Teledyne LeCroy WaveExpert 100H Operators Manual - Manual (Page 64)

Operator’s Manual
62
WE-OM-E Rev A
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40.
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PRBS5.
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PRBS7.
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PRBS9.
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PRBS10.
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PRBS11.
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PRBS15.
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PRBS23.
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PCIe Compl.
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FC CJPAT.
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FC CRPAT.
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Custom.
• Pat. Length (CIS timebase only) – this control is active only when “Custom” is
selected in from the standard pattern list. Enter the desired pattern length in this
control. A value of 1 in this control can be used to view eye patterns on signals
without repeating patterns.
• PLL Bandwidth (CIS timebase only) – Sets the loop bandwidth of the sampling
clock phase locked loop. The low setting results in a loop bandwidth of 10 KHz and
timebase jitter of 210 fs while the high setting results in a loop bandwidth of 1 MHz
and 500 fs timebase jitter.
• Max Samples (CIS timebase only) – Sets the maximum memory available for
waveform capture. This control is used to prevent inadvertently setting the
timebase to a very long size when turning the time/div knob as long acquisitions
can require several minutes to complete. The Max. Samples control setting affects
the standard pattern length that can be selected; only those that are compatible
with the available memory can be used.
• Samples/UI (CIS timebase only) – Sets the number of samples per bit or UI. The
choices available are 8, 16, 32, 64, 128, 256, 512, 1024 and 2048.
Note: In some cases, the Low setting will result in an apparent increase in the observed jitter in the signal under
test. This is because the lower jitter in the timebase allows more of the low frequency jitter in the signal under test
to be visible.
Sequential Sampling Mode
The standard mode for sampling the signal is through a technique known as sequential sampling.
In this mode, a trigger signal applied to either the trigger or prescale inputs on the scope front panel
is used to start the timebase. Once started, the timebase waits for a minimum amount of time
before generating the sampling strobe that causes the sampling modules each to take one voltage
sample. On each subsequent trigger, the sampling strobe is taken at a time slightly longer than the
previous sample after the timebase. The delay difference between each subsequent sample is
controlled by the time/division and record length settings.