Study On Time Difference Method Of 3D Current Measurement Technology

The ocean current measurement has the important economic value, and has always been the marine scientist's research subject. The time-difference-type ocean current meter because of its unique techniques, recently are widely researched by research works. Its principle is that the sound pulse is transmitted in opposite directions between two fixed transducers simultaneously and the difference in arrival time is proportional to the medium flow velocity along the axis of propagation. The acoustic difference travel-time ocean current meter's key technologies are studied in this paper.In the thesis, the author has analyzed the ocean current meter's development history, by comparing the various types of current meter performance characteristics, and establishes the time-difference-type current meter's superiority technology. Besides, the difference travel-time ultrasonic current meter system's measure principle and technical realization of methods are deeply studied, including derive the principle of difference time theoretical formula, sensors installation structure, precise measurement of small time interval techniques etc. According to system's performance index request and under the guide of small time internal analog interpolation stretching technology, the system's key technologies are solved successfully, and the time-to-voltage (TTV) and the time-to-time (TTT) high speed conversion circuit designed. Aiming at the system's structure characteristic, the system's error sources has been overall analysis and study, as well as give the corresponding solution.By designing System's measuring circuit through innovative channel exchange technology, couple with easy data processing, the DC bias of the circuit elimination automatically, and the time interval measuring accuracy reaches a sub-nanosecond magnitude. Realize the ocean's current great measurement range and the sound speed precision measuring, which solve the traditional current meter's measurement range and accuracy limitations. Finally, in the laboratory flume static calibration experiments, the system shows the good performance, which meets the design requirement.