Tektronix TMT4 User Manual page 28

Operation
The eyes are shown in real-time, which means it only takes seconds before results begin to display.
Link training parameters
The Margin Tester shows not only the performance of the link by displaying eye diagrams, but also displays how the Margin Tester's
receivers were adjusted to maximize the generated eye. Some eyes may need especially high levels of equalization in order to form
the link, so having both pieces of information is critical to understanding performance. The Margin Tester displays a table showing the
Attenuation, VGA (Gain), CTLE, and 5 DFE taps values used to maximize the eye opening. This allows you to quickly see how much
equalization is needed for each displayed eye diagram. The possible range of values for each of these equalization settings is shown in the
following table.
Equalization
ATT
VGA
CTLE
DFE Tap 1
DFE Tap 2
DFE Tap 3
DFE Tap 4
DFE Tap 5
DFE Tap 1 has a wide range of possible values, but will typically be within the stated range.
1
28
Number of possible settings
8
15
32
256
128
128
128
128
Range
-10.0 dB to -2.0 dB
0.0 dB to +8.0 dB
+2.0 dB to +15.0 dB
1
-55.0 mV to +55.0 mV (typ )
-44.0 mV to +43.3 mV
-22.0 mV to +21.7 mV
-16.0 mV to +15.8 mV
-11.0 mV to +10.8 mV