mavlink: DISTANCE_SENSOR: propagate signal_quality metric

Tools/sitl_gazebo

@@ -1 +1 @@
-Subproject commit 846190e8a33063a62997f2ad18c9de5c5233d9f9
+Subproject commit 3cb21c0c95e06940a8aa5a2c82f37630d0fb59de

src/modules/mavlink/mavlink_receiver.cpp

@@ -716,11 +716,15 @@ MavlinkReceiver::handle_message_distance_sensor(mavlink_message_t *msg)
 	ds.q[1]             = dist_sensor.quaternion[1];
 	ds.q[2]             = dist_sensor.quaternion[2];
 	ds.q[3]             = dist_sensor.quaternion[3];
-	ds.signal_quality   = -1; // TODO: A dist_sensor.signal_quality field is missing from the mavlink message definition.
 	ds.type             = dist_sensor.type;
 	ds.id               = dist_sensor.id;
 	ds.orientation      = dist_sensor.orientation;
 
+	// MAVLink DISTANCE_SENSOR signal_quality value of 0 means unset/unknown
+	// quality value. Also it comes normalised between 1 and 100 while the uORB
+	// signal quality is normalised between 0 and 100.
+	ds.signal_quality = dist_sensor.signal_quality == 0 ? -1 : 100 * (dist_sensor.signal_quality - 1) / 99;
+
 	_distance_sensor_pub.publish(ds);
 }
 

src/modules/simulator/simulator_mavlink.cpp

@@ -1144,7 +1144,11 @@ int Simulator::publish_distance_topic(const mavlink_distance_sensor_t *dist_mavl
 	dist.type = dist_mavlink->type;
 	dist.id = dist_mavlink->id;
 	dist.variance = dist_mavlink->covariance * 1e-4f; // cm^2 to m^2
-	dist.signal_quality = -1;
+
+	// MAVLink DISTANCE_SENSOR signal_quality value of 0 means unset/unknown
+	// quality value. Also it comes normalised between 1 and 100 while the uORB
+	// signal quality is normalised between 0 and 100.
+	dist.signal_quality = dist_mavlink->signal_quality == 0 ? -1 : 100 * (dist_mavlink->signal_quality - 1) / 99;
 
 	switch (dist_mavlink->orientation) {
 	case MAV_SENSOR_ORIENTATION::MAV_SENSOR_ROTATION_PITCH_270: