using std::string; // General-purpose sawtooth function. Graph looks like this: // /\ . // \/ // Odd symmetry, inversion symmetry about the origin. // Unit slope at the origin. // Max 1, min -1, period 4. // Two zero-crossings per period, one with + slope, one with - slope. // Useful for false localizer courses. static double sawtooth(double xx) { return 4.0 * fabs(xx/4.0 + 0.25 - floor(xx/4.0 + 0.75)) - 1.0; } // Calculate a unit vector in the horizontal tangent plane // starting at the given "tail" of the vector and going off // with the given heading. static SGVec3d tangentVector(const SGGeod& tail, const SGVec3d& tail_xyz, const double heading) { // The fudge factor here is presumably intended to improve // numerical stability. I don't know if it is necessary. // It gets divided out later. double fudge(100.0); SGGeod head; double az2; // ignored SGGeodesy::direct(tail, heading, fudge, head, az2); head.setElevationM(tail.getElevationM()); SGVec3d head_xyz = SGVec3d::fromGeod(head); return (head_xyz - tail_xyz) * (1.0/fudge); } // Create a "serviceable" node with a default value of "true" SGPropertyNode_ptr createServiceableProp(SGPropertyNode* aParent, const char* aName) { SGPropertyNode_ptr n = (aParent->getChild(aName, 0, true)->getChild("serviceable", 0, true)); simgear::props::Type typ = n->getType(); if ((typ == simgear::props::NONE) || (typ == simgear::props::UNSPECIFIED)) { n->setBoolValue(true); } return n; } // Constructor FGNavRadio::FGNavRadio(SGPropertyNode *node) : lon_node(fgGetNode("/position/longitude-deg", true)), lat_node(fgGetNode("/position/latitude-deg", true)), alt_node(fgGetNode("/position/altitude-ft", true)), is_valid_node(NULL), power_btn_node(NULL), freq_node(NULL), alt_freq_node(NULL), sel_radial_node(NULL), vol_btn_node(NULL), ident_btn_node(NULL), audio_btn_node(NULL), backcourse_node(NULL), nav_serviceable_node(NULL), cdi_serviceable_node(NULL), gs_serviceable_node(NULL), tofrom_serviceable_node(NULL), dme_serviceable_node(NULL), fmt_freq_node(NULL), fmt_alt_freq_node(NULL), heading_node(NULL), radial_node(NULL), recip_radial_node(NULL), target_radial_true_node(NULL), target_auto_hdg_node(NULL), time_to_intercept(NULL), to_flag_node(NULL), from_flag_node(NULL), inrange_node(NULL), signal_quality_norm_node(NULL), cdi_deflection_node(NULL), cdi_deflection_norm_node(NULL), cdi_xtrack_error_node(NULL), cdi_xtrack_hdg_err_node(NULL), has_gs_node(NULL), loc_node(NULL), loc_dist_node(NULL), gs_deflection_node(NULL), gs_deflection_deg_node(NULL), gs_deflection_norm_node(NULL), gs_rate_of_climb_node(NULL), gs_dist_node(NULL), gs_inrange_node(NULL), nav_id_node(NULL), id_c1_node(NULL), id_c2_node(NULL), id_c3_node(NULL), id_c4_node(NULL), nav_slaved_to_gps_node(NULL), gps_cdi_deflection_node(NULL), gps_to_flag_node(NULL), gps_from_flag_node(NULL), gps_has_gs_node(NULL), gps_xtrack_error_nm_node(NULL), play_count(0), last_time(0), target_radial(0.0), horiz_vel(0.0), last_x(0.0), last_loc_dist(0.0), last_xtrack_error(0.0), xrate_ms(0.0), _localizerWidth(5.0), _name(node->getStringValue("name", "nav")), _num(node->getIntValue("number", 0)), _time_before_search_sec(-1.0), _sgr(NULL) { SGPath path( globals->get_fg_root() ); SGPath term = path; term.append( "Navaids/range.term" ); SGPath low = path; low.append( "Navaids/range.low" ); SGPath high = path; high.append( "Navaids/range.high" ); term_tbl = new SGInterpTable( term.str() ); low_tbl = new SGInterpTable( low.str() ); high_tbl = new SGInterpTable( high.str() ); } // Destructor FGNavRadio::~FGNavRadio() { delete term_tbl; delete low_tbl; delete high_tbl; } void FGNavRadio::init () { SGSoundMgr *smgr = globals->get_soundmgr(); _sgr = smgr->find("avionics", true); _sgr->tie_to_listener(); morse.init(); string branch; branch = "/instrumentation/" + _name; SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true ); bus_power_node = fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true); // inputs is_valid_node = node->getChild("data-is-valid", 0, true); power_btn_node = node->getChild("power-btn", 0, true); power_btn_node->setBoolValue( true ); vol_btn_node = node->getChild("volume", 0, true); ident_btn_node = node->getChild("ident", 0, true); ident_btn_node->setBoolValue( true ); audio_btn_node = node->getChild("audio-btn", 0, true); audio_btn_node->setBoolValue( true ); backcourse_node = node->getChild("back-course-btn", 0, true); backcourse_node->setBoolValue( false ); nav_serviceable_node = node->getChild("serviceable", 0, true); cdi_serviceable_node = createServiceableProp(node, "cdi"); gs_serviceable_node = createServiceableProp(node, "gs"); tofrom_serviceable_node = createServiceableProp(node, "to-from"); dme_serviceable_node = createServiceableProp(node, "dme"); falseCoursesEnabledNode = fgGetNode("/sim/realism/false-radio-courses-enabled"); if (!falseCoursesEnabledNode) { falseCoursesEnabledNode = fgGetNode("/sim/realism/false-radio-courses-enabled", true); falseCoursesEnabledNode->setBoolValue(true); } // frequencies SGPropertyNode *subnode = node->getChild("frequencies", 0, true); freq_node = subnode->getChild("selected-mhz", 0, true); alt_freq_node = subnode->getChild("standby-mhz", 0, true); fmt_freq_node = subnode->getChild("selected-mhz-fmt", 0, true); fmt_alt_freq_node = subnode->getChild("standby-mhz-fmt", 0, true); // radials subnode = node->getChild("radials", 0, true); sel_radial_node = subnode->getChild("selected-deg", 0, true); radial_node = subnode->getChild("actual-deg", 0, true); recip_radial_node = subnode->getChild("reciprocal-radial-deg", 0, true); target_radial_true_node = subnode->getChild("target-radial-deg", 0, true); target_auto_hdg_node = subnode->getChild("target-auto-hdg-deg", 0, true); // outputs heading_node = node->getChild("heading-deg", 0, true); time_to_intercept = node->getChild("time-to-intercept-sec", 0, true); to_flag_node = node->getChild("to-flag", 0, true); from_flag_node = node->getChild("from-flag", 0, true); inrange_node = node->getChild("in-range", 0, true); signal_quality_norm_node = node->getChild("signal-quality-norm", 0, true); cdi_deflection_node = node->getChild("heading-needle-deflection", 0, true); cdi_deflection_norm_node = node->getChild("heading-needle-deflection-norm", 0, true); cdi_xtrack_error_node = node->getChild("crosstrack-error-m", 0, true); cdi_xtrack_hdg_err_node = node->getChild("crosstrack-heading-error-deg", 0, true); has_gs_node = node->getChild("has-gs", 0, true); loc_node = node->getChild("nav-loc", 0, true); loc_dist_node = node->getChild("nav-distance", 0, true); gs_deflection_node = node->getChild("gs-needle-deflection", 0, true); gs_deflection_deg_node = node->getChild("gs-needle-deflection-deg", 0, true); gs_deflection_norm_node = node->getChild("gs-needle-deflection-norm", 0, true); gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true); gs_dist_node = node->getChild("gs-distance", 0, true); gs_inrange_node = node->getChild("gs-in-range", 0, true); nav_id_node = node->getChild("nav-id", 0, true); id_c1_node = node->getChild("nav-id_asc1", 0, true); id_c2_node = node->getChild("nav-id_asc2", 0, true); id_c3_node = node->getChild("nav-id_asc3", 0, true); id_c4_node = node->getChild("nav-id_asc4", 0, true); node->tie("dme-in-range", SGRawValuePointer(&_dmeInRange)); // gps slaving support nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true); gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true); gps_to_flag_node = fgGetNode("/instrumentation/gps/to-flag", true); gps_from_flag_node = fgGetNode("/instrumentation/gps/from-flag", true); gps_has_gs_node = fgGetNode("/instrumentation/gps/has-gs", true); gps_course_node = fgGetNode("/instrumentation/gps/selected-course-deg", true); gps_xtrack_error_nm_node = fgGetNode("/instrumentation/gps/wp/wp[1]/course-error-nm", true); _magvarNode = fgGetNode("/environment/magnetic-variation-deg", true); std::ostringstream temp; temp << _name << "nav-ident" << _num; nav_fx_name = temp.str(); temp << _name << "dme-ident" << _num; dme_fx_name = temp.str(); } void FGNavRadio::bind () { } void FGNavRadio::unbind () { } // model standard VOR/DME/TACAN service volumes as per AIM 1-1-8 double FGNavRadio::adjustNavRange( double stationElev, double aircraftElev, double nominalRange ) { if (nominalRange <= 0.0) { nominalRange = FG_NAV_DEFAULT_RANGE; } // extend out actual usable range to be 1.3x the published safe range const double usability_factor = 1.3; // assumptions we model the standard service volume, plus // ... rather than specifying a cylinder, we model a cone that // contains the cylinder. Then we put an upside down cone on top // to model diminishing returns at too-high altitudes. // altitude difference double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev ); // cout << "aircraft elev = " << aircraftElev * SG_METER_TO_FEET // << " station elev = " << stationElev << endl; if ( nominalRange < 25.0 + SG_EPSILON ) { // Standard Terminal Service Volume return term_tbl->interpolate( alt ) * usability_factor; } else if ( nominalRange < 50.0 + SG_EPSILON ) { // Standard Low Altitude Service Volume // table is based on range of 40, scale to actual range return low_tbl->interpolate( alt ) * nominalRange / 40.0 * usability_factor; } else { // Standard High Altitude Service Volume // table is based on range of 130, scale to actual range return high_tbl->interpolate( alt ) * nominalRange / 130.0 * usability_factor; } } // model standard ILS service volumes as per AIM 1-1-9 double FGNavRadio::adjustILSRange( double stationElev, double aircraftElev, double offsetDegrees, double distance ) { // assumptions we model the standard service volume, plus // altitude difference // double alt = ( aircraftElev * SG_METER_TO_FEET - stationElev ); // double offset = fabs( offsetDegrees ); // if ( offset < 10 ) { // return FG_ILS_DEFAULT_RANGE; // } else if ( offset < 35 ) { // return 10 + (35 - offset) * (FG_ILS_DEFAULT_RANGE - 10) / 25; // } else if ( offset < 45 ) { // return (45 - offset); // } else if ( offset > 170 ) { // return FG_ILS_DEFAULT_RANGE; // } else if ( offset > 145 ) { // return 10 + (offset - 145) * (FG_ILS_DEFAULT_RANGE - 10) / 25; // } else if ( offset > 135 ) { // return (offset - 135); // } else { // return 0; // } return FG_LOC_DEFAULT_RANGE; } ////////////////////////////////////////////////////////////////////////// // Update the various nav values based on position and valid tuned in navs ////////////////////////////////////////////////////////////////////////// void FGNavRadio::update(double dt) { if (dt <= 0.0) { return; // paused } // Create "formatted" versions of the nav frequencies for // instrument displays. char tmp[16]; sprintf( tmp, "%.2f", freq_node->getDoubleValue() ); fmt_freq_node->setStringValue(tmp); sprintf( tmp, "%.2f", alt_freq_node->getDoubleValue() ); fmt_alt_freq_node->setStringValue(tmp); if (power_btn_node->getBoolValue() && (bus_power_node->getDoubleValue() > 1.0) && nav_serviceable_node->getBoolValue() ) { if (nav_slaved_to_gps_node->getBoolValue()) { updateGPSSlaved(); } else { updateReceiver(dt); } updateCDI(dt); } else { clearOutputs(); } updateAudio(); } void FGNavRadio::clearOutputs() { inrange_node->setBoolValue( false ); cdi_deflection_node->setDoubleValue( 0.0 ); cdi_deflection_norm_node->setDoubleValue( 0.0 ); cdi_xtrack_error_node->setDoubleValue( 0.0 ); cdi_xtrack_hdg_err_node->setDoubleValue( 0.0 ); time_to_intercept->setDoubleValue( 0.0 ); gs_deflection_node->setDoubleValue( 0.0 ); gs_deflection_deg_node->setDoubleValue(0.0); gs_deflection_norm_node->setDoubleValue(0.0); gs_inrange_node->setBoolValue( false ); to_flag_node->setBoolValue( false ); from_flag_node->setBoolValue( false ); _dmeInRange = false; } void FGNavRadio::updateReceiver(double dt) { // Do a nav station search only once a second to reduce // unnecessary work. (Also, make sure to do this before caching // any values!) _time_before_search_sec -= dt; if ( _time_before_search_sec < 0 ) { search(); } if (!_navaid) { _cdiDeflection = 0.0; _cdiCrossTrackErrorM = 0.0; _toFlag = _fromFlag = false; _gsNeedleDeflection = 0.0; _gsNeedleDeflectionNorm = 0.0; inrange_node->setBoolValue(false); return; } SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(), lat_node->getDoubleValue(), alt_node->getDoubleValue()); double nav_elev = _navaid->get_elev_ft(); SGVec3d aircraft = SGVec3d::fromGeod(pos); double loc_dist = dist(aircraft, _navaid->cart()); loc_dist_node->setDoubleValue( loc_dist ); bool is_loc = loc_node->getBoolValue(); double signal_quality_norm = signal_quality_norm_node->getDoubleValue(); double az2, s; ////////////////////////////////////////////////////////// // compute forward and reverse wgs84 headings to localizer ////////////////////////////////////////////////////////// double hdg; SGGeodesy::inverse(pos, _navaid->geod(), hdg, az2, s); heading_node->setDoubleValue(hdg); double radial = az2 - twist; double recip = radial + 180.0; SG_NORMALIZE_RANGE(recip, 0.0, 360.0); radial_node->setDoubleValue( radial ); recip_radial_node->setDoubleValue( recip ); ////////////////////////////////////////////////////////// // compute the target/selected radial in "true" heading ////////////////////////////////////////////////////////// if (!is_loc) { target_radial = sel_radial_node->getDoubleValue(); } // VORs need twist (mag-var) added; ILS/LOCs don't but we set twist to 0.0 double trtrue = target_radial + twist; SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0); target_radial_true_node->setDoubleValue( trtrue ); ////////////////////////////////////////////////////////// // adjust reception range for altitude // FIXME: make sure we are using the navdata range now that // it is valid in the data file ////////////////////////////////////////////////////////// if ( is_loc ) { double offset = radial - target_radial; SG_NORMALIZE_RANGE(offset, -180.0, 180.0); effective_range = adjustILSRange( nav_elev, pos.getElevationM(), offset, loc_dist * SG_METER_TO_NM ); } else { effective_range = adjustNavRange( nav_elev, pos.getElevationM(), _navaid->get_range() ); } double effective_range_m = effective_range * SG_NM_TO_METER; ////////////////////////////////////////////////////////// // compute signal quality // 100% within effective_range // decreases 1/x^2 further out ////////////////////////////////////////////////////////// double last_signal_quality_norm = signal_quality_norm; if ( loc_dist < effective_range_m ) { signal_quality_norm = 1.0; } else { double range_exceed_norm = loc_dist/effective_range_m; signal_quality_norm = 1/(range_exceed_norm*range_exceed_norm); } signal_quality_norm = fgGetLowPass( last_signal_quality_norm, signal_quality_norm, dt ); signal_quality_norm_node->setDoubleValue( signal_quality_norm ); bool inrange = signal_quality_norm > 0.2; inrange_node->setBoolValue( inrange ); ////////////////////////////////////////////////////////// // compute to/from flag status ////////////////////////////////////////////////////////// if (inrange) { if (is_loc) { _toFlag = true; } else { double offset = fabs(radial - target_radial); _toFlag = (offset > 90.0 && offset < 270.0); } _fromFlag = !_toFlag; } else { _toFlag = _fromFlag = false; } // CDI deflection double r = target_radial - radial; SG_NORMALIZE_RANGE(r, -180.0, 180.0); if ( is_loc ) { if (falseCoursesEnabledNode->getBoolValue()) { // The factor of 30.0 gives a period of 120 which gives us 3 cycles and six // zeros i.e. six courses: one front course, one back course, and four // false courses. Three of the six are reverse sensing. _cdiDeflection = 30.0 * sawtooth(r / 30.0); } else { // no false courses, but we do need to create a back course if (fabs(r) > 90.0) { // front course _cdiDeflection = r - copysign(180.0, r); } else { _cdiDeflection = r; // back course } _cdiDeflection = -_cdiDeflection; // reverse for outbound radial } // of false courses disabled const double VOR_FULL_ARC = 20.0; // VOR is -10 .. 10 degree swing _cdiDeflection *= VOR_FULL_ARC / _localizerWidth; // increased localiser sensitivity if (backcourse_node->getBoolValue()) { _cdiDeflection = -_cdiDeflection; } } else { // handle the TO side of the VOR if (fabs(r) > 90.0) { r = ( r<0.0 ? -r-180.0 : -r+180.0 ); } _cdiDeflection = r; } // of non-localiser case SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 ); _cdiDeflection *= signal_quality_norm; // cross-track error (in metres) _cdiCrossTrackErrorM = loc_dist * sin(r * SGD_DEGREES_TO_RADIANS); updateGlideSlope(dt, aircraft, signal_quality_norm); updateDME(aircraft); last_loc_dist = loc_dist; } void FGNavRadio::updateGlideSlope(double dt, const SGVec3d& aircraft, double signal_quality_norm) { _gsNeedleDeflection = 0.0; if (!_gs || !inrange_node->getBoolValue()) { gs_dist_node->setDoubleValue( 0.0 ); gs_inrange_node->setBoolValue(false); _gsNeedleDeflection = 0.0; _gsNeedleDeflectionNorm = 0.0; return; } double gsDist = dist(aircraft, _gsCart); gs_dist_node->setDoubleValue(gsDist); bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER)); gs_inrange_node->setBoolValue(gsInRange); if (!gsInRange) { _gsNeedleDeflection = 0.0; _gsNeedleDeflectionNorm = 0.0; return; } SGVec3d pos = aircraft - _gsCart; // relative vector from gs antenna to aircraft // The positive GS axis points along the runway in the landing direction, // toward the far end, not toward the approach area, so we need a - sign here: double dot_h = -dot(pos, _gsAxis); double dot_v = dot(pos, _gsVertical); double angle = atan2(dot_v, dot_h) * SGD_RADIANS_TO_DEGREES; double deflectionAngle = target_gs - angle; if (falseCoursesEnabledNode->getBoolValue()) { // Construct false glideslopes. The scale factor of 1.5 // in the sawtooth gives a period of 6 degrees. // There will be zeros at 3, 6r, 9, 12r et cetera // where "r" indicates reverse sensing. // This is is consistent with conventional pilot lore // e.g. http://www.allstar.fiu.edu/aerojava/ILS.htm // but inconsistent with // http://www.freepatentsonline.com/3757338.html // // It may be that some of each exist. if (deflectionAngle < 0) { deflectionAngle = 1.5 * sawtooth(deflectionAngle / 1.5); } else { // no false GS below the true GS } } _gsNeedleDeflection = deflectionAngle * 5.0; _gsNeedleDeflection *= signal_quality_norm; SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7); _gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm; ////////////////////////////////////////////////////////// // Calculate desired rate of climb for intercepting the GS ////////////////////////////////////////////////////////// double gs_diff = target_gs - angle; // convert desired vertical path angle into a climb rate double des_angle = angle - 10 * gs_diff; // estimate horizontal speed towards ILS in meters per minute double elapsedDistance = last_x - gsDist; last_x = gsDist; double new_vel = ( elapsedDistance / dt ); horiz_vel = 0.75 * horiz_vel + 0.25 * new_vel; gs_rate_of_climb_node ->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS ) * horiz_vel * SG_METER_TO_FEET ); } void FGNavRadio::updateDME(const SGVec3d& aircraft) { if (!_dme || !dme_serviceable_node->getBoolValue()) { _dmeInRange = false; return; } double dme_distance = dist(aircraft, _dme->cart()); _dmeInRange = (dme_distance < _dme->get_range() * SG_NM_TO_METER); } void FGNavRadio::updateGPSSlaved() { has_gs_node->setBoolValue(gps_has_gs_node->getBoolValue()); _toFlag = gps_to_flag_node->getBoolValue(); _fromFlag = gps_from_flag_node->getBoolValue(); bool gpsValid = (_toFlag | _fromFlag); inrange_node->setBoolValue(gpsValid); if (!gpsValid) { signal_quality_norm_node->setDoubleValue(0.0); _cdiDeflection = 0.0; _cdiCrossTrackErrorM = 0.0; _gsNeedleDeflection = 0.0; return; } // this is unfortunate, but panel instruments use this value to decide // if the navradio output is valid. signal_quality_norm_node->setDoubleValue(1.0); _cdiDeflection = gps_cdi_deflection_node->getDoubleValue(); // clmap to some range (+/- 10 degrees) as the regular deflection SG_CLAMP_RANGE(_cdiDeflection, -10.0, 10.0 ); _cdiCrossTrackErrorM = gps_xtrack_error_nm_node->getDoubleValue() * SG_NM_TO_METER; _gsNeedleDeflection = 0.0; // FIXME, supply this double trtrue = gps_course_node->getDoubleValue() + _magvarNode->getDoubleValue(); SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0); target_radial_true_node->setDoubleValue( trtrue ); } void FGNavRadio::updateCDI(double dt) { bool cdi_serviceable = cdi_serviceable_node->getBoolValue(); bool inrange = inrange_node->getBoolValue(); if (tofrom_serviceable_node->getBoolValue()) { to_flag_node->setBoolValue(_toFlag); from_flag_node->setBoolValue(_fromFlag); } else { to_flag_node->setBoolValue(false); from_flag_node->setBoolValue(false); } if (!cdi_serviceable) { _cdiDeflection = 0.0; _cdiCrossTrackErrorM = 0.0; } cdi_deflection_node->setDoubleValue(_cdiDeflection); cdi_deflection_norm_node->setDoubleValue(_cdiDeflection * 0.1); cdi_xtrack_error_node->setDoubleValue(_cdiCrossTrackErrorM); ////////////////////////////////////////////////////////// // compute an approximate ground track heading error ////////////////////////////////////////////////////////// double hdg_error = 0.0; if ( inrange && cdi_serviceable ) { double vn = fgGetDouble( "/velocities/speed-north-fps" ); double ve = fgGetDouble( "/velocities/speed-east-fps" ); double gnd_trk_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES; if ( gnd_trk_true < 0.0 ) { gnd_trk_true += 360.0; } SGPropertyNode *true_hdg = fgGetNode("/orientation/heading-deg", true); hdg_error = gnd_trk_true - true_hdg->getDoubleValue(); // cout << "ground track = " << gnd_trk_true // << " orientation = " << true_hdg->getDoubleValue() << endl; } cdi_xtrack_hdg_err_node->setDoubleValue( hdg_error ); ////////////////////////////////////////////////////////// // Calculate a suggested target heading to smoothly intercept // a nav/ils radial. ////////////////////////////////////////////////////////// // Now that we have cross track heading adjustment built in, // we shouldn't need to overdrive the heading angle within 8km // of the station. // // The cdi deflection should be +/-10 for a full range of deflection // so multiplying this by 3 gives us +/- 30 degrees heading // compensation. double adjustment = _cdiDeflection * 3.0; SG_CLAMP_RANGE( adjustment, -30.0, 30.0 ); // determine the target heading to fly to intercept the // tgt_radial = target radial (true) + cdi offset adjustmest - // xtrack heading error adjustment double nta_hdg; double trtrue = target_radial_true_node->getDoubleValue(); if ( loc_node->getBoolValue() && backcourse_node->getBoolValue() ) { // tuned to a localizer and backcourse mode activated trtrue += 180.0; // reverse the target localizer heading SG_NORMALIZE_RANGE(trtrue, 0.0, 360.0); nta_hdg = trtrue - adjustment - hdg_error; } else { nta_hdg = trtrue + adjustment - hdg_error; } SG_NORMALIZE_RANGE(nta_hdg, 0.0, 360.0); target_auto_hdg_node->setDoubleValue( nta_hdg ); ////////////////////////////////////////////////////////// // compute the time to intercept selected radial (based on // current and last cross track errors and dt ////////////////////////////////////////////////////////// double t = 0.0; if ( inrange && cdi_serviceable ) { double cur_rate = (last_xtrack_error - _cdiCrossTrackErrorM) / dt; xrate_ms = 0.99 * xrate_ms + 0.01 * cur_rate; if ( fabs(xrate_ms) > 0.00001 ) { t = _cdiCrossTrackErrorM / xrate_ms; } else { t = 9999.9; } } time_to_intercept->setDoubleValue( t ); if (!gs_serviceable_node->getBoolValue() ) { _gsNeedleDeflection = 0.0; _gsNeedleDeflectionNorm = 0.0; } gs_deflection_node->setDoubleValue(_gsNeedleDeflection); gs_deflection_deg_node->setDoubleValue(_gsNeedleDeflectionNorm * 0.7); gs_deflection_norm_node->setDoubleValue(_gsNeedleDeflectionNorm); last_xtrack_error = _cdiCrossTrackErrorM; } void FGNavRadio::updateAudio() { if (!_navaid || !inrange_node->getBoolValue() || !nav_serviceable_node->getBoolValue()) { return; } // play station ident via audio system if on + ident, // otherwise turn it off if (!power_btn_node->getBoolValue() || !(bus_power_node->getDoubleValue() > 1.0) || !ident_btn_node->getBoolValue() || !audio_btn_node->getBoolValue() ) { _sgr->stop( nav_fx_name ); _sgr->stop( dme_fx_name ); return; } SGSoundSample *sound = _sgr->find( nav_fx_name ); double vol = vol_btn_node->getFloatValue(); SG_CLAMP_RANGE(vol, 0.0, 1.0); if ( sound != NULL ) { sound->set_volume( vol ); } else { SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-vor-ident sound" ); } sound = _sgr->find( dme_fx_name ); if ( sound != NULL ) { sound->set_volume( vol ); } else { SG_LOG( SG_COCKPIT, SG_ALERT, "Can't find nav-dme-ident sound" ); } const int NUM_IDENT_SLOTS = 5; const time_t SLOT_LENGTH = 5; // seconds // There are N slots numbered 0 through (NUM_IDENT_SLOTS-1) inclusive. // Each slot is 5 seconds long. // Slots 0 is for DME // the rest are for azimuth. time_t now = globals->get_time_params()->get_cur_time(); if ((now >= last_time) && (now < last_time + SLOT_LENGTH)) { return; // wait longer } last_time = now; play_count = ++play_count % NUM_IDENT_SLOTS; // Previous ident is out of time; if still playing, cut it off: _sgr->stop( nav_fx_name ); _sgr->stop( dme_fx_name ); if (play_count == 0) { // the DME slot if (_dmeInRange && dme_serviceable_node->getBoolValue()) { // play DME ident if (vol > 0.05) _sgr->play_once( dme_fx_name ); } } else { // NAV slot if (inrange_node->getBoolValue() && nav_serviceable_node->getBoolValue()) { if (vol > 0.05) _sgr->play_once(nav_fx_name); } } } FGNavRecord* FGNavRadio::findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz) { FGNavRecord* nav = globals->get_navlist()->findByFreq(aFreqMHz, aPos); if (nav) { return nav; } return globals->get_loclist()->findByFreq(aFreqMHz, aPos); } // Update current nav/adf radio stations based on current postition void FGNavRadio::search() { _time_before_search_sec = 1.0; SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(), lat_node->getDoubleValue(), alt_node->getDoubleValue()); double freq = freq_node->getDoubleValue(); FGNavRecord* nav = findPrimaryNavaid(pos, freq); if (nav == _navaid) { return; // found the same as last search, we're done } _navaid = nav; char identBuffer[5] = " "; if (nav) { _dme = globals->get_dmelist()->findByFreq(freq, pos); nav_id_node->setStringValue(nav->get_ident()); strncpy(identBuffer, nav->ident().c_str(), 5); effective_range = adjustNavRange(nav->get_elev_ft(), pos.getElevationM(), nav->get_range()); loc_node->setBoolValue(nav->type() != FGPositioned::VOR); twist = nav->get_multiuse(); if (nav->type() == FGPositioned::VOR) { target_radial = sel_radial_node->getDoubleValue(); _gs = NULL; has_gs_node->setBoolValue(false); } else { // ILS or LOC _gs = globals->get_gslist()->findByFreq(freq, pos); has_gs_node->setBoolValue(_gs != NULL); _localizerWidth = localizerWidth(nav); twist = 0.0; effective_range = nav->get_range(); target_radial = nav->get_multiuse(); SG_NORMALIZE_RANGE(target_radial, 0.0, 360.0); if (_gs) { int tmp = (int)(_gs->get_multiuse() / 1000.0); target_gs = (double)tmp / 100.0; // until penaltyForNav goes away, we cannot assume we always pick // paired LOC/GS trasmsitters. As we pass over a runway threshold, we // often end up picking the 'wrong' LOC, but the correct GS. To avoid // breaking the basis computation, ensure we use the GS radial and not // the (potentially reversed) LOC radial. double gs_radial = fmod(_gs->get_multiuse(), 1000.0); SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0); // GS axis unit tangent vector // (along the runway) _gsCart = _gs->cart(); _gsAxis = tangentVector(_gs->geod(), _gsCart, gs_radial); // GS baseline unit tangent vector // (perpendicular to the runay along the ground) SGVec3d baseline = tangentVector(_gs->geod(), _gsCart, gs_radial + 90.0); _gsVertical = cross(baseline, _gsAxis); } // of have glideslope } // of found LOC or ILS audioNavidChanged(); } else { // found nothing _gs = NULL; _dme = NULL; nav_id_node->setStringValue(""); _sgr->remove( nav_fx_name ); _sgr->remove( dme_fx_name ); } is_valid_node->setBoolValue(nav != NULL); id_c1_node->setIntValue( (int)identBuffer[0] ); id_c2_node->setIntValue( (int)identBuffer[1] ); id_c3_node->setIntValue( (int)identBuffer[2] ); id_c4_node->setIntValue( (int)identBuffer[3] ); } double FGNavRadio::localizerWidth(FGNavRecord* aLOC) { FGRunway* rwy = aLOC->runway(); assert(rwy); SGVec3d thresholdCart(SGVec3d::fromGeod(rwy->threshold())); double axisLength = dist(aLOC->cart(), thresholdCart); double landingLength = dist(thresholdCart, SGVec3d::fromGeod(rwy->end())); // Reference: http://dcaa.slv.dk:8000/icaodocs/ // ICAO standard width at threshold is 210 m = 689 feet = approx 700 feet. // ICAO 3.1.1 half course = DDM = 0.0775 // ICAO 3.1.3.7.1 Sensitivity 0.00145 DDM/m at threshold // implies peg-to-peg of 214 m ... we will stick with 210. // ICAO 3.1.3.7.1 "Course sector angle shall not exceed 6 degrees." // Very short runway: less than 1200 m (4000 ft) landing length: if (landingLength < 1200.0) { // ICAO fudges localizer sensitivity for very short runways. // This produces a non-monotonic sensitivity-versus length relation. axisLength += 1050.0; } // Example: very short: San Diego KMYF (Montgomery Field) ILS RWY 28R // Example: short: Tom's River KMJX (Robert J. Miller) ILS RWY 6 // Example: very long: Denver KDEN (Denver) ILS RWY 16R double raw_width = 210.0 / axisLength * SGD_RADIANS_TO_DEGREES; return raw_width < 6.0? raw_width : 6.0; } void FGNavRadio::audioNavidChanged() { if (_sgr->exists(nav_fx_name)) { _sgr->remove(nav_fx_name); } try { string trans_ident(_navaid->get_trans_ident()); SGSoundSample* sound = morse.make_ident(trans_ident, LO_FREQUENCY); sound->set_volume( 0.3 ); if (!_sgr->add( sound, nav_fx_name )) { SG_LOG(SG_COCKPIT, SG_WARN, "Failed to add v1-vor-ident sound"); } if ( _sgr->exists( dme_fx_name ) ) { _sgr->remove( dme_fx_name ); } sound = morse.make_ident( trans_ident, HI_FREQUENCY ); sound->set_volume( 0.3 ); _sgr->add( sound, dme_fx_name ); int offset = (int)(sg_random() * 30.0); play_count = offset / 4; last_time = globals->get_time_params()->get_cur_time() - offset; } catch (sg_io_exception& e) { SG_LOG(SG_GENERAL, SG_ALERT, e.getFormattedMessage()); } }