【摘要】：眾多超聲相控陣技術(shù)中,波束合成和空間掃描都是基于對(duì)陣元的時(shí)延或相位控制,要解決的根本問(wèn)題是在聲束形成時(shí)產(chǎn)生具有盡可能低的旁瓣波形,并進(jìn)行空間電子掃描,而作為陣元信號(hào)的另一個(gè)可控變量,輻射幅度一直沒(méi)有得到應(yīng)有的考慮。因此,針對(duì)相控陣超聲信號(hào)處理,我們提出了一種動(dòng)態(tài)變跡的方法,希望通過(guò)對(duì)各個(gè)陣元信號(hào)幅度加上窗函數(shù)的權(quán)值來(lái)獲得主瓣更窄、旁瓣更少、旁瓣數(shù)量級(jí)更低的聲束分布,以此改善波束的指向性。 再有,傳統(tǒng)的相控陣超聲檢測(cè)系統(tǒng)由上位機(jī)生成波束合成所需的各種參數(shù),系統(tǒng)體積龐大且集成度不高,而采用FPGA實(shí)現(xiàn)可很好地避免這一問(wèn)題,需考慮的是數(shù)字控制引起的誤差及精度要求。不僅如此,研究發(fā)現(xiàn),通過(guò)對(duì)陣元幅度進(jìn)行加權(quán),可以實(shí)現(xiàn)人們所需要的遠(yuǎn)場(chǎng)波形及近場(chǎng)聲束聚焦。因此,采用幅度加權(quán)的方法形成波束,采用線性相位控制進(jìn)行空間掃描,還可很大程度降低檢測(cè)系統(tǒng)的復(fù)雜度和節(jié)約成本。 本文理論設(shè)計(jì)通過(guò)Matlab模擬方法的可行性,再在Field Ⅱ超聲仿真平臺(tái)上進(jìn)行相關(guān)算法的聲束控制實(shí)驗(yàn),并驗(yàn)證理論研究；數(shù)字實(shí)現(xiàn)部分先通過(guò)Modelsim的波形仿真時(shí)序驗(yàn)證方案的正確性,進(jìn)而在已有的相控陣超聲檢測(cè)實(shí)驗(yàn)平臺(tái)測(cè)試其功能的完備性及精確度。復(fù)雜算法模塊的信號(hào)處理及各模塊的控制借助FPGA和DSP技術(shù)完成,而強(qiáng)大的設(shè)計(jì)開(kāi)發(fā)工具Quartus Ⅱ、CCS及豐富的EDA電子應(yīng)用使總體方案得以實(shí)現(xiàn)。 以上數(shù)字主控平臺(tái)設(shè)計(jì)主要基于Altera公司的Cyclone系列芯片,該芯片引腳豐富,邏輯門(mén)充足,且內(nèi)嵌DSP核,有利于各種算法處理的實(shí)現(xiàn)。
[Abstract]:In many ultrasonic phased array technologies, beam synthesis and space scanning are based on the time delay or phase control of the opposing elements. The fundamental problem to be solved is to generate as low a sidelobe waveform as possible when the sound beam is formed, and to conduct spatial electronic scanning. As another controllable variable of array element signal, the radiation amplitude has not been given due consideration. Therefore, for the ultrasonic signal processing of phased array, we propose a dynamic method to change the number of nodes. We hope to obtain a narrower main lobe, less sidelobe and lower magnitude of sidelobe by adding the weight of window function to the signal amplitude of each array element. In order to improve the directivity of the beam. Furthermore, the traditional phased array ultrasonic detection system needs all kinds of parameters needed by PC to generate beam synthesis. The system is large in volume and low in integration, but this problem can be avoided by using FPGA. It is necessary to consider the error and precision requirement caused by digital control. Moreover, it is found that the far-field waveform and near-field acoustic beam focus can be realized by weighting the amplitude of the face element. Therefore, using amplitude weighting method to form beam and linear phase control for spatial scanning can greatly reduce the complexity and cost of the detection system. In this paper, the feasibility of the Matlab simulation method is designed, then the acoustic beam control experiment of the related algorithm is carried out on the Field 鈪，

本文編號(hào)：2195912