Anritsu BERTWave Series, Operation Manual, Page: 63 / 466

1.5 Technical Terms
1-37
1
Outline
One Level
At Eye pattern measurement, the maximum level at the center 20% of the
bit interval is the average value of the high histogram.
20 %
100 %
0 level
1 level
3 
1
Eye height
3 
0
Eye
amplitude
Crossing
point level
Figure 1.5-21 0 Level, 1 Level, Eye Amplitude and Eye Height
Outer ExR (Outer Extinction Ratio)
Outer Extinction Ratio is the ratio of Level 3 and Level 0 of the PAM4
waveform, and the calculation formula is as follows.
Outer Extinction Ratio = 10log
10
{(L
3
– L
D
)/( L
0
– L
D
)} (dB)
L
3
:  Level 3 (mW) 
L
0
: Level 0 (mW)
L
D
: Level when no light input (mW)
Figure 1.5-22 The level to measure Outer Extinction Ratio
L
0
–
L
D
L
3
–
L
D
L
D
Outer OMA
Level 3
Level 2
Level 1
Level 0