Design Of Ultrasonic High Speed Data Acquisition Card Based On FPGA And ARM

The scale of China's railway system is huge.Since the reform and opening up,after more than 40 years of development,the mileage of railway operations has increased significantly.The problem of the increasingly difficult task of railway maintenance and inspection can not be ignored.In recent years,the competent authorities have repeatedly emphasized the importance of ensuring the safety of railway transportation.Based on actual needs,this subject has designed a high-speed ultrasonic testing system suitable for rail flaw detection.First of all,the thesis starts with the principle of ultrasonic detection and selects the pulse reflection method as the detection method of this system.Secondly,according to actual needs,formulate the overall system plan and determine system performance indicators.Carry out design work from two aspects of hardware and software.In terms of hardware,ultrasonic excitation module,signal conditioning module,human-computer interaction module,sampling module and Ethernet interface module are designed.The signal conditioning module designs the topological structure of pre-amplifier circuit,program-controlled gain circuit,band-pass filter circuit and attenuation circuit to condition the echo signal.The ultrasonic excitation module can transmit the ultrasonic wave with the repetition frequency of 3kHz at the maximum to meet the requirement of the high-speed flaw detection for the repetition frequency.The signal conditioning module can achieve waveform adjustment within the range of 0?80dB gain.In terms of software,the ARM main control chip is used to design the human-computer interaction module control program.Using FPGA device XC7A100T to achieve high-speed analog-to-digital converter drive,data buffering,digital filtering,data transmission and other functions,the 65MHz sampling rate enables the system to identify higher frequency noise signals,filter the ultrasonic echo from both hardware and software.An ethernet frame communication protocol based on UDP is designed for data interaction between the hardware system and the host computer software.The host computer interface is compiled to realize data saving and waveform display functions.Finally,the subject developed a prototype of the ultrasonic data acquisition system,and tested the hardware and software systems by module.The experimental results show that each module of the system works normally,the performance index can meet the design requirements,The communication between the hardware system and the host computer is normal,which is in line with the original intention of the design.