Quantifi Photonics BERT 1005 Series, Руководство пользователя

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Bit Error Rate Tester | BERT 1005
Quantifi Photonics Ltd. Version 2.04 53
8.5.1.1 Set the cursor and de-emphasis
To set the pre-cursor or post-cursor de-emphasis, follow the steps bellow:
1. Select an appropriate value from the DE-EMPHASIS drop-down list.
2. Select PRE or POST from the CURSOR drop-down list.
8.5.1.2 Example of setting the pre-cursor and post-cursor de-emphasis
Consider the following pre-cursor and post-cursor example:
The Peak Swing is set by the AMPLITUDE field. The de-emphasis control leaves the Peak Swing
unchanged, but it reduces the De-emphasized Swing, to provide the desired level of de-emphasis.
The De-emphasis swing is calculated as
𝑑 = 20 × log (
𝑚
𝑛
)
, where <
d
> represents the de-emphasis,
<
m
> represents the Peak Swing, and <
n
> represents the De-emphasized Swing.
For example, if the value of the AMPLITUDE field (Peak Swing) is set to 800 mV, and the value of De-
emphasized Swing is 505 mV, it can be calculated that the value of the DE-EMPHASIS field must be set
to 4 dB.
The amplitude of the 0 and 1 levels can be calculated by dividing the AMPLITUDE (Peak Swing) by 10 to
the power of the DE-EMPHASIS divided by 20. The difference between the 0 and 1 levels for the above
example would be:
𝑛 = (
800mV
10
4𝑑𝐵
20
) = 505𝑚𝑉
Pre-De-emphasis is set to a lower number while it is x for the post-De-emphasis