3-17
Eye-Diagram Analyzer Reference
Controlling the Display
To Improve the
Sensitivity in
Eyelin e 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 improveme nt. For pattern
repetition frequencies less than 10 MHz, software filtering is applie d 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 o f 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.
1Extend the measurement bandwidth by pressing:
Setup, diagram, EYELINE or PATTERN
The extended 40 GHz bandwidth cannot be used in eye mode.
2Turn 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 us er-corrections include the follow-
ing:
•Filtering input signals to simulate the effects of circuit desi gn.
•Compensating for frequency and phase response of external probes.
•Compensating for frequency and phase response of external test set u ps.
•Compensating for the frequency response of optica l to electrical converters.
Several Bessel-Thomson software filters are in cluded 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 correc tions 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.