ADCP Environmental Adaptability Processing Method

Acoustic Doppler Current Profilers is a kind of the current measurement equipment which was developed in the early 1980s.It is mainly used to measure the speed of a wide range of ocean current, and has been widely used in the river measurement. Based on the Doppler effect, the system receives the doppler frequency of the echo corresponding to the emission signal, layers and calculates the echo signal to gain the profile velocity information. Based on the basic theory of ADCP technique and the numerical modeling, the thesis proposes the idea of the adaptive environment and applies it to the ADCP system, improves the scheme to solve the measuring speed fuzzy and the interlayer interference, which are inevitable in measurement procedure, and finally completes the construction of the system platform and the water experimental analysis. The main works of this thesis are as follows:1. The basic principle of ADCP current measurement is described firstly. The thesis introduces the doppler effect, the different transducer array and the method of measurement at the bottom, demonstrates the relationship of the echo signal and spatial layer, and then discusses the limitation of ADCP current measurement from two aspects:the blind area and the sidelobe disturbance.2. The feasibility of the frequency estimation method is verified based on the theory of the complex autocorrelation in the ADCP current measurement; the performance of different measurement methods are analyzed, including the narrowband incoherent measurement, narrowband coherent measurement and broadband measurement, and it is concluded that the broadband measurement improves the signal correlation and increases the time bandwidth product through coding, because of the combination of the advantages of the narrowband incoherent measurement and the narrowband coherent measurement; the effect of transmitting form is verified through the performance of the speed measurement with changing the parameters of the transmitting signal.3. A kind of ambiguity resolution algorithm is proposed based on the pulse delay variation, to resolve the problems of the measuring speed fuzzy and the interlayer interference. At the same time, the thesis improves the original algorithm by combining determination, which resolves the contradiction of the ambiguity resolution scope, the ambiguity resolution accuracy and the implementation. On the other hand, the thesis uses the moving average algorithm to restrain the interlayer interference in order to resolve the problem of the interlayer interference during the measurement, and further restrains the interlayer interference by increasing the sample points. The feasibility of the above two algorithms are verifiesd by numerical simulations.4. The ADCP system is developed based on the CCS and OMAPL138 processor. The thesis describes the modules of the algorithm, and strengthens the communication between the development board and the various modules. The signal and algorithm parameters can be changed depending on the environment in real time, and the software support is provided for the environmental adaptation. Finally, the outdoor water experiment is carried out, where the experiment result is analyzed and the feasibility of the algorithms above is verified.