Implementation of real-time STFT for Mixed Domain Analyzer

Short-time Fourier transform (STFT) is widely used in electronic measurement and fault diagnosis areas. For multi-domain oscilloscope (MDO) applications, the time-frequency analysis is supported to process the nonstationary signals. Unfortunately, limited by the processing rate and computation capability of the oscilloscope, the refresh rate of the spectrogram is too low to support real-time analysis. In addition, the supported temporal resolution and frequency resolution is limited by the acquisition length of the input signals, and are not flexible for dynamic adjusting. In this work, an STFT implementation structure is designed to support high-speed time-frequency analysis and flexible resolution adjustment. A circular computing mechanism is applied to improve the refresh rate of spectrogram analysis, and an overlap frame generation unit is designed to support high-flexible resolution adjustment. The proposed STFT structure is evaluated on a verification platform, the refresh rate of the spectrogram is up to 10 k frames per second, the temporal resolution can be flexibly adjust from 1 ns to 10 s, and the supported frequency resolution is ranging from 10 Hz to 100 MHz.