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),
133 gps_xtrack_error_nm_node(NULL),
140 last_xtrack_error(0.0),
141 _localizerWidth(5.0),
142 _name(node->getStringValue("name", "nav")),
143 _num(node->getIntValue("number", 0)),
144 _time_before_search_sec(-1.0)
146 SGPath path( globals->get_fg_root() );
148 term.append( "Navaids/range.term" );
150 low.append( "Navaids/range.low" );
152 high.append( "Navaids/range.high" );
154 term_tbl = new SGInterpTable( term.str() );
155 low_tbl = new SGInterpTable( low.str() );
156 high_tbl = new SGInterpTable( high.str() );
161 FGNavRadio::~FGNavRadio()
175 branch = "/instrumentation/" + _name;
177 SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
180 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
183 is_valid_node = node->getChild("data-is-valid", 0, true);
184 power_btn_node = node->getChild("power-btn", 0, true);
185 power_btn_node->setBoolValue( true );
186 vol_btn_node = node->getChild("volume", 0, true);
187 ident_btn_node = node->getChild("ident", 0, true);
188 ident_btn_node->setBoolValue( true );
189 audio_btn_node = node->getChild("audio-btn", 0, true);
190 audio_btn_node->setBoolValue( true );
191 backcourse_node = node->getChild("back-course-btn", 0, true);
192 backcourse_node->setBoolValue( false );
193 nav_serviceable_node = node->getChild("serviceable", 0, true);
194 cdi_serviceable_node = (node->getChild("cdi", 0, true))
195 ->getChild("serviceable", 0, true);
196 gs_serviceable_node = (node->getChild("gs", 0, true))
197 ->getChild("serviceable");
198 tofrom_serviceable_node = (node->getChild("to-from", 0, true))
199 ->getChild("serviceable", 0, true);
202 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
203 freq_node = subnode->getChild("selected-mhz", 0, true);
204 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
205 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
206 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
209 subnode = node->getChild("radials", 0, true);
210 sel_radial_node = subnode->getChild("selected-deg", 0, true);
211 radial_node = subnode->getChild("actual-deg", 0, true);
212 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
213 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
214 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
217 heading_node = node->getChild("heading-deg", 0, true);
218 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
219 to_flag_node = node->getChild("to-flag", 0, true);
220 from_flag_node = node->getChild("from-flag", 0, true);
221 inrange_node = node->getChild("in-range", 0, true);
222 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
223 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
224 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
225 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
226 cdi_xtrack_hdg_err_node
227 = node->getChild("crosstrack-heading-error-deg", 0, true);
228 has_gs_node = node->getChild("has-gs", 0, true);
229 loc_node = node->getChild("nav-loc", 0, true);
230 loc_dist_node = node->getChild("nav-distance", 0, true);
231 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
232 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
233 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
234 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
235 gs_dist_node = node->getChild("gs-distance", 0, true);
236 nav_id_node = node->getChild("nav-id", 0, true);
237 id_c1_node = node->getChild("nav-id_asc1", 0, true);
238 id_c2_node = node->getChild("nav-id_asc2", 0, true);
239 id_c3_node = node->getChild("nav-id_asc3", 0, true);
240 id_c4_node = node->getChild("nav-id_asc4", 0, true);
242 // gps slaving support
243 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
244 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
245 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
246 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
247 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
248 gps_course_node = fgGetNode("/instrumentation/gps/selected-course-deg", true);
249 gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true);
250 _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true);
252 std::ostringstream temp;
253 temp << _name << "nav-ident" << _num;
254 nav_fx_name = temp.str();
255 temp << _name << "dme-ident" << _num;
256 dme_fx_name = temp.str();
262 std::ostringstream temp;
265 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
270 FGNavRadio::unbind ()
272 std::ostringstream temp;
275 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
279 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
280 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
281 double nominalRange )
283 // extend out actual usable range to be 1.3x the published safe range
284 const double usability_factor = 1.3;
286 // assumptions we model the standard service volume, plus
287 // ... rather than specifying a cylinder, we model a cone that
288 // contains the cylinder. Then we put an upside down cone on top
289 // to model diminishing returns at too-high altitudes.
291 // altitude difference
292 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
293 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
294 // << " station elev = " << stationElev << endl;
296 if ( nominalRange < 25.0 + SG_EPSILON ) {
297 // Standard Terminal Service Volume
298 return term_tbl->interpolate( alt ) * usability_factor;
299 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
300 // Standard Low Altitude Service Volume
301 // table is based on range of 40, scale to actual range
302 return low_tbl->interpolate( alt ) * nominalRange / 40.0
305 // Standard High Altitude Service Volume
306 // table is based on range of 130, scale to actual range
307 return high_tbl->interpolate( alt ) * nominalRange / 130.0
313 // model standard ILS service volumes as per AIM 1-1-9
314 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
315 double offsetDegrees, double distance )
317 // assumptions we model the standard service volume, plus
319 // altitude difference
320 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
321 // double offset = fabs( offsetDegrees );
323 // if ( offset < 10 ) {
324 // return FG_ILS_DEFAULT_RANGE;
325 // } else if ( offset < 35 ) {
326 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
327 // } else if ( offset < 45 ) {
328 // return (45 - offset);
329 // } else if ( offset > 170 ) {
330 // return FG_ILS_DEFAULT_RANGE;
331 // } else if ( offset > 145 ) {
332 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
333 // } else if ( offset > 135 ) {
334 // return (offset - 135);
338 return FG_LOC_DEFAULT_RANGE;
342 //////////////////////////////////////////////////////////////////////////
343 // Update the various nav values based on position and valid tuned in navs
344 //////////////////////////////////////////////////////////////////////////
346 FGNavRadio::update(double dt)
352 // Create "formatted" versions of the nav frequencies for
353 // instrument displays.
355 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
356 fmt_freq_node->setStringValue(tmp);
357 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
358 fmt_alt_freq_node->setStringValue(tmp);
360 if (power_btn_node->getBoolValue()
361 && (bus_power_node->getDoubleValue() > 1.0)
362 && nav_serviceable_node->getBoolValue() )
364 if (nav_slaved_to_gps_node->getBoolValue()) {
378 void FGNavRadio::clearOutputs()
380 inrange_node->setBoolValue( false );
381 cdi_deflection_node->setDoubleValue( 0.0 );
382 cdi_deflection_norm_node->setDoubleValue( 0.0 );
383 cdi_xtrack_error_node->setDoubleValue( 0.0 );
384 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
385 time_to_intercept->setDoubleValue( 0.0 );
386 gs_deflection_node->setDoubleValue( 0.0 );
387 gs_deflection_deg_node->setDoubleValue(0.0);
388 gs_deflection_norm_node->setDoubleValue(0.0);
390 to_flag_node->setBoolValue( false );
391 from_flag_node->setBoolValue( false );
394 void FGNavRadio::updateReceiver(double dt)
396 // Do a nav station search only once a second to reduce
397 // unnecessary work. (Also, make sure to do this before caching
399 _time_before_search_sec -= dt;
400 if ( _time_before_search_sec < 0 ) {
405 _cdiDeflection = 0.0;
406 _cdiCrossTrackErrorM = 0.0;
407 _toFlag = _fromFlag = false;
408 _gsNeedleDeflection = 0.0;
409 _gsNeedleDeflectionNorm = 0.0;
410 inrange_node->setBoolValue(false);
414 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
415 lat_node->getDoubleValue(),
416 alt_node->getDoubleValue());
418 double nav_elev = _navaid->get_elev_ft();
419 SGVec3d aircraft = SGVec3d::fromGeod(pos);
420 double loc_dist = dist(aircraft, _navaid->cart());
421 loc_dist_node->setDoubleValue( loc_dist );
422 bool is_loc = loc_node->getBoolValue();
423 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
426 //////////////////////////////////////////////////////////
427 // compute forward and reverse wgs84 headings to localizer
428 //////////////////////////////////////////////////////////
430 SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s);
431 heading_node->setDoubleValue(hdg);
432 double radial = az2 - twist;
433 double recip = radial + 180.0;
434 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
435 radial_node->setDoubleValue( radial );
436 recip_radial_node->setDoubleValue( recip );
438 //////////////////////////////////////////////////////////
439 // compute the target/selected radial in "true" heading
440 //////////////////////////////////////////////////////////
442 target_radial = sel_radial_node->getDoubleValue();
445 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
446 double trtrue = target_radial + twist;
447 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
448 target_radial_true_node->setDoubleValue( trtrue );
450 //////////////////////////////////////////////////////////
451 // adjust reception range for altitude
452 // FIXME: make sure we are using the navdata range now that
453 // it is valid in the data file
454 //////////////////////////////////////////////////////////
456 double offset = radial - target_radial;
457 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
459 = adjustILSRange( nav_elev, pos.getElevationM(), offset,
460 loc_dist * SG_METER_TO_NM );
463 = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() );
466 double effective_range_m = effective_range * SG_NM_TO_METER;
468 //////////////////////////////////////////////////////////
469 // compute signal quality
470 // 100% within effective_range
471 // decreases 1/x^2 further out
472 //////////////////////////////////////////////////////////
473 double last_signal_quality_norm = signal_quality_norm;
475 if ( loc_dist < effective_range_m ) {
476 signal_quality_norm = 1.0;
478 double range_exceed_norm = loc_dist/effective_range_m;
479 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
482 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
483 signal_quality_norm, dt );
485 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
486 bool inrange = signal_quality_norm > 0.2;
487 inrange_node->setBoolValue( inrange );
489 //////////////////////////////////////////////////////////
490 // compute to/from flag status
491 //////////////////////////////////////////////////////////
496 double offset = fabs(radial - target_radial);
497 _toFlag = (offset > 90.0 && offset < 270.0);
499 _fromFlag = !_toFlag;
501 _toFlag = _fromFlag = false;
505 double r = target_radial - radial;
506 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
509 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
510 // zeros i.e. six courses: one front course, one back course, and four
511 // false courses. Three of the six are reverse sensing.
512 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
513 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
514 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
516 // handle the TO side of the VOR
517 if (fabs(r) > 90.0) {
518 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
521 } // of non-localiser case
523 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
524 _cdiDeflection *= signal_quality_norm;
526 // cross-track error (in metres)
527 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
529 updateGlideSlope(dt, aircraft, signal_quality_norm);
531 last_loc_dist = loc_dist;
534 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
536 _gsNeedleDeflection = 0.0;
537 if (!_gs || !inrange_node->getBoolValue()) {
538 gs_dist_node->setDoubleValue( 0.0 );
542 double gsDist = dist(aircraft, _gsCart);
543 gs_dist_node->setDoubleValue(gsDist);
544 if (gsDist > (_gs->get_range() * SG_NM_TO_METER)) {
548 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
549 // The positive GS axis points along the runway in the landing direction,
550 // toward the far end, not toward the approach area, so we need a - sign here:
551 double dot_h = -dot(pos, _gsAxis);
552 double dot_v = dot(pos, _gsVertical);
553 double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES;
554 double deflectionAngle = target_gs - angle;
556 // Construct false glideslopes. The scale factor of 1.5
557 // in the sawtooth gives a period of 6 degrees.
558 // There will be zeros at 3, 6r, 9, 12r et cetera
559 // where "r" indicates reverse sensing.
560 // This is is consistent with conventional pilot lore
561 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
562 // but inconsistent with
563 // http://www.freepatentsonline.com/3757338.html
565 // It may be that some of each exist.
566 if (deflectionAngle < 0) {
567 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
569 // no false GS below the true GS
572 _gsNeedleDeflection = deflectionAngle * 5.0;
573 _gsNeedleDeflection *= signal_quality_norm;
575 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
576 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
578 //////////////////////////////////////////////////////////
579 // Calculate desired rate of climb for intercepting the GS
580 //////////////////////////////////////////////////////////
581 double gs_diff = target_gs - angle;
582 // convert desired vertical path angle into a climb rate
583 double des_angle = angle - 10 * gs_diff;
585 // estimate horizontal speed towards ILS in meters per minute
586 double elapsedDistance = last_x - gsDist;
589 double new_vel = ( elapsedDistance / dt );
590 horiz_vel = 0.75 * horiz_vel + 0.25 * new_vel;
592 gs_rate_of_climb_node
593 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
594 * horiz_vel * SG_METER_TO_FEET );
597 void FGNavRadio::updateGPSSlaved()
599 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
601 _toFlag = gps_to_flag_node->getBoolValue();
602 _fromFlag = gps_from_flag_node->getBoolValue();
604 bool gpsValid = (_toFlag | _fromFlag);
605 inrange_node->setBoolValue(gpsValid);
607 signal_quality_norm_node->setDoubleValue(0.0);
608 _cdiDeflection = 0.0;
609 _cdiCrossTrackErrorM = 0.0;
610 _gsNeedleDeflection = 0.0;
614 // this is unfortunate, but panel instruments use this value to decide
615 // if the navradio output is valid.
616 signal_quality_norm_node->setDoubleValue(1.0);
618 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
619 // clmap to some range (+/- 10 degrees) as the regular deflection
620 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
622 _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER;
623 _gsNeedleDeflection = 0.0; // FIXME, supply this
625 double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue();
626 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
627 target_radial_true_node->setDoubleValue( trtrue );
630 void FGNavRadio::updateCDI(double dt)
632 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
633 bool inrange = inrange_node->getBoolValue();
635 if (tofrom_serviceable_node->getBoolValue()) {
636 to_flag_node->setBoolValue(_toFlag);
637 from_flag_node->setBoolValue(_fromFlag);
639 to_flag_node->setBoolValue(false);
640 from_flag_node->setBoolValue(false);
643 if (!cdi_serviceable) {
644 _cdiDeflection = 0.0;
645 _cdiCrossTrackErrorM = 0.0;
648 cdi_deflection_node->setDoubleValue(_cdiDeflection);
649 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
650 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
652 //////////////////////////////////////////////////////////
653 // compute an approximate ground track heading error
654 //////////////////////////////////////////////////////////
655 double hdg_error = 0.0;
656 if ( inrange && cdi_serviceable ) {
657 double vn = fgGetDouble( "/velocities/speed-north-fps" );
658 double ve = fgGetDouble( "/velocities/speed-east-fps" );
659 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
660 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
662 SGPropertyNode *true_hdg
663 = fgGetNode("/orientation/heading-deg", true);
664 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
666 // cout << "ground track = " << gnd_trk_true
667 // << " orientation = " << true_hdg->getDoubleValue() << endl;
669 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
671 //////////////////////////////////////////////////////////
672 // Calculate a suggested target heading to smoothly intercept
674 //////////////////////////////////////////////////////////
676 // Now that we have cross track heading adjustment built in,
677 // we shouldn't need to overdrive the heading angle within 8km
680 // The cdi deflection should be +/-10 for a full range of deflection
681 // so multiplying this by 3 gives us +/- 30 degrees heading
683 double adjustment = _cdiDeflection * 3.0;
684 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
686 // determine the target heading to fly to intercept the
687 // tgt_radial = target radial (true) + cdi offset adjustmest -
688 // xtrack heading error adjustment
690 double trtrue = target_radial_true_node->getDoubleValue();
691 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
692 // tuned to a localizer and backcourse mode activated
693 trtrue += 180.0; // reverse the target localizer heading
694 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
695 nta_hdg = trtrue - adjustment - hdg_error;
697 nta_hdg = trtrue + adjustment - hdg_error;
700 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
701 target_auto_hdg_node->setDoubleValue( nta_hdg );
703 //////////////////////////////////////////////////////////
704 // compute the time to intercept selected radial (based on
705 // current and last cross track errors and dt
706 //////////////////////////////////////////////////////////
708 if ( inrange && cdi_serviceable ) {
709 double xrate_ms = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
710 if ( fabs(xrate_ms) > 0.00001 ) {
711 t = _cdiCrossTrackErrorM / xrate_ms;
716 time_to_intercept->setDoubleValue( t );
718 if (!gs_serviceable_node->getBoolValue() ) {
719 _gsNeedleDeflection = 0.0;
720 _gsNeedleDeflectionNorm = 0.0;
722 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
723 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
724 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
726 last_xtrack_error = _cdiCrossTrackErrorM;
729 void FGNavRadio::updateAudio()
731 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
735 // play station ident via audio system if on + ident,
736 // otherwise turn it off
737 if (!power_btn_node->getBoolValue()
738 || !(bus_power_node->getDoubleValue() > 1.0)
739 || !ident_btn_node->getBoolValue()
740 || !audio_btn_node->getBoolValue() ) {
741 globals->get_soundmgr()->stop( nav_fx_name );
742 globals->get_soundmgr()->stop( dme_fx_name );
746 SGSoundSample *sound = globals->get_soundmgr()->find( nav_fx_name );
747 double vol = vol_btn_node->getDoubleValue();
748 SG_CLAMP_RANGE(vol, 0.0, 1.0);
750 if ( sound != NULL ) {
751 sound->set_volume( vol );
753 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" );
756 sound = globals->get_soundmgr()->find( dme_fx_name );
757 if ( sound != NULL ) {
758 sound->set_volume( vol );
760 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" );
763 if ( last_time < globals->get_time_params()->get_cur_time() - 30 ) {
764 last_time = globals->get_time_params()->get_cur_time();
768 if ( play_count < 4 ) {
770 if ( !globals->get_soundmgr()->is_playing(nav_fx_name) ) {
771 globals->get_soundmgr()->play_once( nav_fx_name );
774 } else if ( play_count < 5 && has_dme) {
776 if ( !globals->get_soundmgr()->is_playing(nav_fx_name) &&
777 !globals->get_soundmgr()->is_playing(dme_fx_name) ) {
778 globals->get_soundmgr()->play_once( dme_fx_name );
784 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
786 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
791 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
794 // Update current nav/adf radio stations based on current postition
795 void FGNavRadio::search()
797 _time_before_search_sec = 1.0;
798 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
799 lat_node->getDoubleValue(), alt_node->getDoubleValue());
800 double freq = freq_node->getDoubleValue();
802 FGNavRecord* nav = findPrimaryNavaid(pos, freq);
803 if (nav == _navaid) {
804 return; // found the same as last search, we're done
808 char identBuffer[5] = " ";
810 FGNavRecord* dme = globals->get_dmelist()->findByFreq(freq, pos);
811 has_dme = (dme != NULL);
813 nav_id_node->setStringValue(nav->get_ident());
814 strncpy(identBuffer, nav->ident().c_str(), 5);
816 effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range());
817 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
818 twist = nav->get_multiuse();
820 if (nav->type() == FGPositioned::VOR) {
821 target_radial = sel_radial_node->getDoubleValue();
823 } else { // ILS or LOC
824 _gs = globals->get_gslist()->findByFreq(freq, pos);
825 _localizerWidth = localizerWidth(nav);
826 has_gs_node->setBoolValue(_gs != NULL);
828 effective_range = nav->get_range();
830 target_radial = nav->get_multiuse();
831 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
834 int tmp = (int)(_gs->get_multiuse() / 1000.0);
835 target_gs = (double)tmp / 100.0;
837 // GS axis unit tangent vector
838 // (along the runway)
839 _gsCart = _gs->cart();
840 _gsAxis = tangentVector(_gs->geod(), _gsCart, target_radial);
842 // GS baseline unit tangent vector
843 // (perpendicular to the runay along the ground)
844 SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, target_radial + 90.0);
845 _gsVertical = cross(baseline, _gsAxis);
846 } // of have glideslope
847 } // of found LOC or ILS
850 } else { // found nothing
852 nav_id_node->setStringValue("");
854 globals->get_soundmgr()->remove( nav_fx_name );
855 globals->get_soundmgr()->remove( dme_fx_name );
858 is_valid_node->setBoolValue(nav != NULL);
859 id_c1_node->setIntValue( (int)identBuffer[0] );
860 id_c2_node->setIntValue( (int)identBuffer[1] );
861 id_c3_node->setIntValue( (int)identBuffer[2] );
862 id_c4_node->setIntValue( (int)identBuffer[3] );
865 double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
867 FGRunway* rwy = aLOC->runway();
870 SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold()));
871 double axisLength = dist(aLOC->cart(), thresholdCart);
872 double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end()));
874 // Reference: http://dcaa.slv.dk:8000/icaodocs/
875 // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet.
876 // ICAO 3.1.1 half course = DDM = 0.0775
877 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold
878 // implies peg-to-peg of 214 m ... we will stick with 210.
879 // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees."
881 // Very short runway: less than 1200 m (4000 ft) landing length:
882 if (landingLength < 1200.0) {
883 // ICAO fudges localizer sensitivity for very short runways.
884 // This produces a non-monotonic sensitivity-versus length relation.
885 axisLength += 1050.0;
888 // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R
889 // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6
890 // Example: very long: Denver KDEN (Denver) ILS RWY 16R
891 double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES;
892 return raw_width < 6.0? raw_width : 6.0;
895 void FGNavRadio::audioNavidChanged()
897 if ( globals->get_soundmgr()->exists(nav_fx_name)) {
898 globals->get_soundmgr()->remove(nav_fx_name);
902 string trans_ident(_navaid->get_trans_ident());
903 SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY);
904 sound->set_volume( 0.3 );
905 if (!globals->get_soundmgr()->add( sound, nav_fx_name )) {
906 SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound");
909 if ( globals->get_soundmgr()->exists( dme_fx_name ) ) {
910 globals->get_soundmgr()->remove( dme_fx_name );
913 sound = morse.make_ident( trans_ident, HI_FREQUENCY );
914 sound->set_volume( 0.3 );
915 globals->get_soundmgr()->add( sound, dme_fx_name );
917 int offset = (int)(sg_random() * 30.0);
918 play_count = offset / 4;
919 last_time = globals->get_time_params()->get_cur_time() - offset;
920 } catch (sg_io_exception& e) {
921 SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage());