High-resolution sub-bottom profiling technology using parametric array and vector hydrophone.

• A New High-Resolution Sub-Bottom Profile Measurement Scheme: A novel Parametric Sub-Bottom Profiler (PSBP) is developed, employing a parametric transmitting array and a 2D vector hydrophone to achieve high-resolution sub-bottom imaging. • Single Side Frequency Doubling Beamforming (SSFDB) Technique: The use of vector hydrophone and SSFDB signal processing can effectively avoid the influences of ambient noise, ship radiation noises and secondary reflections on the sea surface. The corresponding frequency and bandwidth doubling expansion has achieved an improvement in time detection resolution. • Innovative Application of Signal Enhancement Algorithms: The echo signal is enhanced by combining Low Order Bidirectional Differential Arithmetic Unit (LOBDAU) and Coherent Accumulator (CA), further improving imaging quality. This technology provides technical support for achieving high-resolution sub-bottom profile imaging. • High-Resolution Layering Method (HRLM) Based on Peak Detection: By using HRLM, we can obtain clearer seabed sediment profiles. It can make the layered display more precise and significantly highlight the hierarchical structure information of sedimentary layers. The processing effect is equivalent to narrowing the corresponding echo peak width of each sedimentary layer, the time detection resolution is improved. This paper reports a new method to achieve high-resolution sub-bottom profiling, providing a scheme for the development of Parametric Array Sub-bottom Profiler (PSBP). The high-resolution sub-bottom profiling system is integrated using parametric transmitting array and vector hydrophone, series signal enhancement and high-resolution signal processing methods are proposed to obtain clear sub-bottom profiles. Based on the parametric array, a small-aperture high directivity beam with low frequency, broadband, and without sidelobes is realized, physically achieved high spatial resolution and temporal resolution. By using the vector hydrophone, a single side frequency doubling beamforming (SSFDB) method is used to significantly suppresses the impact of marine environmental noise and sea surface acoustic scattering, the detection resolution is improved due to the frequency doubling characteristics of SSFDB at the same time. Low order bidirectional differential arithmetic unit (LOBDAU) and coherent accumulator (CA) are combined to enhance the echo signal, and finally the high-resolution layering method (HRLM) based on peak detection gives a clear sub-bottom profile of the sediment. The benefits of the combined acoustic array design scheme and the researched signal processing methods had been experimentally evaluated, a clear sub-bottom profile with a semi buried sunken ship was obtained. [ABSTRACT FROM AUTHOR]