Index: trunk/BNC/src/rinex/availplot.cpp
===================================================================
--- trunk/BNC/src/rinex/availplot.cpp	(revision 4666)
+++ trunk/BNC/src/rinex/availplot.cpp	(revision 4667)
@@ -210,2 +210,8 @@
   return curve;
 }
+
+// 
+//////////////////////////////////////////////////////////////////////////////
+void t_availPlot::setNumSat(const QVector<double>& _numSatTim, 
+                            const QVector<double>& _numSat) {
+}
Index: trunk/BNC/src/rinex/availplot.h
===================================================================
--- trunk/BNC/src/rinex/availplot.h	(revision 4666)
+++ trunk/BNC/src/rinex/availplot.h	(revision 4667)
@@ -14,4 +14,6 @@
 public:
   t_availPlot(QWidget* parent, QMap<QString, t_availData>* availDataMap);
+  void setNumSat(const QVector<double>& _numSatTim, 
+                 const QVector<double>& _numSat);
 
 private:
Index: trunk/BNC/src/rinex/reqcanalyze.cpp
===================================================================
--- trunk/BNC/src/rinex/reqcanalyze.cpp	(revision 4666)
+++ trunk/BNC/src/rinex/reqcanalyze.cpp	(revision 4667)
@@ -220,6 +220,21 @@
   // --------------------
   try {
+    int       iEpo = 0;
+    const int step = int( 30.0 / obsFile->interval());
+    unsigned  numSat = 0;
+    _numSat.clear();
+    _numSatTim.clear();
     while ( (_currEpo = obsFile->nextEpoch()) != 0) {
   
+      ++iEpo;
+      if (numSat < _currEpo->rnxSat.size()) {
+        numSat = _currEpo->rnxSat.size();
+      }
+      if ( (iEpo % step) == 0 ) {
+        _numSatTim << _currEpo->tt.mjddec() * 24.0;
+        _numSat    << numSat;
+        numSat = 0;
+      }
+
       // Loop over all satellites
       // ------------------------
@@ -574,4 +589,5 @@
 
     t_availPlot* plotA = new t_availPlot(0, &_availDataMap);
+    plotA->setNumSat(_numSatTim, _numSat);
     plotA->setTitle(title);
 
Index: trunk/BNC/src/rinex/reqcanalyze.h
===================================================================
--- trunk/BNC/src/rinex/reqcanalyze.h	(revision 4666)
+++ trunk/BNC/src/rinex/reqcanalyze.h	(revision 4667)
@@ -136,4 +136,6 @@
   QMap<QString, t_allObs>    _allObsMap;
   QMap<QString, t_availData> _availDataMap;
+  QVector<double>            _numSat;
+  QVector<double>            _numSatTim;
 };