From Table 1, it is seen that
(1) The assessment accuracy of the Fourier transform-based
method does not improve with the increase of SNR. This is
because the accuracy of this method is mainly dependent
upon the resolution of the spectrum;
(2) Owing to the differential calculation algorithm, the Hilbert
transform-based method is very sensitive to the SNR of the
signal, i.e. its frequency assessment accuracy improves
gradually with the increasing SNR;
(3) Among three methods, the new method provides the most
accurate assessment of the signal frequency regardless of the
noise. Its error is smaller than 26% even when the SNR is as
low as 5 dB. Moreover, its accuracy improves quickly with the