Agilent Technologies J-BERT N4903, User Manual

Page: 350 / 434

Setting a Confidence Level is generally recommended. This ensures that
neither too few nor too many bits are captured. See also “Target BER”
on page 340 .
If you enable Absolute Bits/Errors , the measurement proceeds to the next
jitter amplitude as soon as either the number of received bits or the
number of errors is reached.
N O T E
Ensure that you capture a number of bits that suffices to verify (with the desired
probability) that a measured point has a BER below the Target Bit Error Ratio.
This is the wait time that takes effect after the measured BER is higher
than the target BER. It allows the DUT to recover from the situation.
The unit is seconds. The next measurement starts after that time.
Search Specification
On this page of the Jitter Tolerance Properties dialog, you specify how the
measurement proceeds upwards or downwards from one measured
point to the next. The chosen method impacts the measurement
duration. The specified parameters influence both measurement
duration and precision.
You can choose one of six search methods:
•
Downwards linear
•
Downwards logarithmic
•
Upwards linear
•
Upwards logarithmic
•
Binary search
•
Extended binary
For a description of these methods refer to “Vertical Search Methods”
on page 341 .
For linear search, you can set the step size.
•
Downwards linear starts from the maximum (which depends on the
jitter frequency). A step size of 100 mUI, for example, may result in
a sequence of 1000 UI, 999.9 UI, 999.8 UI, and so on.
The test for one frequency stops when the BER limit is met or zero
amplitude is reached.
7
Jitter Tolerance Tests
350 Agilent J-BERT N4903 High-Performance Serial BERT
Confidence Level
Absolute Bits/Errors
Relax Time
Linear search