HP 54750A, User Manual, Page: 101 / 478

Eye , Mask and Eyeline Mode Measurement T utorials
Making Eye Diagram Measurements
Measuring duty cycle distortion
Duty cycle distortion is a measurement of the time separation of the rising
and falling edge of the eye at the center threshold level. The default
center value is 50%, and can be changed in the 4
Dene meas
5 menu. Narrow
horizontal histograms are computed at the center threshold level to determine
the mean location of the rising and falling edge at that level. The time
dierence between the falling and rising edge can be expressed in absolute
time:
D C D time = j T
r ise
center
0 T
f al l
center
j
The time dierence between the falling and rising edge , expressed as a
percentage of the bit period:
D C D per cent =
j T
r ise center
0 T
f all center
j
bit per iod
Figure 5-8. Duty cycle distortion measurement.
5-17