Figure 8: Bit recovery mode for analyzing non-deterministic
traffic.
6 J-BERT N4903A High-Performance Serial BERT Data Sheet
Bit recovery mode (option A01)
This mode is useful for analyzing non-determinis-
tic traffic. This is helpful when you need to analyze
real world traffic, for example in a PCI Express
link where so-called ‘skip ordered sets’ are added
unpredictably to avoid FIFO overflow. This simpli-
fies setup by eliminating the need to setup expect-
ed data for the error detector. Two analyzer sam-
pling points are used to measure a relative BER,
which makes the following measurements possible
with relative BER:
• BERT scan including RJ/DJ separation
• Output levels and Q factor
• Eye contour
• Fast eye mask
• Fast total jitter
• Spectral jitter decomposition
Automatic alignment
The J-BERT N4903A High-Performance Serial
BERT is able to align the voltage threshold and the
delay offset of the sampling point automatically,
either simultaneously or separately. It is possible
to search for the 0/1 threshold automatically on
command, and to track the 0/1 threshold continu-
ously (see figure 9).
Fast total jitter
Agilent implemented a new measurement
technique for TJ (BER), the fast total jitter meas-
urement. This method provides fast and feasible
total jitter measurements, around 40 times faster
than a common BERT scan but with comparable
confidence level. Instead of comparing bits until
the BER reaches a defined number of bits or a
defined number of errors, it only compares bits
until it can decide with a 95% confidence level
whether the actual BER is above or below the
desired BER (see figure 10).
Web-based access to GUI
J-BERT can be operated conveniently from any
remote web location with the built-in web
server (SW 4.5). So even without programming
knowledge, J-BERT can be operated and
monitored from a distance or off-site and in noisy
or environmental test labs.
Figure 9: Auto alignment (center) simplifies correct sampling
even for stressed eyes.
Figure 10: Fast total jitter measurement for quick and
accurate total jitter measurements.
User Interface
(18 Seiten)
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