Next Generation Single Beam Seabed Classification

Background
Quester Tangent's QTC VIEW ™ has been thoroughly proven by many users in a wide variety of applications throughout the world. Applications exist in almost all marine industries: the QTC VIEW ™ has proven itself to be a research tool for all those interested in the composition and diversity of the seabed, including fisheries, geological, survey hydrographic and military needs

New Needs
The QTC VIEW ™ was designed with an operational depth range of 5m to 500m. Today seabed classification applications target operations in a broad spectrum of water depths, from water as shallow as 0.5m, to 2000m or more. Today's scientists and researchers are pushing applications to their limits, requiring a new look at ways to respond to these growing requirements.

Growth in Technology
Exponential growth in technology relating to analogue and digital circuitry and processing power have provided new opportunities for data acquisition and processing. Research at QTC is delving into our core single beam technology to utilise this technological growth in providing solutions related to classifying the seabed in the extremes of water depths now required. Our expertise in dealing with large data volumes, and in acquiring data at very high speeds, has been key to the successful outcome of the project.

Research Goals
Quester Tangent has embarked on the process of producing the next generation of single beam seabed classification technology. Basic goals of the research program include:

• Dynamic Range - designing a system providing a "front-end" with more than 80dB of dynamic range. This eliminates the prospect of signal saturation over extremes of sea floor reflectivity.
• High-Speed Acquisition - digitising a signal at an extremely high rate (5MHz) and filtering the information dynamically to maximise information content while minimising data volume.
• Quality - Increasing the quality of data acquired is a very important consideration. To this end we have:
  • Developed techniques to handle the data volumes generated by high-speed data acquisition
  • Focused on the development of algorithms for logging the original bi-polar waveform
  • Enabled capturing of the fundamental echogram as the base data, which means a larger amount of better quality data
  • Minimised signal processing during acquisition
  • Provided extensive tools for real-time quality assurance during acquisition, and for subsequent post processing
  • Ensured ease-of-use in the field.

Flexibility and Control
Capturing and archiving the fundamental waveform maximises potential for sophisticated post processing and data management. Tools have been built to provide hands free processing using system defaults. Alternately the means are provided to optimise processing for target applications.

Requirements
Capturing and archiving the fundamental waveform maximises potential for sophisticated post processing and data management. Tools have been built to provide hands free processing using system defaults. Alternately the means are provided to optimise processing for target applications.

Aside from the research goals, any product or system designed as a result of this project must meet minimum user criteria:

• It must not require that the user have specialist acoustics knowledge
• It must give consistent, reliable results that are readily understandable
• The process must be the same for all surveys, that is the user must not be required to choose between classification techniques on a survey by survey basis
• The classification results must be free of artifacts, particularly effects of water depth
• The classification system must be expandable, able to work on several levels, to match the developing needs of research oriented users.

Very Shallow Water
Some of the challenges faced by acoustic classification in very shallow water are:

• The transmit and receive pulses are very brief, and perhaps barely separated.
• Amplitudes can be very high.
• The footprint is very small, and so contains very little acoustic information
• The transducer near-field effect can seriously influence results

Results
A new product has grown out of this project, the QTC VIEW Series V . This system achieves accurate, repeatable classification in waters as shallow as 0.5m, overcoming the challenges of limited water environments. At the other end of the spectrum, recent survey work has resulted in data being captured at depths of up to 2000m with encouraging results. For details of a deep water project, visit the deep water Turbot project pages.

There are a number of QTC VIEW Series V systems already in operation, working in very shallow waters, to as deep as 100m. Some of these are:

• RSMAS Opti-Acoustic Project
• Coral reef studies at NOVA South Eastern University National Coral Reef Institute
• Sturgeon Habitat studies at University of Manitoba
• Aquaculture studies at Department of Fisheries and Oceans , Moncton, New Brunswick
• Acoustics research at C-MARS