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)),
103 last_xtrack_error(0.0),
105 _localizerWidth(5.0),
106 _name(node->getStringValue("name", "nav")),
107 _num(node->getIntValue("number", 0)),
108 _time_before_search_sec(-1.0),
111 SGPath path( globals->get_fg_root() );
113 term.append( "Navaids/range.term" );
115 low.append( "Navaids/range.low" );
117 high.append( "Navaids/range.high" );
119 term_tbl = new SGInterpTable( term.str() );
120 low_tbl = new SGInterpTable( low.str() );
121 high_tbl = new SGInterpTable( high.str() );
124 string branch("/instrumentation/" + _name);
125 _radio_node = fgGetNode(branch.c_str(), _num, true);
130 FGNavRadio::~FGNavRadio()
132 gps_course_node->removeChangeListener(this);
133 nav_slaved_to_gps_node->removeChangeListener(this);
144 SGSoundMgr *smgr = globals->get_soundmgr();
145 _sgr = smgr->find("avionics", true);
146 _sgr->tie_to_listener();
150 SGPropertyNode* node = _radio_node.get();
152 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
155 is_valid_node = node->getChild("data-is-valid", 0, true);
156 power_btn_node = node->getChild("power-btn", 0, true);
157 power_btn_node->setBoolValue( true );
158 vol_btn_node = node->getChild("volume", 0, true);
159 ident_btn_node = node->getChild("ident", 0, true);
160 ident_btn_node->setBoolValue( true );
161 audio_btn_node = node->getChild("audio-btn", 0, true);
162 audio_btn_node->setBoolValue( true );
163 backcourse_node = node->getChild("back-course-btn", 0, true);
164 backcourse_node->setBoolValue( false );
166 nav_serviceable_node = node->getChild("serviceable", 0, true);
167 cdi_serviceable_node = createServiceableProp(node, "cdi");
168 gs_serviceable_node = createServiceableProp(node, "gs");
169 tofrom_serviceable_node = createServiceableProp(node, "to-from");
170 dme_serviceable_node = createServiceableProp(node, "dme");
172 falseCoursesEnabledNode =
173 fgGetNode("/sim/realism/false-radio-courses-enabled");
174 if (!falseCoursesEnabledNode) {
175 falseCoursesEnabledNode =
176 fgGetNode("/sim/realism/false-radio-courses-enabled", true);
177 falseCoursesEnabledNode->setBoolValue(true);
181 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
182 freq_node = subnode->getChild("selected-mhz", 0, true);
183 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
184 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
185 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
188 subnode = node->getChild("radials", 0, true);
189 sel_radial_node = subnode->getChild("selected-deg", 0, true);
190 radial_node = subnode->getChild("actual-deg", 0, true);
191 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
192 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
193 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
196 heading_node = node->getChild("heading-deg", 0, true);
197 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
198 to_flag_node = node->getChild("to-flag", 0, true);
199 from_flag_node = node->getChild("from-flag", 0, true);
200 inrange_node = node->getChild("in-range", 0, true);
201 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
202 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
203 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
204 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
205 cdi_xtrack_hdg_err_node
206 = node->getChild("crosstrack-heading-error-deg", 0, true);
207 has_gs_node = node->getChild("has-gs", 0, true);
208 loc_node = node->getChild("nav-loc", 0, true);
209 loc_dist_node = node->getChild("nav-distance", 0, true);
210 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
211 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
212 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
213 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
214 gs_rate_of_climb_fpm_node = node->getChild("gs-rate-of-climb-fpm", 0, true);
215 gs_dist_node = node->getChild("gs-distance", 0, true);
216 gs_inrange_node = node->getChild("gs-in-range", 0, true);
218 nav_id_node = node->getChild("nav-id", 0, true);
219 id_c1_node = node->getChild("nav-id_asc1", 0, true);
220 id_c2_node = node->getChild("nav-id_asc2", 0, true);
221 id_c3_node = node->getChild("nav-id_asc3", 0, true);
222 id_c4_node = node->getChild("nav-id_asc4", 0, true);
224 // gps slaving support
225 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
226 nav_slaved_to_gps_node->addChangeListener(this);
228 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
229 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
230 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
231 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
232 gps_course_node = fgGetNode("/instrumentation/gps/desired-course-deg", true);
233 gps_course_node->addChangeListener(this);
235 gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true);
236 _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true);
238 std::ostringstream temp;
239 temp << _name << "nav-ident" << _num;
240 nav_fx_name = temp.str();
241 temp << _name << "dme-ident" << _num;
242 dme_fx_name = temp.str();
248 tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
249 tie("operable", SGRawValueMethods<FGNavRadio, bool>(*this, &FGNavRadio::isOperable, NULL));
254 FGNavRadio::unbind ()
256 for (unsigned int t=0; t<_tiedNodes.size(); ++t) {
257 _tiedNodes[t]->untie();
263 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
264 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
265 double nominalRange )
267 if (nominalRange <= 0.0) {
268 nominalRange = FG_NAV_DEFAULT_RANGE;
271 // extend out actual usable range to be 1.3x the published safe range
272 const double usability_factor = 1.3;
274 // assumptions we model the standard service volume, plus
275 // ... rather than specifying a cylinder, we model a cone that
276 // contains the cylinder. Then we put an upside down cone on top
277 // to model diminishing returns at too-high altitudes.
279 // altitude difference
280 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
281 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
282 // << " station elev = " << stationElev << endl;
284 if ( nominalRange < 25.0 + SG_EPSILON ) {
285 // Standard Terminal Service Volume
286 return term_tbl->interpolate( alt ) * usability_factor;
287 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
288 // Standard Low Altitude Service Volume
289 // table is based on range of 40, scale to actual range
290 return low_tbl->interpolate( alt ) * nominalRange / 40.0
293 // Standard High Altitude Service Volume
294 // table is based on range of 130, scale to actual range
295 return high_tbl->interpolate( alt ) * nominalRange / 130.0
301 // model standard ILS service volumes as per AIM 1-1-9
302 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
303 double offsetDegrees, double distance )
305 // assumptions we model the standard service volume, plus
307 // altitude difference
308 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
309 // double offset = fabs( offsetDegrees );
311 // if ( offset < 10 ) {
312 // return FG_ILS_DEFAULT_RANGE;
313 // } else if ( offset < 35 ) {
314 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
315 // } else if ( offset < 45 ) {
316 // return (45 - offset);
317 // } else if ( offset > 170 ) {
318 // return FG_ILS_DEFAULT_RANGE;
319 // } else if ( offset > 145 ) {
320 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
321 // } else if ( offset > 135 ) {
322 // return (offset - 135);
326 return FG_LOC_DEFAULT_RANGE;
330 //////////////////////////////////////////////////////////////////////////
331 // Update the various nav values based on position and valid tuned in navs
332 //////////////////////////////////////////////////////////////////////////
334 FGNavRadio::update(double dt)
340 // Create "formatted" versions of the nav frequencies for
341 // instrument displays.
343 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
344 fmt_freq_node->setStringValue(tmp);
345 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
346 fmt_alt_freq_node->setStringValue(tmp);
348 if (power_btn_node->getBoolValue()
349 && (bus_power_node->getDoubleValue() > 1.0)
350 && nav_serviceable_node->getBoolValue() )
353 if (nav_slaved_to_gps_node->getBoolValue()) {
367 void FGNavRadio::clearOutputs()
369 inrange_node->setBoolValue( false );
370 cdi_deflection_node->setDoubleValue( 0.0 );
371 cdi_deflection_norm_node->setDoubleValue( 0.0 );
372 cdi_xtrack_error_node->setDoubleValue( 0.0 );
373 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
374 time_to_intercept->setDoubleValue( 0.0 );
375 gs_deflection_node->setDoubleValue( 0.0 );
376 gs_deflection_deg_node->setDoubleValue(0.0);
377 gs_deflection_norm_node->setDoubleValue(0.0);
378 gs_inrange_node->setBoolValue( false );
380 to_flag_node->setBoolValue( false );
381 from_flag_node->setBoolValue( false );
387 void FGNavRadio::updateReceiver(double dt)
389 // Do a nav station search only once a second to reduce
390 // unnecessary work. (Also, make sure to do this before caching
392 _time_before_search_sec -= dt;
393 if ( _time_before_search_sec < 0 ) {
398 _cdiDeflection = 0.0;
399 _cdiCrossTrackErrorM = 0.0;
400 _toFlag = _fromFlag = false;
401 _gsNeedleDeflection = 0.0;
402 _gsNeedleDeflectionNorm = 0.0;
403 inrange_node->setBoolValue(false);
407 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
408 lat_node->getDoubleValue(),
409 alt_node->getDoubleValue());
411 double nav_elev = _navaid->get_elev_ft();
412 SGVec3d aircraft = SGVec3d::fromGeod(pos);
413 double loc_dist = dist(aircraft, _navaid->cart());
414 loc_dist_node->setDoubleValue( loc_dist );
415 bool is_loc = loc_node->getBoolValue();
416 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
419 //////////////////////////////////////////////////////////
420 // compute forward and reverse wgs84 headings to localizer
421 //////////////////////////////////////////////////////////
423 SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s);
424 heading_node->setDoubleValue(hdg);
425 double radial = az2 - twist;
426 double recip = radial + 180.0;
427 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
428 radial_node->setDoubleValue( radial );
429 recip_radial_node->setDoubleValue( recip );
431 //////////////////////////////////////////////////////////
432 // compute the target/selected radial in "true" heading
433 //////////////////////////////////////////////////////////
435 target_radial = sel_radial_node->getDoubleValue();
438 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
439 double trtrue = target_radial + twist;
440 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
441 target_radial_true_node->setDoubleValue( trtrue );
443 //////////////////////////////////////////////////////////
444 // adjust reception range for altitude
445 // FIXME: make sure we are using the navdata range now that
446 // it is valid in the data file
447 //////////////////////////////////////////////////////////
449 double offset = radial - target_radial;
450 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
452 = adjustILSRange( nav_elev, pos.getElevationM(), offset,
453 loc_dist * SG_METER_TO_NM );
456 = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() );
459 double effective_range_m = effective_range * SG_NM_TO_METER;
461 //////////////////////////////////////////////////////////
462 // compute signal quality
463 // 100% within effective_range
464 // decreases 1/x^2 further out
465 //////////////////////////////////////////////////////////
466 double last_signal_quality_norm = signal_quality_norm;
468 if ( loc_dist < effective_range_m ) {
469 signal_quality_norm = 1.0;
471 double range_exceed_norm = loc_dist/effective_range_m;
472 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
475 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
476 signal_quality_norm, dt );
478 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
479 bool inrange = signal_quality_norm > 0.2;
480 inrange_node->setBoolValue( inrange );
482 //////////////////////////////////////////////////////////
483 // compute to/from flag status
484 //////////////////////////////////////////////////////////
489 double offset = fabs(radial - target_radial);
490 _toFlag = (offset > 90.0 && offset < 270.0);
492 _fromFlag = !_toFlag;
494 _toFlag = _fromFlag = false;
498 double r = target_radial - radial;
499 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
502 if (falseCoursesEnabledNode->getBoolValue()) {
503 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
504 // zeros i.e. six courses: one front course, one back course, and four
505 // false courses. Three of the six are reverse sensing.
506 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
508 // no false courses, but we do need to create a back course
509 if (fabs(r) > 90.0) { // front course
510 _cdiDeflection = r - copysign(180.0, r);
512 _cdiDeflection = r; // back course
515 _cdiDeflection = -_cdiDeflection; // reverse for outbound radial
516 } // of false courses disabled
518 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
519 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
521 if (backcourse_node->getBoolValue()) {
522 _cdiDeflection = -_cdiDeflection;
525 // handle the TO side of the VOR
526 if (fabs(r) > 90.0) {
527 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
530 } // of non-localiser case
532 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
533 _cdiDeflection *= signal_quality_norm;
535 // cross-track error (in metres)
536 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
538 updateGlideSlope(dt, aircraft, signal_quality_norm);
541 last_loc_dist = loc_dist;
544 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
546 _gsNeedleDeflection = 0.0;
547 if (!_gs || !inrange_node->getBoolValue()) {
548 gs_dist_node->setDoubleValue( 0.0 );
549 gs_inrange_node->setBoolValue(false);
550 _gsNeedleDeflection = 0.0;
551 _gsNeedleDeflectionNorm = 0.0;
555 double gsDist = dist(aircraft, _gsCart);
556 gs_dist_node->setDoubleValue(gsDist);
557 bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
558 gs_inrange_node->setBoolValue(gsInRange);
561 _gsNeedleDeflection = 0.0;
562 _gsNeedleDeflectionNorm = 0.0;
566 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
567 // The positive GS axis points along the runway in the landing direction,
568 // toward the far end, not toward the approach area, so we need a - sign here:
569 double dot_h = -dot(pos, _gsAxis);
570 double dot_v = dot(pos, _gsVertical);
571 double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES;
572 double deflectionAngle = target_gs - angle;
574 if (falseCoursesEnabledNode->getBoolValue()) {
575 // Construct false glideslopes. The scale factor of 1.5
576 // in the sawtooth gives a period of 6 degrees.
577 // There will be zeros at 3, 6r, 9, 12r et cetera
578 // where "r" indicates reverse sensing.
579 // This is is consistent with conventional pilot lore
580 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
581 // but inconsistent with
582 // http://www.freepatentsonline.com/3757338.html
584 // It may be that some of each exist.
585 if (deflectionAngle < 0) {
586 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
588 // no false GS below the true GS
592 _gsNeedleDeflection = deflectionAngle * 5.0;
593 _gsNeedleDeflection *= signal_quality_norm;
595 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
596 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
598 //////////////////////////////////////////////////////////
599 // Calculate desired rate of climb for intercepting the GS
600 //////////////////////////////////////////////////////////
601 double gs_diff = target_gs - angle;
602 // convert desired vertical path angle into a climb rate
603 double des_angle = angle - 10 * gs_diff;
604 /* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
605 target_gs, angle, gs_diff, des_angle); */
607 // estimate horizontal speed towards ILS in meters per minute
608 double elapsedDistance = last_x - gsDist;
611 double new_vel = ( elapsedDistance / dt );
612 horiz_vel = 0.99 * horiz_vel + 0.01 * new_vel;
613 /* printf("vel=%.1f (dist=%.1f dt=%.2f)\n", horiz_vel, elapsedDistance, dt);*/
615 gs_rate_of_climb_node
616 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
617 * horiz_vel * SG_METER_TO_FEET );
618 gs_rate_of_climb_fpm_node
619 ->setDoubleValue( gs_rate_of_climb_node->getDoubleValue() * 60 );
622 void FGNavRadio::updateDME(const SGVec3d& aircraft)
624 if (!_dme || !dme_serviceable_node->getBoolValue()) {
629 double dme_distance = dist(aircraft, _dme->cart());
630 _dmeInRange = (dme_distance < _dme->get_range() * SG_NM_TO_METER);
633 void FGNavRadio::valueChanged (SGPropertyNode* prop)
635 if (prop == gps_course_node) {
636 if (!nav_slaved_to_gps_node->getBoolValue()) {
640 // GPS desired course has changed, sync up our selected-course
641 double v = prop->getDoubleValue();
642 if (v != sel_radial_node->getDoubleValue()) {
643 sel_radial_node->setDoubleValue(v);
645 } else if (prop == nav_slaved_to_gps_node) {
646 if (prop->getBoolValue()) {
647 // slaved-to-GPS activated, sync up selected course
648 sel_radial_node->setDoubleValue(gps_course_node->getDoubleValue());
653 void FGNavRadio::updateGPSSlaved()
655 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
657 _toFlag = gps_to_flag_node->getBoolValue();
658 _fromFlag = gps_from_flag_node->getBoolValue();
660 bool gpsValid = (_toFlag | _fromFlag);
661 inrange_node->setBoolValue(gpsValid);
663 signal_quality_norm_node->setDoubleValue(0.0);
664 _cdiDeflection = 0.0;
665 _cdiCrossTrackErrorM = 0.0;
666 _gsNeedleDeflection = 0.0;
670 // this is unfortunate, but panel instruments use this value to decide
671 // if the navradio output is valid.
672 signal_quality_norm_node->setDoubleValue(1.0);
674 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
675 // clmap to some range (+/- 10 degrees) as the regular deflection
676 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
678 _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER;
679 _gsNeedleDeflection = 0.0; // FIXME, supply this
681 double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue();
682 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
683 target_radial_true_node->setDoubleValue( trtrue );
686 void FGNavRadio::updateCDI(double dt)
688 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
689 bool inrange = inrange_node->getBoolValue();
691 if (tofrom_serviceable_node->getBoolValue()) {
692 to_flag_node->setBoolValue(_toFlag);
693 from_flag_node->setBoolValue(_fromFlag);
695 to_flag_node->setBoolValue(false);
696 from_flag_node->setBoolValue(false);
699 if (!cdi_serviceable) {
700 _cdiDeflection = 0.0;
701 _cdiCrossTrackErrorM = 0.0;
704 cdi_deflection_node->setDoubleValue(_cdiDeflection);
705 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
706 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
708 //////////////////////////////////////////////////////////
709 // compute an approximate ground track heading error
710 //////////////////////////////////////////////////////////
711 double hdg_error = 0.0;
712 if ( inrange && cdi_serviceable ) {
713 double vn = fgGetDouble( "/velocities/speed-north-fps" );
714 double ve = fgGetDouble( "/velocities/speed-east-fps" );
715 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
716 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
718 SGPropertyNode *true_hdg
719 = fgGetNode("/orientation/heading-deg", true);
720 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
722 // cout << "ground track = " << gnd_trk_true
723 // << " orientation = " << true_hdg->getDoubleValue() << endl;
725 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
727 //////////////////////////////////////////////////////////
728 // Calculate a suggested target heading to smoothly intercept
730 //////////////////////////////////////////////////////////
732 // Now that we have cross track heading adjustment built in,
733 // we shouldn't need to overdrive the heading angle within 8km
736 // The cdi deflection should be +/-10 for a full range of deflection
737 // so multiplying this by 3 gives us +/- 30 degrees heading
739 double adjustment = _cdiDeflection * 3.0;
740 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
742 // determine the target heading to fly to intercept the
743 // tgt_radial = target radial (true) + cdi offset adjustmest -
744 // xtrack heading error adjustment
746 double trtrue = target_radial_true_node->getDoubleValue();
747 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
748 // tuned to a localizer and backcourse mode activated
749 trtrue += 180.0; // reverse the target localizer heading
750 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
751 nta_hdg = trtrue - adjustment - hdg_error;
753 nta_hdg = trtrue + adjustment - hdg_error;
756 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
757 target_auto_hdg_node->setDoubleValue( nta_hdg );
759 //////////////////////////////////////////////////////////
760 // compute the time to intercept selected radial (based on
761 // current and last cross track errors and dt
762 //////////////////////////////////////////////////////////
764 if ( inrange && cdi_serviceable ) {
765 double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
766 xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate;
767 if ( fabs(xrate_ms) > 0.00001 ) {
768 t = _cdiCrossTrackErrorM / xrate_ms;
773 time_to_intercept->setDoubleValue( t );
775 if (!gs_serviceable_node->getBoolValue() ) {
776 _gsNeedleDeflection = 0.0;
777 _gsNeedleDeflectionNorm = 0.0;
779 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
780 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
781 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
783 last_xtrack_error = _cdiCrossTrackErrorM;
786 void FGNavRadio::updateAudio()
788 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
792 // play station ident via audio system if on + ident,
793 // otherwise turn it off
794 if (!power_btn_node->getBoolValue()
795 || !(bus_power_node->getDoubleValue() > 1.0)
796 || !ident_btn_node->getBoolValue()
797 || !audio_btn_node->getBoolValue() ) {
798 _sgr->stop( nav_fx_name );
799 _sgr->stop( dme_fx_name );
803 SGSoundSample *sound = _sgr->find( nav_fx_name );
804 double vol = vol_btn_node->getFloatValue();
805 SG_CLAMP_RANGE(vol, 0.0, 1.0);
807 if ( sound != NULL ) {
808 sound->set_volume( vol );
810 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" );
813 sound = _sgr->find( dme_fx_name );
814 if ( sound != NULL ) {
815 sound->set_volume( vol );
817 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" );
820 const int NUM_IDENT_SLOTS = 5;
821 const time_t SLOT_LENGTH = 5; // seconds
823 // There are N slots numbered 0 through (NUM_IDENT_SLOTS-1) inclusive.
824 // Each slot is 5 seconds long.
825 // Slots 0 is for DME
826 // the rest are for azimuth.
827 time_t now = globals->get_time_params()->get_cur_time();
828 if ((now >= last_time) && (now < last_time + SLOT_LENGTH)) {
829 return; // wait longer
833 play_count = ++play_count % NUM_IDENT_SLOTS;
835 // Previous ident is out of time; if still playing, cut it off:
836 _sgr->stop( nav_fx_name );
837 _sgr->stop( dme_fx_name );
838 if (play_count == 0) { // the DME slot
839 if (_dmeInRange && dme_serviceable_node->getBoolValue()) {
841 if (vol > 0.05) _sgr->play_once( dme_fx_name );
844 if (inrange_node->getBoolValue() && nav_serviceable_node->getBoolValue()) {
845 if (vol > 0.05) _sgr->play_once(nav_fx_name);
850 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
852 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
857 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
860 // Update current nav/adf radio stations based on current postition
861 void FGNavRadio::search()
863 _time_before_search_sec = 1.0;
864 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
865 lat_node->getDoubleValue(), alt_node->getDoubleValue());
866 double freq = freq_node->getDoubleValue();
868 FGNavRecord* nav = findPrimaryNavaid(pos, freq);
869 if (nav == _navaid) {
870 return; // found the same as last search, we're done
874 char identBuffer[5] = " ";
876 _dme = globals->get_dmelist()->findByFreq(freq, pos);
878 nav_id_node->setStringValue(nav->get_ident());
879 strncpy(identBuffer, nav->ident().c_str(), 5);
881 effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range());
882 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
883 twist = nav->get_multiuse();
885 if (nav->type() == FGPositioned::VOR) {
886 target_radial = sel_radial_node->getDoubleValue();
888 has_gs_node->setBoolValue(false);
889 } else { // ILS or LOC
890 _gs = globals->get_gslist()->findByFreq(freq, pos);
891 has_gs_node->setBoolValue(_gs != NULL);
892 _localizerWidth = localizerWidth(nav);
894 effective_range = nav->get_range();
896 target_radial = nav->get_multiuse();
897 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
900 int tmp = (int)(_gs->get_multiuse() / 1000.0);
901 target_gs = (double)tmp / 100.0;
903 // until penaltyForNav goes away, we cannot assume we always pick
904 // paired LOC/GS trasmsitters. As we pass over a runway threshold, we
905 // often end up picking the 'wrong' LOC, but the correct GS. To avoid
906 // breaking the basis computation, ensure we use the GS radial and not
907 // the (potentially reversed) LOC radial.
908 double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
909 SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
911 // GS axis unit tangent vector
912 // (along the runway)
913 _gsCart = _gs->cart();
914 _gsAxis = tangentVector(_gs->geod(), _gsCart, gs_radial);
916 // GS baseline unit tangent vector
917 // (perpendicular to the runay along the ground)
918 SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, gs_radial + 90.0);
919 _gsVertical = cross(baseline, _gsAxis);
920 } // of have glideslope
921 } // of found LOC or ILS
924 } else { // found nothing
927 nav_id_node->setStringValue("");
929 _sgr->remove( nav_fx_name );
930 _sgr->remove( dme_fx_name );
933 is_valid_node->setBoolValue(nav != NULL);
934 id_c1_node->setIntValue( (int)identBuffer[0] );
935 id_c2_node->setIntValue( (int)identBuffer[1] );
936 id_c3_node->setIntValue( (int)identBuffer[2] );
937 id_c4_node->setIntValue( (int)identBuffer[3] );
940 double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
942 FGRunway* rwy = aLOC->runway();
945 SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold()));
946 double axisLength = dist(aLOC->cart(), thresholdCart);
947 double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end()));
949 // Reference: http://dcaa.slv.dk:8000/icaodocs/
950 // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet.
951 // ICAO 3.1.1 half course = DDM = 0.0775
952 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold
953 // implies peg-to-peg of 214 m ... we will stick with 210.
954 // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees."
956 // Very short runway: less than 1200 m (4000 ft) landing length:
957 if (landingLength < 1200.0) {
958 // ICAO fudges localizer sensitivity for very short runways.
959 // This produces a non-monotonic sensitivity-versus length relation.
960 axisLength += 1050.0;
963 // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R
964 // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6
965 // Example: very long: Denver KDEN (Denver) ILS RWY 16R
966 double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES;
967 return raw_width < 6.0? raw_width : 6.0;
970 void FGNavRadio::audioNavidChanged()
972 if (_sgr->exists(nav_fx_name)) {
973 _sgr->remove(nav_fx_name);
977 string trans_ident(_navaid->get_trans_ident());
978 SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY);
979 sound->set_volume( 0.3 );
980 if (!_sgr->add( sound, nav_fx_name )) {
981 SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound");
984 if ( _sgr->exists( dme_fx_name ) ) {
985 _sgr->remove( dme_fx_name );
988 sound = morse.make_ident( trans_ident, HI_FREQUENCY );
989 sound->set_volume( 0.3 );
990 _sgr->add( sound, dme_fx_name );
992 int offset = (int)(sg_random() * 30.0);
993 play_count = offset / 4;
994 last_time = globals->get_time_params()->get_cur_time() - offset;
995 } catch (sg_io_exception& e) {
996 SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage());