Teledyne LeCroy AORM - Advanced Optical Recording Measurements - Manual (Page 110)

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ISSUED: June 2013 923133 Rev A
DVD PROCESSING MODEL
In many applications, it is important to make measurements directly from the RF signal,
independent of a specific DVD chip. The OData processing function provided in the Advanced
ORM package can emulate the filter, slicer, and/or phase-locked loop (PLL) of a typical optical
recording drive. A schematic of this function is shown in the following diagram. You can view the
equalized, leveled data, threshold, sliced data, or the extracted clock.
You can control the cutoff frequency and boost of the equalizing filter, the closed loop bandwidth
of the slicer, and the bandwidth of the PLL. Alternatively, you can input the equalized signal and
still look at the slicer or PLL output of the function.
Additionally, some of the advanced optical drives have a header and data section. A Gate signal
differentiates the header and data sections. The OR Data function lets you input a gate signal,
and allows you to choose when to analyze the data (gate high or low), so that either the header or
the data area can be analyzed.
DVD RAM
For noisy signals if less than three width peaks are found, the PLL start frequency is set so that T
is the nearest value to the expected bit rate for which the first width peak is an integer multiple of
T. Also, the PLL start phase is derived from the first two edges instead of the first one.