The Dynamic Apodization Technology Of Phased Array Ultrasonic Signal

Many of ultrasonic phased array technology, beam-forming and spatial electronic scan are based on time delay or phased control against elements, the fundamental problem to be solved is producing a waveform with low side-lobe, while as another controllable variable of element signal, radiation amplitude has not been given due consideration. Therefore, we propose a method of dynamic apodization for phased array ultrasonic signals, hope that obtain the narrower main lobe, the less side-lobes and the lower side-lobe magnitude of beam distribution by using window function with the weight for each element, thus improving directivity of the beam.Also, the usual phased array ultrasonic testing system generate beam-forming parameters with PC, which has a huge volume and its integration is not high, while implementation with FPGA may well avoid this problem, what need to consider are errors and precision caused by digital control. Moreover, study has found with the weight for element we can achieve far-field waveform and near-field beam focusing. Therefore, using the amplitude weighting to form beam and the linear phase control to scan spatial, to a large extent can also reduce the complexity of detecting system.In this thesis, first the feasibility of theoretical design is simulated through Matlab, and then experiment upon correlation algorithm of beam-forming on Field II ultrasound simulation platform to verify the study; for digital implementation parts, verify the correctness of program through timing waveform simulation of Modelsim. Signal processing of complex algorithms and module control are completed by means of FPGA and DSP, so the overall program is achieved with these tools.The above designs by digital control are primarily based on Altera’s Cyclone chip, which is pin-rich, abundant logic gates, and embedded DSP core.