Download LECROY 9400A Operating

9.3
Accurate Time Measurements
Two deep acquisition memories, each storing 32000 points, provide the
unprecedented time resolution of the 9400A.
In order to match the time base settings, a maximum of 25000 digitized
points are displayed on the screen with a resolution of 500 display
points. A compacting algorithm showing all minimum and maximum values
ensures that no information is lost in the display of a trace.
Time cursors can be positioned accurately on any one of the 500 display
points of a compacted trace. The corresponding measurement accuracy is
1/500 or 0.2%.
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To improve measurement accuracy, two expansion functions, EXPAND A and
EXPAND B are provided to display every digitized point trace.
When the expansion factor is such that 500 measured points are to be
displayed, every display point corresponds to a digitized point.
When the time base requires that less then 500 digitized points fill
the screen, the 9400A interpolates using straight line segments between
the actual points¯
In the example below, the compacted trace of a 25000 point waveform is
expanded by a factor of I00 with EXPAND A and B to provide maximum time
measurement accuracy.
Under these conditions, each expanded trace displays 250 digitized
points.
Every other display point is interpolated and the time measurement
accuracy is 1/50000 = 0.002%.
Getting the Most Out of Your 9400A
9-3