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()
141 SGSoundMgr *smgr = globals->get_soundmgr();
142 _sgr = smgr->find("avionics", true);
143 _sgr->tie_to_listener();
147 SGPropertyNode* node = _radio_node.get();
149 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
152 is_valid_node = node->getChild("data-is-valid", 0, true);
153 power_btn_node = node->getChild("power-btn", 0, true);
154 power_btn_node->setBoolValue( true );
155 vol_btn_node = node->getChild("volume", 0, true);
156 ident_btn_node = node->getChild("ident", 0, true);
157 ident_btn_node->setBoolValue( true );
158 audio_btn_node = node->getChild("audio-btn", 0, true);
159 audio_btn_node->setBoolValue( true );
160 backcourse_node = node->getChild("back-course-btn", 0, true);
161 backcourse_node->setBoolValue( false );
163 nav_serviceable_node = node->getChild("serviceable", 0, true);
164 cdi_serviceable_node = createServiceableProp(node, "cdi");
165 gs_serviceable_node = createServiceableProp(node, "gs");
166 tofrom_serviceable_node = createServiceableProp(node, "to-from");
167 dme_serviceable_node = createServiceableProp(node, "dme");
169 falseCoursesEnabledNode =
170 fgGetNode("/sim/realism/false-radio-courses-enabled");
171 if (!falseCoursesEnabledNode) {
172 falseCoursesEnabledNode =
173 fgGetNode("/sim/realism/false-radio-courses-enabled", true);
174 falseCoursesEnabledNode->setBoolValue(true);
178 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
179 freq_node = subnode->getChild("selected-mhz", 0, true);
180 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
181 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
182 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
185 subnode = node->getChild("radials", 0, true);
186 sel_radial_node = subnode->getChild("selected-deg", 0, true);
187 radial_node = subnode->getChild("actual-deg", 0, true);
188 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
189 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
190 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
193 heading_node = node->getChild("heading-deg", 0, true);
194 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
195 to_flag_node = node->getChild("to-flag", 0, true);
196 from_flag_node = node->getChild("from-flag", 0, true);
197 inrange_node = node->getChild("in-range", 0, true);
198 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
199 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
200 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
201 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
202 cdi_xtrack_hdg_err_node
203 = node->getChild("crosstrack-heading-error-deg", 0, true);
204 has_gs_node = node->getChild("has-gs", 0, true);
205 loc_node = node->getChild("nav-loc", 0, true);
206 loc_dist_node = node->getChild("nav-distance", 0, true);
207 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
208 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
209 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
210 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
211 gs_rate_of_climb_fpm_node = node->getChild("gs-rate-of-climb-fpm", 0, true);
212 gs_dist_node = node->getChild("gs-distance", 0, true);
213 gs_inrange_node = node->getChild("gs-in-range", 0, true);
215 nav_id_node = node->getChild("nav-id", 0, true);
216 id_c1_node = node->getChild("nav-id_asc1", 0, true);
217 id_c2_node = node->getChild("nav-id_asc2", 0, true);
218 id_c3_node = node->getChild("nav-id_asc3", 0, true);
219 id_c4_node = node->getChild("nav-id_asc4", 0, true);
221 // gps slaving support
222 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
223 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
224 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
225 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
226 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
227 gps_course_node = fgGetNode("/instrumentation/gps/selected-course-deg", true);
228 gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true);
229 _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true);
231 std::ostringstream temp;
232 temp << _name << "nav-ident" << _num;
233 nav_fx_name = temp.str();
234 temp << _name << "dme-ident" << _num;
235 dme_fx_name = temp.str();
241 tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
242 tie("operable", SGRawValueMethods<FGNavRadio, bool>(*this, &FGNavRadio::isOperable, NULL));
247 FGNavRadio::unbind ()
249 for (unsigned int t=0; t<_tiedNodes.size(); ++t) {
250 _tiedNodes[t]->untie();
256 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
257 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
258 double nominalRange )
260 if (nominalRange <= 0.0) {
261 nominalRange = FG_NAV_DEFAULT_RANGE;
264 // extend out actual usable range to be 1.3x the published safe range
265 const double usability_factor = 1.3;
267 // assumptions we model the standard service volume, plus
268 // ... rather than specifying a cylinder, we model a cone that
269 // contains the cylinder. Then we put an upside down cone on top
270 // to model diminishing returns at too-high altitudes.
272 // altitude difference
273 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
274 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
275 // << " station elev = " << stationElev << endl;
277 if ( nominalRange < 25.0 + SG_EPSILON ) {
278 // Standard Terminal Service Volume
279 return term_tbl->interpolate( alt ) * usability_factor;
280 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
281 // Standard Low Altitude Service Volume
282 // table is based on range of 40, scale to actual range
283 return low_tbl->interpolate( alt ) * nominalRange / 40.0
286 // Standard High Altitude Service Volume
287 // table is based on range of 130, scale to actual range
288 return high_tbl->interpolate( alt ) * nominalRange / 130.0
294 // model standard ILS service volumes as per AIM 1-1-9
295 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
296 double offsetDegrees, double distance )
298 // assumptions we model the standard service volume, plus
300 // altitude difference
301 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
302 // double offset = fabs( offsetDegrees );
304 // if ( offset < 10 ) {
305 // return FG_ILS_DEFAULT_RANGE;
306 // } else if ( offset < 35 ) {
307 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
308 // } else if ( offset < 45 ) {
309 // return (45 - offset);
310 // } else if ( offset > 170 ) {
311 // return FG_ILS_DEFAULT_RANGE;
312 // } else if ( offset > 145 ) {
313 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
314 // } else if ( offset > 135 ) {
315 // return (offset - 135);
319 return FG_LOC_DEFAULT_RANGE;
323 //////////////////////////////////////////////////////////////////////////
324 // Update the various nav values based on position and valid tuned in navs
325 //////////////////////////////////////////////////////////////////////////
327 FGNavRadio::update(double dt)
333 // Create "formatted" versions of the nav frequencies for
334 // instrument displays.
336 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
337 fmt_freq_node->setStringValue(tmp);
338 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
339 fmt_alt_freq_node->setStringValue(tmp);
341 if (power_btn_node->getBoolValue()
342 && (bus_power_node->getDoubleValue() > 1.0)
343 && nav_serviceable_node->getBoolValue() )
346 if (nav_slaved_to_gps_node->getBoolValue()) {
360 void FGNavRadio::clearOutputs()
362 inrange_node->setBoolValue( false );
363 cdi_deflection_node->setDoubleValue( 0.0 );
364 cdi_deflection_norm_node->setDoubleValue( 0.0 );
365 cdi_xtrack_error_node->setDoubleValue( 0.0 );
366 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
367 time_to_intercept->setDoubleValue( 0.0 );
368 gs_deflection_node->setDoubleValue( 0.0 );
369 gs_deflection_deg_node->setDoubleValue(0.0);
370 gs_deflection_norm_node->setDoubleValue(0.0);
371 gs_inrange_node->setBoolValue( false );
372 loc_node->setBoolValue( false );
373 has_gs_node->setBoolValue(false);
375 to_flag_node->setBoolValue( false );
376 from_flag_node->setBoolValue( false );
382 void FGNavRadio::updateReceiver(double dt)
384 // Do a nav station search only once a second to reduce
385 // unnecessary work. (Also, make sure to do this before caching
387 _time_before_search_sec -= dt;
388 if ( _time_before_search_sec < 0 ) {
393 _cdiDeflection = 0.0;
394 _cdiCrossTrackErrorM = 0.0;
395 _toFlag = _fromFlag = false;
396 _gsNeedleDeflection = 0.0;
397 _gsNeedleDeflectionNorm = 0.0;
398 inrange_node->setBoolValue(false);
402 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
403 lat_node->getDoubleValue(),
404 alt_node->getDoubleValue());
406 double nav_elev = _navaid->get_elev_ft();
407 SGVec3d aircraft = SGVec3d::fromGeod(pos);
408 double loc_dist = dist(aircraft, _navaid->cart());
409 loc_dist_node->setDoubleValue( loc_dist );
410 bool is_loc = loc_node->getBoolValue();
411 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
414 //////////////////////////////////////////////////////////
415 // compute forward and reverse wgs84 headings to localizer
416 //////////////////////////////////////////////////////////
418 SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s);
419 heading_node->setDoubleValue(hdg);
420 double radial = az2 - twist;
421 double recip = radial + 180.0;
422 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
423 radial_node->setDoubleValue( radial );
424 recip_radial_node->setDoubleValue( recip );
426 //////////////////////////////////////////////////////////
427 // compute the target/selected radial in "true" heading
428 //////////////////////////////////////////////////////////
430 target_radial = sel_radial_node->getDoubleValue();
433 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
434 double trtrue = target_radial + twist;
435 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
436 target_radial_true_node->setDoubleValue( trtrue );
438 //////////////////////////////////////////////////////////
439 // adjust reception range for altitude
440 // FIXME: make sure we are using the navdata range now that
441 // it is valid in the data file
442 //////////////////////////////////////////////////////////
444 double offset = radial - target_radial;
445 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
447 = adjustILSRange( nav_elev, pos.getElevationM(), offset,
448 loc_dist * SG_METER_TO_NM );
451 = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() );
454 double effective_range_m = effective_range * SG_NM_TO_METER;
456 //////////////////////////////////////////////////////////
457 // compute signal quality
458 // 100% within effective_range
459 // decreases 1/x^2 further out
460 //////////////////////////////////////////////////////////
461 double last_signal_quality_norm = signal_quality_norm;
463 if ( loc_dist < effective_range_m ) {
464 signal_quality_norm = 1.0;
466 double range_exceed_norm = loc_dist/effective_range_m;
467 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
470 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
471 signal_quality_norm, dt );
473 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
474 bool inrange = signal_quality_norm > 0.2;
475 inrange_node->setBoolValue( inrange );
477 //////////////////////////////////////////////////////////
478 // compute to/from flag status
479 //////////////////////////////////////////////////////////
484 double offset = fabs(radial - target_radial);
485 _toFlag = (offset > 90.0 && offset < 270.0);
487 _fromFlag = !_toFlag;
489 _toFlag = _fromFlag = false;
493 double r = target_radial - radial;
494 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
497 if (falseCoursesEnabledNode->getBoolValue()) {
498 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
499 // zeros i.e. six courses: one front course, one back course, and four
500 // false courses. Three of the six are reverse sensing.
501 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
503 // no false courses, but we do need to create a back course
504 if (fabs(r) > 90.0) { // front course
505 _cdiDeflection = r - copysign(180.0, r);
507 _cdiDeflection = r; // back course
510 _cdiDeflection = -_cdiDeflection; // reverse for outbound radial
511 } // of false courses disabled
513 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
514 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
516 if (backcourse_node->getBoolValue()) {
517 _cdiDeflection = -_cdiDeflection;
520 // handle the TO side of the VOR
521 if (fabs(r) > 90.0) {
522 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
525 } // of non-localiser case
527 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
528 _cdiDeflection *= signal_quality_norm;
530 // cross-track error (in metres)
531 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
533 updateGlideSlope(dt, aircraft, signal_quality_norm);
536 last_loc_dist = loc_dist;
539 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
541 _gsNeedleDeflection = 0.0;
542 if (!_gs || !inrange_node->getBoolValue()) {
543 gs_dist_node->setDoubleValue( 0.0 );
544 gs_inrange_node->setBoolValue(false);
545 _gsNeedleDeflection = 0.0;
546 _gsNeedleDeflectionNorm = 0.0;
550 double gsDist = dist(aircraft, _gsCart);
551 gs_dist_node->setDoubleValue(gsDist);
552 bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
553 gs_inrange_node->setBoolValue(gsInRange);
556 _gsNeedleDeflection = 0.0;
557 _gsNeedleDeflectionNorm = 0.0;
561 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
562 // The positive GS axis points along the runway in the landing direction,
563 // toward the far end, not toward the approach area, so we need a - sign here:
564 double dot_h = -dot(pos, _gsAxis);
565 double dot_v = dot(pos, _gsVertical);
566 double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES;
567 double deflectionAngle = target_gs - angle;
569 if (falseCoursesEnabledNode->getBoolValue()) {
570 // Construct false glideslopes. The scale factor of 1.5
571 // in the sawtooth gives a period of 6 degrees.
572 // There will be zeros at 3, 6r, 9, 12r et cetera
573 // where "r" indicates reverse sensing.
574 // This is is consistent with conventional pilot lore
575 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
576 // but inconsistent with
577 // http://www.freepatentsonline.com/3757338.html
579 // It may be that some of each exist.
580 if (deflectionAngle < 0) {
581 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
583 // no false GS below the true GS
587 _gsNeedleDeflection = deflectionAngle * 5.0;
588 _gsNeedleDeflection *= signal_quality_norm;
590 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
591 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
593 //////////////////////////////////////////////////////////
594 // Calculate desired rate of climb for intercepting the GS
595 //////////////////////////////////////////////////////////
596 double gs_diff = target_gs - angle;
597 // convert desired vertical path angle into a climb rate
598 double des_angle = angle - 10 * gs_diff;
599 /* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
600 target_gs, angle, gs_diff, des_angle); */
602 // estimate horizontal speed towards ILS in meters per minute
603 double elapsedDistance = last_x - gsDist;
606 double new_vel = ( elapsedDistance / dt );
607 horiz_vel = 0.99 * horiz_vel + 0.01 * new_vel;
608 /* printf("vel=%.1f (dist=%.1f dt=%.2f)\n", horiz_vel, elapsedDistance, dt);*/
610 gs_rate_of_climb_node
611 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
612 * horiz_vel * SG_METER_TO_FEET );
613 gs_rate_of_climb_fpm_node
614 ->setDoubleValue( gs_rate_of_climb_node->getDoubleValue() * 60 );
617 void FGNavRadio::updateDME(const SGVec3d& aircraft)
619 if (!_dme || !dme_serviceable_node->getBoolValue()) {
624 double dme_distance = dist(aircraft, _dme->cart());
625 _dmeInRange = (dme_distance < _dme->get_range() * SG_NM_TO_METER);
628 void FGNavRadio::updateGPSSlaved()
630 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
632 _toFlag = gps_to_flag_node->getBoolValue();
633 _fromFlag = gps_from_flag_node->getBoolValue();
635 bool gpsValid = (_toFlag | _fromFlag);
636 inrange_node->setBoolValue(gpsValid);
638 signal_quality_norm_node->setDoubleValue(0.0);
639 _cdiDeflection = 0.0;
640 _cdiCrossTrackErrorM = 0.0;
641 _gsNeedleDeflection = 0.0;
645 // this is unfortunate, but panel instruments use this value to decide
646 // if the navradio output is valid.
647 signal_quality_norm_node->setDoubleValue(1.0);
649 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
650 // clmap to some range (+/- 10 degrees) as the regular deflection
651 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
653 _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER;
654 _gsNeedleDeflection = 0.0; // FIXME, supply this
656 double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue();
657 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
658 target_radial_true_node->setDoubleValue( trtrue );
661 void FGNavRadio::updateCDI(double dt)
663 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
664 bool inrange = inrange_node->getBoolValue();
666 if (tofrom_serviceable_node->getBoolValue()) {
667 to_flag_node->setBoolValue(_toFlag);
668 from_flag_node->setBoolValue(_fromFlag);
670 to_flag_node->setBoolValue(false);
671 from_flag_node->setBoolValue(false);
674 if (!cdi_serviceable) {
675 _cdiDeflection = 0.0;
676 _cdiCrossTrackErrorM = 0.0;
679 cdi_deflection_node->setDoubleValue(_cdiDeflection);
680 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
681 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
683 //////////////////////////////////////////////////////////
684 // compute an approximate ground track heading error
685 //////////////////////////////////////////////////////////
686 double hdg_error = 0.0;
687 if ( inrange && cdi_serviceable ) {
688 double vn = fgGetDouble( "/velocities/speed-north-fps" );
689 double ve = fgGetDouble( "/velocities/speed-east-fps" );
690 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
691 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
693 SGPropertyNode *true_hdg
694 = fgGetNode("/orientation/heading-deg", true);
695 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
697 // cout << "ground track = " << gnd_trk_true
698 // << " orientation = " << true_hdg->getDoubleValue() << endl;
700 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
702 //////////////////////////////////////////////////////////
703 // Calculate a suggested target heading to smoothly intercept
705 //////////////////////////////////////////////////////////
707 // Now that we have cross track heading adjustment built in,
708 // we shouldn't need to overdrive the heading angle within 8km
711 // The cdi deflection should be +/-10 for a full range of deflection
712 // so multiplying this by 3 gives us +/- 30 degrees heading
714 double adjustment = _cdiDeflection * 3.0;
715 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
717 // determine the target heading to fly to intercept the
718 // tgt_radial = target radial (true) + cdi offset adjustmest -
719 // xtrack heading error adjustment
721 double trtrue = target_radial_true_node->getDoubleValue();
722 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
723 // tuned to a localizer and backcourse mode activated
724 trtrue += 180.0; // reverse the target localizer heading
725 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
726 nta_hdg = trtrue - adjustment - hdg_error;
728 nta_hdg = trtrue + adjustment - hdg_error;
731 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
732 target_auto_hdg_node->setDoubleValue( nta_hdg );
734 //////////////////////////////////////////////////////////
735 // compute the time to intercept selected radial (based on
736 // current and last cross track errors and dt
737 //////////////////////////////////////////////////////////
739 if ( inrange && cdi_serviceable ) {
740 double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
741 xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate;
742 if ( fabs(xrate_ms) > 0.00001 ) {
743 t = _cdiCrossTrackErrorM / xrate_ms;
748 time_to_intercept->setDoubleValue( t );
750 if (!gs_serviceable_node->getBoolValue() ) {
751 _gsNeedleDeflection = 0.0;
752 _gsNeedleDeflectionNorm = 0.0;
754 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
755 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
756 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
758 last_xtrack_error = _cdiCrossTrackErrorM;
761 void FGNavRadio::updateAudio()
763 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
767 // play station ident via audio system if on + ident,
768 // otherwise turn it off
769 if (!power_btn_node->getBoolValue()
770 || !(bus_power_node->getDoubleValue() > 1.0)
771 || !ident_btn_node->getBoolValue()
772 || !audio_btn_node->getBoolValue() ) {
773 _sgr->stop( nav_fx_name );
774 _sgr->stop( dme_fx_name );
778 SGSoundSample *sound = _sgr->find( nav_fx_name );
779 double vol = vol_btn_node->getFloatValue();
780 SG_CLAMP_RANGE(vol, 0.0, 1.0);
782 if ( sound != NULL ) {
783 sound->set_volume( vol );
785 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" );
788 sound = _sgr->find( dme_fx_name );
789 if ( sound != NULL ) {
790 sound->set_volume( vol );
792 SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" );
795 const int NUM_IDENT_SLOTS = 5;
796 const time_t SLOT_LENGTH = 5; // seconds
798 // There are N slots numbered 0 through (NUM_IDENT_SLOTS-1) inclusive.
799 // Each slot is 5 seconds long.
800 // Slots 0 is for DME
801 // the rest are for azimuth.
802 time_t now = globals->get_time_params()->get_cur_time();
803 if ((now >= last_time) && (now < last_time + SLOT_LENGTH)) {
804 return; // wait longer
808 play_count = ++play_count % NUM_IDENT_SLOTS;
810 // Previous ident is out of time; if still playing, cut it off:
811 _sgr->stop( nav_fx_name );
812 _sgr->stop( dme_fx_name );
813 if (play_count == 0) { // the DME slot
814 if (_dmeInRange && dme_serviceable_node->getBoolValue()) {
816 if (vol > 0.05) _sgr->play_once( dme_fx_name );
819 if (inrange_node->getBoolValue() && nav_serviceable_node->getBoolValue()) {
820 if (vol > 0.05) _sgr->play_once(nav_fx_name);
825 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
827 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
832 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
835 // Update current nav/adf radio stations based on current postition
836 void FGNavRadio::search()
838 _time_before_search_sec = 1.0;
839 SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
840 lat_node->getDoubleValue(), alt_node->getDoubleValue());
841 double freq = freq_node->getDoubleValue();
843 FGNavRecord* nav = findPrimaryNavaid(pos, freq);
844 if (nav == _navaid) {
845 return; // found the same as last search, we're done
849 char identBuffer[5] = " ";
851 _dme = globals->get_dmelist()->findByFreq(freq, pos);
853 nav_id_node->setStringValue(nav->get_ident());
854 strncpy(identBuffer, nav->ident().c_str(), 5);
856 effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range());
857 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
858 twist = nav->get_multiuse();
860 if (nav->type() == FGPositioned::VOR) {
861 target_radial = sel_radial_node->getDoubleValue();
863 has_gs_node->setBoolValue(false);
864 } else { // ILS or LOC
865 _gs = globals->get_gslist()->findByFreq(freq, pos);
866 has_gs_node->setBoolValue(_gs != NULL);
867 _localizerWidth = localizerWidth(nav);
869 effective_range = nav->get_range();
871 target_radial = nav->get_multiuse();
872 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
875 int tmp = (int)(_gs->get_multiuse() / 1000.0);
876 target_gs = (double)tmp / 100.0;
878 // until penaltyForNav goes away, we cannot assume we always pick
879 // paired LOC/GS trasmsitters. As we pass over a runway threshold, we
880 // often end up picking the 'wrong' LOC, but the correct GS. To avoid
881 // breaking the basis computation, ensure we use the GS radial and not
882 // the (potentially reversed) LOC radial.
883 double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
884 SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
886 // GS axis unit tangent vector
887 // (along the runway)
888 _gsCart = _gs->cart();
889 _gsAxis = tangentVector(_gs->geod(), _gsCart, gs_radial);
891 // GS baseline unit tangent vector
892 // (perpendicular to the runay along the ground)
893 SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, gs_radial + 90.0);
894 _gsVertical = cross(baseline, _gsAxis);
895 } // of have glideslope
896 } // of found LOC or ILS
899 } else { // found nothing
902 nav_id_node->setStringValue("");
903 loc_node->setBoolValue(false);
904 has_gs_node->setBoolValue(false);
906 _sgr->remove( nav_fx_name );
907 _sgr->remove( dme_fx_name );
910 is_valid_node->setBoolValue(nav != NULL);
911 id_c1_node->setIntValue( (int)identBuffer[0] );
912 id_c2_node->setIntValue( (int)identBuffer[1] );
913 id_c3_node->setIntValue( (int)identBuffer[2] );
914 id_c4_node->setIntValue( (int)identBuffer[3] );
917 double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
919 FGRunway* rwy = aLOC->runway();
922 SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold()));
923 double axisLength = dist(aLOC->cart(), thresholdCart);
924 double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end()));
926 // Reference: http://dcaa.slv.dk:8000/icaodocs/
927 // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet.
928 // ICAO 3.1.1 half course = DDM = 0.0775
929 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold
930 // implies peg-to-peg of 214 m ... we will stick with 210.
931 // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees."
933 // Very short runway: less than 1200 m (4000 ft) landing length:
934 if (landingLength < 1200.0) {
935 // ICAO fudges localizer sensitivity for very short runways.
936 // This produces a non-monotonic sensitivity-versus length relation.
937 axisLength += 1050.0;
940 // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R
941 // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6
942 // Example: very long: Denver KDEN (Denver) ILS RWY 16R
943 double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES;
944 return raw_width < 6.0? raw_width : 6.0;
947 void FGNavRadio::audioNavidChanged()
949 if (_sgr->exists(nav_fx_name)) {
950 _sgr->remove(nav_fx_name);
954 string trans_ident(_navaid->get_trans_ident());
955 SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY);
956 sound->set_volume( 0.3 );
957 if (!_sgr->add( sound, nav_fx_name )) {
958 SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound");
961 if ( _sgr->exists( dme_fx_name ) ) {
962 _sgr->remove( dme_fx_name );
965 sound = morse.make_ident( trans_ident, HI_FREQUENCY );
966 sound->set_volume( 0.3 );
967 _sgr->add( sound, dme_fx_name );
969 int offset = (int)(sg_random() * 30.0);
970 play_count = offset / 4;
971 last_time = globals->get_time_params()->get_cur_time() - offset;
972 } catch (sg_io_exception& e) {
973 SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage());