LeCroy DDA 7 Zi series, Operator'S Manual

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WavePro 7Zi
339
WP700Zi-OM-E-RevA
may be too spread out from detectable peaks in the distribution. (See How the Starting VCO Frequency is
Determined for more details.) Example: CD data has T = 231 ns, about 4.33 MHz. We can extract the clock from
CD data at 100 MS/s (23x) and 200 MS/s (46x) or 250 MS/s (58x). At 50 MS/s (11.5x) and at 500 MS/s (115x), it
sometimes does not find the right starting frequency. Another example: DVD has T = 1/26.16 MHz, about 38.2 ns.
We can extract the clock from DVD data at 500 MS/s (19x), 1 GS/s (38x), and 2 GS/s (76x). At 250 MS/s (9.5x)
and at 4 GS/s (153x), it sometimes does not find the right starting frequency.
Following are some interesting pictures to show what can be handled:
Figure 5-13. A small section of a 1 ms long noisy DVD waveform. Acquired with an ungrounded AP020
probe at 500 MS/s.
Figure 5-14. Same piece of the same signal, equalized and leveled.
It should be mentioned that the extracted clock output is also exactly five divisions high (without vertical zoom),
and its edges are linear from -0.1 to +0.1 * T and from +0.4 to +0.6 * T. Therefore, if there are 20 samples per T,