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Fixed some problems with marker beacon range:

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a) I was compairing feet vs. meter (making the range 3x too. big)
b) I was using the diameter in place of the radius (making the range an
   additional 2x too big.)
c) Updated the equation for calculating range to model the weak transmitter
   not being picked up at upper altitudes.

We still might need some additional tweaking, but I think we are starting to
get in the right ball park.
This commit is contained in:
curt 2001-03-19 13:56:19 +00:00
parent 4cf4edcfb4
commit eccd695f91
3 changed files with 26 additions and 9 deletions
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6
src/GUI/gui_local.hxx
View file

@ -1,3 +1,9 @@
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <simgear/compiler.h>
#include "trackball.h"
#if defined(WIN32) || defined(__CYGWIN32__)

25
src/Navaids/mkrbeacons.cxx
View file

@ -172,7 +172,7 @@ FGBeacon::fgMkrBeacType FGMarkerBeacons::query( double lon, double lat,
// cout << " aircraft = " << aircraft << " station = " << station
// << endl;
double d = aircraft.distance3Dsquared( station );
double d = aircraft.distance3Dsquared( station ); // meters^2
// cout << " distance = " << d << " ("
// << FG_ILS_DEFAULT_RANGE * NM_TO_METER
// * FG_ILS_DEFAULT_RANGE * NM_TO_METER
@ -187,20 +187,31 @@ FGBeacon::fgMkrBeacType FGMarkerBeacons::query( double lon, double lat,
// cout << "elev = " << elev * METER_TO_FEET
// << " current->get_elev() = " << current->get_elev() << endl;
double delev = elev * METER_TO_FEET - current->get_elev();
double maxrange = 4200 * delev / 1000;
// max range is the area under r = 2.4 * alt or r^2 = 4000^2 - alt^2
// whichever is smaller. The intersection point is 1538 ...
double maxrange2; // feet^2
if ( delev < 1538.0 ) {
maxrange2 = 2.4 * 2.4 * delev * delev;
} else if ( delev < 4000.0 ) {
maxrange2 = 4000 * 4000 - delev * delev;
} else {
maxrange2 = 0.0;
}
maxrange2 *= FEET_TO_METER * FEET_TO_METER; // convert to meter^2
// cout << "delev = " << delev << " maxrange = " << maxrange << endl;
// match up to twice the published range so we can model
// reduced signal strength
if ( d < maxrange * maxrange ) {
// cout << "lon = " << lon << " lat = " << lat
// << " closest beacon = " << sqrt( min_dist ) << endl;
if ( d < maxrange2 ) {
cout << "lon = " << lon << " lat = " << lat
<< " closest beacon = " << sqrt( min_dist ) << endl;
return current->get_type();
}
}
// cout << "lon = " << lon << " lat = " << lat
// << " closest beacon = " << sqrt( min_dist ) << endl;
cout << "lon = " << lon << " lat = " << lat
<< " closest beacon = " << sqrt( min_dist ) << endl;
return FGBeacon::NOBEACON;
}