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Manufacturers of Underwater Acoustic Solutions
Exail
Cutting-Edge Acoustic Positioning & Subsea Imagery Solutions for Unmanned & Robotic Systems
Platinum Partner
Teledyne Marine
Autonomous and Unmanned Marine Vehicles: USV, AUV, Marine ROV; Profiling Floats & Towed Systems
Platinum Partner
Cerulean Sonar
Advanced Underwater Imaging & Positioning Solutions for Uncrewed & Autonomous Marine Vehicles
Gold Partner
ALSEAMAR
Leading-Edge Solutions & Services for Defense, Ocean & Marine Energies Applications
Gold Partner
Kraken Robotics
Innovative High-Resolution Subsea Imaging and Power Technologies for Commercial, Scientific & Military Underwater Survey Missions
Gold Partner
SatLab Geosolutions
GNSS Positioning Systems, 3D SLAM & Mobile Mapping, Unmanned Surface Vehicles
Gold Partner
Sonardyne International
Tracking, Navigation, Positioning and Communication Sensors for AUV, ROV, USV
Gold Partner
Forcys
Integrated Systems & Payloads for Unmanned Surface & Underwater Platforms Operating in Complex Maritime Environments
Silver Partner
Hydro-Tech
Hydrographic Survey Equipment: Multibeam Echo Sounders, Side Scan Sonars, Sound Velocity Sensors & Profilers
Silver Partner
CHC Navigation
GNSS Positioning & Navigation Systems, Mobile Mapping UAV LiDAR & Unmanned Surface Vehicles
Silver Partner
Airmar Technology Corporation
Weather Monitoring Stations, Marine Transducers, Side-Scan Sonar & Underwater Altimeters
Silver Partner
Underwater Acoustic Products & Sensors
Overview of Underwater Acoustics for ROV, AUV & USV Systems
Introduction to Underwater Acoustic Systems
Underwater acoustic systems provide the core mechanism for sensing, communicating, and navigating beneath the surface, where conventional radio-frequency signals, including satellite navigation signals, attenuate rapidly. Remotely Operated Vehicles (ROVs) often rely on sonar and echosounders for piloting and close-range inspection, while Autonomous Underwater Vehicles (AUVs) may carry acoustic payloads for mapping, target detection, and navigation. Unmanned Surface Vessels (USVs) serve as surface nodes and communication gateways between subsea assets and topside operators.
Evaluating underwater acoustics requires looking beyond nominal range figures or operating frequencies. Factors like platform self-noise, sound-speed variations, water depth, seabed composition, and vehicle dynamics directly influence signal quality. Engineers must design underwater acoustic transducers, signal processing electronics, and mechanical mountings as an integrated platform capability, often fusing acoustic data with inertial navigation systems (INS), Doppler velocity logs (DVL), pressure depth sensors, and surface GNSS inputs.
Key Types of Underwater Acoustic Sensors
Underwater Acoustic Transducers
An underwater acoustic transducer converts energy between electrical and acoustic forms, operating as a projector during transmission and an underwater acoustic sensor or hydrophone during reception. Many sonar heads and underwater acoustic modem systems use reversible piezoelectric ceramic elements configured as rings, stacks, or composites to balance beamwidth, sensitivity, bandwidth, and depth rating. Sensor selection depends on factors such as usable bandwidth, transmitting and receiving response, beam pattern, and impedance matching, with hydrophone calibration guided by standards such as IEC 60500 and the IEC 60565 series.
Hydrophone and Sonar Array Configurations
HydroFlow ACDP by SatLab Geosolutions
Arrays combine multiple underwater acoustic sensors in precise geometries to estimate target bearing, form directional beams, and suppress ambient background noise. Configurations range from linear towed arrays and planar grids to hull-conformal arrays. Overall aperture and operating frequency influence angular resolution, while element spacing must be controlled to avoid spatial grating lobes. Onboard underwater acoustic signal processing can execute adaptive beamforming at the edge, while fairings and decoupled mountings help isolate arrays from thruster noise and structural vibration.
Active Sonar Systems
Active sonar transmits known acoustic waveforms and processes returning echoes to calculate range and bearing, estimate relative velocity, and characterize physical targets. Systems range from forward-looking sonar for ROV piloting and side-scan or multibeam echosounders for seabed imaging and bathymetry to synthetic aperture sonar and acoustic video systems for high-resolution imaging. System selection balances the longer potential range of lower frequencies against the finer spatial detail generally available at higher frequencies. Many systems use frequency-modulated chirp pulses and pulse-compression processing to improve range resolution and signal-to-noise performance.
Passive Acoustic Sensing
SMART Transponder by Sonardyne International
Passive acoustic systems monitor ambient soundscapes without emitting signals, making them valuable for covert naval operations and long-duration environmental monitoring. Processing pipelines use time-frequency analysis to detect machinery tones, cavitation, and biological vocalizations from hydrophone arrays. Embedded machine learning algorithms can support automated contact detection and classification onboard, providing real-time classification cues while minimizing bandwidth demands for underwater acoustic monitoring.
Underwater Acoustic Communications
An underwater acoustic modem enables wireless subsea communication between vehicles, seabed instruments, and surface gateways for command updates and telemetry exchange. Given long propagation delays, multipath reflections, and Doppler shifts, a reliable underwater acoustic communication system employs robust modulation schemes, channel coding, and signal processing adapted to the acoustic channel. Standardization frameworks like JANUS digital underwater acoustic communications (STANAG 4748) provide a common digital signalling method for initial contact and basic interoperability across multi-vendor subsea assets.
Acoustic Positioning and Navigation
An underwater acoustic positioning system calculates subsea coordinates using signal travel times and, depending on the architecture, direction-of-arrival measurements between transducers. These systems operate through Ultra-Short Baseline (USBL), Short Baseline (SBL), or seabed Long Baseline (LBL) configurations. Modern navigation integrates acoustic range or position fixes with an inertial navigation system (INS), Doppler velocity log (DVL), and depth sensors inside an Extended Kalman Filter to bound long-term position drift. Auxiliary hardware, including underwater acoustic beacons and underwater acoustic releases, supports transponder networks and the recovery of deployed instruments or moorings.
Key Applications of Underwater Acoustic Systems
Anti-Submarine Warfare and Mine Countermeasures
Unmanned surface and subsea assets extend naval reach by deploying passive towed arrays, variable-depth sonar, and low-frequency active sensors for submarine detection and tracking. For mine countermeasures, AUVs carry synthetic aperture sonar and multibeam payloads to execute autonomous search patterns and map seabed clutter, using automated target recognition software to flag potential hazards without placing personnel in risk zones.
Underwater Intrusion Detection and Diver Detection
Advanced Navigation’s Subsonus Underwater Acoustic Positioning System
High-frequency active diver detection sonar protects harbors, naval bases, and offshore assets by detecting and tracking small, slow-moving targets such as open-circuit divers and small UUVs. Automated software filters background reverberation and biological noise, fusing acoustic tracks with surface radar, AIS feeds, and electro-optical cameras to create a more complete security picture.
Hydrographic and Bathymetric Surveying
Hydrographic surveys utilize multibeam echosounders mounted on USVs and AUVs to generate high-density bathymetric models, while side-scan sonars produce detailed imagery of seabed texture and objects. Bathymetric or interferometric side-scan systems can also derive depth information. USVs improve survey efficiency and safety in shallow or hazardous surface environments, while AUVs can maintain stable altitudes close to the seafloor for high-resolution data collection.
Offshore Energy and Subsea Infrastructure Inspection
Offshore energy operators rely on imaging sonars, subsea acoustic products, and acoustic video systems to inspect pipelines, jacket structures, and subsea cables in zero-visibility conditions. Georeferenced positioning supports precise anomaly tracking, enabling comparative change detection over successive inspection cycles.
Bioacoustics and Environmental Monitoring
Bioacoustic monitoring uses passive hydrophones on ocean gliders, moorings, and drifting buoys to track marine mammal vocalizations and ambient noise without introducing artificial sound. Automated processing screens continuous recordings and can deliver near-real-time environmental monitoring or compliance data to topside receivers via surface gateways.
Standards and Regulatory Considerations
Establishing clear operational frameworks and measurement protocols relies on globally recognized industry standards.
- ISO Standards for Underwater Acoustic Measurement: Provide standardized terminology, quantities, measurement methods, and reporting procedures for specific underwater acoustic applications.
- ISO 17208 Ship Underwater-Radiated Noise Measurement: Defines procedures for measuring and reporting vessel underwater-radiated noise, with different parts addressing deep-water and shallow-water measurement conditions.
- IEC Standards for Electroacoustics and Hydrophones: Define hydrophone characteristics and calibration methods across specified frequency ranges and acoustic field conditions.
- NATO Standards for Underwater Acoustic Communications: Establish common signalling and interoperability requirements for selected military underwater communication applications.
- JANUS Digital Underwater Signalling: Defines an open digital signalling standard for initial subsea contact, identification, and coordination.
Adhering to these international benchmarks supports cross-platform interoperability, reliable calibration, consistent measurement, and environmental compliance across diverse marine operations.
Emerging Underwater Acoustic Technologies
Recent developments in digital processing and hybrid sensor payloads are reshaping the capabilities of unmanned subsea platforms.
- Software-Defined Acoustic Systems: Dynamically changes frequencies, waveforms, and processing functions through software updates within the limits of the acoustic hardware.
- Integrated Acoustic and Optical Communications: Combines long-range acoustic communication and link coordination with high-speed optical terminals for close-range data offloading.
- Acoustic-Inertial Cooperative Navigation: Shares acoustic ranges across vehicle clusters to bound inertial drift and potentially reduce dependence on seabed transponders.
- Persistent Seabed Sensor Networks: Uses low-power subsea nodes with edge processing to monitor strategic maritime zones continuously.
These technological advancements are expanding the operational duration, autonomy, and payload throughput of unmanned subsea fleets.
