User guide

Three Available Views
The Output Levels measurement provides three different graphical views to
visualize the calculated results:
•
BER versus Threshold
This graph shows the relationship between the analyzer decision threshold and
the resulting BER. It presents the raw data.
•
dB Histogram versus Threshold
This graph shows the relationship between the analyzer decision threshold and
the derivative of the bit error rate (dBER/dTh). A Gaussian marker allows you
investigate the peaks of this graph.
•
Q from BER versus Threshold
This graph shows the extrapolation of the Q-factor and the optimum threshold
level from a limited number of measured points.
Example Results
The following illustration shows the BER versus Threshold graph of a simple
Output Levels measurement:
Changing Properties
If you change the measurement settings after the measurement has been run,
please note:
• Parameters that affect the data capture.
Changes on the Parameters tab take only effect if you run the measurement
again. To remind you that the present results have not been obtained with the
modified settings and that you should repeat the measurement, the result
display shows a yellow bar.
• Parameters that change the display of the measured data.
6 Advanced Analysis
264 Agilent J-BERT N4903B High-Performance Serial BERT