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Ultrasonic nondestructive testing technology industry is widely used as a detection technology, it has no damage to the workpiece, simple operation, stable performance, high reliability, can the workpiece from the production to the various aspects of the Battle for the entire detection . With the development of the ultrasonic flaw detection technology and digital signal processing technology, digital ultrasonic NDT system came into being. Compared with analog ultrasonic flaw detection system, digital ultrasonic flaw detection system has many advantages of high accuracy, high reliability, and the use of flexible, is gradually replacing analog ultrasonic flaw detection system and become the inevitable trend of development of ultrasonic flaw detection system. Digital ultrasonic flaw detection system but there are also disadvantages, as a single testing method, data processing capability is not strong, programmable resources are limited, slow data transfer rate. In this paper, on the basis of the analysis of a variety of ultrasonic flaw detection method, the principle of digital ultrasonic flaw detection system shortcomings, a major for the axle, rail flaw detection A digital ultrasonic NDT system design. Pulse reflection and penetration Two testing mode to achieve better testing results and the broader use of the system, high-performance FPGA system core, USB communication, based on the PC. The system is modular in design thinking, ultrasonic flaw in hardware on the system is divided into modules, data acquisition and processing module and communication interface module, using the powerful data processing capabilities of the FPGA, coordinated control of each module. The hardware part of each module are used to high-precision, low noise, and high reliability of the device as well as a variety of measures to reduce noise, improve accuracy, and improve the anti-jamming capability. On the basis of complete hardware design, digital ultrasonic flaw detection system FIR filter and adaptive filter. The first to use MATLAB and System Generator tool to create simulation models and simulation of the performance of the digital filter design, and be modified according to the simulation results. Then Xilinx ISE Design Suite FPGA development environment, complete the design and FPGA implementation of the FIR filter and adaptive filter. Finally, ultrasonic flaw detection system debugging, elaborated the main hardware circuits and digital filter debugging, debugging results to modify and optimize the system design. After repeated testing, the modified design digital ultrasonic flaw detection system is operating normally, a good performance.
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