Agilent Technologies J-BERT N4903, User Manual

Page: 224 / 434

•
Executing the measurement (see “How to Execute the Eye Opening
Measurement” on page 225 )
•
Optimizing the view of the results (see “How to Optimize the View of
the Results” on page 225 )
•
Using the color bar (see “How to Use the Color Bar” on page 226 )
•
Adding or changing colors (see “How to Add or Change Colors” on
page 227 )
•
Changing the BER threshold (see “How to Change the BER
Threshold” on page 227 )
•
Changing the BER range of a color (see “How to Change the BER
Range of a Color” on page 228 )
How to Prepare the Eye Opening Measurement
To prepare an Eye Opening measurement to test a shielded cable:
1 Disable the pattern generator outputs by pressing the 0V (Disable)
button in the PG Output Setup screen.
2
Use a shielded cable to connect the pattern generator's Data Out port
and the error detector's Data In port.
3
Terminate all non-connected pattern generator output ports with
50
Ω
.
4 Switch to the Pattern panel and press Pattern Select . Select an
appropriate pattern, for example a pure 2^15-1 PRBS, for both the
pattern generator and the error detector.
5 For the pattern generator setup you need to specify the logic levels
and the bit rate. Select
ECL levels and a clock speed of 1250 MHz in
this example. This corresponds to a clock period of 0.8ns. See
“Setting up the Pattern Generator - Concepts ” on page 69 for more
information.
6 Set up the error detector so that the input range and the termination
matches the pattern generator's levels:
– Select an Input Range from -2V to 0V
– Set the Data Termination to -2V
– Set the
Alignment BER Threshold to 1E-6.
– Set the Clock Setup to Clock Data Recovery to get the error detector's
clock from the incoming data stream.
7
Enable the pattern generator outputs by pressing the 0V (Disable)
button.
5
Advanced Analysis
224 Agilent J-BERT N4903 High-Performance Serial BERT