Index: trunk/BNC/src/PPP/pppParlist.cpp
===================================================================
--- trunk/BNC/src/PPP/pppParlist.cpp	(revision 10583)
+++ trunk/BNC/src/PPP/pppParlist.cpp	(revision 10584)
@@ -389,6 +389,9 @@
     const t_pppSatObs* satObs = obsVector[jj];
     char sys = satObs->prn().system();
-    _usedSystems[sys]++;
-  }
+    if (OPT->LCs(sys).size()) {
+      _usedSystems[sys]++;
+    }
+  };
+
 
   // Check whether parameters have observations
@@ -428,17 +431,17 @@
   // Receiver Clocks
   // ---------------
-   if (_usedSystems.contains('G')) {
+   if (_usedSystems['G']) {
      required.push_back(new t_pppParam(t_pppParam::rClkG, t_prn(), t_lc::dummy));
    }
 
-   if (_usedSystems.contains('R')) {
+   if (_usedSystems['R']) {
      required.push_back(new t_pppParam(t_pppParam::rClkR, t_prn(), t_lc::dummy));
    }
 
-   if (_usedSystems.contains('E')) {
+   if (_usedSystems['E']) {
      required.push_back(new t_pppParam(t_pppParam::rClkE, t_prn(), t_lc::dummy));
    }
 
-   if (_usedSystems.contains('C')) {
+   if (_usedSystems['C']) {
      required.push_back(new t_pppParam(t_pppParam::rClkC, t_prn(), t_lc::dummy));
    }