Fig. 4

Double-window apFFT spectrum of x(n). The double-window apFFT spectrum of the test signal is listed in Fig. 2. The rising-cosine window is taken as window function here, and the expression of the window function is given in Eq. (4). The upper half of Fig. 3 is the apFFT amplitude spectrum of the experimental signal, and the bottom part is the apFFT phase spectrum of the signal