Tektronix WFM 601i, User Manual

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Functional Overview
WFM 601i Serial Component Monitor
2–9
Eye Pattern Display
The eye pattern display is a voltage-verses-time display of the serial bit stream.
This mode is used to observe the amplitude, rise time, aberrations, and jitter of
the serial signal.
In EYE mode the serial signal that is applied to the rear panel loop-through input
is directly displayed. In EQ EYE the serial signal is displayed after equalization.
Two trigger modes are available: OVERLAY and 10-EYE. The trigger mode is
indicated by a readout in the upper left corner of the CRT.
The trigger mode is selected in the CONFIGure\EYE PATTERN menu. Press the
CONFIG key, then move the “selector box” to the EYE PATTERN menu
selection. Pressing the bezel button adjacent to DISPLAY will cause the trigger
mode to toggle between OVERLAY and 10 EYE.
OVERLAY
– In OVERLAY all of the bits of a serial word are overlaid at each eye
location. This shows peak jitter at each eye crossing. Approximately three eyes
are shown on screen, with the horizontal deflection calibrated at 1 ns/div (It is
actually a “9-eye” mode with the sweep running at a 3H rate). Figure 2-3 shows
the Overlay Eye display.
100 mV/DIV
OVERLAY
1 nS/DIV
10 Hz
Figure 2-3: Overlay Eye display.
10 EYE – In 10-EYE every tenth bit of the scrambled serial signal appears at a
fixed location in the display. Events that are correlated with the serial word rate,
or horizontal line rate, can be observed in this mode. The horizontal deflection
factor is calibrated at 3 ns/div.
EYE and EQ EYE
Trigger Modes