PoC 3 - Synchronized USV Hydrophone Dataset for Ocean Noise Pollution Monitoring (Trials 1 & 2)

OpenSwarm PoC 3: Synchronized USV Hydrophone Dataset for Ocean Noise Pollution Monitoring (Trials 1 & 2) Abstract This dataset contains acoustic, spatial, and synchronization data collected during Trial 1 (2026.03.04). and Trial 2 (2026.04.20) of the OpenSwarm European Project, specifically supporting Proof of Concept (PoC) 3: Ocean Noise Pollution Monitoring. The primary objective of this dataset is to provide highly synchronized multi-node acoustic recordings of marine environments to evaluate noise pollution. The setup features a distributed network of Unmanned Surface Vehicles (USVs) configured as sensory buoys, alongside a mobile ground-truth sound source. A critical feature of this dataset is the implementation of a wireless local synchronization system across all nodes, ensuring a common timestamp reference for precise spatiotemporal analysis of the acoustic data. Description of the Files Trial 1: 2026.03.04 2026_03_04_datasets.zip: dataset 2026_03_04_drone_dji_top_view.mp4: video from the drone camera at the top of the experiment Trial 2: 2026.04.20 2026_04_20_datasets.zip: dataset 2026_04_20_top_view.zip: video from the drone camera at the top of the experiment Experimental Setup & Hardware The experimental architecture consists of four primary nodes—three stationary sensory buoys and one mobile ground-truth vessel. Sensory Nodes (x3 USV Buoys): Acoustic Sensors: Each buoy is equipped with an array of three H1a Hydrophones (Aquarian Audio). Acquisition & Compute: Acoustic signals are processed via a HiFiBerry DAC+ ADC HAT connected to a Raspberry Pi. Synchronization: A SmartMesh (LTC5800) wireless synchronization system is deployed across all nodes, providing a common time-span reference updating at a frequency of 2Hz. Ground-Truth Node (x1 Vessel): Vessel Specifications: A 4-meter boat powered by a petrol engine, acting as the primary acoustic source for validation and testing. Spatial Tracking: Equipped with a RTK (Real-Time Kinematic) GPS module for high-precision localization. Synchronization: Integrated with the same SmartMesh (LTC5800) system to perfectly align the boat's spatial data and engine noise events with the acoustic data captured by the sensory buoys. Data Structure & Formats The dataset provides raw and processed data streams across multiple standard formats to facilitate robotic framework integration and standalone signal processing. ROS 2 Bags (.db3): Contains the complete serialized message streams for all sensor topics, allowing for full playback of the experimental trials within a Robot Operating System 2 (ROS 2) environment. CSV Files (.csv): Extracted tabular data for straightforward data analysis. These files contain: High-precision RTK GPS positioning (Ground Truth). SmartMesh synchronization timestamps (2Hz). Corresponding ROS time (rostime). Sensor telemetry and metadata. Audio Files (.wav): Uncompressed, raw multi-channel acoustic data captured by the H1a hydrophone arrays, synced to the timeline established by the SmartMesh system. Topics /mavros/gpsstatus/gps1/raw mavros_msgs/GPSRAW /rms_stream/data msg/StreamData.msg mavros_msgs/GPSRAW # FCU GPS RAW message for the gps_status plugin # A merge of mavlink GPS_RAW_INT and # mavlink GPS2_RAW messages. std_msgs/Header header ## GPS_FIX_TYPE enum uint8 GPS_FIX_TYPE_NO_GPS = 0 # No GPS connected uint8 GPS_FIX_TYPE_NO_FIX = 1 # No position information, GPS is connected uint8 GPS_FIX_TYPE_2D_FIX = 2 # 2D position uint8 GPS_FIX_TYPE_3D_FIX = 3 # 3D position uint8 GPS_FIX_TYPE_DGPS = 4 # DGPS/SBAS aided 3D position uint8 GPS_FIX_TYPE_RTK_FLOATR = 5 # TK float, 3D position uint8 GPS_FIX_TYPE_RTK_FIXEDR = 6 # TK Fixed, 3D position uint8 GPS_FIX_TYPE_STATIC = 7 # Static fixed, typically used for base stations uint8 GPS_FIX_TYPE_PPP = 8 # PPP, 3D position uint8 fix_type # [GPS_FIX_TYPE] GPS fix type int32 lat # [degE7] Latitude (WGS84, EGM96 ellipsoid) int32 lon # [degE7] Longitude (WGS84, EGM96 ellipsoid) int32 alt # [mm] Altitude (MSL). Positive for up. Note that virtually all GPS modules provide the MSL altitude in addition to the WGS84 altitude. uint16 eph # GPS HDOP horizontal dilution of position (unitless). If unknown, set to: UINT16_MAX uint16 epv # GPS VDOP vertical dilution of position (unitless). If unknown, set to: UINT16_MAX uint16 vel # [cm/s] GPS ground speed. If unknown, set to: UINT16_MAX uint16 cog # [cdeg] Course over ground (NOT heading, but direction of movement), 0.0..359.99 degrees. If unknown, set to: UINT16_MAX uint8 satellites_visible # Number of satellites visible. If unknown, set to 255 # -*- only available with MAVLink v2.0 and GPS_RAW_INT messages -*- int32 alt_ellipsoid # [mm] Altitude (above WGS84, EGM96 ellipsoid). Positive for up. uint32 h_acc # [mm] Position uncertainty. Positive for up. uint32 v_acc # [mm] Altitude uncertainty. Positive for up. uint32 vel_acc # [mm] Speed uncertainty. Positive for up. int32 hdg_acc # [degE5] Heading / track uncertainty uint16 yaw # [cdeg] Yaw in earth frame from north. # -*- only available with MAVLink v2.0 and GPS2_RAW messages -*- uint8 dgps_numch # Number of DGPS satellites uint32 dgps_age # [ms] Age of DGPS info msg/StreamData.msg string timestamp sensor_msgs/NavSatFix localization std_msgs/Float64MultiArray rms_data string node_id string utc_time std_msgs/Float64MultiArray raw_data