Research And Realization Of Phased Array System Of Parametric Array

For its highly-directivity and transmission distance under water, parametric array isused in sonar, fish finding in deep ocean, exhibition room, birds repellent in airport, andso on. Mechanical method and phased array are the ways of controlling beamdirectivities. Compared to mechanical method, phased array has some advantages, suchas flexibility, high changing rate, deflection arbitrariness, random reflection and so on.So it is significance to the application of parametric array of study phase array.To solve the problem of theory and key technology of parametric array, the paperfocused research on the theory of parametric array and phased array. The influencingfactors and regularities are also discussed. Then a good performance system isimplementation. The main research contents are as follows: The fundamental theories ofparametric array and phased array, including "Westervelt formula","Berktay far fieldsolution","KZK formula", and theoretical basis of phase array, are studied firstly. Theparameters of transducer array influences the form of the wave beam, including anglerange, grating lobe, side lobe and the phased angle of the acoustic beam. So thedirectivity function of the transducer array is deduced, added the factor of phase controlat the same time. In addition, a lot of simulation is done with the help of MATLAB. Asthe key point of the system, theory of digital bean forming is studied. Time delays ofeach channel that are necessary for the phased angle is computed, and the ideal result isanalyzed according to the simulation. The whole system is realized in the FPGA on thebasis of fundamental theories. The software is divided into five modules according tothe top-down design method, and the codes of each module are edited in verilog. Themodules are debugged and simulated respectively. Then the whole software is debuggedand simulated after finishing the modules. The drive circuit is studied in the laterchapter. Class-d power amplifier and LC filter are selected as the power amplifier andfilter.Through research of directivity of the system, two phenomenon, called "restraintto main lobe amplitude while deflection" and "misalignment of the beam deflection",are discovered. Then through testing of digital beam forming system, multipath signal with relative time delay are observed with ChipScope and oscilloscope, and amplifiedsignals are observed when the drive circuit is tested. The modules of the system arecompleted.