Agilent Technologies J-BERT N4903B Manual de usuario descargar pdf (Pagina 8)

User Interface

Bit recovery mode (Option A01)

This mode is useful for analyzing non-deterministic 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 simplifies setup by

eliminating the need to setup expected data for the error detector.

Two analyzer sampling 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 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

continuously (see Figure 11).

Fast total jitter

Agilent implemented a new measurement technique for TJ (BER),

the fast total jitter measurement. 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 12).

Web-based access to GUI

J-BERT can be operated conveniently from any remote web

location with the built-in web server. So even without program-

ming knowledge, J-BERT can be operated and monitored from a

distance or off-site and in noisy or environmental test labs.

Figure 10. Bit recovery mode for analyzing non-deterministic trafﬁc

Figure 11. Auto alignment (center) simpliﬁes correct sampling

Figure 12. Fast total jitter measurement for quick and accurate total jitter

measurements

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Agilent Technologies J-BERT N4903B Manual de usuario Pagina 8