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Keysight N4917BSCB 400G Optical Receiver Test Application User Guide
3
Concepts and Features of N4917BSCB Software
1 The pattern generator output amplitude is adjusted so that the clean
eye signal (i.e., sinusoidal jitter, sinusoidal interferer and Gaussian
noise turned off) has approximately the minimum extinction ratio as
specified in the standard.
2 The clean eye signal should have at least half of the dB value of SECQ
due to ISI created by a low-pass filter and the frequency response of
the E/O converter. The N4917BSCB software stress signal calibration
offers an automated procedure that adjusts the initial SECQ value by
means of changing the BERT deemphasis coefficients and thus
changing the residual ISI level.
3 After turning on the sinusoidal jitter (SJ), sinusoidal interferer (SI) and
Gaussian noise (GN), the software changes iteratively the amplitudes
of the stress components until all stressed signal metrics are met.
4 The parameters of the stressed receiver test signal are stored in a
calibration file to be recalled for the same setup at a later point in time.
The stressed receiver conformance test signal as defined in the IEEE
standard allows certain degrees of freedom to meet the specified target
metrics SECQ, ER and OMAouter. For example, the frequencies of
sinusoidal jitter and sinusoidal amplitude interferer are not exactly
specified by the standard but can be set in the given range (see Table 2).
Also, the ratio between sinusoidal interferer and Gaussian noise is not
specified in the IEEE 802.3bs standard but may be specified by the user.
The N4917BSCB software also offers to change these parameters by using
the calibration configuration variables (explained in
“Performing Stressed Receiver Compliance Tests with N4917BSCB
Software”).
• Periodic Jitter Frequency (default: 119.2 MHz)
400G-FR4
Signaling rate
Modulation format
Calibration test pattern
Stressed receiver test pattern
53.125 +/- 100ppm GBd
PAM4
SSPRQ
PRBS31Q
Stress Components
Sinusoidal jitter (sinusoidally jittered clock)
Sinusoidal amplitude interferer (SI)
Gaussian noise (GN)
Inter-symbol-interference (ISI)
Same as for the other supported 400GBASE and
200GBASE standards
Stress Signal Target Metrics
Stressed eye closure (SECQ)
Extinction ratio (ER)
Stressed receiver sensitivity (OMAouter)
from 0.9 to 3.4 dB
3.5 dB
SECQ-dependent
Transmission Standard
Signal Parameter
Value