feat(simulation): add sensor_adsb_sim for simulated ADS-B traffic

ROMFS/px4fmu_common/init.d-posix/px4-rc.gzsim

@@ -199,3 +199,7 @@ if param compare -s SENS_EN_ARSPDSIM 1
 then
 	sensor_airspeed_sim start
 fi
+if param compare -s SENS_EN_ADSBSIM 1
+then
+	sensor_adsb_sim start
+fi

ROMFS/px4fmu_common/init.d-posix/px4-rc.sihsim

@@ -31,6 +31,10 @@ if simulator_sih start; then
 	then
 		sensor_agp_sim start
 	fi
+	if param compare -s SENS_EN_ADSBSIM 1
+	then
+		sensor_adsb_sim start
+	fi
 
 else
 	echo "ERROR [init] simulator_sih failed to start"

ROMFS/px4fmu_common/init.d/rcS

@@ -392,6 +392,10 @@ else
 			sensor_mag_sim start
 			sensor_gps_sim start
 			sensor_agp_sim start
+			if param compare -s SENS_EN_ADSBSIM 1
+			then
+				sensor_adsb_sim start
+			fi
 		fi
 
 	else

src/modules/simulation/Kconfig

@@ -8,6 +8,7 @@ menu "Simulation"
         select MODULES_SIMULATION_SENSOR_AIRSPEED_SIM
         select MODULES_SIMULATION_SENSOR_BARO_SIM
         select MODULES_SIMULATION_SENSOR_GPS_SIM
+        select MODULES_SIMULATION_SENSOR_ADSB_SIM
         select MODULES_SIMULATION_SENSOR_MAG_SIM
         select MODULES_SIMULATION_SYSTEM_POWER_SIMULATOR
         select MODULES_SIMULATION_SIMULATOR_MAVLINK

src/modules/simulation/sensor_adsb_sim/CMakeLists.txt

@@ -0,0 +1,45 @@
+############################################################################
+#
+#   Copyright (c) 2026 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+px4_add_module(
+	MODULE modules__simulation__sensor_adsb_sim
+	MAIN sensor_adsb_sim
+	COMPILE_FLAGS
+	SRCS
+		SensorAdsbSim.cpp
+		SensorAdsbSim.hpp
+	MODULE_CONFIG
+		parameters.yaml
+	DEPENDS
+		px4_work_queue
+	)

src/modules/simulation/sensor_adsb_sim/Kconfig

@@ -0,0 +1,5 @@
+menuconfig MODULES_SIMULATION_SENSOR_ADSB_SIM
+	bool "sensor_adsb_sim"
+	default n
+	---help---
+		Enable support for sensor_adsb_sim

src/modules/simulation/sensor_adsb_sim/SensorAdsbSim.cpp

@@ -0,0 +1,237 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2026 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#include "SensorAdsbSim.hpp"
+
+#include <mathlib/mathlib.h>
+
+#include <cstdio>
+#include <cstdlib>
+#include <cmath>
+
+ModuleBase::Descriptor SensorAdsbSim::desc{task_spawn, custom_command, print_usage};
+
+SensorAdsbSim::SensorAdsbSim() :
+	ModuleParams(nullptr),
+	ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::hp_default)
+{
+	srand((unsigned)hrt_absolute_time()); // seed with time so that each run produces different random traffic patterns
+}
+
+SensorAdsbSim::~SensorAdsbSim()
+{
+	perf_free(_loop_perf);
+}
+
+bool SensorAdsbSim::init()
+{
+	ScheduleOnInterval(1_s); // 1 Hz matches real ADS-B transponder squitter rate
+	return true;
+}
+
+float SensorAdsbSim::random_float(float min, float max)
+{
+	return min + (max - min) * (float)rand() / (float)RAND_MAX;
+}
+
+void SensorAdsbSim::spawn_vehicle(uint8_t index, double lat_ref, double lon_ref)
+{
+	SimulatedVehicle &v = _vehicles[index];
+
+	const float radius  = _param_radius.get();
+	const float bearing = random_float(0.f, 2.f * M_PI_F);
+	const float distance = random_float(radius * 0.5f, radius);
+
+	waypoint_from_heading_and_distance(lat_ref, lon_ref, bearing, distance, &v.lat, &v.lon);
+	v.alt = _param_alt.get();
+
+	const float speed   = random_float(MIN_SPEED_M_S, MAX_SPEED_M_S);
+	const float heading = random_float(0.f, 2.f * M_PI_F);
+	v.vel_n = speed * cosf(heading);
+	v.vel_e = speed * sinf(heading);
+	v.vel_u = random_float(-MAX_VERTICAL_SPEED_M_S, MAX_VERTICAL_SPEED_M_S);
+
+	// Stable ICAO per slot so the conflict buffer doesn't accumulate stale entries on respawn
+	v.icao_address = ICAO_BASE + index;
+
+	v.emitter_type = EMITTER_TYPES[rand() % sizeof(EMITTER_TYPES)];
+
+	v.initialized = true;
+}
+
+void SensorAdsbSim::Run()
+{
+	if (should_exit()) {
+		ScheduleClear();
+		exit_and_cleanup(desc);
+		return;
+	}
+
+	perf_begin(_loop_perf);
+
+	if (_parameter_update_sub.updated()) {
+		parameter_update_s param_update;
+		_parameter_update_sub.copy(&param_update);
+		updateParams();
+	}
+
+	vehicle_global_position_s gpos{};
+
+	if (!_vehicle_global_position_sub.copy(&gpos) || gpos.timestamp == 0) {
+		perf_end(_loop_perf);
+		return;
+	}
+
+	const hrt_abstime now = hrt_absolute_time();
+	const float dt = math::constrain((now - _last_update) * 1e-6f, 0.001f, 2.0f);
+	_last_update = now;
+
+	const int count  = math::min((int)_param_count.get(), (int)MAX_VEHICLES);
+	const float radius = _param_radius.get();
+
+	for (int i = 0; i < count; i++) {
+		SimulatedVehicle &v = _vehicles[i];
+
+		if (!v.initialized) {
+			spawn_vehicle(i, gpos.lat, gpos.lon);
+		}
+
+		// Respawn if the aircraft has flown out of the radius
+		float dist_h, dist_v;
+		get_distance_to_point_global_wgs84(gpos.lat, gpos.lon, gpos.alt,
+						   v.lat, v.lon, v.alt, &dist_h, &dist_v);
+
+		if (dist_h > radius || v.alt < 0.f || v.alt > _param_alt.get() + 1000.f) {
+			spawn_vehicle(i, gpos.lat, gpos.lon);
+		}
+
+		// Integrate position forward using flat-earth approximation
+		v.lat += (double)(v.vel_n * dt) / CONSTANTS_RADIUS_OF_EARTH * (180.0 / M_PI);
+		v.lon += (double)(v.vel_e * dt) / (CONSTANTS_RADIUS_OF_EARTH * cos(v.lat * M_PI / 180.0)) * (180.0 / M_PI);
+		v.alt += v.vel_u * dt;
+
+		// Course over ground [0, 2pi], north = 0
+		float cog = atan2f(v.vel_e, v.vel_n);
+
+		if (cog < 0.f) {
+			cog += 2.f * M_PI_F;
+		}
+
+		transponder_report_s report{};
+		report.timestamp     = now;
+		report.icao_address  = v.icao_address;
+		report.lat           = v.lat;
+		report.lon           = v.lon;
+		report.altitude_type = 1;
+		report.altitude      = v.alt;
+		report.heading       = cog;
+		report.hor_velocity  = sqrtf(v.vel_n * v.vel_n + v.vel_e * v.vel_e);
+		report.ver_velocity  = v.vel_u;
+		report.emitter_type  = v.emitter_type;
+		report.tslc          = 1;
+		report.squawk        = 1200;
+		report.flags         = transponder_report_s::PX4_ADSB_FLAGS_VALID_COORDS
+				       | transponder_report_s::PX4_ADSB_FLAGS_VALID_ALTITUDE
+				       | transponder_report_s::PX4_ADSB_FLAGS_VALID_HEADING
+				       | transponder_report_s::PX4_ADSB_FLAGS_VALID_VELOCITY
+				       | transponder_report_s::PX4_ADSB_FLAGS_VALID_CALLSIGN
+				       | transponder_report_s::PX4_ADSB_FLAGS_VALID_SQUAWK
+				       | transponder_report_s::PX4_ADSB_FLAGS_RETRANSLATE;
+
+		snprintf(report.callsign, sizeof(report.callsign), "SIM%02u", i);
+
+		_transponder_report_pub.publish(report);
+	}
+
+	perf_end(_loop_perf);
+}
+
+int SensorAdsbSim::task_spawn(int argc, char *argv[])
+{
+	SensorAdsbSim *instance = new SensorAdsbSim();
+
+	if (instance) {
+		desc.object.store(instance);
+		desc.task_id = task_id_is_work_queue;
+
+		if (instance->init()) {
+			return PX4_OK;
+		}
+
+	} else {
+		PX4_ERR("alloc failed");
+	}
+
+	delete instance;
+	desc.object.store(nullptr);
+	desc.task_id = -1;
+
+	return PX4_ERROR;
+}
+
+int SensorAdsbSim::custom_command(int argc, char *argv[])
+{
+	return print_usage("unknown command");
+}
+
+int SensorAdsbSim::print_usage(const char *reason)
+{
+	if (reason) {
+		PX4_WARN("%s\n", reason);
+	}
+
+	PRINT_MODULE_DESCRIPTION(
+		R"DESCR_STR(
+### Description
+
+Publishes simulated ADS-B transponder reports for nearby traffic, enabling
+testing of Navigator conflict detection and avoidance without hardware.
+
+Each simulated aircraft is assigned a stable ICAO address per slot, spawned
+at a random bearing and distance within SIM_ADSB_RADIUS, and flies a constant
+random heading at a random speed. Aircraft that leave the radius, hit the
+ground, or exceed the max alt by 1000m are re-spawned at a new random position.
+
+)DESCR_STR");
+
+	PRINT_MODULE_USAGE_NAME("sensor_adsb_sim", "system");
+	PRINT_MODULE_USAGE_COMMAND("start");
+	PRINT_MODULE_USAGE_DEFAULT_COMMANDS();
+
+	return 0;
+}
+
+extern "C" __EXPORT int sensor_adsb_sim_main(int argc, char *argv[])
+{
+	return ModuleBase::main(SensorAdsbSim::desc, argc, argv);
+}