Index: trunk/BNC/src/PPP/pppFilter.cpp
===================================================================
--- trunk/BNC/src/PPP/pppFilter.cpp	(revision 6006)
+++ trunk/BNC/src/PPP/pppFilter.cpp	(revision 6007)
@@ -439,7 +439,9 @@
   const vector<t_pppParam*>& params = _parlist->params();
 
+  bool first = (_QFlt[0][0] == 0.0 && _QFlt[1][1] == 0.0 && _QFlt[2][2] == 0.0);
+
   for (unsigned ii = 0; ii < 3; ii++) {
     const t_pppParam* par1 = params[ii];
-    if (_QFlt[ii][ii] == 0.0) {
+    if (first) {
       _QFlt[ii][ii] = par1->sigma0() * par1->sigma0(); // new parameter
     }