A D 2 4 0 2 - 9 6 - O P E R A T I N G M A N U A L
to be identical in length. Jitter can and does change the length of time between successive
samples of audio. As a result, the digital delay elements no longer represent equally spaced
points in time. Jitter modulates the time interval between samples, and this can radically alter
the response of the filter. For example, if converter clock in the AD2402-96 were derived
directly from the AES/EBU receiver (as it is in
many
converter products) the stopband
attenuation at 100 kHz would be degraded from 117 dB to only 28 dB. The 100 kHz signal
that should have been removed is now splattered all over the audio band (see graph).
F
IGURE
5. 100
K
H
Z
S
TOP BAND
A
TTENUATION VS
. J
ITTER AT THE
C
ONVERTER
C
HIP
A second graph below shows the effect of jitter on the stop band attenuation with a 26-kHz
input signal.
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