Changeset 11110 in ntrip for trunk/BNC/src/bnchelp.html

Timestamp:

Oct 22, 2026, 11:10:34 AM (7 days ago)

Author:

stuerze

Message:

clock combination: some updates regarding attitude correction

File:

• trunk/BNC/src/bnchelp.html (modified) (4 diffs)

trunk/BNC/src/bnchelp.html

@@ -7986 +7986 @@
 </pre>
   <pre>
- dC_att = (yawAngle_AC - yawAngle_MasterAC) / (2*PI) * wavelength(IF)
+ dC_att = (yawAngle_MasterAC - yawAngle_AC) / (2*PI) * wavelength(IF)
 </pre>
   <p>
@@ -7992 +7992 @@
     ionosphere-free combination of the reference signals (about 10.7 cm for GPS). The yaw angle of each AC is taken
     from its attitude selected in the 'Attitude' field (SSR yaw angle, or BNC's 'Computed' or 'Nominal' model); the
-    yaw angle difference is reduced to +-180 degrees. dC_att is therefore zero for two ACs with the same attitude model
+    yaw angle difference is followed continuously over time, so a turn of the AC in the opposite direction than
+    the master orbit AC leaves one full cycle (wavelength(IF)) in its clock, as observed in the clocks. dC_att is therefore zero for two ACs with the same attitude model
     and differs from zero mainly during eclipse seasons and noon/midnight turns, if an AC sends its yaw angles and
     'SSR' is selected for it. A constant part is absorbed by the AC's satellite offset. dC_att requires an ANTEX file.
@@ -8320 +8321 @@
     <li><b>Computed</b> (default): BNC applies its own kinematic attitude model:
       GPS noon/midnight turn manoeuvres (Kouba 2009/2015, Bar-Sever 1996),
-      GLONASS yaw-fixed mode (Dilssner et al. 2011), and
+      GLONASS-M noon turns and midnight turns in the Earth's shadow (Dilssner et al. 2011), and
       Galileo / BDS orbit-normal mode switching (Kouba 2017, Dai et al. 2015, Steigenberger et al. 2018).</li>
     <li><b>Nominal</b>: a simplified, continuous Sun-pointing model is used without any manoeuvre modelling.</li>
@@ -9287 +9288 @@
     yaw attitude. BNC assumes the nominal Sun-pointing yaw-steering law used for the other GNSS systems, except
     close to the orbit noon and midnight points when the Sun's elevation above the orbital plane (the 'beta'
-    angle) is small. There, GLONASS-M satellites are known to stop tracking that law and instead hold the yaw
-    angle fixed, following the model described in Dilssner, Springer, Flohrer, Dow (2011), 'The GLONASS-M
+    angle) is small. There, GLONASS-M satellites cannot follow that law: at noon they yaw at their maximum rate
+    in the direction of the nominal yaw rate until they have caught up with the nominal yaw; in the Earth's shadow
+    they yaw at the maximum rate until they reach the nominal yaw at shadow exit and hold it until leaving the
+    shadow. This follows the model described in Dilssner, Springer, Gienger, Dow (2011), 'The GLONASS-M
     satellite yaw-attitude model', Advances in Space Research 47(1), 160-171. Without that correction, the
     converted GLONASS CoM position can be off by several decimeters in the along-track and cross-track