Chapter 1 Outline
1-38
Outer OMA
It is the optical modulation amplitude of PAM 4 waveform, and it is the
difference between Level 3 and Level 0.
Overshoot
It is the ratio of the maximum power to Level 3 in the PAM4 waveform
and is calculated by the following formula:
Overshoot =
Pmax –Level 3
Outer OMA
100
Pmax: Maximum power measured in the waveform
p-p (peak to peak)
Indicates difference between maximum and minimum values for signal
amplitude and data distribution width
For example, Vp-p means the difference between the maximum and
minimum values of the AC voltage.
Jitter p-p means the difference between the maximum and minimum
values of the jitter time distribution.
PRBS (Pseudo-Random Bit Sequence)
PRBS is the abbreviation for pseudorandom bit sequence. It is a bit string
approximating actual communications data with a random distribution of
“1” and “0”. In a bit length of 2
n
–1, n is called the number of the PRBS.
Using the BERTWave, n can be set to 7, 9, 15, 23, and 31.
Table 1.5-2 PRBS Bit Length
n 2
n
–1
7 127
9 511
15 32767
23 8388607
31 2147483647
The number of the PRBS used for measuring the Rx sensitivity is
determined by the communications standard.
RIN OMA
RIN OMA is a measurement of the ratio of the light source's noise power
to signal power (dB/Hz) based on OMA and is calculated by the following
formula.
RIN OMA = 10log
10
(RN
one
+RN
zero
)
2
OMA
2
×BW
(dB/Hz)
RNone: Electrical random noise power measured at the top level
Use Level 1 for NRZ signals and Level 3 for PAM4 signals.
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