#include "navradio.hxx"
#include <sstream>
+#include <cstring>
#include <simgear/sg_inlines.h>
#include <simgear/timing/sg_time.hxx>
-#include <simgear/math/vector.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>
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)
+// 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 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());
+// 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);
- return (head_xyz - tail_xyz) * (1.0/fudge);
+ 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 createServiceableProp(SGPropertyNode* aParent,
+ const char* aName)
{
- SGPropertyNode_ptr n = (aParent->getChild(aName, 0, true)->getChild("serviceable", 0, true));
+ 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);
// 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_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),
+ _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() );
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;
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);
// 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/selected-course-deg", 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);
&& nav_serviceable_node->getBoolValue() )
{
_operable = true;
- if (nav_slaved_to_gps_node->getBoolValue()) {
- updateGPSSlaved();
- } else {
- updateReceiver(dt);
- }
-
+ updateReceiver(dt);
updateCDI(dt);
} else {
clearOutputs();
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!)
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;
}
- 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();
_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)
bool gsInRange = (gsDist < (_gs->get_range() * SG_NM_TO_METER));
gs_inrange_node->setBoolValue(gsInRange);
- if (!gsInRange) {
- _gsNeedleDeflection = 0.0;
- _gsNeedleDeflectionNorm = 0.0;
- return;
- }
+ 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 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;
+ 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
}
}
+// 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;
- 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;
+ double gs_diff = target_gs - _gsDirect;
// convert desired vertical path angle into a climb rate
- double des_angle = angle - 10 * gs_diff;
+ double des_angle = _gsDirect - 10 * gs_diff;
/* printf("target_gs=%.1f angle=%.1f gs_diff=%.1f des_angle=%.1f\n",
- target_gs, angle, gs_diff, des_angle); */
+ target_gs, _gsDirect, gs_diff, des_angle); */
// estimate horizontal speed towards ILS in meters per minute
double elapsedDistance = last_x - gsDist;
_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());
_cdiDeflection = 0.0;
_cdiCrossTrackErrorM = 0.0;
_gsNeedleDeflection = 0.0;
+ _gsNeedleDeflectionNorm = 0.0;
return;
}
//////////////////////////////////////////////////////////
// compute the time to intercept selected radial (based on
- // current and last cross track errors and dt
+ // current and last cross track errors and dt)
//////////////////////////////////////////////////////////
double t = 0.0;
if ( inrange && cdi_serviceable ) {
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;
}
}
_navaid = nav;
- char identBuffer[5] = " ";
+ string identBuffer(4, ' ');
if (nav) {
- _dme = globals->get_dmelist()->findByFreq(freq, pos);
+ // use ILS signals as DME, otherwise search by frequency
+ if (nav->type()==FGPositioned::ILS)
+ _dme = nav;
+ else
+ _dme = globals->get_dmelist()->findByFreq(freq, pos);
nav_id_node->setStringValue(nav->get_ident());
- strncpy(identBuffer, nav->ident().c_str(), 5);
+ 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);
} else { // ILS or LOC
_gs = globals->get_gslist()->findByFreq(freq, pos);
has_gs_node->setBoolValue(_gs != NULL);
- _localizerWidth = localizerWidth(nav);
+ _localizerWidth = nav->localizerWidth();
twist = 0.0;
effective_range = nav->get_range();
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 axis unit tangent vector
+ // (along the runway):
+ _gsAxis = tangentVector(_gs->geod(), 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);
+ // (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
id_c4_node->setIntValue( (int)identBuffer[3] );
}
-double FGNavRadio::localizerWidth(FGNavRecord* aLOC)
-{
- FGRunway* rwy = aLOC->runway();
- if (!rwy) {
- return 6.0; // no runway associated, return default value
- }
-
-
- 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)) {
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