Phase difference correcting spectrum method based on all-phase spectrum analysis

To estimate sinusoidal signal's real frequency, amplitude and original phase precisely under noisy circumstances, a novel phase difference correcting spectrum method which combines both all-phase FFT and conventional FFT is proposed. This technique is of low computation complexity and convenient. The frequency and amplitude estimation can be acquired by implementing simple operation on these two spectral analysis results at main spectral position, moreover the all-phase FFT phase-spectrum value at main spectral position can be directly viewed as the original phase without any correcting measures. Due to all-phase FFT's excellent property of inhibiting spectral leakage, the proposed method is also feasible in the cases of dense spectrum distribution. And the phase estimation error is very tiny in the 10-7 resolution level with no noise added.