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Chapter 4 Operation
4-46
4.7 Jitter Tolerance Test Procedure
4.7.1 Measurement Sequence
Jitter Tolerance measures the tolerance of jitter per each listed jitter
frequency.
Jitter tolerance is the maximum jitter amplitude at which the number of
errors or the error rate becomes equal to or below the Pass/Fail
Threshold. The following types of measurement methods are available:
● Binary
The binary search method is used to search for the target jitter
amplitude.
The binary search method decreases its searching range of jitter
amplitude by half for every measurement execution. If the error
measurement value is equal to or below the value of Threshold, the jitter
amplitude is increased; if it exceeds the value of Threshold, the jitter
amplitude is decreased. The search ends when the amount of searching
range becomes equal to or below the value of the permitted resolution
setting. In the figure below, the jitter amplitude of the fourth
measurement represents the final measurement result.
Number of retries
Ji
tte
r
amp
lit
ude
Upper Value
Lower Value
<Step
Resolution
:Measurement value ≤ Threshold
:Measurement value
>
Threshold
1 2 3 4 5
Figure 4.7.1-1 Procedure for the Binary Search measurement method
● Downwards
The jitter amplitude is decreased from the Start Value until the error
measurement value becomes equal to or below the value of Threshold.
In the case of Downwards Linear, the jitter amplitude is decreased by the
value set in Step.
In the case of Downwards Log, the jitter amplitude is decreased by the
magnification set in Ratio.
In cases that the error measurement value still exceeds the Threshold
even when the jitter amplitude becomes equal to or below Lower Value,
the next step jitter amplitude will be taken as the final measurement
value.