User's Manual

Screen Service SDT ARK 1 ECHO Operations
Jan, 2012 v 1.ATSC_FCC Page 3 - 56
3.6 Channel filter & complex filter
Click on Filter button icon, highlighted in the nex figure, to access the channel and complex filters
window.
Figure 17. Channel filter & complex filter window
Use the Filter window to manage and monitor channel and complex filters.
To understand the behavior of the Echo’s Channel Filter, a brief explanation is needed. The
Fold-back mode is an algorithm that makes use of 3 thresholds, determined by the
characteristics of the system (receiver and transmitter’s antenna front and back gains), to
calculate the optimal range of the transmitter’s output RF power that results in controlled
echo level on the receiver side antenna. The so introduced thresholds are:
 Threshold Fold Back Alarm: individuates the level of the transmitter’s output RF
power that determines an uncontrollable echo level on the receiver side antenna.
 Threshold Fold Back Down: individuates the upper limit of the optimal range of the
transmitter’s output RF power. When the “Module” value is higher than this
threshold, the controller decreases the output RF power.
 Threshold Fold Back Up: individuates the lower limit of the optimal range of the
transmitter’s output RF power. When the “Module” value is lower than this threshold,
the controller increases the output RF power.