Sencore DMG 3000, Руководство пользователя

Страница: 159 / 306

DMG 3200/3100/3000 – User Manual
Page 159 (306)
Figure 7.47- DVB-S2 Output –Linear Precorrection
The graphical view for Gain and Group delay consist of two graphs, the filter characteristics of a
transmission chain (provided by the user) and the system response utilizing the optimized
precorrection filter computed on the MMI card.
Please note that the optimization algorithm for group delay contains some
random elements and might not give the desired result 100% of the time. Since
the optimization runs only if new information is provided, to the user will have to
change one value slightly before pressing
Apply to re-optimize and obtain the
desired result.
The graphical view may also be switched to a textual view where the points can be added and
changed. This can be done by pressing the co-ordinates button. In this view, the graph window
ranges may also be changed through “Min X, Max X” and “Min Y, Max Y”. This values can be
chosen freely within reasonable values (Gain: Min X ≥ 0, Max X ≤ 35, Min Y ≥ -5, Max Y ≤5 and
for Group Delay: Min X ≥ 0, Max X ≤ 35, Min Y ≥ 0, Max Y ≤ 300). The restrictions for the points
are as following:
Gain:
•
Each X-value has to be unique.
•
Y has to decrease with increasing X
•
At least 5 points.
•
Only two decimals places.
Group Delay:
•
Each X-value has to be unique.
•
Y has to increase with increasing X
•
At least 5 points.
•
Only two decimals places.