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.
26 #include "navradio.hxx"
31 #include <simgear/sg_inlines.h>
32 #include <simgear/timing/sg_time.hxx>
33 #include <simgear/math/sg_random.h>
34 #include <simgear/misc/sg_path.hxx>
35 #include <simgear/math/sg_geodesy.hxx>
36 #include <simgear/structure/exception.hxx>
37 #include <simgear/math/interpolater.hxx>
38 #include <simgear/misc/strutils.hxx>
40 #include <Navaids/navrecord.hxx>
41 #include <Sound/audioident.hxx>
42 #include <Airports/runways.hxx>
43 #include <Navaids/navlist.hxx>
44 #include <Main/util.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);
100 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 SGPath path( globals->get_fg_root() );
132 term.append( "Navaids/range.term" );
134 low.append( "Navaids/range.low" );
136 high.append( "Navaids/range.high" );
138 term_tbl = new SGInterpTable( term.str() );
139 low_tbl = new SGInterpTable( low.str() );
140 high_tbl = new SGInterpTable( high.str() );
142 string branch("/instrumentation/" + _name);
143 _radio_node = fgGetNode(branch.c_str(), _num, true);
148 FGNavRadio::~FGNavRadio()
150 if (gps_course_node) {
151 gps_course_node->removeChangeListener(this);
154 if (nav_slaved_to_gps_node) {
155 nav_slaved_to_gps_node->removeChangeListener(this);
169 SGPropertyNode* node = _radio_node.get();
171 fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
174 is_valid_node = node->getChild("data-is-valid", 0, true);
175 power_btn_node = node->getChild("power-btn", 0, true);
176 power_btn_node->setBoolValue( true );
177 vol_btn_node = node->getChild("volume", 0, true);
178 ident_btn_node = node->getChild("ident", 0, true);
179 ident_btn_node->setBoolValue( true );
180 audio_btn_node = node->getChild("audio-btn", 0, true);
181 audio_btn_node->setBoolValue( true );
182 backcourse_node = node->getChild("back-course-btn", 0, true);
183 backcourse_node->setBoolValue( false );
185 nav_serviceable_node = node->getChild("serviceable", 0, true);
186 cdi_serviceable_node = createServiceableProp(node, "cdi");
187 gs_serviceable_node = createServiceableProp(node, "gs");
188 tofrom_serviceable_node = createServiceableProp(node, "to-from");
190 falseCoursesEnabledNode =
191 fgGetNode("/sim/realism/false-radio-courses-enabled");
192 if (!falseCoursesEnabledNode) {
193 falseCoursesEnabledNode =
194 fgGetNode("/sim/realism/false-radio-courses-enabled", true);
195 falseCoursesEnabledNode->setBoolValue(true);
199 SGPropertyNode *subnode = node->getChild("frequencies", 0, true);
200 freq_node = subnode->getChild("selected-mhz", 0, true);
201 alt_freq_node = subnode->getChild("standby-mhz", 0, true);
202 fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true);
203 fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true);
204 is_loc_freq_node = subnode->getChild("is-localizer-frequency", 0, true );
207 subnode = node->getChild("radials", 0, true);
208 sel_radial_node = subnode->getChild("selected-deg", 0, true);
209 radial_node = subnode->getChild("actual-deg", 0, true);
210 recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true);
211 target_radial_true_node = subnode->getChild("target-radial-deg", 0, true);
212 target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true);
215 heading_node = node->getChild("heading-deg", 0, true);
216 time_to_intercept = node->getChild("time-to-intercept-sec", 0, true);
217 to_flag_node = node->getChild("to-flag", 0, true);
218 from_flag_node = node->getChild("from-flag", 0, true);
219 inrange_node = node->getChild("in-range", 0, true);
220 signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true);
221 cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true);
222 cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true);
223 cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true);
224 cdi_xtrack_hdg_err_node
225 = node->getChild("crosstrack-heading-error-deg", 0, true);
226 has_gs_node = node->getChild("has-gs", 0, true);
227 loc_node = node->getChild("nav-loc", 0, true);
228 loc_dist_node = node->getChild("nav-distance", 0, true);
229 gs_deflection_node = node->getChild("gs-needle-deflection", 0, true);
230 gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true);
231 gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true);
232 gs_direct_node = node->getChild("gs-direct-deg", 0, true);
233 gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
234 gs_rate_of_climb_fpm_node = node->getChild("gs-rate-of-climb-fpm", 0, true);
235 gs_dist_node = node->getChild("gs-distance", 0, true);
236 gs_inrange_node = node->getChild("gs-in-range", 0, true);
238 nav_id_node = node->getChild("nav-id", 0, true);
239 id_c1_node = node->getChild("nav-id_asc1", 0, true);
240 id_c2_node = node->getChild("nav-id_asc2", 0, true);
241 id_c3_node = node->getChild("nav-id_asc3", 0, true);
242 id_c4_node = node->getChild("nav-id_asc4", 0, true);
244 // gps slaving support
245 nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
246 nav_slaved_to_gps_node->addChangeListener(this);
248 gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
249 gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true);
250 gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true);
251 gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true);
252 gps_course_node = fgGetNode("/instrumentation/gps/desired-course-deg", true);
253 gps_course_node->addChangeListener(this);
255 gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true);
256 _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true);
258 std::ostringstream temp;
259 temp << _name << "-ident-" << _num;
260 if( NULL == _audioIdent )
261 _audioIdent = new VORAudioIdent( temp.str() );
264 // dme-in-range is deprecated,
265 // temporarily create dme-in-range alias for instrumentation/dme[0]/in-range
266 // remove after flightgear 2.6.0
267 node->getNode( "dme-in-range", true )->alias( fgGetNode("/instrumentation/dme[0]/in-range", true ) );
273 _radio_node->tie( "operable", SGRawValueMethods<FGNavRadio,bool>( *this, &FGNavRadio::isOperable ) );
278 FGNavRadio::unbind ()
280 _radio_node->untie("operable");
284 // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8
285 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev,
286 double nominalRange )
288 if (nominalRange <= 0.0) {
289 nominalRange = FG_NAV_DEFAULT_RANGE;
292 // extend out actual usable range to be 1.3x the published safe range
293 const double usability_factor = 1.3;
295 // assumptions we model the standard service volume, plus
296 // ... rather than specifying a cylinder, we model a cone that
297 // contains the cylinder. Then we put an upside down cone on top
298 // to model diminishing returns at too-high altitudes.
300 // altitude difference
301 double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
302 // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET
303 // << " station elev = " << stationElev << endl;
305 if ( nominalRange < 25.0 + SG_EPSILON ) {
306 // Standard Terminal Service Volume
307 return term_tbl->interpolate( alt ) * usability_factor;
308 } else if ( nominalRange < 50.0 + SG_EPSILON ) {
309 // Standard Low Altitude Service Volume
310 // table is based on range of 40, scale to actual range
311 return low_tbl->interpolate( alt ) * nominalRange / 40.0
314 // Standard High Altitude Service Volume
315 // table is based on range of 130, scale to actual range
316 return high_tbl->interpolate( alt ) * nominalRange / 130.0
322 // model standard ILS service volumes as per AIM 1-1-9
323 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev,
324 double offsetDegrees, double distance )
326 // assumptions we model the standard service volume, plus
328 // altitude difference
329 // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev );
330 // double offset = fabs( offsetDegrees );
332 // if ( offset < 10 ) {
333 // return FG_ILS_DEFAULT_RANGE;
334 // } else if ( offset < 35 ) {
335 // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
336 // } else if ( offset < 45 ) {
337 // return (45 - offset);
338 // } else if ( offset > 170 ) {
339 // return FG_ILS_DEFAULT_RANGE;
340 // } else if ( offset > 145 ) {
341 // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25;
342 // } else if ( offset > 135 ) {
343 // return (offset - 135);
347 return FG_LOC_DEFAULT_RANGE;
350 // Frequencies with odd 100kHz numbers in the range from 108.00 - 111.95
351 // are LOC/GS (ILS) frequency pairs
352 // (108.00, 108.05, 108.20, 108.25.. =VOR)
353 // (108.10, 108.15, 108.30, 108.35.. =ILS)
354 static inline bool IsLocalizerFrequency( double f )
356 if( f < 108.0 || f >= 112.00 ) return false;
357 return (((SGMiscd::roundToInt(f * 100.0) % 100)/10) % 2) != 0;
361 //////////////////////////////////////////////////////////////////////////
362 // Update the various nav values based on position and valid tuned in navs
363 //////////////////////////////////////////////////////////////////////////
365 FGNavRadio::update(double dt)
371 // Create "formatted" versions of the nav frequencies for
372 // instrument displays.
374 sprintf( tmp, "%.2f", freq_node->getDoubleValue() );
375 fmt_freq_node->setStringValue(tmp);
376 sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() );
377 fmt_alt_freq_node->setStringValue(tmp);
378 is_loc_freq_node->setBoolValue( IsLocalizerFrequency( freq_node->getDoubleValue() ));
380 if (power_btn_node->getBoolValue()
381 && (bus_power_node->getDoubleValue() > 1.0)
382 && nav_serviceable_node->getBoolValue() )
394 void FGNavRadio::clearOutputs()
396 inrange_node->setBoolValue( false );
397 signal_quality_norm_node->setDoubleValue( 0.0 );
398 cdi_deflection_node->setDoubleValue( 0.0 );
399 cdi_deflection_norm_node->setDoubleValue( 0.0 );
400 cdi_xtrack_error_node->setDoubleValue( 0.0 );
401 cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 );
402 time_to_intercept->setDoubleValue( 0.0 );
403 heading_node->setDoubleValue(0.0);
404 gs_deflection_node->setDoubleValue( 0.0 );
405 gs_deflection_deg_node->setDoubleValue(0.0);
406 gs_deflection_norm_node->setDoubleValue(0.0);
407 gs_direct_node->setDoubleValue(0.0);
408 gs_inrange_node->setBoolValue( false );
409 loc_node->setBoolValue( false );
410 has_gs_node->setBoolValue(false);
412 to_flag_node->setBoolValue( false );
413 from_flag_node->setBoolValue( false );
414 is_valid_node->setBoolValue(false);
415 nav_id_node->setStringValue("");
421 void FGNavRadio::updateReceiver(double dt)
423 SGVec3d aircraft = SGVec3d::fromGeod(globals->get_aircraft_position());
426 // Do a nav station search only once a second to reduce
427 // unnecessary work. (Also, make sure to do this before caching
429 _time_before_search_sec -= dt;
430 if ( _time_before_search_sec < 0 ) {
436 loc_dist = dist(aircraft, _navaid->cart());
437 loc_dist_node->setDoubleValue( loc_dist );
440 if (nav_slaved_to_gps_node->getBoolValue()) {
441 // when slaved to GPS: only allow stuff above: tune NAV station
442 // All other data driven by GPS only.
448 _cdiDeflection = 0.0;
449 _cdiCrossTrackErrorM = 0.0;
450 _toFlag = _fromFlag = false;
451 _gsNeedleDeflection = 0.0;
452 _gsNeedleDeflectionNorm = 0.0;
453 heading_node->setDoubleValue(0.0);
454 inrange_node->setBoolValue(false);
455 signal_quality_norm_node->setDoubleValue(0.0);
459 double nav_elev = _navaid->get_elev_ft();
461 bool is_loc = loc_node->getBoolValue();
462 double signal_quality_norm = signal_quality_norm_node->getDoubleValue();
465 //////////////////////////////////////////////////////////
466 // compute forward and reverse wgs84 headings to localizer
467 //////////////////////////////////////////////////////////
469 SGGeodesy::inverse(globals->get_aircraft_position(), _navaid->geod(), hdg, az2, s);
470 heading_node->setDoubleValue(hdg);
471 double radial = az2 - twist;
472 double recip = radial + 180.0;
473 SG_NORMALIZE_RANGE(recip, 0.0, 360.0);
474 radial_node->setDoubleValue( radial );
475 recip_radial_node->setDoubleValue( recip );
477 //////////////////////////////////////////////////////////
478 // compute the target/selected radial in "true" heading
479 //////////////////////////////////////////////////////////
481 target_radial = sel_radial_node->getDoubleValue();
484 // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0
485 double trtrue = target_radial + twist;
486 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
487 target_radial_true_node->setDoubleValue( trtrue );
489 //////////////////////////////////////////////////////////
490 // adjust reception range for altitude
491 // FIXME: make sure we are using the navdata range now that
492 // it is valid in the data file
493 //////////////////////////////////////////////////////////
495 double offset = radial - target_radial;
496 SG_NORMALIZE_RANGE(offset, -180.0, 180.0);
498 = adjustILSRange( nav_elev, globals->get_aircraft_position().getElevationM(), offset,
499 loc_dist * SG_METER_TO_NM );
502 = adjustNavRange( nav_elev, globals->get_aircraft_position().getElevationM(), _navaid->get_range() );
505 double effective_range_m = effective_range * SG_NM_TO_METER;
507 //////////////////////////////////////////////////////////
508 // compute signal quality
509 // 100% within effective_range
510 // decreases 1/x^2 further out
511 //////////////////////////////////////////////////////////
512 double last_signal_quality_norm = signal_quality_norm;
514 if ( loc_dist < effective_range_m ) {
515 signal_quality_norm = 1.0;
517 double range_exceed_norm = loc_dist/effective_range_m;
518 signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm);
521 signal_quality_norm = fgGetLowPass( last_signal_quality_norm,
522 signal_quality_norm, dt );
524 signal_quality_norm_node->setDoubleValue( signal_quality_norm );
525 bool inrange = signal_quality_norm > 0.2;
526 inrange_node->setBoolValue( inrange );
528 //////////////////////////////////////////////////////////
529 // compute to/from flag status
530 //////////////////////////////////////////////////////////
535 double offset = fabs(radial - target_radial);
536 _toFlag = (offset > 90.0 && offset < 270.0);
538 _fromFlag = !_toFlag;
540 _toFlag = _fromFlag = false;
544 double r = target_radial - radial;
545 SG_NORMALIZE_RANGE(r, -180.0, 180.0);
548 if (falseCoursesEnabledNode->getBoolValue()) {
549 // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six
550 // zeros i.e. six courses: one front course, one back course, and four
551 // false courses. Three of the six are reverse sensing.
552 _cdiDeflection = 30.0 * sawtooth(r / 30.0);
554 // no false courses, but we do need to create a back course
555 if (fabs(r) > 90.0) { // front course
556 _cdiDeflection = r - copysign(180.0, r);
558 _cdiDeflection = r; // back course
561 _cdiDeflection = -_cdiDeflection; // reverse for outbound radial
562 } // of false courses disabled
564 const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing
565 _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity
567 if (backcourse_node->getBoolValue()) {
568 _cdiDeflection = -_cdiDeflection;
571 // handle the TO side of the VOR
572 if (fabs(r) > 90.0) {
573 r = ( r<0.0 ? -r-180.0 : -r+180.0 );
576 } // of non-localiser case
578 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
579 _cdiDeflection *= signal_quality_norm;
581 // cross-track error (in metres)
582 _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS);
584 updateGlideSlope(dt, aircraft, signal_quality_norm);
587 void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm)
589 _gsNeedleDeflection = 0.0;
590 if (!_gs || !inrange_node->getBoolValue()) {
591 gs_dist_node->setDoubleValue( 0.0 );
592 gs_inrange_node->setBoolValue(false);
593 _gsNeedleDeflection = 0.0;
594 _gsNeedleDeflectionNorm = 0.0;
598 double gsDist = dist(aircraft, _gsCart);
599 gs_dist_node->setDoubleValue(gsDist);
600 bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
601 gs_inrange_node->setBoolValue(gsInRange);
603 if (!gsInRange) return;
605 SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft
606 // The positive GS axis points along the runway in the landing direction,
607 // toward the far end, not toward the approach area, so we need a - sign here:
608 double comp_h = -dot(pos, _gsAxis); // component in horiz direction
609 double comp_v = dot(pos, _gsVertical); // component in vertical direction
610 //double comp_b = dot(pos, _gsBaseline); // component in baseline direction
611 //if (comp_b) {} // ... (useful for debugging)
613 // _gsDirect represents the angle of elevation of the aircraft
614 // as seen by the GS transmitter.
615 _gsDirect = atan2(comp_v, comp_h) * SGD_RADIANS_TO_DEGREES;
616 // At this point, if the aircraft is centered on the glide slope,
617 // _gsDirect will be a small positive number, e.g. 3.0 degrees
619 // Aim the branch cut straight down
620 // into the ground below the GS transmitter:
621 if (_gsDirect < -90.0) _gsDirect += 360.0;
623 double deflectionAngle = target_gs - _gsDirect;
625 if (falseCoursesEnabledNode->getBoolValue()) {
626 // Construct false glideslopes. The scale factor of 1.5
627 // in the sawtooth gives a period of 6 degrees.
628 // There will be zeros at 3, 6r, 9, 12r et cetera
629 // where "r" indicates reverse sensing.
630 // This is is consistent with conventional pilot lore
631 // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm
632 // but inconsistent with
633 // http://www.freepatentsonline.com/3757338.html
635 // It may be that some of each exist.
636 if (deflectionAngle < 0) {
637 deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5);
639 // no false GS below the true GS
643 // GS is documented to be 1.4 degrees thick,
644 // i.e. plus or minus 0.7 degrees from the midline:
645 SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
647 // Many older instrument xml frontends depend on
648 // the un-normalized gs-needle-deflection.
649 // Apparently the interface standard is plus or minus 3.5 "volts"
650 // for a full-scale deflection:
651 _gsNeedleDeflection = deflectionAngle * 5.0;
652 _gsNeedleDeflection *= signal_quality_norm;
654 _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
656 //////////////////////////////////////////////////////////
657 // Calculate desired rate of climb for intercepting the GS
658 //////////////////////////////////////////////////////////
659 double gs_diff = target_gs - _gsDirect;
660 // convert desired vertical path angle into a climb rate
661 double des_angle = _gsDirect - 10 * gs_diff;
662 /* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
663 target_gs, _gsDirect, gs_diff, des_angle); */
665 // estimate horizontal speed towards ILS in meters per minute
666 double elapsedDistance = last_x - gsDist;
669 double new_vel = ( elapsedDistance / dt );
670 horiz_vel = 0.99 * horiz_vel + 0.01 * new_vel;
671 /* printf("vel=%.1f (dist=%.1f dt=%.2f)\n", horiz_vel, elapsedDistance, dt);*/
673 gs_rate_of_climb_node
674 ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
675 * horiz_vel * SG_METER_TO_FEET );
676 gs_rate_of_climb_fpm_node
677 ->setDoubleValue( gs_rate_of_climb_node->getDoubleValue() * 60 );
680 void FGNavRadio::valueChanged (SGPropertyNode* prop)
682 if (prop == gps_course_node) {
683 if (!nav_slaved_to_gps_node->getBoolValue()) {
687 // GPS desired course has changed, sync up our selected-course
688 double v = prop->getDoubleValue();
689 if (v != sel_radial_node->getDoubleValue()) {
690 sel_radial_node->setDoubleValue(v);
692 } else if (prop == nav_slaved_to_gps_node) {
693 if (prop->getBoolValue()) {
694 // slaved-to-GPS activated, clear obsolete NAV outputs and sync up selected course
696 sel_radial_node->setDoubleValue(gps_course_node->getDoubleValue());
698 // slave-to-GPS enabled/disabled, resync NAV station (update all outputs)
700 _time_before_search_sec = 0;
704 void FGNavRadio::updateGPSSlaved()
706 has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue());
708 _toFlag = gps_to_flag_node->getBoolValue();
709 _fromFlag = gps_from_flag_node->getBoolValue();
711 bool gpsValid = (_toFlag | _fromFlag);
712 inrange_node->setBoolValue(gpsValid);
714 signal_quality_norm_node->setDoubleValue(0.0);
715 _cdiDeflection = 0.0;
716 _cdiCrossTrackErrorM = 0.0;
717 _gsNeedleDeflection = 0.0;
718 _gsNeedleDeflectionNorm = 0.0;
722 // this is unfortunate, but panel instruments use this value to decide
723 // if the navradio output is valid.
724 signal_quality_norm_node->setDoubleValue(1.0);
726 _cdiDeflection = gps_cdi_deflection_node->getDoubleValue();
727 // clmap to some range (+/- 10 degrees) as the regular deflection
728 SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 );
730 _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER;
731 _gsNeedleDeflection = 0.0; // FIXME, supply this
733 double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue();
734 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
735 target_radial_true_node->setDoubleValue( trtrue );
738 void FGNavRadio::updateCDI(double dt)
740 bool cdi_serviceable = cdi_serviceable_node->getBoolValue();
741 bool inrange = inrange_node->getBoolValue();
743 if (tofrom_serviceable_node->getBoolValue()) {
744 to_flag_node->setBoolValue(_toFlag);
745 from_flag_node->setBoolValue(_fromFlag);
747 to_flag_node->setBoolValue(false);
748 from_flag_node->setBoolValue(false);
751 if (!cdi_serviceable) {
752 _cdiDeflection = 0.0;
753 _cdiCrossTrackErrorM = 0.0;
756 cdi_deflection_node->setDoubleValue(_cdiDeflection);
757 cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1);
758 cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM);
760 //////////////////////////////////////////////////////////
761 // compute an approximate ground track heading error
762 //////////////////////////////////////////////////////////
763 double hdg_error = 0.0;
764 if ( inrange && cdi_serviceable ) {
765 double vn = fgGetDouble( "/velocities/speed-north-fps" );
766 double ve = fgGetDouble( "/velocities/speed-east-fps" );
767 double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
768 if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; }
770 SGPropertyNode *true_hdg
771 = fgGetNode("/orientation/heading-deg", true);
772 hdg_error = gnd_trk_true - true_hdg->getDoubleValue();
774 // cout << "ground track = " << gnd_trk_true
775 // << " orientation = " << true_hdg->getDoubleValue() << endl;
777 cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error );
779 //////////////////////////////////////////////////////////
780 // Calculate a suggested target heading to smoothly intercept
782 //////////////////////////////////////////////////////////
784 // Now that we have cross track heading adjustment built in,
785 // we shouldn't need to overdrive the heading angle within 8km
788 // The cdi deflection should be +/-10 for a full range of deflection
789 // so multiplying this by 3 gives us +/- 30 degrees heading
791 double adjustment = _cdiDeflection * 3.0;
792 SG_CLAMP_RANGE( adjustment, -30.0, 30.0 );
794 // determine the target heading to fly to intercept the
795 // tgt_radial = target radial (true) + cdi offset adjustmest -
796 // xtrack heading error adjustment
798 double trtrue = target_radial_true_node->getDoubleValue();
799 if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) {
800 // tuned to a localizer and backcourse mode activated
801 trtrue += 180.0; // reverse the target localizer heading
802 SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0);
803 nta_hdg = trtrue - adjustment - hdg_error;
805 nta_hdg = trtrue + adjustment - hdg_error;
808 SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0);
809 target_auto_hdg_node->setDoubleValue( nta_hdg );
811 //////////////////////////////////////////////////////////
812 // compute the time to intercept selected radial (based on
813 // current and last cross track errors and dt)
814 //////////////////////////////////////////////////////////
816 if ( inrange && cdi_serviceable ) {
817 double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt;
818 xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate;
819 if ( fabs(xrate_ms) > 0.00001 ) {
820 t = _cdiCrossTrackErrorM / xrate_ms;
825 time_to_intercept->setDoubleValue( t );
827 if (!gs_serviceable_node->getBoolValue() ) {
828 _gsNeedleDeflection = 0.0;
829 _gsNeedleDeflectionNorm = 0.0;
831 gs_deflection_node->setDoubleValue(_gsNeedleDeflection);
832 gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7);
833 gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm);
834 gs_direct_node->setDoubleValue(_gsDirect);
836 last_xtrack_error = _cdiCrossTrackErrorM;
839 void FGNavRadio::updateAudio( double dt )
841 if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) {
842 _audioIdent->setIdent("", 0.0 );
846 // play station ident via audio system if on + ident,
847 // otherwise turn it off
848 if (!power_btn_node->getBoolValue()
849 || !(bus_power_node->getDoubleValue() > 1.0)
850 || !ident_btn_node->getBoolValue()
851 || !audio_btn_node->getBoolValue() ) {
852 _audioIdent->setIdent("", 0.0 );
856 _audioIdent->setIdent( _navaid->get_trans_ident(), vol_btn_node->getFloatValue() );
858 _audioIdent->update( dt );
861 FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz)
863 FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos);
868 return globals->get_loclist()->findByFreq(aFreqMHz, aPos);
871 // Update current nav/adf radio stations based on current postition
872 void FGNavRadio::search()
874 _time_before_search_sec = 1.0;
875 double freq = freq_node->getDoubleValue();
877 FGNavRecord* nav = findPrimaryNavaid(globals->get_aircraft_position(), freq);
878 if (nav == _navaid) {
879 return; // found the same as last search, we're done
883 string identBuffer(4, ' ');
885 nav_id_node->setStringValue(nav->get_ident());
886 identBuffer = simgear::strutils::rpad( nav->ident(), 4, ' ' );
888 effective_range = adjustNavRange(nav->get_elev_ft(), globals->get_aircraft_position().getElevationM(), nav->get_range());
889 loc_node->setBoolValue(nav->type() != FGPositioned::VOR);
890 twist = nav->get_multiuse();
892 if (nav->type() == FGPositioned::VOR) {
893 target_radial = sel_radial_node->getDoubleValue();
895 has_gs_node->setBoolValue(false);
896 } else { // ILS or LOC
897 _gs = globals->get_gslist()->findByFreq(freq, globals->get_aircraft_position());
898 has_gs_node->setBoolValue(_gs != NULL);
899 _localizerWidth = nav->localizerWidth();
901 effective_range = nav->get_range();
903 target_radial = nav->get_multiuse();
904 SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0);
907 int tmp = (int)(_gs->get_multiuse() / 1000.0);
908 target_gs = (double)tmp / 100.0;
910 double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
911 SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
912 _gsCart = _gs->cart();
914 // GS axis unit tangent vector
915 // (along the runway):
916 _gsAxis = tangentVector(_gs->geod(), gs_radial);
918 // GS baseline unit tangent vector
919 // (transverse to the runay along the ground)
920 _gsBaseline = tangentVector(_gs->geod(), gs_radial + 90.0);
921 _gsVertical = cross(_gsBaseline, _gsAxis);
922 } // of have glideslope
923 } // of found LOC or ILS
925 } else { // found nothing
927 nav_id_node->setStringValue("");
928 loc_node->setBoolValue(false);
929 has_gs_node->setBoolValue(false);
930 _audioIdent->setIdent("", 0.0 );
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] );