User's Manual

Screen Service SDT ARK 1 ECHO Purpose and planning
Jan, 2012 v 1.ATSC_FCC Page 2 - 15
2.6 FUNCTIONAL DESCRIPTION
2.6.1 GENERAL
The ARK 1 receives on its inputs An RF signal or four MPEG-2 Transport Stream in serial ASI format.
The RF input signal is converted into a standard 36 MHz IF frequency by a fully agile down converter.
This signal is digitally filtered, elaborated, precorrected and then presented at 997 MHz to the channel
converter.
The channel converter provides to generate the final frequency in a fully agile mode.
The LO with a very low phase noise is locked to the 146 MHz high stability reference.
Reference signal coming from GPS board allow precision offset
The switching power supply module generates the following voltages to feed the different circuits: +32 V,
+ 24V.
2.6.2 RF AMPLIFICATION
The signal coming from the agile up converter goes to the RF amplifier section. The RF amplification is done
by class A and AB stages.
Out of the final stage, the RF signal passes through a directional coupler. The directional coupler detects
samples of direct and reflected power and passes this information to the check function