Application of FFT in frequency domain characteristics test system for ultrasonic flaw detector

To test the frequency domain characteristics of ultrasonic flaw detector, this paper designs a test system which based on the Fast Fourier Transform (FFT) algorithm and VC++ platform. After sampling the time domain waveform of launching and the receiving amplifier of ultrasonic flaw detector, amplitude spectra of frequency domain was got through the C++ program which had a core of fast Fourier transform (FFT) processing discrete data. Then the system obtained the characterization parameters (center frequency and bandwidth) of the output pulse frequency of ultrasonic flaw detector´s launching amplifiers and the frequency response of ultrasonic flaw detector´s receiving amplifier. At the same time, test interface of the detector frequency domain characteristics parameter was designed with VC++ platform. Experiments results showed that the system had the capability to quickly and accurately test the frequency domain characteristics of ultrasonic flaw detector, and visually displayed them.