User guide

If you compare the Low Level result with the limit we have set on the Pass/Fail
tab, you will find that the measured result fails the upper pass/fail limit for this
parameter.
View Tab
The graph shows either the BER vs. Threshold, the dBER vs. Threshold, or the
QBER vs. Threshold.
This graph shows the relationship between the analyzer decision threshold and
the measured BER.
The BER considers all errors. It is calculated as:
This graph shows the relationship between the analyzer decision threshold and
the absolute values of the derivative of the bit error rate (dBER/dTh).
It is recommended to view this graph with a linear scale because a linear scale
reveals the distribution more clearly:
This distribution can often be approximated by a Gaussian normal distribution. With
a Gaussian marker you can measure the mean and standard deviation of the normal
distribution (see also “The Gaussian Marker” on page 237 and “Graph Tab” on
page 276).
6 Advanced Analysis
274 Agilent J-BERT N4903B High-Performance Serial BERT
BER vs. Threshold Graph
dBER vs. Threshold Graph