Acoustic Surveying Methods -
Instrumentation and Strategies
For marine investigations, a wide variety of instruments is available on the market. but instrumentation is only as good and suitable, as it fits to the task. Therefore, a detailed knowledge about physical principles, technical design, operational considerations and geologic boundary conditions are crucial requirements to properly carry out surveys, to evluate customer expectations and meet them with an appropriate concept including a risk evaluation and declaration of limits, wherever geology is different from expecations.
In this course we cover the following aspects:
(1) Georeferencing and Quality Control
- Navigation and Positioning, towed vs. hull-mounted
- Reference systems (GNSS, ship, towed)
- Motion Control
- Noise, interference
- Precision, Uncertainties
(2) Physical Principles of Acoustic Surveying
- Waves & Interfaces, Wave propagation in layered media
- Frequency, Wavelength, Attenuation, Signals, Chirp
- Dimensions, Directivity, Lobes
- Physical Parameters/Properties
Cavitation- Sound and Marine Life
(3) Acoustic Instrumentation
Echosounder
- Parametric Effect
- Chirp Sonars
- Transducer Design
- Sediment Echosounder
- Water Column Imaging / Fish Sounder
Multibeam
Mills-Cross Principle- Bottom Detection
Side Scan Sonar
- Backscattering
- Lithology of seafloor
- Geometry of targets
(4) Spatial, Structural and Temporal Resolution of Survey Grids
- Range, Overlaps, Mosaicking, Gridding
Frequency- Angle (Reflection, Scattering)
- Layer Spacing/Thickness
- Limit of Visibility, Detection Limit
(5) Surveying Concepts – Exercises
- Criteria, Commercial RFPs
- Geology
- Detection vs Imaging
- Academic vs Commercial Approaches
- Examples / Case Studies
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