22
Multiple Measurements
The multiple measurements give the user the ability to view the different measurements: Top,
Base, Min, Max, Fall/ Rise time, Peak to Peak, Eye Amplitude, Eye Height, Eye Width, Jitter,
and the crossing percentage for a number of measurements specified in the repetitive box or
for an undetermined number. Use the
Check All
text box to display all the measurements.
SNDR
Signal-to-Noise Distortion Ratio in dB.
SNDR is defined by:
10 × log
10
(
𝑃
𝑚𝑎𝑥2
𝜎
𝑒2
+ 𝜎
𝑛2
)
where
P
max
is
the
maximum value of P(k) which is the linear fit
pulse response,
𝜎
𝑒
is the standard deviation
of the error e(k) and
𝜎
𝑛
is the RMS deviation
from the mean voltage at a fixed point in a
run of at least 8 consecutive identical levels.
Outer VMA
The outer VMA (Voltage Modulation
Amplitude) depicts the difference between
the power levels of the highest logic level (11
in PAM4) and the lowest logic level (00 in
PAM4) in dBm. It is measured from
consecutive identical bits of the two levels.
TDECQ
Transmitter and Dispersion Eye Closure for
Quaternary.
TDECQ is, as defined by the IEEE, a measure
of each optical transmitter's vertical eye
closure when transmitted through a worst-
case optical channel, as measured through
an optical to electrical converter (O/E) and
equalized with the reference equalizer.
VMA
The standard VMA (Voltage Modulation
Amplitude) depicts the difference between
the power levels of the ‘1’ and the ‘0’ logic
level of an NRZ signal in dBm.
