Propagate broadcast SISA and NAPA to PVT

src/algorithms/libs/rtklib/rtklib.h

@@ -434,7 +434,7 @@ typedef struct
 {                          /* GPS/QZS/GAL broadcast ephemeris type */
     int sat;               /* satellite number */
     int iode, iodc;        /* IODE,IODC */
-    int sva;               /* SV accuracy (URA index) */
+    int sva;               /* SV accuracy (URA index, GAL: SISA index) */
     int svh;               /* SV health (0:ok) */
     int week;              /* GPS/QZS: gps week, GAL: galileo week */
     int code;              /* GPS/QZS: code on L2, GAL/BDS: data sources */

src/algorithms/libs/rtklib/rtklib_conversions.cc

@@ -430,6 +430,7 @@ eph_t eph_to_rtklib(const Galileo_Ephemeris& gal_eph,
         0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, {}, {}, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, false, 0, 0, 0, 0, 0.0, -1, 0};
     // Galileo is the third satellite system for RTKLIB, so, add the required offset to discriminate Galileo ephemeris
     rtklib_sat.sat = gal_eph.PRN + NSATGPS + NSATGLO;
+    rtklib_sat.sva = gal_eph.SISA;
     rtklib_sat.A = gal_eph.sqrtA * gal_eph.sqrtA;
     rtklib_sat.M0 = gal_eph.M_0;
     rtklib_sat.deln = gal_eph.delta_n;

src/algorithms/libs/rtklib/rtklib_ephemeris.cc

@@ -77,6 +77,41 @@ double var_uraeph(int ura)
 }
 
 
+/* variance by galileo sisa ephemeris (OS SIS ICD, table 91) ----------------*/
+double var_sisaeph(int sisa)
+{
+    double sisa_m;
+    if (sisa == -1)
+        {
+            // Reduced CED does not contain SISA. Retain RTKLIB's default
+            // broadcast-ephemeris accuracy when no index was supplied.
+            sisa_m = 2.4;
+        }
+    else if (sisa < 0 || sisa > 125)
+        {
+            // Spare values and NAPA (255) provide no usable accuracy prediction.
+            sisa_m = 6144.0;
+        }
+    else if (sisa <= 49)
+        {
+            sisa_m = static_cast<double>(sisa) * 0.01;
+        }
+    else if (sisa <= 74)
+        {
+            sisa_m = 0.50 + static_cast<double>(sisa - 50) * 0.02;
+        }
+    else if (sisa <= 99)
+        {
+            sisa_m = 1.00 + static_cast<double>(sisa - 75) * 0.04;
+        }
+    else
+        {
+            sisa_m = 2.00 + static_cast<double>(sisa - 100) * 0.16;
+        }
+    return std::pow(sisa_m, 2.0);
+}
+
+
 static double cnav_ura_upper_bound_m(int ura_index)
 {
     switch (ura_index)
@@ -517,7 +552,18 @@ void eph2pos(gtime_t time, const eph_t *eph, double *rs, double *dts,
         }
 
     /* position and clock error variance */
-    *var = eph->cnav_ura_valid ? std::pow(cnav_uraeph(time, eph), 2.0) : var_uraeph(eph->sva);
+    if (eph->cnav_ura_valid)
+        {
+            *var = std::pow(cnav_uraeph(time, eph), 2.0);
+        }
+    else if (satsys(eph->sat, nullptr) == SYS_GAL)
+        {
+            *var = var_sisaeph(eph->sva);
+        }
+    else
+        {
+            *var = var_uraeph(eph->sva);
+        }
 }
 
 

src/algorithms/libs/rtklib/rtklib_ephemeris.h

@@ -38,6 +38,7 @@
 
 
 double var_uraeph(int ura);
+double var_sisaeph(int sisa);
 double var_urassr(int ura);
 void alm2pos(gtime_t time, const alm_t *alm, double *rs, double *dts);
 double eph2clk(gtime_t time, const eph_t *eph);

src/core/system_parameters/galileo_ephemeris.h

@@ -50,7 +50,7 @@ public:
     int32_t IOD_nav{};
 
     // SV status
-    int32_t SISA{};      //!< Signal in space accuracy index
+    int32_t SISA{-1};    //!< Signal in space accuracy index (-1 if unavailable in the source data)
     int32_t E5a_HS{};    //!< E5a Signal Health Status
     int32_t E5b_HS{};    //!< E5b Signal Health Status
     int32_t E1B_HS{};    //!< E1B Signal Health Status

src/core/system_parameters/galileo_fnav_message.cc

@@ -407,6 +407,7 @@ Galileo_Ephemeris Galileo_Fnav_Message::get_ephemeris() const
     ephemeris.af0 = FNAV_af0_1;        // SV clock bias correction coefficient [s]
     ephemeris.af1 = FNAV_af1_1;        // SV clock drift correction coefficient [s/s]
     ephemeris.af2 = FNAV_af2_1;        // SV clock drift rate correction coefficient [s/s^2]
+    ephemeris.SISA = FNAV_SISA_1;      // Signal In Space Accuracy index
     ephemeris.BGD_E1E5a = FNAV_BGD_1;  // E1-E5a Broadcast Group Delay [s]
 
     // GST