A Design For A Digital Ultrasonic Inspection Device

In recent decades, with the support of the advance of electronics and the computer technology, the ultrasonic testing technology is developing towards minimization, intelligentization and integration in the testing industry field. In order to obtain excellent effect of detection and System Integration, more designs of testing instruments appear in nowadays. In this paper, a digital ultrasonic testing (pulse-echo) device based on FPGA and ARM is designed.The working principle of the digital ultrasonic testing device is as follows: Firstly, the ultrasonic pulse signal is generated by an ultrasonic probe through the ultrasonic pulse exciting circuit; Secondly, the echo signal of the ultrasonic pulse signal was received through the ultrasonic receiving circuit; Thirdly, under the control of the FPGA in the device, the echo signal is amplified by the program-controlled amplifier and is sampled by ADC converting circuit. Fourthly, the data of the echo signal is processed by digital filter and FFT on the FPGA, the digital filter is designed as a band-pass filter and the FFT is analyzed in frequency domain; Fifthly, in order to transfer data form the FPGA to ARM module a communication unit is build using serial-port technology; at lastly, a ARM embedded desktop is achieved through the touch screen technology, with which user can set testing system parameters and handle easily.The FPGA has many advantages: high-speed parallel processing, rich I/O interface, etc, in which we build five functional units: storage unit, computing and control unit, timing control unit, communication unit, and external circuit control unit. In the FPGA some algorithm is adopt for signal analysis and processing, such as digital filtering, FFT, and etc. An ARM9 development kit is selected to design the program of a display and control panel based on ARM-Linux / Qtopia. The Experiments showed that this device is stable and reliable, and the device can be used in actual testing situation.