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Short-pulse method for acoustic backscatter amplitude calibration at MHz frequencies
Gregory W Wilson1, Alex E Hay2
1College of Earth Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97330-5503, USA.
The Journal of the Acoustical Society of America
|October 2, 2017
Summary
This study validates a short-pulse acoustic backscatter calibration technique for MHz frequencies, crucial for measuring suspended sediment. The method accurately calibrates systems by using a tungsten carbide sphere, achieving results within 20% of theoretical predictions.
Area of Science:
- Acoustics
- Environmental Science
- Sedimentology
Background:
- Acoustic backscatter techniques are vital for measuring environmental suspended sediment concentration.
- Accurate calibration is essential for reliable acoustic measurements in the MHz frequency range.
Purpose of the Study:
- To evaluate the Dragonette, Numrich, and Frank short-pulse acoustic backscatter amplitude calibration technique for MHz frequency systems.
- To assess the applicability of this calibration method for environmental suspended sediment measurements.
Main Methods:
- Employed a 16 mm diameter tungsten carbide sphere as a target, mounted on a support rod for precise positioning.
- Utilized elastic scattering theory to reconstruct backscatter time series and validate the influence of the support rod.
- Measured backscatter from polystyrene beads in water (1-2 MHz) to verify calibration results.
Main Results:
- The support rod was found to have no significant influence on the calibration accuracy.
- Backscatter form factors for polystyrene bead suspensions were within 20% of theoretical predictions after attenuation correction.
- The evaluated calibration technique is suitable for MHz frequency systems used in environmental monitoring.
Conclusions:
- The short-pulse acoustic backscatter calibration technique is effective and accurate for MHz frequency systems.
- This validated technique can reliably be used for measuring environmental suspended sediment concentration.
- The use of a rigid sphere target on a support rod provides a stable and precise calibration method.
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