From a48a94345dd720770977f268cf3e0e4631515609 Mon Sep 17 00:00:00 2001
From: oaq <info@ourairquality.org>
Date: Wed, 27 May 2026 11:53:36 +1000
Subject: [PATCH] rtksrv ssr update

Leave it to the rtcm3 decoder to set the update flag, so that it can use this
to also flag when the state is consistent and ready to be used in an update.

Search the previous ephemeris for an IODE consistent with the SSR data so that
SSR updates can occur even if they still reference the prior ephemeris - when
the ephemeris is updated with a new IODE before the SSR data.
---
 src/rtksvr.c | 64 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 36 insertions(+), 28 deletions(-)

diff --git a/src/rtksvr.c b/src/rtksvr.c
index 35259e1f3..da8f0b5d0 100644
--- a/src/rtksvr.c
+++ b/src/rtksvr.c
@@ -198,7 +198,6 @@ static void update_eph(rtksvr_t *svr, nav_t *nav, int ephsat, int ephset,
                 *eph3=*eph2; /* current ->previous */
                 *eph2=*eph1; /* received->current */
                 trace(4,"update_eph: sat=%d iode %d->%d\n",ephsat,eph3->iode,eph2->iode);
-                svr->rtcm[index].ssr[ephsat-1].update=1;   // Force update of SSR corrections
                 }
             }
             svr->nmsg[index][1]++;
@@ -215,7 +214,6 @@ static void update_eph(rtksvr_t *svr, nav_t *nav, int ephsat, int ephset,
                    *geph2=*geph1;
                    update_glofcn(svr);
                    trace(4,"update_eph: sat=%d iode %d->%d\n",ephsat,geph3->iode,geph2->iode);
-                   svr->rtcm[index].ssr[ephsat-1].update=1;   // Force update of SSR corrections
                }
            }
            svr->nmsg[index][6]++;
@@ -315,36 +313,46 @@ static void update_antpos(rtksvr_t *svr, int index) {
 /* update ssr corrections ----------------------------------------------------*/
 static void update_ssr(rtksvr_t *svr, int index)
 {
-    for (int i=0;i<MAXSAT;i++) {
-        int sat=i+1;
-        if (!svr->rtcm[index].ssr[i].update) continue;
-        svr->rtcm[index].ssr[i].update=0; // just check once per update 
+    for (int i = 0; i < MAXSAT; i++) {
+      if (!svr->rtcm[index].ssr[i].update) continue;
 
-        // Check consistency between iods of orbit and clock.
-        if (svr->rtcm[index].ssr[i].iod[0]!=svr->rtcm[index].ssr[i].iod[1])
-            continue;
+      // Check consistency between iods of orbit and clock.
+      if (svr->rtcm[index].ssr[i].iod[0] != svr->rtcm[index].ssr[i].iod[1])
+        continue;
 
-        // Check consistency of iode between ssr and broadcast.
-        int ssr_iode=svr->rtcm[index].ssr[i].iode, iode=-1;
-        if (ssr_iode<0) continue;
-        int prn;
-        if (satsys(sat, &prn)!=SYS_GLO) {
-            eph_t *eph=svr->nav.eph+i;
-            if (eph->sat==sat&&ssr_iode==eph->iode) {
-                iode=eph->iode;
-            }
-        } else { // SYS_GLO
-            geph_t *geph=svr->nav.geph+prn-1;
-            if (geph->sat==sat&&ssr_iode==geph->iode) {
-                iode=geph->iode;
+      // Check consistency of iode between ssr and broadcast.
+      int ssr_iode = svr->rtcm[index].ssr[i].iode, iode = -1;
+      if (ssr_iode < 0) continue;
+      int sat = i + 1, prn, sys = satsys(sat, &prn);
+      if (sys != SYS_GLO) {
+        for (int j = 0; j < 4; j++) {
+          eph_t *eph = &svr->nav.eph[i + j * MAXSAT];
+          if (eph->sat == sat && ssr_iode == eph->iode) {
+            // Galileo SSR is wrt the I/NAV broadcast clock, skip F/NAV.
+            if (sys == SYS_GAL && (eph->code & (1 << 8)) != 0) {
+              trace(4, "update_ssr skipping F/NAV sat=%d\n", sat);
+              continue;
             }
+            iode = eph->iode;
+            break;
+          }
         }
-        if (iode!=-1) {
-            if (svr->nav.ssr[i].iode!=ssr_iode) {
-                trace(4,"update_ssr_iode: sat=%d %d->%d\n",sat,svr->nav.ssr[i].iode,ssr_iode);
-            }
-            svr->nav.ssr[i]=svr->rtcm[index].ssr[i];
-       }
+      } else {
+        for (int j = 0; j < 2; j++) {
+          geph_t *geph = &svr->nav.geph[prn - 1 + j * MAXPRNGLO];
+          if (geph->sat == sat && ssr_iode == geph->iode) {
+            iode = geph->iode;
+            break;
+          }
+        }
+      }
+      if (iode == -1) {
+        trace(4, "update_ssr deferred sat=%d ssr_iode=%d\n", sat, ssr_iode);
+        continue;
+      }
+
+      svr->nav.ssr[i] = svr->rtcm[index].ssr[i];
+      svr->rtcm[index].ssr[i].update = 0;
     }
     svr->nmsg[index][7]++;