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.
29 #include <simgear/sg_inlines.h>
30 #include <simgear/timing/sg_time.hxx>
31 #include <simgear/math/sg_random.h>
32 #include <simgear/misc/sg_path.hxx>
33 #include <simgear/math/sg_geodesy.hxx>
34 #include <simgear/structure/exception.hxx>
35 #include <simgear/math/interpolater.hxx>
36 #include <simgear/misc/strutils.hxx>
38 #include <Navaids/navrecord.hxx>
39 #include <Sound/audioident.hxx>
40 #include <Airports/runways.hxx>
41 #include <Navaids/navlist.hxx>
42 #include <Main/util.hxx>
44 #include "navradio.hxx"
48 // General-purpose sawtooth function. Graph looks like this:
51 // Odd symmetry, inversion symmetry about the origin.
52 // Unit slope at the origin.
53 // Max 1, min -1, period 4.
54 // Two zero-crossings per period, one with + slope, one with - slope.
55 // Useful for false localizer courses.
56 static double sawtooth(double xx)
58 return 4.0 * fabs(xx/4.0 + 0.25 - floor(xx/4.0 + 0.75)) - 1.0;
61 // Calculate a Cartesian unit vector in the
62 // local horizontal plane, i.e. tangent to the
63 // surface of the earth at the local ground zero.
64 // The tangent vector passes through the given <midpoint>
65 // and points forward along the given <heading>.
66 // The <heading> is given in degrees.
67 static SGVec3d tangentVector(const SGGeod& midpoint, const double heading)
69 // The size of the delta is presumably chosen to give
70 // numerical stability. I don't know how the value was chosen.
71 // It probably doesn't matter much. It gets divided out.
72 double delta(100.0); // in meters
74 double az2; // ignored
75 SGGeodesy::direct(midpoint, heading, delta, head, az2);
76 SGGeodesy::direct(midpoint, 180+heading, delta, tail, az2);
77 head.setElevationM(midpoint.getElevationM());
78 tail.setElevationM(midpoint.getElevationM());
79 SGVec3d head_xyz = SGVec3d::fromGeod(head);
80 SGVec3d tail_xyz = SGVec3d::fromGeod(tail);
81 // Awkward formula here, needed because vector-by-scalar
82 // multiplication is defined, but not vector-by-scalar division.
83 return (head_xyz - tail_xyz) * (0.5/delta);
86 // Create a "serviceable" node with a default value of "true"
87 SGPropertyNode_ptr createServiceableProp(SGPropertyNode* aParent,
90 SGPropertyNode_ptr n =
91 aParent->getChild(aName, 0, true)->getChild("serviceable", 0, true);
92 simgear::props::Type typ = n->getType();
93 if ((typ == simgear::props::NONE) || (typ == simgear::props::UNSPECIFIED)) {
94 n->setBoolValue(true);
99 static std::auto_ptr<SGInterpTable> static_terminalRangeInterp,
100 static_lowRangeInterp, static_highRangeInterp;
103 FGNavRadio::FGNavRadio(SGPropertyNode *node) :
108 effective_range(0.0),
113 last_xtrack_error(0.0),
115 _localizerWidth(5.0),
116 _name(node->getStringValue("name", "nav")),
117 _num(node->getIntValue("number", 0)),
118 _time_before_search_sec(-1.0),
119 _gsCart(SGVec3d::zeros()),
120 _gsAxis(SGVec3d::zeros()),
121 _gsVertical(SGVec3d::zeros()),
125 _cdiCrossTrackErrorM(0.0),
126 _gsNeedleDeflection(0.0),
127 _gsNeedleDeflectionNorm(0.0),
130 if (!static_terminalRangeInterp.get()) {
131 // one-time interpolator init
132 SGPath path( globals->get_fg_root() );
134 term.append( "Navaids/range.term" );
136 low.append( "Navaids/range.low" );
138 high.append( "Navaids/range.high" );
140 static_terminalRangeInterp.reset(new SGInterpTable(term.str()));
141 static_lowRangeInterp.reset(new SGInterpTable(low.str()));
142 static_highRangeInterp.reset(new SGInterpTable(high.str()));
145 string branch("/instrumentation/" + _name);
146 _radio_node = fgGetNode(branch.c_str(), _num, true);
151 FGNavRadio::~FGNavRadio()
153 if (gps_course_node) {
154 gps_course_node->removeChangeListener(this);
157 if (nav_slaved_to_gps_node) {
158 nav_slaved_to_gps_node->removeChangeListener(this);
168 SGPropertyNode* node = _radio_node.get();
170 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
173 is_valid_node = node->getChild("data-is-valid", 0, true);
174 power_btn_node = node->getChild("power-btn", 0, true);
175 power_btn_node->setBoolValue( true );
176 vol_btn_node = node->getChild("volume", 0, true);
177 ident_btn_node = node->getChild("ident", 0, true);
178 ident_btn_node->setBoolValue( true );
179 audio_btn_node = node->getChild("audio-btn", 0, true);
180 audio_btn_node->setBoolValue( true );
181 backcourse_node = node->getChild("back-course-btn", 0, true);
182 backcourse_node->setBoolValue( false );
184 nav_serviceable_node = node->getChild("serviceable", 0, true);
185 cdi_serviceable_node = createServiceableProp(node, "cdi");
186 gs_serviceable_node = createServiceableProp(node, "gs");
187 tofrom_serviceable_node = createServiceableProp(node, "to-from");
189 falseCoursesEnabledNode =
190 fgGetNode("/sim/realism/false-radio-courses-enabled");
191 if (!falseCoursesEnabledNode) {
192 falseCoursesEnabledNode =
193 fgGetNode("/sim/realism/false-radio-courses-enabled", true);
194 falseCoursesEnabledNode->setBoolValue(true);
198 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
199 freq_node = subnode->getChild("selected-mhz", 0, true);
200 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
201 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
202 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
203 is_loc_freq_node = subnode->getChild("is-localizer-frequency", 0, true );
206 subnode = node->getChild("radials", 0, true);
207 sel_radial_node = subnode->getChild("selected-deg", 0, true);
208 radial_node = subnode->getChild("actual-deg", 0, true);
209 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
210 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
211 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
214 heading_node = node->getChild("heading-deg", 0, true);
215 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
216 to_flag_node = node->getChild("to-flag", 0, true);
217 from_flag_node = node->getChild("from-flag", 0, true);
218 inrange_node = node->getChild("in-range", 0, true);
219 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
220 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
221 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
222 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
223 cdi_xtrack_hdg_err_node
224 = node->getChild("crosstrack-heading-error-deg", 0, true);
225 has_gs_node = node->getChild("has-gs", 0, true);
226 loc_node = node->getChild("nav-loc", 0, true);
227 loc_dist_node = node->getChild("nav-distance", 0, true);
228 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
229 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
230 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
231 gs_direct_node = node->getChild("gs-direct-deg", 0, true);
232 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
233 gs_rate_of_climb_fpm_node = node->getChild("gs-rate-of-climb-fpm", 0, true);
234 gs_dist_node = node->getChild("gs-distance", 0, true);
235 gs_inrange_node = node->getChild("gs-in-range", 0, true);
237 nav_id_node = node->getChild("nav-id", 0, true);
238 id_c1_node = node->getChild("nav-id_asc1", 0, true);
239 id_c2_node = node->getChild("nav-id_asc2", 0, true);
240 id_c3_node = node->getChild("nav-id_asc3", 0, true);
241 id_c4_node = node->getChild("nav-id_asc4", 0, true);
243 // gps slaving support
244 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
245 nav_slaved_to_gps_node->addChangeListener(this);
247 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
248 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
249 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
250 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
251 gps_course_node = fgGetNode("/instrumentation/gps/desired-course-deg", true);
252 gps_course_node->addChangeListener(this);
254 gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true);
255 _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true);
257 std::ostringstream temp;
258 temp << _name << "-ident-" << _num;
259 if( NULL == _audioIdent )
260 _audioIdent = new VORAudioIdent( temp.str() );
263 // dme-in-range is deprecated,
264 // temporarily create dme-in-range alias for instrumentation/dme[0]/in-range
265 // remove after flightgear 2.6.0
266 node->getNode( "dme-in-range", true )->alias( fgGetNode("/instrumentation/dme[0]/in-range", true ) );
270 FGNavRadio::reinit ()
272 _time_before_search_sec = -1.0;
278 _radio_node->tie( "operable", SGRawValueMethods<FGNavRadio,bool>( *this, &FGNavRadio::isOperable ) );
283 FGNavRadio::unbind ()
285 _radio_node->untie("operable");
289 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
290 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
291 double nominalRange )
293 if (nominalRange <= 0.0) {
294 nominalRange = FG_NAV_DEFAULT_RANGE;
297 // extend out actual usable range to be 1.3x the published safe range
298 const double usability_factor = 1.3;
300 // assumptions we model the standard service volume, plus
301 // ... rather than specifying a cylinder, we model a cone that
302 // contains the cylinder. Then we put an upside down cone on top
303 // to model diminishing returns at too-high altitudes.
305 // altitude difference
306 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
307 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
308 // << " station elev = " << stationElev << endl;
310 if ( nominalRange < 25.0 + SG_EPSILON ) {
311 // Standard Terminal Service Volume
312 return static_terminalRangeInterp->interpolate( alt ) * usability_factor;
313 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
314 // Standard Low Altitude Service Volume
315 // table is based on range of 40, scale to actual range
316 return static_lowRangeInterp->interpolate( alt ) * nominalRange / 40.0
319 // Standard High Altitude Service Volume
320 // table is based on range of 130, scale to actual range
321 return static_highRangeInterp->interpolate( alt ) * nominalRange / 130.0
327 // model standard ILS service volumes as per AIM 1-1-9
328 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
329 double offsetDegrees, double distance )
331 // assumptions we model the standard service volume, plus
333 // altitude difference
334 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
335 // double offset = fabs( offsetDegrees );
337 // if ( offset < 10 ) {
338 // return FG_ILS_DEFAULT_RANGE;
339 // } else if ( offset < 35 ) {
340 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
341 // } else if ( offset < 45 ) {
342 // return (45 - offset);
343 // } else if ( offset > 170 ) {
344 // return FG_ILS_DEFAULT_RANGE;
345 // } else if ( offset > 145 ) {
346 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
347 // } else if ( offset > 135 ) {
348 // return (offset - 135);
352 return FG_LOC_DEFAULT_RANGE;
355 // Frequencies with odd 100kHz numbers in the range from 108.00 - 111.95
356 // are LOC/GS (ILS) frequency pairs
357 // (108.00, 108.05, 108.20, 108.25.. =VOR)
358 // (108.10, 108.15, 108.30, 108.35.. =ILS)
359 static inline bool IsLocalizerFrequency( double f )
361 if( f < 108.0 || f >= 112.00 ) return false;
362 return (((SGMiscd::roundToInt(f * 100.0) % 100)/10) % 2) != 0;
366 //////////////////////////////////////////////////////////////////////////
367 // Update the various nav values based on position and valid tuned in navs
368 //////////////////////////////////////////////////////////////////////////
370 FGNavRadio::update(double dt)
376 // Create "formatted" versions of the nav frequencies for
377 // instrument displays.
379 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
380 fmt_freq_node->setStringValue(tmp);
381 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
382 fmt_alt_freq_node->setStringValue(tmp);
383 is_loc_freq_node->setBoolValue( IsLocalizerFrequency( freq_node->getDoubleValue() ));
385 if (power_btn_node->getBoolValue()
386 && (bus_power_node->getDoubleValue() > 1.0)
387 && nav_serviceable_node->getBoolValue() )
399 void FGNavRadio::clearOutputs()
401 inrange_node->setBoolValue( false );
402 signal_quality_norm_node->setDoubleValue( 0.0 );
403 cdi_deflection_node->setDoubleValue( 0.0 );
404 cdi_deflection_norm_node->setDoubleValue( 0.0 );
405 cdi_xtrack_error_node->setDoubleValue( 0.0 );
406 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
407 time_to_intercept->setDoubleValue( 0.0 );
408 heading_node->setDoubleValue(0.0);
409 gs_deflection_node->setDoubleValue( 0.0 );
410 gs_deflection_deg_node->setDoubleValue(0.0);
411 gs_deflection_norm_node->setDoubleValue(0.0);
412 gs_direct_node->setDoubleValue(0.0);
413 gs_inrange_node->setBoolValue( false );
414 loc_node->setBoolValue( false );
415 has_gs_node->setBoolValue(false);
417 to_flag_node->setBoolValue( false );
418 from_flag_node->setBoolValue( false );
419 is_valid_node->setBoolValue(false);
420 nav_id_node->setStringValue("");
426 void FGNavRadio::updateReceiver(double dt)
428 SGVec3d aircraft = SGVec3d::fromGeod(globals->get_aircraft_position());
431 // Do a nav station search only once a second to reduce
432 // unnecessary work. (Also, make sure to do this before caching
434 _time_before_search_sec -= dt;
435 if ( _time_before_search_sec < 0 ) {
441 loc_dist = dist(aircraft, _navaid->cart());
442 loc_dist_node->setDoubleValue( loc_dist );
445 if (nav_slaved_to_gps_node->getBoolValue()) {
446 // when slaved to GPS: only allow stuff above: tune NAV station
447 // All other data driven by GPS only.
453 _cdiDeflection = 0.0;
454 _cdiCrossTrackErrorM = 0.0;
455 _toFlag = _fromFlag = false;
456 _gsNeedleDeflection = 0.0;
457 _gsNeedleDeflectionNorm = 0.0;
458 heading_node->setDoubleValue(0.0);
459 inrange_node->setBoolValue(false);
460 signal_quality_norm_node->setDoubleValue(0.0);
461 gs_dist_node->setDoubleValue( 0.0 );
462 gs_inrange_node->setBoolValue(false);
466 double nav_elev = _navaid->get_elev_ft();
468 bool is_loc = loc_node->getBoolValue();
469 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
472 //////////////////////////////////////////////////////////
473 // compute forward and reverse wgs84 headings to localizer
474 //////////////////////////////////////////////////////////
476 SGGeodesy::inverse(globals->get_aircraft_position(), _navaid->geod(), hdg, az2, s);
477 heading_node->setDoubleValue(hdg);
478 double radial = az2 - twist;
479 double recip = radial + 180.0;
480 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
481 radial_node->setDoubleValue( radial );
482 recip_radial_node->setDoubleValue( recip );
484 //////////////////////////////////////////////////////////
485 // compute the target/selected radial in "true" heading
486 //////////////////////////////////////////////////////////
488 target_radial = sel_radial_node->getDoubleValue();
491 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
492 double trtrue = target_radial + twist;
493 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
494 target_radial_true_node->setDoubleValue( trtrue );
496 //////////////////////////////////////////////////////////
497 // adjust reception range for altitude
498 // FIXME: make sure we are using the navdata range now that
499 // it is valid in the data file
500 //////////////////////////////////////////////////////////
502 double offset = radial - target_radial;
503 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
505 = adjustILSRange( nav_elev, globals->get_aircraft_position().getElevationM(), offset,
506 loc_dist * SG_METER_TO_NM );
509 = adjustNavRange( nav_elev, globals->get_aircraft_position().getElevationM(), _navaid->get_range() );
512 double effective_range_m = effective_range * SG_NM_TO_METER;
514 //////////////////////////////////////////////////////////
515 // compute signal quality
516 // 100% within effective_range
517 // decreases 1/x^2 further out
518 //////////////////////////////////////////////////////////
519 double last_signal_quality_norm = signal_quality_norm;
521 if ( loc_dist < effective_range_m ) {
522 signal_quality_norm = 1.0;
524 double range_exceed_norm = loc_dist/effective_range_m;
525 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
528 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
529 signal_quality_norm, dt );
531 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
532 bool inrange = signal_quality_norm > 0.2;
533 inrange_node->setBoolValue( inrange );
535 //////////////////////////////////////////////////////////
536 // compute to/from flag status
537 //////////////////////////////////////////////////////////
542 double offset = fabs(radial - target_radial);
543 _toFlag = (offset > 90.0 && offset < 270.0);
545 _fromFlag = !_toFlag;
547 _toFlag = _fromFlag = false;
551 double r = target_radial - radial;
552 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
555 if (falseCoursesEnabledNode->getBoolValue()) {
556 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
557 // zeros i.e. six courses: one front course, one back course, and four
558 // false courses. Three of the six are reverse sensing.
559 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
561 // no false courses, but we do need to create a back course
562 if (fabs(r) > 90.0) { // front course
563 _cdiDeflection = r - copysign(180.0, r);
565 _cdiDeflection = r; // back course
568 _cdiDeflection = -_cdiDeflection; // reverse for outbound radial
569 } // of false courses disabled
571 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
572 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
574 if (backcourse_node->getBoolValue()) {
575 _cdiDeflection = -_cdiDeflection;
578 // handle the TO side of the VOR
579 if (fabs(r) > 90.0) {
580 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
583 } // of non-localiser case
585 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
586 _cdiDeflection *= signal_quality_norm;
588 // cross-track error (in meters)
589 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
591 updateGlideSlope(dt, aircraft, signal_quality_norm);
594 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
596 bool gsInRange = (_gs && inrange_node->getBoolValue());
601 gsDist = dist(aircraft, _gsCart);
602 gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
605 gs_inrange_node->setBoolValue(gsInRange);
606 gs_dist_node->setDoubleValue( gsDist );
610 _gsNeedleDeflection = 0.0;
611 _gsNeedleDeflectionNorm = 0.0;
615 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
616 // The positive GS axis points along the runway in the landing direction,
617 // toward the far end, not toward the approach area, so we need a - sign here:
618 double comp_h = -dot(pos, _gsAxis); // component in horiz direction
619 double comp_v = dot(pos, _gsVertical); // component in vertical direction
620 //double comp_b = dot(pos, _gsBaseline); // component in baseline direction
621 //if (comp_b) {} // ... (useful for debugging)
623 // _gsDirect represents the angle of elevation of the aircraft
624 // as seen by the GS transmitter.
625 _gsDirect = atan2(comp_v, comp_h) * SGD_RADIANS_TO_DEGREES;
626 // At this point, if the aircraft is centered on the glide slope,
627 // _gsDirect will be a small positive number, e.g. 3.0 degrees
629 // Aim the branch cut straight down
630 // into the ground below the GS transmitter:
631 if (_gsDirect < -90.0) _gsDirect += 360.0;
633 double deflectionAngle = target_gs - _gsDirect;
635 if (falseCoursesEnabledNode->getBoolValue()) {
636 // Construct false glideslopes. The scale factor of 1.5
637 // in the sawtooth gives a period of 6 degrees.
638 // There will be zeros at 3, 6r, 9, 12r et cetera
639 // where "r" indicates reverse sensing.
640 // This is is consistent with conventional pilot lore
641 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
642 // but inconsistent with
643 // http://www.freepatentsonline.com/3757338.html
645 // It may be that some of each exist.
646 if (deflectionAngle < 0) {
647 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
649 // no false GS below the true GS
653 // GS is documented to be 1.4 degrees thick,
654 // i.e. plus or minus 0.7 degrees from the midline:
655 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
657 // Many older instrument xml frontends depend on
658 // the un-normalized gs-needle-deflection.
659 // Apparently the interface standard is plus or minus 3.5 "volts"
660 // for a full-scale deflection:
661 _gsNeedleDeflection = deflectionAngle * 5.0;
662 _gsNeedleDeflection *= signal_quality_norm;
664 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
666 //////////////////////////////////////////////////////////
667 // Calculate desired rate of climb for intercepting the GS
668 //////////////////////////////////////////////////////////
669 double gs_diff = target_gs - _gsDirect;
670 // convert desired vertical path angle into a climb rate
671 double des_angle = _gsDirect - 10 * gs_diff;
672 /* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
673 target_gs, _gsDirect, gs_diff, des_angle); */
675 // estimate horizontal speed towards ILS in meters per minute
676 double elapsedDistance = last_x - gsDist;
679 double new_vel = ( elapsedDistance / dt );
680 horiz_vel = 0.99 * horiz_vel + 0.01 * new_vel;
681 /* printf("vel=%.1f (dist=%.1f dt=%.2f)\n", horiz_vel, elapsedDistance, dt);*/
683 gs_rate_of_climb_node
684 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
685 * horiz_vel * SG_METER_TO_FEET );
686 gs_rate_of_climb_fpm_node
687 ->setDoubleValue( gs_rate_of_climb_node->getDoubleValue() * 60 );
690 void FGNavRadio::valueChanged (SGPropertyNode* prop)
692 if (prop == gps_course_node) {
693 if (!nav_slaved_to_gps_node->getBoolValue()) {
697 // GPS desired course has changed, sync up our selected-course
698 double v = prop->getDoubleValue();
699 if (v != sel_radial_node->getDoubleValue()) {
700 sel_radial_node->setDoubleValue(v);
702 } else if (prop == nav_slaved_to_gps_node) {
703 if (prop->getBoolValue()) {
704 // slaved-to-GPS activated, clear obsolete NAV outputs and sync up selected course
706 sel_radial_node->setDoubleValue(gps_course_node->getDoubleValue());
708 // slave-to-GPS enabled/disabled, resync NAV station (update all outputs)
710 _time_before_search_sec = 0;
714 void FGNavRadio::updateGPSSlaved()
716 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
718 _toFlag = gps_to_flag_node->getBoolValue();
719 _fromFlag = gps_from_flag_node->getBoolValue();
721 bool gpsValid = (_toFlag | _fromFlag);
722 inrange_node->setBoolValue(gpsValid);
724 signal_quality_norm_node->setDoubleValue(0.0);
725 _cdiDeflection = 0.0;
726 _cdiCrossTrackErrorM = 0.0;
727 _gsNeedleDeflection = 0.0;
728 _gsNeedleDeflectionNorm = 0.0;
732 // this is unfortunate, but panel instruments use this value to decide
733 // if the navradio output is valid.
734 signal_quality_norm_node->setDoubleValue(1.0);
736 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
737 // clmap to some range (+/- 10 degrees) as the regular deflection
738 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
740 _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER;
741 _gsNeedleDeflection = 0.0; // FIXME, supply this
743 double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue();
744 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
745 target_radial_true_node->setDoubleValue( trtrue );
748 void FGNavRadio::updateCDI(double dt)
750 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
751 bool inrange = inrange_node->getBoolValue();
753 if (tofrom_serviceable_node->getBoolValue()) {
754 to_flag_node->setBoolValue(_toFlag);
755 from_flag_node->setBoolValue(_fromFlag);
757 to_flag_node->setBoolValue(false);
758 from_flag_node->setBoolValue(false);
761 if (!cdi_serviceable) {
762 _cdiDeflection = 0.0;
763 _cdiCrossTrackErrorM = 0.0;
766 cdi_deflection_node->setDoubleValue(_cdiDeflection);
767 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
768 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
770 //////////////////////////////////////////////////////////
771 // compute an approximate ground track heading error
772 //////////////////////////////////////////////////////////
773 double hdg_error = 0.0;
774 if ( inrange && cdi_serviceable ) {
775 double vn = fgGetDouble( "/velocities/speed-north-fps" );
776 double ve = fgGetDouble( "/velocities/speed-east-fps" );
777 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
778 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
780 SGPropertyNode *true_hdg
781 = fgGetNode("/orientation/heading-deg", true);
782 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
784 // cout << "ground track = " << gnd_trk_true
785 // << " orientation = " << true_hdg->getDoubleValue() << endl;
787 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
789 //////////////////////////////////////////////////////////
790 // Calculate a suggested target heading to smoothly intercept
792 //////////////////////////////////////////////////////////
794 // Now that we have cross track heading adjustment built in,
795 // we shouldn't need to overdrive the heading angle within 8km
798 // The cdi deflection should be +/-10 for a full range of deflection
799 // so multiplying this by 3 gives us +/- 30 degrees heading
801 double adjustment = _cdiDeflection * 3.0;
802 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
804 // determine the target heading to fly to intercept the
805 // tgt_radial = target radial (true) + cdi offset adjustment -
806 // xtrack heading error adjustment
808 double trtrue = target_radial_true_node->getDoubleValue();
809 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
810 // tuned to a localizer and backcourse mode activated
811 trtrue += 180.0; // reverse the target localizer heading
812 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
813 nta_hdg = trtrue - adjustment - hdg_error;
815 nta_hdg = trtrue + adjustment - hdg_error;
818 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
819 target_auto_hdg_node->setDoubleValue( nta_hdg );
821 //////////////////////////////////////////////////////////
822 // compute the time to intercept selected radial (based on
823 // current and last cross track errors and dt)
824 //////////////////////////////////////////////////////////
826 if ( inrange && cdi_serviceable ) {
827 double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
828 xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate;
829 if ( fabs(xrate_ms) > 0.00001 ) {
830 t = _cdiCrossTrackErrorM / xrate_ms;
835 time_to_intercept->setDoubleValue( t );
837 if (!gs_serviceable_node->getBoolValue() ) {
838 _gsNeedleDeflection = 0.0;
839 _gsNeedleDeflectionNorm = 0.0;
841 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
842 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
843 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
844 gs_direct_node->setDoubleValue(_gsDirect);
846 last_xtrack_error = _cdiCrossTrackErrorM;
849 void FGNavRadio::updateAudio( double dt )
851 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
852 _audioIdent->setIdent("", 0.0 );
856 // play station ident via audio system if on + ident,
857 // otherwise turn it off
858 if (!power_btn_node->getBoolValue()
859 || !(bus_power_node->getDoubleValue() > 1.0)
860 || !ident_btn_node->getBoolValue()
861 || !audio_btn_node->getBoolValue() ) {
862 _audioIdent->setIdent("", 0.0 );
866 _audioIdent->setIdent( _navaid->get_trans_ident(), vol_btn_node->getFloatValue() );
868 _audioIdent->update( dt );
871 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
873 return FGNavList::findByFreq(aFreqMHz, aPos, FGNavList::navFilter());
876 // Update current nav/adf radio stations based on current position
877 void FGNavRadio::search()
879 // set delay for next search
880 _time_before_search_sec = 1.0;
882 double freq = freq_node->getDoubleValue();
884 // immediate NAV search when frequency has changed (toggle between nav and g/s search otherwise)
885 _nav_search |= (_last_freq != freq);
887 // do we need to search a new NAV station in this iteration?
891 FGNavRecord* nav = findPrimaryNavaid(globals->get_aircraft_position(), freq);
892 if (nav == _navaid) {
893 if (nav && (nav->type() != FGPositioned::VOR))
894 _nav_search = false; // search glideslope on next iteration
895 return; // nav hasn't changed, we're done
897 // remember new navaid station
901 // search glideslope station
902 if ((_navaid.valid()) && (_navaid->type() != FGPositioned::VOR))
904 FGNavList::TypeFilter gsFilter(FGPositioned::GS);
905 FGNavRecord* gs = FGNavList::findByFreq(freq, globals->get_aircraft_position(),
907 if ((!_nav_search) && (gs == _gs))
909 _nav_search = true; // search NAV on next iteration
910 return; // g/s hasn't changed, neither has nav - we're done
912 // remember new glideslope station
916 _nav_search = true; // search NAV on next iteration
918 // nav or gs station has changed
922 // Update current nav/adf/glideslope outputs when station has changed
923 void FGNavRadio::updateNav()
925 // update necessary, nav and/or gs has changed
926 FGNavRecord* nav = _navaid;
927 string identBuffer(4, ' ');
929 nav_id_node->setStringValue(nav->get_ident());
930 identBuffer = simgear::strutils::rpad( nav->ident(), 4, ' ' );
932 effective_range = adjustNavRange(nav->get_elev_ft(), globals->get_aircraft_position().getElevationM(), nav->get_range());
933 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
934 twist = nav->get_multiuse();
936 if (nav->type() == FGPositioned::VOR) {
937 target_radial = sel_radial_node->getDoubleValue();
939 } else { // ILS or LOC
940 _localizerWidth = nav->localizerWidth();
942 effective_range = nav->get_range();
944 target_radial = nav->get_multiuse();
945 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
948 int tmp = (int)(_gs->get_multiuse() / 1000.0);
949 target_gs = (double)tmp / 100.0;
951 double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
952 SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
953 _gsCart = _gs->cart();
955 // GS axis unit tangent vector
956 // (along the runway):
957 _gsAxis = tangentVector(_gs->geod(), gs_radial);
959 // GS baseline unit tangent vector
960 // (transverse to the runway along the ground)
961 _gsBaseline = tangentVector(_gs->geod(), gs_radial + 90.0);
962 _gsVertical = cross(_gsBaseline, _gsAxis);
963 } // of have glideslope
964 } // of found LOC or ILS
966 } else { // found nothing
968 nav_id_node->setStringValue("");
969 loc_node->setBoolValue(false);
970 _audioIdent->setIdent("", 0.0 );
973 has_gs_node->setBoolValue(_gs != NULL);
974 is_valid_node->setBoolValue(nav != NULL);
975 id_c1_node->setIntValue( (int)identBuffer[0] );
976 id_c2_node->setIntValue( (int)identBuffer[1] );
977 id_c3_node->setIntValue( (int)identBuffer[2] );
978 id_c4_node->setIntValue( (int)identBuffer[3] );