The Research On Key Techniques Of 1MHz Acoustic Doppler Current Profiler

Flow velocity is a very important parameter in the ocean. For knowing the environmental changes of the ocean, improving the ocean environment and utilizing the marine resources, it has very significant meaning to measure flow velocity conveniently, quickly and accurately. ADCP(Acoustic Doppler Current Profiler) can measure vertical profile distribution of river according to Acoustic Doppler Theory. A number of flow velocity in a profile can be measured by ADCP one time. ADCP which utilizes ultrasonic transducer to measure flow velocity has many advantages. For example, the measurement point in the front of the probe can ensure the flow field can't be destructed and the measuring result has high precision and wide range. Both weak current and high current can be measured by ADCP. The measuring is linear and the flow velocity verification curve can't be changed easily. There are no mechanical rotating parts in the measurement, so the problem of the sediment jam and water grass winding are not existing. Compared with traditional current meter, ADCP is more accurate. ADCP is also widely applied in oceanographic survey, velocity of seawater in oceanography research, measurement of inland river velocity profile, etc. Acoustic Doppler Theory has been widely accepted by people in measuring flow velocity.In the thesis, the average frequency of the signal is estimated by using the phase angle of the autocorrelation function and the design and software development are introduced in detail. Firstly, the application of ADCP in measuring flow velocity is described. Then, the principle of auto-correlation algorithm in the measurement of flow velocity is analyzed. The hardware platform is also set up and the function of hardware structure of each part is elaborated. Finally, the related algorithm is realized by software programming. The result of the experiment reaches the expected goal and shows that the auto-correlation algorithm based on ZoomFFT is more accurate than traditional algorithm in measuring flow velocity.