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flightgear/src/Instrumentation/navradio.cxx
ThorstenB 3c3f3a096e John Denker: move branch cut and apply clamps 
fixed un-normalized outputs
2011-02-16 19:53:10 +01:00

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// navradio.cxx -- class to manage a nav radio instance
//
// Written by Curtis Olson, started April 2000.
//
// Copyright (C) 2000 - 2002 Curtis L. Olson - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "navradio.hxx"
#include <sstream>
#include <cstring>
#include <simgear/sg_inlines.h>
#include <simgear/timing/sg_time.hxx>
#include <simgear/math/sg_random.h>
#include <simgear/misc/sg_path.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/structure/exception.hxx>
#include <simgear/math/interpolater.hxx>
#include <simgear/misc/strutils.hxx>
#include <Navaids/navrecord.hxx>
#include <Airports/runways.hxx>
#include <Navaids/navlist.hxx>
#include <Main/util.hxx>
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 Cartesian unit vector in the
// local horizontal plane, i.e. tangent to the
// surface of the earth at the local ground zero.
// The tangent vector passes through the given <midpoint>
// and points forward along the given <heading>.
// The <heading> is given in degrees.
static SGVec3d tangentVector(const SGGeod& midpoint, const double heading)
{
// The size of the delta is presumably chosen to give
// numerical stability. I don't know how the value was chosen.
// It probably doesn't matter much. It gets divided out.
double delta(100.0); // in meters
SGGeod head, tail;
double az2; // ignored
SGGeodesy::direct(midpoint, heading, delta, head, az2);
SGGeodesy::direct(midpoint, 180+heading, delta, tail, az2);
head.setElevationM(midpoint.getElevationM());
tail.setElevationM(midpoint.getElevationM());
SGVec3d head_xyz = SGVec3d::fromGeod(head);
SGVec3d tail_xyz = SGVec3d::fromGeod(tail);
// Awkward formula here, needed because vector-by-scalar
// multiplication is defined, but not vector-by-scalar division.
return (head_xyz - tail_xyz) * (0.5/delta);
}
// 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) :
term_tbl(NULL),
low_tbl(NULL),
high_tbl(NULL),
lon_node(fgGetNode("/position/longitude-deg", true)),
lat_node(fgGetNode("/position/latitude-deg", true)),
alt_node(fgGetNode("/position/altitude-ft", true)),
_operable(false),
play_count(0),
last_time(0),
target_radial(0.0),
effective_range(0.0),
target_gs(0.0),
twist(0.0),
horiz_vel(0.0),
last_x(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),
_gsCart(SGVec3d::zeros()),
_gsAxis(SGVec3d::zeros()),
_gsVertical(SGVec3d::zeros()),
_dmeInRange(false),
_toFlag(false),
_fromFlag(false),
_cdiDeflection(0.0),
_cdiCrossTrackErrorM(0.0),
_gsNeedleDeflection(0.0),
_gsNeedleDeflectionNorm(0.0),
_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() );
string branch("/instrumentation/" + _name);
_radio_node = fgGetNode(branch.c_str(), _num, true);
}
// Destructor
FGNavRadio::~FGNavRadio()
{
if (gps_course_node) {
gps_course_node->removeChangeListener(this);
}
if (nav_slaved_to_gps_node) {
nav_slaved_to_gps_node->removeChangeListener(this);
}
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();
SGPropertyNode* node = _radio_node.get();
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_direct_node = node->getChild("gs-direct-deg", 0, true);
gs_rate_of_climb_node = node->getChild("gs-rate-of-climb", 0, true);
gs_rate_of_climb_fpm_node = node->getChild("gs-rate-of-climb-fpm", 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);
// gps slaving support
nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
nav_slaved_to_gps_node->addChangeListener(this);
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/desired-course-deg", true);
gps_course_node->addChangeListener(this);
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 ()
{
tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
tie("operable", SGRawValueMethods<FGNavRadio, bool>(*this, &FGNavRadio::isOperable, NULL));
}
void
FGNavRadio::unbind ()
{
for (unsigned int t=0; t<_tiedNodes.size(); ++t) {
_tiedNodes[t]->untie();
}
_tiedNodes.clear();
}
// 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() )
{
_operable = true;
updateReceiver(dt);
updateCDI(dt);
} else {
clearOutputs();
}
updateAudio();
}
void FGNavRadio::clearOutputs()
{
inrange_node->setBoolValue( false );
signal_quality_norm_node->setDoubleValue( 0.0 );
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 );
heading_node->setDoubleValue(0.0);
gs_deflection_node->setDoubleValue( 0.0 );
gs_deflection_deg_node->setDoubleValue(0.0);
gs_deflection_norm_node->setDoubleValue(0.0);
gs_direct_node->setDoubleValue(0.0);
gs_inrange_node->setBoolValue( false );
loc_node->setBoolValue( false );
has_gs_node->setBoolValue(false);
to_flag_node->setBoolValue( false );
from_flag_node->setBoolValue( false );
is_valid_node->setBoolValue(false);
nav_id_node->setStringValue("");
_dmeInRange = false;
_operable = false;
_navaid = NULL;
}
void FGNavRadio::updateReceiver(double dt)
{
SGGeod pos = SGGeod::fromDegFt(lon_node->getDoubleValue(),
lat_node->getDoubleValue(),
alt_node->getDoubleValue());
SGVec3d aircraft = SGVec3d::fromGeod(pos);
double loc_dist = 0;
// 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)
{
loc_dist = dist(aircraft, _navaid->cart());
loc_dist_node->setDoubleValue( loc_dist );
}
updateDME(aircraft);
if (nav_slaved_to_gps_node->getBoolValue()) {
// when slaved to GPS: only allow stuff above: tune NAV station
// upate DME. All other data driven by GPS only.
updateGPSSlaved();
return;
}
if (!_navaid) {
_cdiDeflection = 0.0;
_cdiCrossTrackErrorM = 0.0;
_toFlag = _fromFlag = false;
_gsNeedleDeflection = 0.0;
_gsNeedleDeflectionNorm = 0.0;
heading_node->setDoubleValue(0.0);
inrange_node->setBoolValue(false);
return;
}
double nav_elev = _navaid->get_elev_ft();
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);
}
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) 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 comp_h = -dot(pos, _gsAxis); // component in horiz direction
double comp_v = dot(pos, _gsVertical); // component in vertical direction
//double comp_b = dot(pos, _gsBaseline); // component in baseline direction
//if (comp_b) {} // ... (useful for debugging)
// _gsDirect represents the angle of elevation of the aircraft
// as seen by the GS transmitter.
_gsDirect = atan2(comp_v, comp_h) * SGD_RADIANS_TO_DEGREES;
// At this point, if the aircraft is centered on the glide slope,
// _gsDirect will be a small positive number, e.g. 3.0 degrees
// Aim the branch cut straight down
// into the ground below the GS transmitter:
if (_gsDirect < -90.0) _gsDirect += 360.0;
double deflectionAngle = target_gs - _gsDirect;
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
}
}
// GS is documented to be 1.4 degrees thick,
// i.e. plus or minus 0.7 degrees from the midline:
SG_CLAMP_RANGE(deflectionAngle, -0.7, 0.7);
// Many older instrument xml frontends depend on
// the un-normalized gs-needle-deflection.
// Apparently the interface standard is plus or minus 3.5 "volts"
// for a full-scale deflection:
_gsNeedleDeflection = deflectionAngle * 5.0;
_gsNeedleDeflection *= signal_quality_norm;
_gsNeedleDeflectionNorm = (deflectionAngle / 0.7) * signal_quality_norm;
//////////////////////////////////////////////////////////
// Calculate desired rate of climb for intercepting the GS
//////////////////////////////////////////////////////////
double gs_diff = target_gs - _gsDirect;
// convert desired vertical path angle into a climb rate
double des_angle = _gsDirect - 10 * gs_diff;
/* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
target_gs, _gsDirect, gs_diff, des_angle); */
// estimate horizontal speed towards ILS in meters per minute
double elapsedDistance = last_x - gsDist;
last_x = gsDist;
double new_vel = ( elapsedDistance / dt );
horiz_vel = 0.99 * horiz_vel + 0.01 * new_vel;
/* printf("vel=%.1f (dist=%.1f dt=%.2f)\n", horiz_vel, elapsedDistance, dt);*/
gs_rate_of_climb_node
->setDoubleValue( -sin( des_angle * SGD_DEGREES_TO_RADIANS )
* horiz_vel * SG_METER_TO_FEET );
gs_rate_of_climb_fpm_node
->setDoubleValue( gs_rate_of_climb_node->getDoubleValue() * 60 );
}
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::valueChanged (SGPropertyNode* prop)
{
if (prop == gps_course_node) {
if (!nav_slaved_to_gps_node->getBoolValue()) {
return;
}
// GPS desired course has changed, sync up our selected-course
double v = prop->getDoubleValue();
if (v != sel_radial_node->getDoubleValue()) {
sel_radial_node->setDoubleValue(v);
}
} else if (prop == nav_slaved_to_gps_node) {
if (prop->getBoolValue()) {
// slaved-to-GPS activated, clear obsolete NAV outputs and sync up selected course
clearOutputs();
sel_radial_node->setDoubleValue(gps_course_node->getDoubleValue());
}
// slave-to-GPS enabled/disabled, resync NAV station (update all outputs)
_navaid = NULL;
_time_before_search_sec = 0;
}
}
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;
_gsNeedleDeflectionNorm = 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);
gs_direct_node->setDoubleValue(_gsDirect);
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;
string identBuffer(4, ' ');
if (nav) {
_dme = globals->get_dmelist()->findByFreq(freq, pos);
nav_id_node->setStringValue(nav->get_ident());
identBuffer = simgear::strutils::rpad( nav->ident(), 4, ' ' );
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 = nav->localizerWidth();
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;
double gs_radial = fmod(_gs->get_multiuse(), 1000.0);
SG_NORMALIZE_RANGE(gs_radial, 0.0, 360.0);
_gsCart = _gs->cart();
// GS axis unit tangent vector
// (along the runway):
_gsAxis = tangentVector(_gs->geod(), gs_radial);
// GS baseline unit tangent vector
// (transverse to the runay along the ground)
_gsBaseline = tangentVector(_gs->geod(), gs_radial + 90.0);
_gsVertical = cross(_gsBaseline, _gsAxis);
} // of have glideslope
} // of found LOC or ILS
audioNavidChanged();
} else { // found nothing
_gs = NULL;
_dme = NULL;
nav_id_node->setStringValue("");
loc_node->setBoolValue(false);
has_gs_node->setBoolValue(false);
_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] );
}
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());
}
}
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