An Approach to FPGA-based Time-Frequency Spectrogram by Real-Time Sweep Spectral Extraction Algorithm

We have proposed an approach to build up an FPGA-based time-frequency spectrogram for time-varying signal. Instead of short time FFT algorithm, we have adopted real-time sweep spectral extraction algorithm to reduce large memory usage. By fixing the sweep frequency range of local oscillator and the center frequency of finite impulse response (FIR) filter, we can obtain more effective usage of FPGA hardware resource and stable spectrum analysis performance. The time-frequency scaling algorithm has been used to guarantee the measurement of wide frequency range (sub-Hz to MHz) for arbitrary input time-varying signal. The high speed FPGA performance enables us to build up a three dimension time-frequency spectrogram for audio signal by accumulating the spectral data against the evolution time.