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9.15. USE OF DELAY COMPENSATION
The Delay Compensation field of the DISPLAY SETUP can be used to add an artificial
compensation for system delays to phase curves of complex frequency domain func-
tions. It can also be used to read the Group Delay within a system. This is achieved by
adjusting the Phase Compensation such that the phase curve within the frequency
band of interest is flat. The reading of the Phase Compensation Field, plus the setting
of the Delay between Channels field of the MEASUREMENT SETUP will be equal to the
Group Delay in the band.
9.16. INTERPRETATION OF THE CEPSTRUM
The Cepstrum is always scaled in dB. The amplitude of a line in the Cepstrum can be
interpreted as being equal in dB to the amplitude of a corresponding sinusoidal fluctu-
ation in the logarithm of the autospectrum. For instance, suppose a white noise spec-
trum has a ± 5 dB sinusoidal fluctuation imposed upon it. The corresponding Cep-
strum would exhibit a line of 5 dB at the quefrency corresponding to !/fluctuation fre-
quency, see Fig.9.5.
Ampl itude
dB
Log.
Autospectrum
Amp litude
dB
_____...5 d B - - - - -
Frequency,
Hz
1
/
~F
Cepstrum
Fig. 9.5. Interpretation of the Cepstrum
Quefrency,s
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