User guide

• Every window reduces the spectral power.
• Results obtained from different devices can only be compared if the same
window is used.
Spectral Jitter - Procedures
This section shows how to set up and use the Spectral Jitter measurement. As an
example, we measure the spectral jitter behavior of a shielded cable.
This requires the following steps:
• “How to Prepare the Spectral Jitter Measurement” on page 351
• “How to Execute the Spectral Jitter Measurement” on page 352
How to Prepare the Spectral Jitter Measurement
To use the Spectral Jitter measurement to test a shielded cable:
1
Disable the pattern generator outputs by pressing the 0V (Disable) button in
the PG Setup -> Data Output 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 menu 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:
– Logic levels: LVPECL
– Clock speed: Gb Ethernet (1.06250Gb/s)
See “Setting up the Pattern Generator - Concepts ” on page 121 for more
information.
6
Set up the error detector so that the input range and the termination matches
the pattern generator's levels. Select Normal as the Active Input, an Input
Range of 1-3V, and set the Data Termination to 1.3V.
7
Enable the pattern generator outputs by pressing the 0V (Disable) button.
8
Also make sure that the error detector derives its clock from the incoming data
stream using Clock Data Recovery. See “Clock Setup - Procedures” on page
178 for details.
Advanced Analysis 6
Agilent J-BERT N4903B High-Performance Serial BERT 351