研究目的
To develop and validate a three-dimensional downward-looking synthetic aperture sonar (SAS) imaging algorithm based on a T-type sparse planar array for enhancing the imaging performance and efficiency of detecting both unburied and buried underwater objects.
研究成果
The T-type sparse planar array SAS algorithm effectively enhances 3D imaging of underwater objects, improving SNR and resolution in along-track direction while maintaining efficiency. Simulations and sea trials confirm its capability for detecting both buried and unburied targets, with trade-offs in across-track resolution when increasing elements or depth. Future work could focus on optimizing for deeper waters and reducing computational complexity.
研究不足
The method is constrained by the sonar's operation velocity to avoid blur from overlapped or under-sampling, as defined by v < cL/(4R). Across-track resolution degrades with increased number of along-track elements or water depth. The algorithm's performance in very deep or highly reverberant environments may be limited, and real-time processing efficiency could be optimized further.
1：Experimental Design and Method Selection:
The study employs a T-type sparse planar array for synthetic aperture sonar (SAS) imaging, utilizing pulse compression in the vertical direction, multi narrow-beam nearfield beamforming in the across-track direction, and synthetic aperture processing in the along-track direction. Theoretical algorithm analysis and simulations are conducted to verify the method's effectiveness.
2：Sample Selection and Data Sources:
Simulations use a point target at coordinates (2m, 0m, 10m). Sea trial data is obtained from a shallow seawater area with water depth of approximately 100m, where linear objects are buried at about 3m depth.
3：List of Experimental Equipment and Materials:
A sonar system with a T-type array (12 elements across-track, 4 elements along-track, element spacing 0.16m), transmitting LFM signals (central frequency 10kHz for simulation, 9.5kHz for sea trial; bandwidth 10kHz for simulation, 9kHz for sea trial; pulse duration 50ms for simulation, 5ms for sea trial). Sound speed in water is assumed as 1500m/s.
4：16m), transmitting LFM signals (central frequency 10kHz for simulation, 5kHz for sea trial; bandwidth 10kHz for simulation, 9kHz for sea trial; pulse duration 50ms for simulation, 5ms for sea trial). Sound speed in water is assumed as 1500m/s.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The sonar platform moves uniformly (velocity 3m/s in simulation, 2-2.5m/s in sea trial) with pulse repetition time (prt) of 0.1s in simulation and 0.3s in sea trial. Echo signals are processed through quadrature demodulation, pulse compression, beamforming, and synthetic aperture processing to generate 3D images.
5：5m/s in sea trial) with pulse repetition time (prt) of 1s in simulation and 3s in sea trial. Echo signals are processed through quadrature demodulation, pulse compression, beamforming, and synthetic aperture processing to generate 3D images.
Data Analysis Methods:
5. Data Analysis Methods: Performance is analyzed based on resolution and signal-to-noise ratio (SNR) from simulation results under varying conditions (e.g., number of elements, water depth, velocity). Imaging results are visualized in 2D planes (X-Y, Y-Z, along-track, across-track, vertical).
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