On the cross-terms in spectrograms

The authors show that the spectrogram does, in general, have cross-terms. Depending on the signal structure and the window used, the cross-terms may sometimes be reduced or completely eliminated. If the cross-terms are located far from the origin in the ambiguity domain, they can be easily eliminated. If, however, the cross-terms are located near the origin, it is very difficult to reduce the cross-terms. To explore the mechanism of the cross-terms in the spectrogram, the ambiguity domain interpretation is adopted. Some experimental results are provided to illustrate this mechanism