Control Of The Quality Of The Velocity Data And Correction For System Error In ADCP

Acoustic Doppler Current Profiler (ADCP) is ultrasound equipment for current, which works based on the principle of acoustic Doppler. As an instrument of the current measurement, ADCP has been applied to many modern hydrology tests and the technology adopted by ADCP has aroused people's attention increasingly. The quality of the velocity data is easily influenced by the complex water environment and error in the operation during the measurement of ADCP. Therefore, the research on how to obtain the accurate velocity and the flow data becomes essential. The major task of this paper is to forward the method, which can improve the velocity and flow data, and analyze all kinds of the error sources in operations. Finally, reasonable correction algorithms are selected to correct kinds of errors for improving the accuracy and quality of the data in ADCP. The main research contents are as follows:First of all, the basic principle of ADCP and the ADCP system frameworks are described briefly, which leads to the complete data processing in the module of the data processing. Accurate sound speed in real-time, applied for the transform from the Doppler shift to the radial velocity, is obtained by selecting a suitable empirical formula; velocity of the geographic coordinate system is gained by four radial velocity combined with the attitude sensor data; the precise speed of the ship and the water depth are computed according to the bottom-tracking technology; finally, the calculation of the flow is provided by the method of velocity-area.Furthermore, some methods are forwarded to improve the quality of the velocity data after analysis for sources of the abnormal data during the measurement of ADCP. The ineffective portion of the radial velocity is estimated after establishing the standard of the invalid data during a cell layer; the fusion of GPS and the bottom-tracking technology provides examination for ship speed; velocity data of the non-observed regional areas is computed by the combination correlation with the measured velocity.Then, the appropriate solutions are adopted after analysis of the possible error in ADCP. The present error sources in the system are the blind area of the tranducer, mounting angle error introduced by the transducer and the attitude sensor, random error or Synchronization from the external auxiliary equipment (temperature sensor, pressure sensor, attitude sensor, GPS, etc). Reasonable correction algorithm is adopted to make compensation or reduce the impact on the flow measurement.Finally, based on the theoretical research, the velocity data processing and the error calibration algorithm are implemented in the actual system. Key points focus on the debugging process of the temperature sensor, the attitude sensor, GPS and the software design process of the velocity data. According to the experimental conditions, the data processing technology and the error correction algorithm are verified partially.