User's Manual

Screen Service SDT ARK 1 ECHO Operations
Jan, 2012 v 1.ATSC_FCC Page 3 - 53
Figure 15. AM/PM 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.
The tool is prevented to send an “overflowing” amount of data to the device: curve changes
will be applied only when the mouse button is released.
In the module grid, the red curve is used to monitor the current module curve calculating and
saving. The last saved coefficients are locally downloaded from the FPGA runtime memory
registers in order to redraw the curve.
Click two times the right mouse button on the grid to open the zoom menu. The “H” options
are used to horizontally zoom (x01,x02,x04,x08,x16). The “V” options are used to vertically
zoom (x01,x02,x04).
During saving actions are created two nonlinear pre-correction files:
 *.dpre files: files containing digital coefficients values.
 *.apre files: files containing analog coefficients values.