User guide

How to Change the Output Levels Properties
In the example measurement, we have set the focus on speed: 100 threshold levels
and 1,000,000 compared bits per measuring point. You may wish to obtain more
precise results.
1
Press Properties and switch to the Parameters tab.
2
Increase the Number of Compared Bits to 100,000,000.
Remember: One failure per 1 million bits yields a BER resolution of 10
-6
. One
failure per 100 million bits yields a BER resolution of 10
-8
.
3
Decrease the Resolution (the threshold step size) to 2mV.
This gives us 500 steps per Volt.
4
Press OK to confirm your changes.
5
Press the Start button to repeat the measurement with the new parameters.
The measurement now takes more time than the previous, but it is also much
more precise.
When you move the BER Threshold bar, you will see that some of the calculated
values change. This is explained in “Explanation of the Numerical Results” on page
277.
How to Use the Different Views
To switch between the different views of the Output Levels measurement:
1
Press Properties and switch to the View tab.
2
Select dB Histogram versus Threshold.
This gives you another view of the measured data.
3
Switch to the Graph tab and select Linear Scale.
The data remains the same, but a linear scale makes it easier to see the
distribution.
Advanced Analysis 6
Agilent J-BERT N4903B High-Performance Serial BERT 269