EXFO PSO-100 Series Optical Sampling Oscilloscopes - Manual (Page 42)

Setting up and Using the Optical Sampling Oscilloscope
34 PSO-100
Managing SoftSync Input
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If you select an incorrect interval, you will still see an eye-diagram, but
with an incorrect time scale; it will actually show a reversed time scale
for odd intervals.
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If you select an incorrect interval in pattern mode, you will notice that
you see numerous eye diagrams instead of a pattern. Although this is
not the expected result, this can be used to determine the correct
interval or signal frequency by selecting a value untils you see a
pattern.
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When the external clock (option) is selected from the Clock menu,
Clock subrate becomes active. You can then select the correct clock
sub rate from the list. For example, if a 10 GHz clock and 40 Gb/s data is
used, a ¼ sub rate clock should be used. If an incorrect value is chosen
from the list, the time scale will be incorrect.
I
MPORTANT
Different signal generators may have different calibrations. The
sampling frequency also drifts slightly with temperature. Therefore,
a 40 GHz setting in SoftSync inputs is not guaranteed to fully match
a signal generator set to 40.000 GHz. You may have to tune the
signal frequency in SoftSync to find the correct interval.
You can also calibrate the sampling frequency in the Utilities menu,,
using the Find pattern feature.