Changeset 11205 in ntrip for trunk/BNC/src/combination/bnccomb.cpp

Timestamp:

Nov 13, 2026, 6:46:33 PM (79 minutes ago)

Author:

stuerze

Message:

kalman filter combination improved

File:

• trunk/BNC/src/combination/bnccomb.cpp (modified) (4 diffs)

trunk/BNC/src/combination/bnccomb.cpp

@@ -1870 +1870 @@
   }
 
-  const int nCon = (_method == filter) ? 1 + maxSat + excludedACs.size() : 0;
+  // ACs of this epoch, each with a zero-sum condition of its satellite offsets
+  QStringList epoACs;
+  for (int ii = 0; ii < corrs(sys).size(); ii++) {
+    if (!epoACs.contains(corrs(sys)[ii]->_acName)) {
+      epoACs << corrs(sys)[ii]->_acName;
+    }
+  }
+
+  const int nCon = (_method == filter) ? 1 + maxSat + epoACs.size() : 0;
 
   AA.ReSize(nObs+nCon, nPar);  AA = 0.0;
@@ -1944 +1952 @@
     int iCond = 1;
     QSet<int>     offExcluded; // offsets excluded from the zero-sum condition of their satellite
+    QSet<int>     offInDatum;  // offsets in the zero-sum condition of their satellite
     QSet<QString> acsInDatum;  // ACs with at least one offset in the zero-sum conditions
     // GNSS
@@ -1969 +1978 @@
         if (offUsed.contains(iPar)) {
           AA(nObs+iCond, iPar) = 1.0;
+          offInDatum << iPar;
           acsInDatum.insert(_params[sys][iPar-1]->AC);
         }
@@ -1976 +1986 @@
       }
     }
-    // ACs with all their offsets excluded from the zero-sum conditions above:
-    // the sum of their offsets is constrained to zero (otherwise not
-    // separable from the AC's epoch offset)
-    for (const QString& acName : excludedACs) {
+    // Zero-sum condition of the satellite offsets of each AC: without it, the
+    // AC epoch offsets can be shifted by a_i, compensated by the satellite
+    // offsets and, for a satellite not provided by all ACs, by its combined
+    // clock (shift: mean of a_i over the ACs providing it). This would leave
+    // the clocks of such satellites to the history of the filter (e.g. G13
+    // +1.4 m after a restart). With it, the AC epoch offset is the mean clock
+    // difference of the AC. Sum over the offsets in the satellite conditions
+    // above; for an AC with all its offsets excluded from them, over these
+    // (otherwise not separable from the AC's epoch offset).
+    for (const QString& acName : epoACs) {
       ++iCond;
-      if (acsInDatum.contains(acName)) {
-        continue;
-      }
       PP(nObs+iCond) = Ph;
-      for (int iPar : offExcluded) {
+      const QSet<int>& offAC = acsInDatum.contains(acName) ? offInDatum : offExcluded;
+      for (int iPar : offAC) {
         if (_params[sys][iPar-1]->AC == acName) {
           AA(nObs+iCond, iPar) = 1.0;