LeCroy DDA 7 Zi series, Руководство оператора

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Operator's Manual
WP700Zi-OM-E-RevA
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Case 4: The entire head signal is analyzed
DDA Markers
If Read Clock is acquired by the DDA, the "sample time" markers can be drawn. Because the phase relation of
RCLK to the head signal is not known, it is adjustable. It is worth noting here that the ML markers are at positions
determined by the instrument's channel emulation; the sample time markers are at positions determined by the
channel's sample clock signal with ML markers ("+" signs) and level markers (horizontal lines).
Setting Up to Use Drive Channel Analysis
There are several basic considerations when you are preparing to use Drive Channel Analysis. Which signals are
to be provided to the DDA? What waveform section or sections will be analyzed? What will be used as the
reference waveform? What trigger and time/div settings should be used?
Which Signals to Provide
The following is an overview of the signals that can be used by the DDA.
x
Head Signal: The drive head signal is the only signal the DDA requires. The drive head signal can either be
the signal after the pre-amplifier, or the one after the drive filter if available.
x
Read Gate: Read Gate is "optional" for all error find methods; however, it is strongly recommended that
you use Read Gate.
Choosing the Waveform Section to Be Analyzed
Before using Drive Channel Analysis, you should determine which part of the head signal will be analyzed.
The options you have are to analyze:
x
Part of a single Read Gate cycle
x
A single Read Gate cycle
x
Multiple Read Gate cycles.
There are additional considerations for each of these choices.
If you choose to analyze a part of a single Read Gate cycle, it is important that it include the VCO Synch signal.
Because it will be difficult to set up a reference signal if it is less than a single Read Gate cycle, it is
recommended that this not be done with either the Analog Compare or Channel Emulation methods.
If you want to analyze a single Read Gate cycle, the easiest approach is to use the Read Gate signal and, if
necessary, the Analyze Region cursors, to determine which section is analyzed. If you are using Channel
Emulation or Analog Compare, you must make sure that the reference signal is the same length (see the
following
Selecting the Reference Waveform ).
If you wish to analyze multiple Read Gate cycles, the setup is the same as for a single Read Gate cycle. The
Read Gate signal and, if necessary, the Analyze Region cursors are used to determine which sections are
analyzed. If you are using Channel Emulation or Analog Compare, you need to ensure that the reference signal is
of similar makeup.
Except for Analog Compare, there are limits as to how much data the channel analysis methods can analyze at
the same time:
x
Channel Emulation without a reference saves ML sample results for up to 20,000 bits, which are used to
draw the ML sample (+) markers.