Design And Implementation Of Underwater Ultrasonic Imaging System Based On The Principle Of Phased Array

Conventional underwater detecting equipment work with large aperture moved. With the rapid development of marine mining, the demand for convenient and portable ultrasound imaging system is more and more urgent. Phased array imaging technology has high testing sensitivity and resolution, which can control the direction of ultrasonic beam easily and research dynamic focusing and deflection. Therefore, it is important and meaningful to study the application of phased array technology in underwater ultrasonic imaging.According to the requirements of the underwater ultrasonic imaging system, the design of underwater acoustic imaging system based on the principle of phased array is proposed.Firstly, the detecting theory of ultrasonic phased array technology is introduced in this paper,including ultrasonic field characteristic and beam directivity of phased linear array. The principle of focusing and deflection of ultrasonic beam under phased transmitting and receiving control is analyzed, and the concrete detection method has established.Secondly,based on the theoretical analysis, the overall design of underwater ultrasonic imaging system is carried out. The capacitive micro-machined ultrasonic transducer array is determined for the system, and the hardware circuits of the system including transmitting circuits and receiving circuits are designed and tested. While, the transmitting circuits including pulse generating module, digital-to-analog converter, signal amplifier. The receiving circuits are consisted of transceiver isolation circuit, filter and amplifier circuit, high speed data acquisition and data storage module.Thirdly, FPGA is used for hardware system control and the realization of phased key technology. According to the requirements for phased delay accuracy of the design, the delay time of phased focusing and deflection is analyzed and FPGA internal phased-locked loop is adopt to achieve the minimum delay. In addition, IP ROM is called for automatic scanning ofthe phased array. FPGA and the upper computer are communicated through the PCI bus, and the high speed transmission of the command and data is achieved.Finally, the phased array underwater ultrasonic imaging system is verified by the pool test. The results show that the transmitting circuit generates high power signal with good phase control performance. And the phased receiving and acquisition circuit works stable,data transmission meet the functional requirement. The results demonstrate that the whole system has excellent performance and a certain prospect of application.