User's Manual

Screen Service SDT 200UB – SDT 500UB ARK-1 ATSC Operations
July, 2009 v 1.0 Page 3 - 69
3.8.5 AM/PM pre-correction tool
The ARK1 ATSC system provides a pre-correction tool for AM/PM output signal pre-
correction.
Remember to click on the Save as button the first time you change the factory default curves
in order to do not overwrite them.
Before closing the connection to port 5000, save curves changes otherwise they will be lost.
Note: the operation of uploading and downloading pre-correction curves moves a large
amount of data from and to the device. The use of these tools over low badwidth, not stable
or high distances netwoks could cause frequently time-out disconnections and it is not
recommended.
Click on AM/PM button icon, highlighted in the nex figure, to access the pre-correction
window.
Table 14. AM/PM pre-correction window
Two main actions are possible in this section:
• AM/AM and AM/PM curve drawing: used to change the AM/PM pre-correction
coefficient.
• AM/PM pre-correction files management: used to open or save AM/PM pre-
correction setting file.
AM/AM and AM/PM curves are specific for each power range of each output channel.
The two curves are used to calculate the AM/PM pre-correction coefficients. The curves are
drawn by the interpolation of 1024 points referring to the points inserted and using a linear or
polynomial interpolation algorithm.
Knob points can be added with a left-click of the mouse on the grid and deleted with a right-
click, drag and move a point to change the curve.
Each coefficient variation, due to curves change, is saved in the FPGA “runtime” memory
registers and dynamically changes the device’s output.