diff --git a/Tools/check_submodules.sh b/Tools/check_submodules.sh
index 0c03396e7b..3904a27753 100755
--- a/Tools/check_submodules.sh
+++ b/Tools/check_submodules.sh
@@ -73,8 +73,8 @@ then
 		exit 1
 	fi
 else
-	git submodule init
-	git submodule update
+	git submodule init;
+	git submodule update;
 fi
 
 exit 0
diff --git a/src/drivers/drv_tone_alarm.h b/src/drivers/drv_tone_alarm.h
index b7981e9c4b..19f792d19c 100644
--- a/src/drivers/drv_tone_alarm.h
+++ b/src/drivers/drv_tone_alarm.h
@@ -149,6 +149,7 @@ enum {
 	TONE_GPS_WARNING_TUNE,
 	TONE_ARMING_FAILURE_TUNE,
 	TONE_PARACHUTE_RELEASE_TUNE,
+	TONE_EKF_WARNING_TUNE,
 	TONE_NUMBER_OF_TUNES
 };
 
diff --git a/src/drivers/stm32/tone_alarm/tone_alarm.cpp b/src/drivers/stm32/tone_alarm/tone_alarm.cpp
index 810f4aacc4..03c7bd399f 100644
--- a/src/drivers/stm32/tone_alarm/tone_alarm.cpp
+++ b/src/drivers/stm32/tone_alarm/tone_alarm.cpp
@@ -336,6 +336,7 @@ ToneAlarm::ToneAlarm() :
 	_default_tunes[TONE_GPS_WARNING_TUNE] = "MFT255L4AAAL1F#";					//gps warning slow
 	_default_tunes[TONE_ARMING_FAILURE_TUNE] = "MFT255L4<<<BAP";
 	_default_tunes[TONE_PARACHUTE_RELEASE_TUNE] = "MFT255L16agagagag";			// parachute release
+	_default_tunes[TONE_EKF_WARNING_TUNE] = "MFT255L8ddd#d#eeff";				// ekf warning
 
 	_tune_names[TONE_STARTUP_TUNE] = "startup";			// startup tune
 	_tune_names[TONE_ERROR_TUNE] = "error";				// ERROR tone
@@ -348,6 +349,7 @@ ToneAlarm::ToneAlarm() :
 	_tune_names[TONE_GPS_WARNING_TUNE] = "gps_warning";	            // gps warning
 	_tune_names[TONE_ARMING_FAILURE_TUNE] = "arming_failure";            //fail to arm
 	_tune_names[TONE_PARACHUTE_RELEASE_TUNE] = "parachute_release";	// parachute release
+	_tune_names[TONE_EKF_WARNING_TUNE] = "ekf_warning";				// ekf warning
 }
 
 ToneAlarm::~ToneAlarm()
diff --git a/src/modules/uORB/topics/vehicle_status.h b/src/modules/uORB/topics/vehicle_status.h
index b46c00b758..cbb148edaf 100644
--- a/src/modules/uORB/topics/vehicle_status.h
+++ b/src/modules/uORB/topics/vehicle_status.h
@@ -186,7 +186,7 @@ struct vehicle_status_s {
 	bool condition_system_sensors_initialized;
 	bool condition_system_returned_to_home;
 	bool condition_auto_mission_available;
-	bool condition_global_position_valid;		/**< set to true by the commander app if the quality of the gps signal is good enough to use it in the position estimator */
+	bool condition_global_position_valid;		/**< set to true by the commander app if the quality of the position estimate is good enough to use it for navigation */
 	bool condition_launch_position_valid;		/**< indicates a valid launch position */
 	bool condition_home_position_valid;		/**< indicates a valid home position (a valid home position is not always a valid launch) */
 	bool condition_local_position_valid;
diff --git a/uavcan b/uavcan
index dca2611c31..d84fc8a846 160000
--- a/uavcan
+++ b/uavcan
@@ -1 +1 @@
-Subproject commit dca2611c3186eaa1cac42557f07b013e2dc633d3
+Subproject commit d84fc8a84678d93f97f93b240c81472797ca5889