Research And Implementation Of Data Acquisition And Processing System For Upward-looking Acoustic Wave Measurement Equipment

Waves are a natural phenomenon that can be both destructive and beneficial.Wave energy can be used for wave power generation,but it can also cause great damage in coastal protection,port and wharf,thus it’s important to observe the waves.With the continuous progress of technology,wave measurement methods are constantly upgraded.A relatively mature ecological chain of acoustic wave measuring instruments has been formed abroad,these instruments have the characteristics of adapting to a variety of occasions and rich measurement information.In contrast,the function of domestic acoustic wave measuring instruments is relatively single,the application of the occasions are also limited,resulting in foreign instruments in the domestic market to occupy the majority of the share,which seriously threatens the national security of our ocean.Therefore,the task of domesticating acoustic wave measuring instruments is particularly urgent.To solve the above problems,a new acoustic wave measuring instrument is proposed in this article,which is unique in that it obtain the wave height data by acoustic ranging and use the wave height data as physical quantity of the Maximum Likelihood Method in estimating the wave direction.Compared with most wave measurement instruments that use Doppler shift to measure wave direction,the acoustic ranging method used in this article has the advantages of relatively simple data processing algorithm and high practical value.At the same time,in order to simplify the complex process of underwater host software design and facilitate the later maintenance,the domestic RT-thread realtime operating system is adopted in this article as the underwater main engine system to complete the function realization.This can effectively reduce the complexity of the system program design and make the system structure more clear.The development of acoustic Doppler current profiler is firstly introduced in the article.On this basis,the overall design framework of the instrument and the technical index of the prototype are determined.Then,the hardware and software design parts of the acoustic wave measurement equipment are introduced in detail.In the hardware part,the acoustic wave measurement equipment adopts modular design,which is divided into acoustic measurement circuit and system peripheral circuit.The acoustic measurement circuit includes ultrasonic transmitting circuit and signal receiving and processing circuit.The acoustic transducer is controlled by the single chip microcomputer to obtain the time series of the wave height of the sea surface.The instrument contains pressure,temperature and nine-axis sensors for wave height correction to calculate ocean wave(wave height,wave period,wave direction)and tide data.In the software part,the data acquisition process and the calculation process of wave inversion algorithm are introduced in detail.The program of underwater host is written in multithreaded form,which simplifies the design logic.It uses the Maximum Likelihood Method to estimate the wave direction spectrum.Compared with the Acoustic Doppler Current Profiler,which uses the velocity as the measuring point array,and the acoustic wave measurement equipment uses the wave height as the measuring point array to estimate the wave direction,which has the characteristics of simple transfer function and low computational cost.Finally,the modules of the system were tested and the function was verified in the indoor wave-making pool.Meanwhile,the reliability and accuracy were proved by comparison tests with foreign instruments Nortek AWAC under actual marine environment.