Anritsu BERTWave Series, Operation Manual, Page: 53 / 466

1.5 Technical Terms
1-27
1
Outline
The Dual Dirac distribution assumes that RJ is the normal distribution
and DJ is a constant value. The Jitter Analysis software displays
σ
and
µ
R
–µ
L
of the Dual Dirac distribution approximated from the measured
histogram to RJ (d-d) and DJ (d-d) respectively.
Extinction Ratio
The extinction ratio is the ratio of 1 Level and 0 Level; it is used for
evaluating optical signal waveforms.
The extinction ratio is calculated by the following formula.
Extinction Ratio = 10log
10
{(L
1
– L
D
)/(L
0
– L
D
)} (dB)
L
1
: 1 Level (mW) 
L
0
: 0 Level (mW)
L
D
: Level without optical input (mW)
L
0
L
1
–
L
D
L
1
L
D
L
0
–
L
D
Figure 1.5-9 Extinction Ratio Measurement Level
For the extinction ratio of PAM4, refer to “Outer ExR (Outer Extinction
Ratio)”.
Eye Amplitude
For NRZ, eye amplitude is the difference between 1 Level and 0 Level.
Refer to Figure 1.5-21.
In PAM4, eye amplitude is the difference between the levels. There are
three of Upper, Middle, Lower. Refer to Figure 1.5-10.
Eye Crossing Percentage
Eye Crossing Percentage is the ratio of the Eye amplitude rising and
falling waveforms. The calculation formula is as follows. Refer to Figure
1.5-21.
Crossing = (crossing point level–0 Level)/(1 Level–0 Level)