To estimate the frequency and phase information of the signals containing dense spectral components

a novel discrimination and correction method for dense all-phase FFT (apFFT)spectrums is proposed.Due to apFFT’s excellent performance in suppressing spectral leakage and the property of 'phase invariant’

this paper can distinguish the dense spectrum from single-tone spectrum by judging whether the phase spectral lines behave as flat distribution

when the conventional discrimination method by identifying peak amplitude lines malfunctions.Combining with all-phase time-shift correcting spectrum method and the phase relation between adjacent spectral lines

this paper deduces a novel method to estimate frequencies and phases for dense spectrums and gives the discrimination index for these two cases .Simulation shows that

for the different cases of SNR(Signal to Noise Ratio)

the accuracy of the proposed method is higher than that of the conventional correcting dense spectrum method

guaranteeing that the proposed method is of high applied value when SNR＞20dB.