CVS: source/src/Navaids navrecord.cxx, 1.13, 1.14 navrecord.hxx, 1.23, 1.24

Update of /var/cvs/FlightGear-0.9/source/src/Navaids
In directory baron.flightgear.org:/tmp/cvs-serv24394/src/Navaids

Modified Files:
	navrecord.cxx navrecord.hxx 
Log Message:
MapWidget for the GUI, initial commit.


Index: navrecord.cxx
===================================================================
RCS file: /var/cvs/FlightGear-0.9/source/src/Navaids/navrecord.cxx,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -r1.13 -r1.14
--- navrecord.cxx	19 Dec 2009 17:55:22 -0000	1.13
+++ navrecord.cxx	27 Mar 2010 17:01:12 -0000	1.14
@@ -181,6 +181,38 @@
   }
 }
 
+double FGNavRecord::localizerWidth() const
+{
+  if (!mRunway) {
+    return 6.0;
+  }
+  
+  SGVec3d thresholdCart(SGVec3d::fromGeod(mRunway->threshold()));
+  double axisLength = dist(cart(), thresholdCart);
+  double landingLength = dist(thresholdCart, SGVec3d::fromGeod(mRunway->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;
+
+}
+
 FGTACANRecord::FGTACANRecord(void) :
     channel(""),
     freq(0)

Index: navrecord.hxx
===================================================================
RCS file: /var/cvs/FlightGear-0.9/source/src/Navaids/navrecord.hxx,v
retrieving revision 1.23
retrieving revision 1.24
diff -u -r1.23 -r1.24
--- navrecord.hxx	30 Aug 2009 17:13:54 -0000	1.23
+++ navrecord.hxx	27 Mar 2010 17:01:45 -0000	1.24
@@ -96,6 +96,13 @@
    * Retrieve the runway this navaid is associated with (for ILS/LOC/GS)
    */
   FGRunway* runway() const { return mRunway; }
+  
+  /**
+   * return the localizer width, in degrees
+   * computation is based up ICAO stdandard width at the runway threshold
+   * see implementation for further details.
+   */
+  double localizerWidth() const;
 };
 
 class FGTACANRecord : public SGReferenced {


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