Impact Subsea’s compact, robust, and highly versatile ISS360 Imaging Sonar is redefining standards in underwater imaging technology. Read more >>
The imaging sonar is a leading solution for integration into underwater Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs). Beyond vehicle integration, the sonar excels in standalone applications such as search and recovery, offering unmatched capabilities in compact sonar systems.
This feature delves into the advanced technical innovations and operational advantages of the ISS360 Imaging Sonar, underscoring why it stands out in the underwater technology landscape.
Precision in Sonar Imagery
High-quality imagery is a cornerstone of effective sonar technology. The ISS360 delivers unparalleled precision through a combination of 2.2° angular resolution (at 700 kHz) and 2.5 mm range resolution, with an impressive measurement range extending up to 90 meters (295 feet).
Range Resolution: A Measure of Detail
Range resolution determines a sonar’s ability to distinguish between targets at varying distances. At shorter ranges, the ISS360’s range resolution significantly enhances detail clarity. This capability diminishes the effects of image compression at longer ranges, which can obscure finer details on computer displays.
Leveraging a CHIRP (Compressed High-Intensity Radar Pulse) signal between 600 to 900 kHz, the ISS360 achieves a range resolution of 2.5 mm. To put this into context:
- A 200 kHz bandwidth CHIRP typically achieves 3.75 mm range resolution.
- A 100 kHz bandwidth CHIRP provides 7.5 mm range resolution
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- No CHIRP
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- Pool Corner
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- With CHIRP
Compared to non-CHIRP sonar systems, where resolution is tied to single-frequency pulse lengths, CHIRP technology offers significantly sharper results. For example, a 200 µs pulse in a non-CHIRP system yields a coarse 150 mm resolution, assuming a sound velocity of 1,500 m/s. The images below illustrate this difference:
Angular Resolution: Defining Clarity
Angular resolution measures a sonar’s ability to differentiate targets at the same distance but at varying angles. The ISS360 achieves a class-leading 2.2° angular resolution, optimizing target separation and image clarity, particularly at greater distances.
Using a mechanically stepped 360° acoustic beam, the ISS360 generates full sonar plots with remarkable precision.
Enhancing Image Quality Through Digital Innovations
Several factors influence sonar image quality, from acoustic detection methods to transducer design. The ISS360 leverages digital correlation technology to process returning acoustic pulses. Unlike systems that filter incoming data, this sonar processes raw data through its correlator, ensuring no loss of quality. The result is notably cleaner imagery compared to alternative systems with similar angular resolutions.
Furthermore, the ISS360’s design incorporates advanced hardware features:
- High-quality electronic analog front-end design.
- Optimized CHIRP implementation.
- Custom detection algorithms tailored for noise reduction and clarity.
Manufacturers’ specifications offer insights into a sonar’s performance, but actual imagery tests remain the gold standard for evaluation. Sample images from the ISS360 are available on the official product page.
Breaking Barriers in Scanning Speed
Mechanically scanning sonar systems often face limitations in scan speed due to acoustic pulse travel times. The ISS360 nearly eliminates these barriers, achieving speeds close to theoretical maxima through two critical innovations:
Unrestricted Communication via Ethernet
The ISS360 supports Ethernet connectivity alongside traditional RS232 and RS485 serial communications. Ethernet’s high bandwidth ensures no communication bottlenecks, enabling rapid data transfer for faster scanning.
High-Speed Processing
Powered by an advanced digital correlation processor, the ISS360 rapidly detects acoustic waveforms, particularly at shorter ranges where processing demands are higher. Independent benchmarking demonstrates that the ISS360 scans up to six times faster than comparable sonars under similar conditions.
These advancements significantly benefit obstacle avoidance operations, often eliminating the need for multibeam sonars in such applications.
Compact and Lightweight Design
Weighing only 0.37 kg (0.82 lbs) in air, the ISS360 is the world’s most compact mechanically scanned imaging sonar. Despite its small size, its advanced digital acoustic engine ensures performance that surpasses many larger systems.
This compact design facilitates seamless integration across a range of underwater vehicles, from observation-class ROVs to heavy-duty work-class units.
Reliability in Harsh Environments
Durability is a hallmark of the ISS360’s design. Its titanium housing offers superior longevity compared to anodized aluminum alternatives, eliminating the need for frequent replacements. Key reliability features include:
- Inductively coupled transducers (no slip rings).
- Fused power inputs and communication lines.
- Built-in undervoltage and reverse voltage protection.
Together, these attributes ensure the ISS360 remains operational even in the most demanding underwater environments.
Software Integration
The ISS360 integrates seamlessly with Impact Subsea’s seaView V3 software, enabling users to pair it with complementary sensors, such as altimeters, depth sensors, and attitude heading reference systems (AHRS).
For autonomous underwater operations, the sonar is supported by a freely available Software Development Kit (SDK), streamlining integration into AUVs.
Optional Attitude Reference System
The optional Attitude Reference System (ARS) adds pitch and roll data as a secondary output, enhancing precision in standalone applications. By ensuring perfect leveling, the ARS optimizes sonar performance for consistent range measurements in all directions.
Versatility Through Configurations
The ISS360’s modular design accommodates a variety of configurations, allowing integration into AUVs, ASVs, and ROVs. Its versatility makes it suitable for a broad spectrum of underwater applications, from detailed surveying to efficient obstacle avoidance.
The ISS360 Imaging Sonar represents a leap forward in underwater imaging technology. Combining high-resolution imaging, rapid scanning speeds, and a compact, rugged design, it addresses the needs of diverse applications with exceptional versatility.
Read the original article, or find further information on the Impact Subsea website.
