Design And Realize On Software Of Ocean Current Meter

The ocean current measuring is an important part in marine scientific research field. Current measuring instrument not only support oceanography research, but also has the broad applications in many fields, such as hydrology and water resources research, flood forecasting, water resource management and national defense.The basis principle of time different type current measuring instrument is that the sound speed is different when two ways sound wave are transmitted in opposite directions. So if the sound propagation delays in bi-directions are estimated, the current velocity can be calculated. In the paper, the correlation method, the phase difference method as well as the phase spectral method of time-delay estimation methods are studied. The cross-correlation method compares the similarity of two signals to estimate the time delay. In order to improve the accuracy of time-delay estimation in correlation method, the interpolation technique is researched which improves the signals time resolution, so does the accuracy of time-delay estimation. Then how to detect the phase difference of the two signals is studied deeply for estimating the time delay. The principle of the phase difference and the window functions selection criteria are discussed. At last, how to use the slope of linear regression in cross-power spectrum's phase spectrum to estimate the time delay is also presented.Finally, the display and control software for the time difference type current measurement is designed and completed. The software is based on Visual C+ +6.0 integrated development environment, applying ActiveX programming technique and using multi-thread method and graphics dynamic non-twinkle display technology, and realizes the current velocity measurement in real-time.