An Acoustic Signal Based Measuring Method And Its Implementation On Embedded Systems

Acoustic Doppler flow measurement technology can be divided into three types.There are non-coherent pulse flow measurement technology,coherent pulsed flow measurement technology and broadband flow measurement technology.The main work of this thesis is to achieve broadband flow measurement system,which would execute flow measurement in high accuracy.Broadband Acoustic Doppler Current Profiler's transmit signals are generated by repeating pseudorandom binary pulse code modulated sinusoidal signals,then scattered echo signals from different layers of water are received.Afterwards the profiler calculates the value of the Doppler shift by the phase difference,and gets the flow rate of the beam direction,then ultimately accomplishes the goal of the water flow rate measurement of the different layers.This thesis analyzed the relevant key technologies of the broadband Acoustic Doppler flow measurement,and the current profiling embedded system was designed and implemented with the project task support,and the profiler's performance was verified by the lake dynamic verification experiments.First of all,this thesis studies the basic principle and related flow measurement about the Acoustic Doppler flow measurement technology,proposes a flow measuring method based on broadband Doppler,complex correlation algorithms for measuring the Doppler echo signal was used,and then smoothing algorithm is brought in the data post-processing.to deal with outliers to obtain highly accurate flow measurement results.Secondly,in view of the miniaturization of measurement equipment,the implementation of the embedded hardware platform is proposed.Mainly based on OMAP+FPGA dual system hardware platform,and the flow rate measuring algorithm is mainly built on the OMAP-L137 dual-core chip,and then the real-time broadband Doppler flow measurement system is accomplished.In this system,OMAP system is mainly responsible for the controlling,data transmission and the echo signal real-time processing,and FPGA system is mainly responsible for converting data formats.High precision measurement results of velocity data and outputs are achieved because the powerful data management and processing performance of the OMAP system is used.The simulation experiment of the above method on the embedded platform is carried out in this thesis.The precision of the speed measurement is good,which can meet the design requirements of the project index.