Translations:Illustrations of spectra/10/en

Let us review the terminology we introduced at the beginning of this chapter. As we know, there is phase lead and there is phase lag, with one being the negative of the other. In particular, the phase-lag spectrum is the negative of the phase-lead spectrum. Either one can be called the phase spectrum. According to the electrical engineering convention (which we follow), the exponential in the direct Fourier transform carries a negative sign. For that reason, we choose to let the word phase refer to the phase lag and not to the phase lead. Electrical engineers often say phase for phase lag, so we are in good company. For example, electrical engineers say minimum phase for minimum-phase lag, as we do.