Figure 4

The spectrogram and its maximum frequency waveform, which is superimposed on the spectrogram with a solid curve, of a simulated Doppler signal. The theoretical (a), the STFT (b), the MPWD (c), the PCNN denoised (d), and the PCNN noise and speckle reduced (e) versions of the original signal. The STFT versions (f, k, p), the STFT versions after the MP denoising (g, l, q), the MPWD versions (h, m, r), the STFT versions after PCNN denoising (i, n, s), and the PCNN noise and speckle reduced version (j, o, t) of the signals added noise with SNR = 0 dB ( f, g, h, i, j), 5 dB (k, l, m, n, o), and 10 dB (p, q, r, s, t).