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Eye-Diagram Analyzer Reference
Controlling the Display
To Improve the
Sensitivity in
Eyeline Mode
In eyeline mode, additional eye filtering can be applied to improve the mea-
surement sensitivity. This can be an advantage when measuring extinction
ratios on low-level signals. Use the eyefltr ON OFF softkey to apply the filter.
When the pattern repetition frequency is greater than 10 MHz, internal filter-
ing is applied that provides a 20 dB signal-to-noise improvement. For pattern
repetition frequencies less than 10 MHz, software filtering is applied that
allows variable signal-to-noise improvement versus sweep time.
To improve sensitivity, press:
Setup, diagram, EYELINE or PATTERN, eyefltr ON OFF ON
Use the front-panel knob to adjust the amount of filtering applied.
To Extend the
Bandwidth to 40
GHz
Use the extd BW ON OFF softkey to enable RF corrections which extend the
measurement bandwidth of the eye-diagram analyzer to 40 GHz. Extended
bandwidth operation can be used in both eyeline and pattern modes, but not
in eye mode.
1 Extend the measurement bandwidth by pressing:
Setup, diagram, EYELINE or PATTERN
The extended 40 GHz bandwidth cannot be used in eye mode.
2 Turn the extended bandwidth on by pressing:
Trg, Cal, more 1 of 2,, extd BW ON|OFF ON
To Apply User-
Corrections
User-corrections provide a convenient method for modifying the display of
input signals. Some of the applications for user-corrections include the follow-
ing:
• Filtering input signals to simulate the effects of circuit design.
• Compensating for frequency and phase response of external probes.
• Compensating for frequency and phase response of external test setups.
• Compensating for the frequency response of optical to electrical converters.
Several Bessel-Thomson software filters are included on the 70874A eye-dia-
gram analyzer’s memory card. These filters can be applied as user-corrections
in the eyeline and pattern modes. (User corrections must be off in eye mode.)
User correction files are identified by the prefix a_ as shown in the following
table. The files AUTOST and 70874 comprise the eye-diagram analyzer pro-
gram.