AP_NavEKF2: Add fix status to GPS check report message

libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp

@@ -343,9 +343,11 @@ bool NavEKF2_core::readDeltaVelocity(uint8_t ins_index, Vector3f &dVel, float &d
 void NavEKF2_core::readGpsData()
 {
     // check for new GPS data
-    if ((_ahrs->get_gps().last_message_time_ms() != lastTimeGpsReceived_ms) &&
-            (_ahrs->get_gps().status() >= AP_GPS::GPS_OK_FIX_3D))
-    {
+    if (_ahrs->get_gps().last_message_time_ms() != lastTimeGpsReceived_ms) {
+        if (_ahrs->get_gps().status() >= AP_GPS::GPS_OK_FIX_3D) {
+            // report GPS fix status
+            gpsCheckStatus.bad_fix = false;
+
             // store fix time from previous read
             secondLastGpsTime_ms = lastTimeGpsReceived_ms;
 
@@ -426,6 +428,10 @@ void NavEKF2_core::readGpsData()
 
             // declare GPS available for use
             gpsNotAvailable = false;
+        } else {
+            // report GPS fix status
+            gpsCheckStatus.bad_fix = true;
+        }
     }
 
     // We need to handle the case where GPS is lost for a period of time that is too long to dead-reckon

libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp

@@ -429,6 +429,7 @@ void  NavEKF2_core::getFilterGpsStatus(nav_gps_status &faults) const
     faults.flags.bad_hAcc   = gpsCheckStatus.bad_hAcc; // reported horizontal position accuracy is insufficient
     faults.flags.bad_sats   = gpsCheckStatus.bad_sats; // reported number of satellites is insufficient
     faults.flags.bad_yaw    = gpsCheckStatus.bad_yaw; // EKF heading accuracy is too large for GPS use
+    faults.flags.bad_fix    = gpsCheckStatus.bad_fix; // The GPS cannot provide the 3D fix required
 }
 
 // send an EKF_STATUS message to GCS

libraries/AP_NavEKF2/AP_NavEKF2_core.h

@@ -824,6 +824,7 @@ private:
         bool bad_hAcc:1;
         bool bad_sats:1;
         bool bad_yaw:1;
+        bool bad_fix:1;
     } gpsCheckStatus;
 
     // states held by magnetomter fusion across time steps