LL40LS: Implement driver-specific filtering based on the datasheet and experiments

src/platforms/posix/drivers/df_bebop_rangefinder_wrapper/df_bebop_rangefinder_wrapper.cpp

@@ -162,6 +162,8 @@ int DfBebopRangeFinderWrapper::_publish(struct bebop_range &data)
 
 	distance_data.covariance = 1.0f; // TODO set correct value
 
+	distance_data.signal_strength = -1;
+
 	if (_range_topic == nullptr) {
 		_range_topic = orb_advertise_multi(ORB_ID(distance_sensor), &distance_data,
 						   &_orb_class_instance, ORB_PRIO_DEFAULT);

src/platforms/posix/drivers/df_isl29501_wrapper/df_isl29501_wrapper.cpp

@@ -169,6 +169,8 @@ int DfISL29501Wrapper::_publish(struct range_sensor_data &data)
 
 	d.covariance = 0.0f;
 
+	d.signal_strength = -1;
+
 	if (_range_topic == nullptr) {
 		_range_topic = orb_advertise_multi(ORB_ID(distance_sensor), &d,
 						   &_orb_class_instance, ORB_PRIO_DEFAULT);

src/platforms/posix/drivers/df_trone_wrapper/df_trone_wrapper.cpp

@@ -175,6 +175,8 @@ int DfTROneWrapper::_publish(struct range_sensor_data &data)
 
 	d.covariance = 0.0f;
 
+	d.signal_strength = -1;
+
 	if (_range_topic == nullptr) {
 		_range_topic = orb_advertise_multi(ORB_ID(distance_sensor), &d,
 						   &_orb_class_instance, ORB_PRIO_DEFAULT);