Tektronix WFM 601i, User Manual

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Functional Overview
2–10
WFM 601i Serial Component Monitor
100 mV/DIV
10–EYE
3 nS/DIV
10 Hz
Figure 2-4: 10-EYE display screen.
In Figure 2-4 the eye display has been changed to the 10-EYE mode.
Approximately 10 eyes are displayed per horizontal sweep, and the horizontal
scale is 3 ns/Div. The display is triggered so that a given bit of the scrambled
serial word always appears in the same location; the display is word correlated.
Systematic errors that repeatedly affect certain bits in the word can be observed
in this mode.
Both EYE pattern displays can be set to attenuate jitter via three different jitter
high-pass filters. Filter choices are 10 Hz, 100 Hz, and 1 KHz, and are selected
in the CONFIGURE\EYE PATTERN menu. Each filter will suppress jitter terms
below the indicated 3 dB point, allowing medium and high frequency jitter to be
separated from low frequency jitter. The 10 Hz and 1 KHz filters allow jitter
measurements according to the proposed SMPTE standard.
The selected jitter high pass filter is indicated in a readout field directly below
the horizontal deflection factor as 10Hz, 100Hz, or 1KHz.
Calibrated vertical gain for the EYE and EQ EYE modes is 100 mV/div. The
deflection factor is displayed in the upper left corner of the CRT screen. Both X5
and X10 vertical gains are available via the Gain menu. The deflection factor
readout shows 20 mV/div in X5 and 10 mV/div in X10. Variable Gain also
works in the EYE pattern modes. When Variable Gain is enabled, a “>” is placed
in front of the deflection factor to indicate the uncalibrated condition: e.g. “>100
mV/DIV.”
Jitter Filters
Vertical Gain