(),
413 alt_node->getDoubleValue());
415 double nav_elev = _navaid->get_elev_ft();
416 SGVec3d aircraft = SGVec3d::fromGeod(pos);
417 double loc_dist = dist(aircraft, _navaid->cart());
418 loc_dist_node->setDoubleValue( loc_dist );
419 bool is_loc = loc_node->getBoolValue();
420 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
423 //////////////////////////////////////////////////////////
424 // compute forward and reverse wgs84 headings to localizer
425 //////////////////////////////////////////////////////////
427 SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s);
428 heading_node->setDoubleValue(hdg);
429 double radial = az2 - twist;
430 double recip = radial + 180.0;
431 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
432 radial_node->setDoubleValue( radial );
433 recip_radial_node->setDoubleValue( recip );
435 //////////////////////////////////////////////////////////
436 // compute the target/selected radial in "true" heading
437 //////////////////////////////////////////////////////////
439 target_radial = sel_radial_node->getDoubleValue();
442 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
443 double trtrue = target_radial + twist;
444 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
445 target_radial_true_node->setDoubleValue( trtrue );
447 //////////////////////////////////////////////////////////
448 // adjust reception range for altitude
449 // FIXME: make sure we are using the navdata range now that
450 // it is valid in the data file
451 //////////////////////////////////////////////////////////
453 double offset = radial - target_radial;
454 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
456 = adjustILSRange( nav_elev, pos.getElevationM(), offset,
457 loc_dist * SG_METER_TO_NM );
460 = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() );
463 double effective_range_m = effective_range * SG_NM_TO_METER;
465 //////////////////////////////////////////////////////////
466 // compute signal quality
467 // 100% within effective_range
468 // decreases 1/x^2 further out
469 //////////////////////////////////////////////////////////
470 double last_signal_quality_norm = signal_quality_norm;
472 if ( loc_dist < effective_range_m ) {
473 signal_quality_norm = 1.0;
475 double range_exceed_norm = loc_dist/effective_range_m;
476 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
479 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
480 signal_quality_norm, dt );
482 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
483 bool inrange = signal_quality_norm > 0.2;
484 inrange_node->setBoolValue( inrange );
486 //////////////////////////////////////////////////////////
487 // compute to/from flag status
488 //////////////////////////////////////////////////////////
493 double offset = fabs(radial - target_radial);
494 _toFlag = (offset > 90.0 && offset < 270.0);
496 _fromFlag = !_toFlag;
498 _toFlag = _fromFlag = false;
502 double r = target_radial - radial;
503 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
506 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
507 // zeros i.e. six courses: one front course, one back course, and four
508 // false courses. Three of the six are reverse sensing.
509 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
510 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
511 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
513 // handle the TO side of the VOR
514 if (fabs(r) > 90.0) {
515 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
518 } // of non-localiser case
520 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
521 _cdiDeflection *= signal_quality_norm;
523 // cross-track error (in metres)
524 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
526 updateGlideSlope(dt, aircraft, signal_quality_norm);
528 last_loc_dist = loc_dist;
531 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
533 _gsNeedleDeflection = 0.0;
534 if (!_gs || !inrange_node->getBoolValue()) {
535 gs_dist_node->setDoubleValue( 0.0 );
539 double gsDist = dist(aircraft, _gsCart);
540 gs_dist_node->setDoubleValue(gsDist);
541 if (gsDist > (_gs->get_range() * SG_NM_TO_METER)) {
545 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
546 // The positive GS axis points along the runway in the landing direction,
547 // toward the far end, not toward the approach area, so we need a - sign here:
548 double dot_h = -dot(pos, _gsAxis);
549 double dot_v = dot(pos, _gsVertical);
550 double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES;
551 double deflectionAngle = target_gs - angle;
553 // Construct false glideslopes. The scale factor of 1.5
554 // in the sawtooth gives a period of 6 degrees.
555 // There will be zeros at 3, 6r, 9, 12r et cetera
556 // where "r" indicates reverse sensing.
557 // This is is consistent with conventional pilot lore
558 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
559 // but inconsistent with
560 // http://www.freepatentsonline.com/3757338.html
562 // It may be that some of each exist.
563 if (deflectionAngle < 0) {
564 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
566 // no false GS below the true GS
569 _gsNeedleDeflection = deflectionAngle * 5.0;
570 _gsNeedleDeflection *= signal_quality_norm;
572 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
573 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
575 //////////////////////////////////////////////////////////
576 // Calculate desired rate of climb for intercepting the GS
577 //////////////////////////////////////////////////////////
578 double gs_diff = target_gs - angle;
579 // convert desired vertical path angle into a climb rate
580 double des_angle = angle - 10 * gs_diff;
582 // estimate horizontal speed towards ILS in meters per minute
583 double elapsedDistance = last_x - gsDist;
586 double new_vel = ( elapsedDistance / dt );
587 horiz_vel = 0.75 * horiz_vel + 0.25 * new_vel;
589 gs_rate_of_climb_node
590 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
591 * horiz_vel * SG_METER_TO_FEET );
594 void FGNavRadio::updateGPSSlaved()
596 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
598 _toFlag = gps_to_flag_node->getBoolValue();
599 _fromFlag = gps_from_flag_node->getBoolValue();
601 inrange_node->setBoolValue(_toFlag | _fromFlag);
603 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
604 // clmap to some range (+/- 10 degrees) as the regular deflection
605 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
607 _cdiCrossTrackErrorM = 0.0; // FIXME, supply this
608 _gsNeedleDeflection = 0.0; // FIXME, supply this
610 //sel_radial_node->setDoubleValue(gps_course_node->getDoubleValue());
613 void FGNavRadio::updateCDI(double dt)
615 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
616 bool inrange = inrange_node->getBoolValue();
618 if (tofrom_serviceable_node->getBoolValue()) {
619 to_flag_node->setBoolValue(_toFlag);
620 from_flag_node->setBoolValue(_fromFlag);
622 to_flag_node->setBoolValue(false);
623 from_flag_node->setBoolValue(false);
626 if (!cdi_serviceable) {
627 _cdiDeflection = 0.0;
628 _cdiCrossTrackErrorM = 0.0;
631 cdi_deflection_node->setDoubleValue(_cdiDeflection);
632 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
633 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
635 //////////////////////////////////////////////////////////
636 // compute an approximate ground track heading error
637 //////////////////////////////////////////////////////////
638 double hdg_error = 0.0;
639 if ( inrange && cdi_serviceable ) {
640 double vn = fgGetDouble( "/velocities/speed-north-fps" );
641 double ve = fgGetDouble( "/velocities/speed-east-fps" );
642 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
643 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
645 SGPropertyNode *true_hdg
646 = fgGetNode("/orientation/heading-deg", true);
647 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
649 // cout << "ground track = " << gnd_trk_true
650 // << " orientation = " << true_hdg->getDoubleValue() << endl;
652 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
654 //////////////////////////////////////////////////////////
655 // Calculate a suggested target heading to smoothly intercept
657 //////////////////////////////////////////////////////////
659 // Now that we have cross track heading adjustment built in,
660 // we shouldn't need to overdrive the heading angle within 8km
663 // The cdi deflection should be +/-10 for a full range of deflection
664 // so multiplying this by 3 gives us +/- 30 degrees heading
666 double adjustment = _cdiDeflection * 3.0;
667 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
669 // determine the target heading to fly to intercept the
670 // tgt_radial = target radial (true) + cdi offset adjustmest -
671 // xtrack heading error adjustment
673 double trtrue = target_radial_true_node->getDoubleValue();
674 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
675 // tuned to a localizer and backcourse mode activated
676 trtrue += 180.0; // reverse the target localizer heading
677 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
678 nta_hdg = trtrue - adjustment - hdg_error;
680 nta_hdg = trtrue + adjustment - hdg_error;
683 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
684 target_auto_hdg_node->setDoubleValue( nta_hdg );
686 //////////////////////////////////////////////////////////
687 // compute the time to intercept selected radial (based on
688 // current and last cross track errors and dt
689 //////////////////////////////////////////////////////////
691 if ( inrange && cdi_serviceable ) {
692 double xrate_ms = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
693 if ( fabs(xrate_ms) > 0.00001 ) {
694 t = _cdiCrossTrackErrorM / xrate_ms;
699 time_to_intercept->setDoubleValue( t );
701 if (!gs_serviceable_node->getBoolValue() ) {
702 _gsNeedleDeflection = 0.0;
703 _gsNeedleDeflectionNorm = 0.0;
705 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
706 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
707 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
709 last_xtrack_error = _cdiCrossTrackErrorM;
712 void FGNavRadio::updateAudio()
714 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
718 // play station ident via audio system if on + ident,
719 // otherwise turn it off
720 if (!power_btn_node->getBoolValue()
721 || !(bus_power_node->getDoubleValue() > 1.0)
722 || !ident_btn_node->getBoolValue()
723 || !audio_btn_node->getBoolValue() ) {
724 globals->get_soundmgr()->stop( nav_fx_name );
725 globals->get_soundmgr()->stop( dme_fx_name );
729 SGSoundSample *sound = globals->get_soundmgr()->find( nav_fx_name );
730 double vol = vol_btn_node->getDoubleValue();
731 SG_CLAMP_RANGE(vol, 0.0, 1.0);
733 if ( sound != NULL ) {
734 sound->set_volume( vol );
736 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" );
739 sound = globals->get_soundmgr()->find( dme_fx_name );
740 if ( sound != NULL ) {
741 sound->set_volume( vol );
743 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" );
746 if ( last_time < globals->get_time_params()->get_cur_time() - 30 ) {
747 last_time = globals->get_time_params()->get_cur_time();
751 if ( play_count < 4 ) {
753 if ( !globals->get_soundmgr()->is_playing(nav_fx_name) ) {
754 globals->get_soundmgr()->play_once( nav_fx_name );
757 } else if ( play_count < 5 && has_dme) {
759 if ( !globals->get_soundmgr()->is_playing(nav_fx_name) &&
760 !globals->get_soundmgr()->is_playing(dme_fx_name) ) {
761 globals->get_soundmgr()->play_once( dme_fx_name );
767 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
769 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
774 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
777 // Update current nav/adf radio stations based on current postition
778 void FGNavRadio::search()
780 _time_before_search_sec = 1.0;
781 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
782 lat_node->getDoubleValue(), alt_node->getDoubleValue());
783 double freq = freq_node->getDoubleValue();
785 FGNavRecord* nav = findPrimaryNavaid(pos, freq);
786 if (nav == _navaid) {
787 return; // found the same as last search, we're done
791 char identBuffer[5] = " ";
793 FGNavRecord* dme = globals->get_dmelist()->findByFreq(freq, pos);
794 has_dme = (dme != NULL);
796 nav_id_node->setStringValue(nav->get_ident());
797 strncpy(identBuffer, nav->ident().c_str(), 5);
799 effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range());
800 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
801 twist = nav->get_multiuse();
803 if (nav->type() == FGPositioned::VOR) {
804 target_radial = sel_radial_node->getDoubleValue();
806 } else { // ILS or LOC
807 _gs = globals->get_gslist()->findByFreq(freq, pos);
808 _localizerWidth = localizerWidth(nav);
809 has_gs_node->setBoolValue(_gs != NULL);
811 effective_range = nav->get_range();
813 target_radial = nav->get_multiuse();
814 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
817 int tmp = (int)(_gs->get_multiuse() / 1000.0);
818 target_gs = (double)tmp / 100.0;
820 // GS axis unit tangent vector
821 // (along the runway)
822 _gsCart = _gs->cart();
823 _gsAxis = tangentVector(_gs->geod(), _gsCart, target_radial);
825 // GS baseline unit tangent vector
826 // (perpendicular to the runay along the ground)
827 SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, target_radial + 90.0);
828 _gsVertical = cross(baseline, _gsAxis);
829 } // of have glideslope
830 } // of found LOC or ILS
833 } else { // found nothing
835 nav_id_node->setStringValue("");
837 globals->get_soundmgr()->remove( nav_fx_name );
838 globals->get_soundmgr()->remove( dme_fx_name );
841 is_valid_node->setBoolValue(nav != NULL);
842 id_c1_node->setIntValue( (int)identBuffer[0] );
843 id_c2_node->setIntValue( (int)identBuffer[1] );
844 id_c3_node->setIntValue( (int)identBuffer[2] );
845 id_c4_node->setIntValue( (int)identBuffer[3] );
848 double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
850 FGRunway* rwy = aLOC->runway();
853 SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold()));
854 double axisLength = dist(aLOC->cart(), thresholdCart);
855 double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end()));
857 // Reference: http://dcaa.slv.dk:8000/icaodocs/
858 // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet.
859 // ICAO 3.1.1 half course = DDM = 0.0775
860 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold
861 // implies peg-to-peg of 214 m ... we will stick with 210.
862 // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees."
864 // Very short runway: less than 1200 m (4000 ft) landing length:
865 if (landingLength < 1200.0) {
866 // ICAO fudges localizer sensitivity for very short runways.
867 // This produces a non-monotonic sensitivity-versus length relation.
868 axisLength += 1050.0;
871 // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R
872 // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6
873 // Example: very long: Denver KDEN (Denver) ILS RWY 16R
874 double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES;
875 return raw_width < 6.0? raw_width : 6.0;
878 void FGNavRadio::audioNavidChanged()
880 if ( globals->get_soundmgr()->exists(nav_fx_name)) {
881 globals->get_soundmgr()->remove(nav_fx_name);
885 string trans_ident(_navaid->get_trans_ident());
886 SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY);
887 sound->set_volume( 0.3 );
888 if (!globals->get_soundmgr()->add( sound, nav_fx_name )) {
889 SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound");
892 if ( globals->get_soundmgr()->exists( dme_fx_name ) ) {
893 globals->get_soundmgr()->remove( dme_fx_name );
896 sound = morse.make_ident( trans_ident, HI_FREQUENCY );
897 sound->set_volume( 0.3 );
898 globals->get_soundmgr()->add( sound, dme_fx_name );
900 int offset = (int)(sg_random() * 30.0);
901 play_count = offset / 4;
902 last_time = globals->get_time_params()->get_cur_time() - offset;
903 } catch (sg_io_exception& e) {
904 SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage());