User's Manual

Screen Service SDT ARK 1 ECHO Operations
Jan, 2012 v 1.ATSC_FCC Page 3 - 52
This tool provides two grids for the drawing of:
 Module of the filter’s curve.
 Group Delay of the filter’s curve.
The two curves are used to calculate the linear 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 the saving actions are created two nonlinear pre-correction files:
 *.dlin files: files containing digital coefficients values for Digital-IF linear pre-
correction curves.
 *.alin files: files containing analog coefficients values for ATSC Re-modulator linear
pre-correction curves.
The following buttons allow the management of linear pre-correction files and the
management of the connection to port 5000:
 Save: used to save in the device memory the current curves setting. The previously
saved file will be overwritten except in the evet that no files have been saved before;
in this case a dedicated window appears in order to let the user name the new file.
 Save as: used to save in the device memory the current curves setting. The
previously saved file will be overwritten with a new name. in the evet that no files
have been saved before, a new file will be created.
 Read file: used to reload the last saved file.
 Export: used to download pre-correction files on the user PC. A browser window
allows the selection of the saving path.
 Release: release the connection in order to allow others remote machines to
connect to port 5000 (refer to Connection to port 5000 paragraph).
Files are separately managed in analog and in digital AGC mode.
3.5.2 AM/PM
Click on AM/PM button icon, highlighted in the nex figure, to access the pre-correction
window.