ADSB: add param ADSB_LIST_ALT to filter aircraft by altitude. default is disabled

libraries/AP_ADSB/AP_ADSB.cpp

@@ -66,9 +66,10 @@ const AP_Param::GroupInfo AP_ADSB::var_info[] = {
 
     // @Param: LIST_RADIUS
     // @DisplayName: ADSB vehicle list radius filter
-    // @Description: ADSB vehicle list radius filter. Vehicles detected outside this radius will be completely ignored. They will not show up in the SRx_ADSB stream to the GCS and will not be considered in any avoidance calculations.
-    // @Range: 1 100000
+    // @Description: ADSB vehicle list radius filter. Vehicles detected outside this radius will be completely ignored. They will not show up in the SRx_ADSB stream to the GCS and will not be considered in any avoidance calculations. A value of 0 will disable this filter.
+    // @Range: 0 100000
     // @User: Advanced
+    // @Units: m
     AP_GROUPINFO("LIST_RADIUS",   3, AP_ADSB, in_state.list_radius, ADSB_LIST_RADIUS_DEFAULT),
 
     // @Param: ICAO_ID
@@ -129,6 +130,14 @@ const AP_Param::GroupInfo AP_ADSB::var_info[] = {
     // @User: Advanced
     AP_GROUPINFO("RF_CAPABLE",  11, AP_ADSB, out_state.cfg.rf_capable, 0),
 
+    // @Param: LIST_ALT
+    // @DisplayName: ADSB vehicle list altitude filter
+    // @Description: ADSB vehicle list altitude filter. Vehicles detected above this altitude will be completely ignored. They will not show up in the SRx_ADSB stream to the GCS and will not be considered in any avoidance calculations. A value of 0 will disable this filter.
+    // @Range: 0 32767
+    // @User: Advanced
+    // @Units: m
+    AP_GROUPINFO("LIST_ALT",   12, AP_ADSB, in_state.list_altitude, 0),
+
 
     AP_GROUPEND
 };
@@ -366,6 +375,7 @@ void AP_ADSB::handle_vehicle(const mavlink_message_t* packet)
     bool my_loc_is_zero = _my_loc.is_zero();
     float my_loc_distance_to_vehicle = _my_loc.get_distance(vehicle_loc);
     bool out_of_range = in_state.list_radius > 0 && !my_loc_is_zero && my_loc_distance_to_vehicle > in_state.list_radius;
+    bool out_of_range_alt = in_state.list_altitude > 0 && !my_loc_is_zero && abs(vehicle_loc.alt - _my_loc.alt) > in_state.list_altitude*100;
     bool is_tracked_in_list = find_index(vehicle, &index);
     uint32_t now = AP_HAL::millis();
 
@@ -377,6 +387,7 @@ void AP_ADSB::handle_vehicle(const mavlink_message_t* packet)
 
     if (vehicle_loc.is_zero() ||
             out_of_range ||
+            out_of_range_alt ||
             detected_ourself ||
             (vehicle.info.ICAO_address > 0x00FFFFFF) || // ICAO address is 24bits, so ignore higher values.
             !(vehicle.info.flags & required_flags_position) ||

libraries/AP_ADSB/AP_ADSB.h

@@ -133,6 +133,7 @@ private:
         adsb_vehicle_t *vehicle_list = nullptr;
         uint16_t    vehicle_count;
         AP_Int32    list_radius;
+        AP_Int16    list_altitude;
 
         // streamrate stuff
         uint32_t    send_start_ms[MAVLINK_COMM_NUM_BUFFERS];