Section 4. Advanced Features and PlexTools Professional
PX-716UF Installation and Users Manual
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Figure 25:Q-Check TA Test on a poor-quality disc
A DVD has a total of 10 different pits, including nine from 3T to 11T
and one 14T pit. These histograms show the degree of jitter occurring at
each pit. An ideal condition (when jitter is small) is when the adjacent
pit/land peaks are thin, long and clearly separated from each other.
A better quality disc will have histograms in which the peaks are
narrow, indicating less variation in length deviation. Also, in a good disc
there will be no peak shift—that is, peaks will lie along the green axes.
If the frequency distribution of the lands and pits seems “muddy,” or the
segments run together, the disc quality is not good.
