Method for Frequency Measurement with ApFFT Based on FPGA

The conventional method of frequency measurement based on traditional fast Fourier transform (FFT) can't provide to an ideal performance due to the fence effect and the leakage of frequency spectrum. As an improved algorithm of the traditional FFT, the all phase FFT (apFFT) spectrum analysis has a perfect performance on suppressing the spectrum leakage and the property of phase invariant. In this paper, a novel method for frequency measurement which takes the advantage of all phase FFT is proposed. This method utilizing two largest spectrum lines of the signal from time-domain provides a higher precision than traditional method. In the paper, a corresponding frequency measurement design based on Field Programmable Gate Array (FPGA) is implemented. The functional simulation results show that the design based on FPGA has better performance compared with the traditional method for frequency measurement.