Study Of The Data Collection And Processing System Of Ocean Microstructure Profiler

Turbulence is the most important dissipation form of ocean internal kinetic energy,and it is also the driving force of the marine macro phenomenon. It is of great significance to observe ocean turbulence and get accurate data about the motion of ocean turbulence for the analysis of ocean macro movement and the research of physical oceanography. Ocean microstructure profiler is an important equipment for observing marine microstructure turbulence. The sensors carried by ocean microstructure profiler can detect a variety of signals about ocean turbulence. In recent years, the development of the profiler platform technology has greatly promoted the research of ocean interior mixing theories, including turbulent mixing theory. Signal acquisition and processing system is an important part of microstructure profiler, and its performance directly determines the accuracy of the turbulence data measured by the profiler . Therefore, it is a critical task for the profiler design to study the turbulence data acquisition and processing method and then develop a high-precision signal acquisition and processing system.In recent years, great concern has been paid to the research of turbulence observation platform technology in the world, and relevant research has been carried out in many foreign institutions. Canada, the United States and some other countries have developed microstructure profiler of different characteristics respectively, and conducted experiments in the oceans. In China, the research of turbulence observing technology started relatively late,and relevant equipments are mainly imported. Therefore, to carry out the research of turbulence measuring platform, and develop economical and reliable turbulence signal acquisition and processing system, can greatly promote the development of ocean observation technology.In this thesis, a profiler signal acquisition and processing system is developed based on deep research on the turbulence signal acquisition and processing theory. With 16-bit digital precision, low power consumption and stable performance, the circuit system meets the ocean microstructure profiler signal acquisition and processing requirements well. Because turbulence observation is vulnerable to adverse sea conditions , platform vibration and some other factors, the turbulence signal will inevitably contain some noise. Based on the turbulence signal de-noising mechanism, a new turbulence signal de-noising method based on the theory of wavelet analysis is proposed. The main contents and results of this thesis aresummarized as follows: 1. turbulence Signal pre-processing theory is deduced, and a turbulence signal pre-processing circuit is designed. The pre-processing circuit is consisted with a differentiator, an amplification, and a filter, which lays the foundation for subsequent data collection and data analysis.2. Ocean microstructure profiler can carry a variety of different sensors. In this thesis characteristics of different sensors are analyzed, and a high-precision signal acquisition system is designed to meet all sensors'requirements .3.The theory of wavelet analysis is applied to the turbulence signal de-noising process. Applicability of wavelet thresholding denoising method for turbulence signal denoising is analyzed and the operating procedures are determined. As the frequency band of the noise in turbulence signal is very wide, traditional filtering methods based on Fourier transform is not suitable for turbulence signal. Experimental results show that wavelet thresholding method is preferable for turbulence signal denoising.4. Function verification experiments for each module of the signal acquisition and processing system are conducted to test the performance of each module. Comprehensive experiments are also carried out in the oceans, and the overall performance of the circuit system is verified. Experimental results demonstrate that the signal acquisition and processing system, with its comprehensive function and stable performance , is suitable for ocean turbulence measuring.