Development Of Sound Velocity Profiler Based On Time-of-Flight Method

In the current worldwide background of Marine development, as a sea power, our country's demand of observation and research equipment in the field of Marine has become more and more urgent, and as a very important field, the ocean sonar equipments received more attention, and have been widely used in national defense, scientific research, fishery and many other areas. However, the accuracy of these equipments is affected by sound velocity, temperature, depth and other conditions in the ocean, therefore, it is particularly important to abtain the real-time profile data in the ocean environment.The porpose of this paper is to develop a set of high precision sound velocity profiler based on TOF(Time of Flight), of which the main part achieves the function of sound velocity measurement, and the data of temperature and depth is collected by an independent module. This profiler can analyze and measure the profile data in different sea area in the real time, and finally get the sound velocity, temperature and depth data of the sea area. In this paper, after considering many methods of measuring sound velocity, the STM32F407 is chosen as the main chip and the high-speed AD is used to get data for measurement, and finally get the velocity of sound in the sea with the principle of the TOF method.The work involved in this paper mainly includes the following aspects:(1)Analyzing the factors which affect the propogation of the sound in the sea, integrating the research status of the sound velocity measurement at home and abroad, comparing the advantages and disadvantages of each method, proposing the method of sound velocity measurement based on TOF.(2)According to the TOF method, designing the hardware system of ultrasonic velocity measurement based on STM32F407 kernel and ADS901 high-speed AD converter, finally achieving the high precision measurement of sound velocity in sea water after debugging. At the same time, the temperature and depth measurement module is designed based on ATmega64 core, improving the whole hardware design of sound velocity profiler in the end.(3)Completing the design of system software, including the timing and enable control of sound velocity module and TD(Temperature and Depth) module, the communication between different modules, the communication between the profiler and the host computer, and the algorithm of sound velocity calculation, finally improving the accuracy and stability of sound velocity measurement through digital signal processing.(4)Analyzing the final result of the experiment, validating the overall accuracy of the system. This system meets the predetermined accuracy requirements through the final experiment.