Fact-checked by Grok 2 weeks ago

Side-scan sonar

Side-scan sonar is an active acoustic imaging system that uses a transducer array to emit fan-shaped pulses of sound waves perpendicular to the direction of travel, capturing echoes from the seafloor to produce high-resolution images of underwater terrain, objects, and features.^[1] These systems typically operate at frequencies ranging from 50 kHz to 1 MHz, with lower frequencies providing broader coverage for large-area surveys and higher frequencies enabling detailed resolution down to centimeters for smaller targets.^[2] The resulting sonographs typically depict areas of strong backscatter (such as hard rocks or shipwrecks) as darker shades and weaker returns (from soft sediments) as lighter tones, though conventions can vary with processing, allowing for efficient mapping without direct contact with the bottom.^[1] Developed in the early 1960s by engineers Martin Klein and Harold Edgerton at MIT, side-scan sonar evolved from World War II-era acoustic detection technologies to become commercially viable for civilian use following declassification of related patents.^[3]^[4] Its principles rely on the propagation of sound in water, where pulse travel time and echo intensity determine range and reflectivity, though it does not measure depth (bathymetry) and is often complemented by multibeam or single-beam sonar for three-dimensional profiling.^[2] Key advantages include wide swath widths—up to several kilometers—and rapid coverage rates, making it far more efficient than visual surveys from remotely operated vehicles for expansive areas.^[1] Side-scan sonar finds broad applications in marine science, including seafloor habitat characterization, underwater archaeology (e.g., locating shipwrecks), environmental monitoring, and resource exploration.^[1] In fisheries management, it aids in estimating fish school densities by detecting acoustic returns from aggregated populations.^[5] Military and security uses encompass mine countermeasures and search-and-recovery operations, while offshore engineering employs it for pipeline routing and geohazard assessment.^[2] Limitations such as signal distortion from water currents or bottom roughness highlight the need for skilled interpretation, but ongoing advancements in digital processing continue to enhance image quality and automation.^[2]

Principles of Operation

Basic Mechanism

Side-scan sonar is an active sonar system that emits acoustic pulses into the water to produce two-dimensional images of the seafloor and submerged objects. It operates by transmitting short bursts of sound from a transducer and measuring the intensity and time-of-flight of returning echoes, which reflect off underwater features based on their acoustic properties such as hardness and composition.^[1]^[6] Stronger echoes from hard surfaces like rocks or wrecks appear darker in the resulting imagery, while weaker returns from soft sediments like sand or mud appear lighter, enabling visualization of seafloor texture and topography.^[1] The system employs a fan-shaped beam pattern to achieve broad coverage. The beam is narrow in the along-track direction, typically 1-2 degrees, to provide good resolution parallel to the vehicle's path, and wide in the across-track direction, often up to 100 degrees or more, allowing a swath perpendicular to the motion that can span hundreds of meters depending on frequency and depth.^[6]^[7] As the sonar platform—such as a towed vehicle or hull-mounted unit—moves forward at a constant speed, the sweeping beam insonifies successive strips of the seafloor, building a continuous acoustic image over time.^[1] To ensure uniform image brightness despite acoustic signal weakening with distance, side-scan sonar incorporates time-variable gain (TVG), which dynamically amplifies received echoes based on their travel time. TVG compensates for attenuation due to geometric spreading and absorption in water, applying increasing gain as range from the transducer grows, thereby normalizing echo intensities across the swath.^[8]^[9] Echoes from the seafloor also produce shadow zones behind obstacles, where no acoustic returns occur due to blockage of the beam. These shadows appear as light areas in the image and allow inference of object height and shape, as the shadow length is proportional to the obstacle's elevation relative to the surrounding terrain.^[7]^[6] Range resolution, which determines the ability to distinguish closely spaced features along the beam's radial direction, is governed by the equation:

\delta r = \frac{c}{2B}

where c is the speed of sound in water (approximately 1500 m/s) and B is the sonar's bandwidth. Wider bandwidths yield finer resolution, enabling detailed imaging of small-scale features.^[6]

Acoustic Signal Characteristics

Side-scan sonar systems employ acoustic signals across a range of frequencies to balance coverage and resolution in underwater imaging. Low-frequency operations, typically between 30 and 100 kHz, enable long-range coverage extending up to several kilometers, suitable for broad-area surveys where detailed imagery is secondary to swath width.^[10] In contrast, high-frequency signals from 300 kHz to 1 MHz provide centimeter-scale resolution for fine-scale features, though limited to shorter ranges due to increased attenuation.^[1] These frequency choices directly influence the trade-offs in system performance, as higher frequencies attenuate more rapidly in seawater, with absorption coefficient α approximately proportional to the square of the frequency (α ≈ f²), reducing signal strength over distance.^[11] The temporal characteristics of the acoustic pulses are optimized for range resolution. Pulses are typically short, lasting on the order of microseconds (e.g., 100 μs), which allows discrimination of closely spaced targets along the range axis by minimizing temporal overlap in echoes.^[12] Pulse repetition rates are adjusted dynamically, often around 4 Hz, to prevent interference between successive pings across the swath, ensuring that the time for a full round-trip echo exceeds the interval between transmissions.^[13] Beamforming enhances directional control of the acoustic signal through phased array transducers. These arrays consist of multiple elements whose phases are adjusted to steer and shape the beam, producing a narrow fan in the along-track direction for focused ensonification. The along-track beam width θ is fundamentally determined by the formula θ ≈ λ / D (in radians, for small angles), where λ is the acoustic wavelength and D is the aperture size of the array; more precisely, the half-power beam width in degrees is approximately 50.6 × (λ / D).^[14] This relationship underscores how larger apertures or shorter wavelengths (higher frequencies) yield narrower beams, improving angular resolution but requiring trade-offs in array design. Signal propagation is profoundly affected by water column properties, particularly salinity and temperature, which govern the speed of sound c, approximately 1500 m/s in typical seawater.^[15] Increases in salinity (e.g., from 0 to 35 ppt) raise c by about 1.3 m/s per ppt, while temperature rises of 1°C can boost it by roughly 4 m/s; these variations create sound speed profiles that refract beams, potentially distorting range estimates if not accounted for.^[15] Such environmental factors thus necessitate calibration to maintain accurate signal timing and imaging fidelity.

System Components and Processing

Hardware Elements

The towfish serves as the primary underwater vehicle in a side-scan sonar system, designed as a streamlined, torpedo-shaped housing to minimize hydrodynamic drag while traversing the seafloor. It encapsulates the transducers and associated electronics, typically towed 50 to 100 meters behind a surface vessel to maintain optimal positioning away from surface noise and prop wash. In modern configurations, towfish can also be integrated into autonomous underwater vehicles (AUVs) or remotely operated vehicles (ROVs) for self-propelled operations in constrained environments. For stability during towing, the towfish often incorporates tailfins or wings, along with safety features such as weak links to detach from obstructions.^[7]^[16]^[17] Transducer arrays form the core acoustic elements within the towfish, consisting of port and starboard pairs arranged in linear configurations to enable bilateral imaging of the seafloor. These arrays, typically mounted on opposite sides of the towfish, convert electrical signals into acoustic pulses and vice versa, utilizing piezoelectric ceramics such as lead zirconate titanate (PZT) for efficient energy transduction. The transducers generate a fan-shaped beam perpendicular to the vehicle's path, with higher-frequency variants (e.g., 500 kHz) providing sharper resolution for detailed surveys and lower-frequency ones (e.g., 100 kHz) covering broader areas.^[18]^[19]^[20] Cable and deployment systems facilitate the connection between the towfish and surface platform, comprising armored coaxial or fiber-optic tow cables that transmit power, data, and control signals while withstanding underwater stresses. These cables, often 50 to 150 meters in length depending on survey depth, are deployed via mechanical winches on the vessel for controlled payout and retrieval, enabling variable tow altitudes typically 10 to 20 percent of the desired imaging range. Depth control is achieved through integrated depressors or hydroplanes on the towfish, which help maintain a consistent altitude above the seafloor despite currents or vessel motion.^[7]^[21]^[19] Integration with navigation systems ensures precise georeferencing of sonar data, incorporating global positioning system (GPS) receivers and inertial navigation systems (INS) on the surface vessel to track towfish position in real-time. These systems account for cable layback—the horizontal offset between the vessel and towfish—using motion sensors like gyrocompasses for accurate positioning. Winches with tension monitoring further support dynamic adjustments to tow depth, optimizing coverage during surveys.^[18]^[16] The evolution toward compact systems has produced portable side-scan sonar units suitable for small boats, drones, or handheld deployment, with towfish weighing under 10 kg to enhance mobility for search-and-recovery operations. These lightweight designs retain dual-frequency capabilities and streamlined housings but prioritize ease of handling, often with shorter cables (e.g., 50 meters) and simplified winch setups for rapid deployment by single operators. Such systems are particularly valued in law enforcement and environmental monitoring, where accessibility outweighs the need for extensive vessel support.^[7]^[21]

Data Processing Techniques

Raw side-scan sonar (SSS) data, acquired from transducers as time-series intensity returns, undergoes a series of processing steps to correct distortions and enhance interpretability. These techniques transform acoustic backscatter measurements into geometrically accurate images, accounting for factors like vehicle motion, altitude variations, and environmental noise. Key processes include bottom detection, noise suppression, image stitching, and advanced automation via artificial intelligence.^[22] Bottom-tracking algorithms are essential for estimating the sonar's altitude above the seafloor, enabling corrections for geometric distortions caused by terrain variations and slant-range effects. These methods typically analyze the intensity profile of each acoustic ping to identify the first strong return from the seabed, distinguishing it from water-column echoes. A universal automatic approach employs semantic segmentation with deep learning models like DeepLabv3+, enhanced by symmetrical information synthesis to exploit the bilateral symmetry in SSS images, achieving sub-pixel accuracy in bottom-line detection across diverse seafloor topographies. This coarse-to-fine strategy processes images in overlapping patches, refines classifications by removing symmetric water-column interference, and uses a fast search from prior pings to track the bottom line, supporting real-time adjustments for undulating terrains. Earlier adaptive techniques, such as those based on LOG/Canny edge detection combined with threshold segmentation, further improve robustness in noisy conditions by iteratively refining the bottom boundary.^[23]^[24] Speckle noise, arising from coherent acoustic scattering, degrades SSS image quality by introducing granular artifacts that obscure fine details. Reduction techniques focus on adaptive filtering to smooth homogeneous regions while preserving edges and point targets. The Lee filter applies a local statistics-based correction, weighting each pixel by the ratio of noise variance to image variance, effectively acting as a low-pass filter in low-variance areas and retaining details in high-contrast edges. Similarly, the Frost filter uses an exponentially damped convolution kernel that adapts damping based on local intensity, inhibiting smoothing across boundaries to maintain structural integrity. Comparative evaluations on SSS datasets demonstrate that both filters yield high peak signal-to-noise ratios (e.g., Lee: ~33.9 dB, Frost: ~33.8 dB at low noise levels) and structural similarity indices, outperforming non-adaptive methods like median filtering in edge preservation without excessive blurring.^[25]^[26] Mosaicking integrates multiple SSS swaths into seamless, large-scale maps by addressing overlaps and geometric inconsistencies. The process begins with georectification, projecting raw slant-range images onto a horizontal plane using bottom-tracking altitudes and navigation data to correct for distortions. Overlap correction then aligns adjacent strips via feature matching or affine transformations, blending intensities in common areas to eliminate seams—often employing resolution-weighted models that prioritize higher-quality regions based on metrics like gradient energy or entropy. Advanced fusion techniques, such as curvelet transforms, decompose images into multi-scale layers (coarse for low-frequency content, fine for details), fusing coefficients with maximum selection in detailed layers and resolution constraints in coarse ones, followed by inverse transformation for artifact-free composites. This yields georeferenced mosaics suitable for extended surveys, with USGS processing pipelines exemplifying the integration of radiometric equalization to ensure uniform backscatter representation.^[27]^[28] Recent integrations of artificial intelligence have revolutionized SSS data processing, particularly for automatic target detection and image enhancement. Convolutional neural networks (CNNs), such as improved YOLOv7 variants incorporating attention mechanisms like Swin-Transformer and CBAM, enable real-time classification of seafloor objects including shipwrecks, debris, aircraft, and marine hazards. Trained on datasets from 2020–2025 ocean experiments (e.g., SCTD with 366 images, SSS-VOC with 242 images), these models achieve mean average precisions of 77–88% at IoU 0.5, surpassing baselines by 8–9% through enhanced feature extraction for sparse, low-contrast targets. Such AI-driven enhancements also automate noise reduction and bottom-tracking, processing large-scale surveys with minimal human intervention while adapting to variable resolutions.^[29]^[30] Processed SSS data is typically output as grayscale images where pixel intensity directly corresponds to backscatter strength, facilitating intuitive interpretation of seafloor composition—darker tones for high backscatter (e.g., hard substrates) and lighter for low (e.g., soft sediments). These 8-bit or 256-level rasters, often in GeoTIFF format with 0.5–1 m resolution, incorporate enhancements like histogram equalization for uniform tonal distribution. Color mapping may be applied post-processing for visualization, assigning hues to intensity ranges (e.g., blue for low backscatter, red for high) to highlight geological features, though grayscale remains standard for quantitative analysis.^[22]^[31]^[32]

Applications

Military and Security

Side-scan sonar plays a critical role in military and security operations by providing high-resolution imaging of underwater environments to detect and classify submerged threats, enabling forces to conduct safe navigation and tactical maneuvers in contested waters.^[7] Its ability to produce detailed acoustic shadows and contours of objects distinguishes it for identifying hazards that forward-looking sonars might miss, leveraging basic imaging principles to reveal object shapes against the seafloor.^[33] In mine countermeasures (MCM), side-scan sonar is essential for detecting and classifying naval mines through high-resolution modes that analyze shape, size, and material properties, allowing operators to differentiate explosive threats from debris. Systems like the AN/AQS-20C, integrated into unmanned surface vessels, use side-scan arrays to scan wide swaths at depths up to 200 meters, achieving resolutions as fine as 5 centimeters for precise mine identification and neutralization.^[34] When combined with synthetic aperture sonar (SAS), these systems enhance azimuth resolution by coherently processing multiple pings, improving mine detection accuracy in cluttered environments by factors of 10 or more compared to conventional side-scan alone.^[35] For submarine and wreck detection, side-scan sonar facilitates long-range searches for submerged threats, mapping large areas to locate hostile vessels or downed aircraft that pose navigational or intelligence risks. Towed arrays on surface ships or submarines can cover swaths exceeding 1 kilometer at low frequencies (below 100 kHz), enabling the identification of wreck shadows and hull signatures even in turbid waters.^[36] Integration with SAS further refines this capability, providing spotlight-mode imaging with resolutions approaching optical quality over kilometers, as demonstrated in forensic searches for lost submarines where side-scan data corroborated visual confirmations.^[37] In maritime security, side-scan sonar supports border patrol and anti-smuggling efforts by detecting illegal vessels or submerged contraband, with real-time imaging aiding rapid response to incursions. During NATO's historical ordnance disposal operations in the Baltic Sea, towed side-scan systems classified seabed contacts over vast areas, contributing to the safe removal of unexploded munitions that threatened shipping lanes.^[38] Similarly, in protecting critical infrastructure, navies like Belgium's employ side-scan on unmanned platforms to scan for sabotage devices, increasing patrol frequency without risking manned assets.^[39] Stealth adaptations in side-scan sonar emphasize low-frequency operations (typically 10-50 kHz) to extend detection ranges while minimizing the system's acoustic signature, reducing the risk of counter-detection by enemy sensors. Covert deployment via unmanned underwater vehicles (UUVs) or autonomous underwater vehicles (AUVs) further enhances this, allowing persistent surveillance without surface presence; for instance, low-power side-scan payloads on UUVs enable silent mine hunting in denied areas.^[40] These systems, often integrated into programs like the U.S. Navy's Littoral Combat Ship, prioritize electromagnetic quieting and burst transmission modes to evade passive sonar intercepts.^[41] A notable case study is the 1991 Gulf War, where side-scan sonar towed by helicopters and surface vessels cleared Iraqi minefields, scanning channels to depths of 50 meters and identifying over 1,000 contacts for safe passage of coalition ships.^[42] This evolved into 2020s autonomous systems, as seen in U.S. and allied MCM programs deploying AUVs with side-scan for real-time mine classification.

Commercial, Scientific, and Environmental

Side-scan sonar plays a crucial role in the offshore oil and gas industry, where it is employed for pipeline route surveys and the identification of seabed hazards to ensure safe installation and operation of infrastructure. High-resolution geophysical (HRG) surveys using side-scan sonar, often integrated with other tools like sub-bottom profilers, evaluate seabed conditions along proposed pipeline paths, detecting buried features, debris, or unstable sediments that could compromise structural integrity. For instance, surveys conducted by companies like Walter Oil & Gas Corporation in the Gulf of Mexico utilize side-scan sonar to map potential hazards, minimizing risks during laying and maintenance activities.^[43] Similarly, this technology has been recognized for its effectiveness in locating and imaging oil and gas pipelines in marine environments, providing acoustic images that reveal pipeline alignments and surrounding seabed topography.^[44] In port and coastal engineering, side-scan sonar facilitates the inspection and monitoring of structures such as breakwaters, detecting erosion, damage, or sediment accumulation that could affect stability. The U.S. Army Corps of Engineers (USACE) has evaluated side-scan sonar for reconnaissance and detailed inspections of coastal structures, including rubble-mound breakwaters, where it produces photograph-like images of submerged surfaces to identify voids, scour, or displaced armor units without requiring divers in hazardous conditions. Applications include annual monitoring to assess wave-induced erosion and structural integrity, enabling timely repairs to prevent failures during storms. For example, side-scan sonar surveys have been used to evaluate breakwater conditions by imaging underwater slopes and adjacent seabeds, revealing patterns of sediment movement and material degradation.^[45]^[46] Underwater archaeology benefits significantly from side-scan sonar's ability to map shipwrecks and ancient sites, providing high-resolution images that support non-invasive documentation and 3D reconstructions. This technology detects and outlines wreck sites by capturing acoustic returns from metallic and wooden structures, often towed near the seafloor to cover large areas efficiently. A prominent example is the 2022 Magellan expedition to the RMS Titanic wreck, where side-scan sonar data contributed to the creation of the first full-sized digital 3D model, revealing details of the ship's breakup and deterioration at 3,800 meters depth, aiding preservation efforts and historical analysis.^[47] NOAA's Ocean Exploration program routinely employs side-scan sonar for cultural heritage mapping, such as imaging World War II-era wrecks to characterize site extents and associated artifacts.^[1] In fisheries and environmental monitoring, side-scan sonar assesses fish stocks through echo returns from schools and maps habitats like coral reefs to support conservation strategies. By classifying benthic features such as hard bottoms, reefs, and soft sediments, it helps quantify habitat distribution critical for commercially important species, enabling better stock management and impact assessments. NOAA studies have demonstrated its utility in coral reef ecosystems, where side-scan imagery distinguishes reef types and fragmentation, informing restoration and protection efforts in areas like the U.S. Caribbean. For instance, integrated sonar mapping has identified low-relief hard bottoms as key fish habitats, guiding regulations to reduce overfishing and habitat degradation.^[48]^[49] Scientific research leverages side-scan sonar for geological seafloor studies, including the examination of volcanic features and sediment transport dynamics, with NOAA leading expeditions in the 2020s to expand knowledge of ocean basins. Onboard systems like those on NOAA Ship Okeanos Explorer provide detailed imagery of seafloor morphology, revealing volcanic seamounts, lava flows, and rift zones through acoustic shadowing and backscatter patterns. These surveys contribute to understanding tectonic processes and resource potential in unexplored regions. Additionally, side-scan data elucidates sediment transport by imaging bedforms like ripples and dunes, indicating current directions and deposition rates, as seen in USGS analyses of coastal and deep-sea environments. NOAA's 2020s expeditions, such as those in the Pacific, have used side-scan sonar to map sediment layers and volcanic terrains, supporting broader oceanographic models.^[1]^[50]^[51]

History and Advancements

Early Development

The development of side-scan sonar originated in the military sector during the 1950s, driven by the need for seabed imaging in naval operations. Early prototypes were created as classified projects by the U.S. Navy and collaborators to support underwater reconnaissance and mine countermeasures, with initial systems emerging around 1956.^[52] These devices employed sideways-directed acoustic beams to map large swaths of the seafloor, marking a shift from traditional vertical echo sounders to lateral scanning for broader coverage.^[53] A pivotal advancement came in the early 1960s through the work of Martin Klein, an MIT-trained engineer who is widely recognized as the pioneer of practical side-scan sonar, in collaboration with Harold Edgerton at MIT. While at E.G&G International, Klein designed and built the first commercially viable systems, introduced in the late 1960s as dual-channel towed units operating at frequencies around 100 kHz for high-resolution seafloor imaging.^[54]^[3] This innovation was inspired by Klein's involvement in the 1963 search for the sunken USS Thresher submarine, where early side-scan technology faced challenges in locating the wreckage on the ocean floor.^[55] The late 1960s release enabled broader oceanographic applications, transitioning the technology from military exclusivity following the 1958 declassification of key patents and further declassifications in the late 1960s and 1970s.^[52] Early systems faced significant technical hurdles, including limitations in analog signal processing, which produced noisy images requiring manual interpretation, and instability in towfish designs that complicated deployment in varying sea conditions.^[56] These challenges restricted operational ranges and resolution, often to a few kilometers at best. Initially applied by the U.S. Navy during the Cold War for submarine wreck detection, minefield surveys, and seafloor obstacle identification, the technology's military roots emphasized covert seabed surveillance.^[57] Declassification in the late 1960s and 1970s further spurred civilian adoption in marine geology and hydrography.^[3] A landmark contribution to the field's early literature was the 1972 compilation Sonographs of the Sea Floor by Belderson, Kenyon, Stride, and Stubbs, which synthesized developments in side-scan sonar techniques and showcased applications in mapping continental shelves and submarine features through acoustic imagery examples.^[58] This work highlighted the technology's potential for geological interpretation while addressing interpretive challenges in analog sonographs.

Modern Innovations

The transition to digital signal processing (DSP) in side-scan sonar systems during the 1990s marked a significant advancement, enabling real-time data acquisition and enhanced image quality through improved noise filtering and beamforming techniques.^[59] This shift from analog to digital architectures allowed for more precise control over acoustic signals, reducing artifacts and facilitating automated post-processing that was previously limited by hardware constraints.^[60] In the 2020s, higher-frequency dual systems, such as those operating at 850 kHz and 1600 kHz, have been introduced to achieve sub-centimeter resolution for detailed seafloor mapping, particularly in shallow waters where fine-scale features like small debris or biological structures require high fidelity imaging.^[61] These configurations balance range and detail by switching frequencies dynamically, supporting applications in search-and-recovery operations with resolutions down to 1 cm at short ranges.^[61] Integration with autonomous underwater vehicles (AUVs) and unmanned vehicles (UVs) has expanded side-scan sonar deployment for deep-sea surveys, exemplified by datasets collected via the Teledyne Gavia AUV from 2010 to 2021, which include over 1,170 real sonar images used for mine detection and environmental monitoring.^[62] This autonomy reduces operational costs and risks, enabling persistent coverage in challenging environments like Arctic waters or deep ocean trenches.^[63] Developments in 3D side-scan sonar have progressed to create volumetric reconstructions from multiple passes, with the global market projected to reach $255 million by 2031, driven by demand in offshore infrastructure inspection.^[64] Complementing this, synthetic aperture sonar (SAS) techniques enhance azimuth resolution to levels approaching the range resolution, overcoming traditional side-scan limitations by coherently processing motion-induced phase data across pings.^[65] From 2020 to 2025, artificial intelligence (AI) and machine learning (ML) have advanced automated target recognition (ATR) in side-scan sonar imagery, achieving detection accuracies exceeding 90% for underwater objects through convolutional neural networks trained on diverse datasets.^[66] These methods also enable effective noise reduction via generative adversarial networks, improving signal-to-noise ratios by up to 10 dB in reverberant environments, motivated by needs in maritime security and offshore energy exploration.^[30]

References

[1]
Side-Scan Sonar - NOAA Ocean Exploration
Jun 22, 2020 · Side-scan sonar is an active sonar system using acoustic pulses to detect and image seafloor objects, mapping the seafloor as it travels.
[2]
Side-Scan Sonar as a Tool for Seafloor Imagery - IntechOpen
Imaging of the seabed started in the 1940s, when the first side-scan sonar (SSS) sonograph (hard copy output of sonar data) was recorded (Fish and Carr, 1990).Missing: invention | Show results with:invention
[3]
Martin Klein Collection | MIT Museum
Martin Klein, a long-time leader in underwater exploration technology, developed the first commercially viable sidescan sonar system in the 1960s.
[4]
Alumnus Uses Unique Sonar to Reveal Underwater Mysteries
Dec 4, 2017 · Side-scan sonar, developed by Martin Klein '62 five decades ago, has detected many submerged objects—including mysterious circular stone ...
[5]
Side-scan sonar as a tool for measuring fish populations - USGS.gov
Jul 1, 2024 · In principle, SSS uses dual transducers to transmit a narrow-beam, wide-angle acoustic signal as the survey vessel transits an area.Missing: definition | Show results with:definition
[6]
https://journals.lib.unb.ca/index.php/ihr/article/view/23812/27597
[7]
[PDF] Side-Scan Sonar - Homeland Security
Basic operating principles for side-scan sonar should be reviewed when considering these systems for various applications. For example, maneuvering the ...<|control11|><|separator|>
[8]
[PDF] A Discussion of TVG - Xylem
Time-Varied Gain (TVG) is a method used to compensate for signal loss in echosounder data. As range increases, so does the applied gain.
[9]
Adjusting the TVG (Time Variable Gain) setting - Simrad
TVG (Time Variable Gain) compensates for the loss of acoustic energy due to geometric spreading and absorption. Prerequisites. The sonar must be running to ...
[10]
The Impact of Side-Scan Sonar Resolution and Acoustic Shadow ...
Low-frequency side-scan sonar operates at frequencies of a few kHz to tens of kHz, ensonifying many kilometers in a single pass; however, the resolution of ...2. Materials And Methods · 2.2. Sonar Systems Used For... · 3. Results
[11]
Calculation of absorption of sound in seawater - Underlying Physics
The coefficient α is found to increase with the square of the frequency f, so at frequencies greater than 1 MHz, results are usually given in dB/m, since the ...Missing: f² | Show results with:f²
[12]
A SONAR PRIMER - Cerulean Sonar
Oct 8, 2019 · Sound waves below 20kHz, yield poorer resolution, but provide higher ranges, compared to higher frequencies. High frequency sound waves, yield ...
[13]
[PDF] Registration and variability of side scan sonar imagery. - CORE
Sonar pulse repetition rate was 4 Hz which resulted in a axial spatial ... As can be seen the pulse duration is approximately 100 microseconds. An ...
[14]
[PDF] Multibeam Sonar Theory of Operation
Chapter 5, “Sidescan Sonar,” discusses sea floor imaging using sidescan sonars and how the ... Principles of Sonar” in Chapter 2). Figure Chapter 4 - -4: ...
[15]
Tutorial: Speed of Sound - Discovery of Sound in the Sea
Feb 11, 2022 · Sound travels about 1500 meters per second in seawater. That's approximately 15 soccer fields end-to-end in one second.
[16]
Hydrographic Survey Equipment - NOAA Nautical Charts
Side scan sonar typically consists of three basic components: a towfish, a transmission cable and the topside processing unit. ... Any side scan sonar system ...Missing: hardware | Show results with:hardware
[17]
Study on Control System of Integrated Unmanned Surface Vehicle ...
May 5, 2020 · The UUV performs two major roles in the integrated platform: (1) it processes data of the side scan sonar (SSS) and the underwater camera ...
[18]
Equipment and Processing - Archive of Side Scan Sonar and ...
Nov 28, 2016 · The towfish is equipped with a linear array of transducers that emit and receive an acoustic energy pulse in a specific frequency range. The ...
[19]
[PDF] remr technical noteco-se-1,4 side scan sonar for inspection of ...
EQUIPMENT AND PERSONNEL REQUIRED: Components of an SSS system include: a. “tow fish” and cable, a control/processing/display/recording/power unit, and a.<|control11|><|separator|>
[20]
Study of 1-3-2 type piezoelectric composite transducer array
... piezoelectric composite transducers also. ... The transducer array can be applied in the fields of synthetic aperture sonar (SAS), hunting mine, side scan sonar ...
[21]
[PDF] HRG Acoustic Source Manufacturer Specs - NOAA Fisheries
Tow cables may be up to 150m in length with standard power supply or up to 700m with a high capacity voltage sense supply.
[22]
Sidescan-Sonar Acquisition and Processing Methods - USGS.gov
Dec 7, 2016 · Lighter backscatter tones in the enhanced sidescan-sonar imagery are now predominantly caused by stronger acoustic returns and tend to reflect ...Missing: output | Show results with:output
[23]
A Universal Automatic Bottom Tracking Method of Side Scan Sonar ...
May 17, 2021 · Determining the altitude of side-scan sonar (SSS) above the seabed is critical to correct the geometric distortions in the sonar images.
[24]
Bottom Tracking Method Based on LOG/Canny and the Threshold ...
Aug 10, 2025 · Bottom Tracking Method Based on LOG/Canny and the Threshold Method for Side-scan Sonar. December 2019; Journal of Engineering Science and ...
[25]
Speckle Noise Filtering in Side-Scan Sonar Images Based on the ...
Jun 30, 2019 · The Frost filter calculates the grey level for each pixel using an exponentially dumped convolution kernel that can adapt its parameters [4].
[26]
Speckle Noise Reduction in Sonar Image Based on Adaptive ... - MDPI
The denoising comparison algorithms used in this paper include Lee filter [36], Kuan filter [37], Frost filter [38], SRAD filter [39], Wavelet-based denoising ...
[27]
A Mosaic Method for Side-Scan Sonar Strip Images Based on ...
Sep 9, 2021 · We proposed a mosaic method for side-scan sonar strip images based on curvelet transform and resolution constraints.Missing: georectification | Show results with:georectification
[28]
Processing, mosaicking and management of the Monterey Bay ...
In the preprocessing stage, sensor-specific algorithms are applied to correct for both geometric and intensity/radiometric distortions introduced by the sensor.Missing: overlap georectification
[29]
Underwater Side-Scan Sonar Target Detection: YOLOv7 Model ...
Jul 8, 2024 · This article addresses this problem by improving the You Only Look Once v7 (YOLOv7) model to achieve high-precision object detection in side-scan sonar images.
[30]
Computer vision methods for side scan sonar imagery - IOPscience
The objective of this work is to review current deep learning methods for automatic image classification, object detection, semantic segmentation, and instance ...
[31]
Sidescan sonar meets airborne and satellite remote sensing
Feb 12, 2020 · Low and high backscatter values were displayed in a 256 greyscale palette (high backscatter = low greyscale values = darker greyscale tones; low ...
[32]
Side-scan sonar image processing: Seabed classification based on ...
Generally, to generate acoustic images, the acoustic backscatter intensity is converted into the pixel value of a grayscale image (called the backscatter mosaic) ...
[33]
AQS-24B/C Minehunting System - Northrop Grumman
The only deployed and operationally proven high-speed airborne mine detection system in the world. · High-resolution, side-scan sonar for real-time detection, ...Missing: applications | Show results with:applications
[34]
AN/AQS-20C Mine-Hunting Sonar | Raytheon - RTX
The AN/AQS-20C sonar mine-hunting system is the US Navy's choice for mine-hunting technology, which is integrated into the Mine Countermeasure Unmanned Surface ...
[35]
Advances in Synthetic Aperture Sonar Transform Mine ... - DON CIO
Active synthetic aperture sonar (SAS) is a powerful imaging technique that coherently combines echoes from multiple pings along the trajectory of a survey path ...
[36]
Sidescan Sonar - an overview | ScienceDirect Topics
The frequency used by SSS systems normally range from below 100 kHz to above 500 kHz. The higher frequencies restrict the length of the sonar transducer and ...
[37]
Searching for Lost Submarines: An Overview of Forensic ...
Mar 18, 2024 · Side-scan sonar systems exist as a vital apparatus to any search operation because the alternatives for mapping are minimal. Methods other than ...<|control11|><|separator|>
[38]
NATO conducts historical ordnance disposal operation in the Baltic ...
Apr 24, 2025 · The Dutch staff ship Luymes contributed to the HODOPS by scanning the seabed using its Towed Side Scan Sonar, classifying contacts, and handing ...
[39]
Hoe de Belgische marine kritieke infrastructuur beschermt
Aug 19, 2025 · NMSA may therefore increase the frequency of seabed scans using side-scan sonar on civilian vessels, beyond the usual annual schedule. The ...
[40]
Military-Grade Sonar Solutions - Defense Advancement
Oct 4, 2025 · Mine Detection & Clearance. High-resolution imaging sonar, such as side scan or SAS, is used to detect and classify underwater mines. Systems ...
[41]
Low-Frequency Active Towed Sonar | L3Harris® Fast. Forward.
The VDS-100 is a low frequency, variable depth, active sonar system used on surface ships to detect, localize and prosecute all types of submarines.Benefits · Sonar Processing · Displays And OperatorMissing: scan stealth military
[42]
[PDF] The Operational Theater Mine Countermeasures Plan - DTIC
operations in the 1950 Korean War and 1991 Persian Gulf War show that theater ... Additionally, the helicopter tows a side scanning sonar device (speed ...
[43]
[PDF] 2020 China Military Power Report - DoD
Sep 1, 2020 · advanced military capabilities. This included remotely operated side scan sonar systems, hydrophones, robotic boats, unmanned underwater ...
[44]
[PDF] ECHO OFFSHORE - WALTER OIL & GAS CORPORATION SURVEY ...
Non-airgun HRG surveys are conducted in leases and along pipeline routes to evaluate the ... side-scan sonars, boomers, sparkers (in limited situations) and ...
[45]
[PDF] Side-scan sonar imaging of the Colorado River, Grand Canyon
Side-scan sonar has proven to be a useful tool in the marine environment to investigate oil and gas pipeline locations, shipwrecks, rock outcrops, and ...Missing: offshore | Show results with:offshore
[46]
[PDF] Side-Scan Sonar Applications for Evaluating Coastal Structures - DTIC
Jan 2, 2025 · Applications discussed include recon- naissance, inspection, and monitoring. Side-scan sonar is most useful as a reconnaissance and inspection ...
[47]
[PDF] Underwater inspection of coastal structures using commercially ...
The purpose of this report is to give a general introduction to the side scan sonar (SSS) and its uses in coastal engineering studies, including some ...Missing: erosion | Show results with:erosion
[48]
Digital 'resurrection' of the Titanic sheds light on fateful night the ship ...
May 5, 2025 · In 2022, deep-sea mapping company Magellan created the 3D digital model featured in the documentary by taking sonar images of the wreck.
[49]
[PDF] The Applicability of Sonars for Habitat Mapping: a Bibliography
Apr 3, 2016 · Abstract: Sidescan sonar can be an effective tool for the determination of the habitat distribution of commercially important species. This ...
[50]
[PDF] Mapping Southern Florida's Shallow-water Coral Ecosystems
There are three types of sonar systems of interest to habitat mapping work: vertical beam echosounder (VBES); multibeam echosounder (MBES), and side scan sonar.
[51]
[PDF] Ocean Exploration Capabilities of NOAA Ship Okeanos Explorer
The Knudsen Chirp 3260 (3.5 kHz) sonar provides echogram images of surficial geological sediment layers underneath the seafloor to a maximum depth of about 80 m ...
[52]
Sidescan Sonar - USGS Publications Warehouse
Dec 7, 2016 · The ripple orientation suggests a sediment bedload transport direction within these features that is perpendicular to shore, most likely in ...Missing: studies volcanic NOAA 2020s
[53]
Historical development of side scan sonar - ResearchGate
Aug 6, 2025 · Military side-scan sonars were made in the 1950s and commercial units were developed in the 1960s after declassification of the original patent in 1958.Missing: principles applications authoritative
[54]
[PDF] HISTORICAL DEVELOPMENT OF SEABED MAPPING SYNTHETIC ...
An example is the 1950s invention of the seabed imaging side scan sonar.28 This technology transitioned to the C-MK-1 SHADOWGRAPH mine hunting sonar fielded on ...
[55]
Martin Klein - Nautilus Live
An MIT graduate, he was Program Manager for Sonar Systems at E.G.& G. International where he developed the first commercially successful side scan sonar systems ...Missing: Laboratory | Show results with:Laboratory
[56]
Martin Klein '62 | MIT Technology Review
Oct 24, 2017 · Side-scan sonar, developed by Martin Klein five decades ago, has detected many submerged objects—including mysterious circular stone structures ...Missing: 1965 | Show results with:1965
[57]
Stability Of Towfish Used As Sonar Platforms - Semantic Scholar
Motion of a sonar platform, caused by wave-driven motions of the towing vessel, can significantly degrade side-scan sonar images.Missing: challenges analog signal processing
[58]
Klein's Side Scan Sonar, Then And Now - Marine Technology News
Oct 3, 2017 · Marty Klein, who many consider to be the father of side scan sonar, began building his own devices from his home in Lexington, Mass.Missing: principles sources
[59]
Long-range sonar mapping of the continental shelf - ScienceDirect
Belderson et al., 1972. R.H. Belderson, N.H. Kenyon, A.H. Stride. Sonographs of the Sea Floor. Elsevier, Amsterdam (1972), p. 185. Google Scholar. Belderson et ...
[60]
Sidescan Sonar - an overview | ScienceDirect Topics
Side scan sonar through the transducer emits low-incident angle fan-shaped beam of high-frequency acoustic pulse to the seabed at both ends along the shipping ...Missing: mechanism | Show results with:mechanism
[61]
Digital processing of side-scan sonar data with the Woods Hole ...
Digital processing of side-scan sonar data with the Woods Hole image processing system software. January 1, 1992. Since 1985, the Branch of Atlantic Marine ...Missing: advancements 1990s
[62]
EdgeTech Introduces New Sonar Frequency Combination
Sep 2, 2020 · The new 850kHz and 1600kHz dual frequency combination provides high resolution side scan sonar imagery at both frequencies and optional ...Missing: kHz 2020s
[63]
Side-scan sonar imaging data of underwater vehicles for mine ...
The collected dataset contains 1170 real sonar images taken between 2010 and 2021 using a Teledyne Marine Gavia Autonomous Underwater Vehicle (AUV).
[64]
Side Scan Sonar for Gavia AUV - Teledyne Marine
Side Scan Sonars (SSS) can be installed on the Gavia in the control and communication module. Available frequencies range from 600 kHz to 1.8 MHz in both ...Missing: 2010-2021 | Show results with:2010-2021
[65]
3D Side Scan Sonar Market, Global Outlook and Forecast 2025-2031
The global 3D Side Scan Sonar market was valued at 218 million in 2024 and is projected to reach US$ 255 million by 2031, at a CAGR of 2.3% during the ...
[66]
Synthetic Aperture Sonar - HISAS - Kongsberg Discovery
The azimuth (along-track) resolution of a sonar can be computed as the ratio between the acoustic wavelength and the length of the array. For typical side scan ...
[67]
(PDF) A study on modern deep learning detection algorithms for ...
Aug 10, 2025 · A study on modern deep learning detection algorithms for automatic target recognition in sidescan sonar images ... Detection in Side Scan Sonar.