Teledyne LeCroy WavePro Automation Command - Manual (Page 391)

Automation Command and Query Reference Manual - Control Reference
UpSampleSUT Integer
From 1 to 50 step 1 Range
This control specifies how much upsampling should be applied. Upsampling creates more samples
using a quite accurate sin(x)/x interpolation. There are two reasons you might want to upsample. The
first is, internally, our transition time measurement uses cubic interpolation (and more) to find the time
of the threshold crossing. For cubic interpolation it is ideal to have 4 or more samples on the
transition. At 40GS/s, spacing between samples is 25ps, so 100ps edge will have four samples on the
edge; faster edges than that might benefit from upsampling by 2 or more if required. The second
reason to upsample is that some signals, like PCIE at 5Gb/s, are at an exact submultiple of the
scope's sampling rate. At 40GS/s, there are exactly 8 samples per UI on a 5Gb/s signal. The scopes
sample clock is calibrated and, in SDA scopes, temperature stabilized. It is extremely accurate. If the
signal does not have SSC and is also extremely accurately clocked, then all the points will occur at 8
horizontal positions in an 8 diagram; the eye will not form closed curves. This is more likely to be
noticable if the acquisition size is fairly short. For example: if the acqusition size is 100,000 UI long
then without upsampling, each of the 8 positions must drift to the next position to form the eye; that
requires 1/100000 / 8 = 1.25 ppm frequency difference. But with the default upsampling of 5, the
samples fall at 8 x 5 = 40 horizontal positions in the eye; so that requires only 10ppm / 40 = 0.25ppm
frequency difference to form the eye. The eye is much more likely to be completely formed. (Please
note that in general we recommend long acquisitions for SDA2 analysis, longer acquistions than used
in the example above reduce the likelyhood of needing upsampling.)
Description
SDAINPUT app.SDA2.SignalInput.SDAInput
Input signal used by SDA2. If the signal under test was differential, this is after the subtraction.
AxisXRotation Integer
From -90 to 90 step 1 Range
AxisXRotation Integer
AxisYRotation Integer
ClearSweeps Action
LabelsPosition String
LabelsText String
Persist3DQuality Enum
PersistDotJoined Bool
Persisted Bool
Persistence3d Bool
PersistenceMonoChrome Bool
PersistenceSaturation Integer
PersistenceTime Enum
ShowLastTrace Bool
UseGrid String
View Bool
ViewLabels Bool
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