Index: trunk/BNC/combination/bnccomb.cpp
===================================================================
--- trunk/BNC/combination/bnccomb.cpp	(revision 3451)
+++ trunk/BNC/combination/bnccomb.cpp	(revision 3452)
@@ -375,4 +375,19 @@
   }
 
+  // Check Number of Observations per Satellite
+  // ------------------------------------------
+  QMap<QString, int> numObs;
+  for (int iGps = 1; iGps <= MAXPRN_GPS; iGps++) {
+    QString prn = QString("G%1").arg(iGps, 2, 10, QChar('0'));
+    numObs[prn] = 0;
+    QVectorIterator<cmbCorr*> itCorr(corrs());
+    while (itCorr.hasNext()) {
+      cmbCorr* corr = itCorr.next();
+      if (corr->prn == prn) {
+        ++numObs[prn];
+      }
+    }
+  }
+
   // Prediction Step
   // ---------------
@@ -410,5 +425,5 @@
     ++iObs;
 
-    if (resCorr.find(prn) == resCorr.end()) {
+    if (numObs[prn] >= 3 && resCorr.find(prn) == resCorr.end()) {
       resCorr[prn] = new t_corr(*corr);
     }