User's Manual

Screen Service SDT ARK 1 ECHO Purpose and planning
Jan, 2012 v 1.ATSC_FCC Page 2 - 3
2.1 GENERALITY
Propagation is a critical issue in ATSC / Mobile TV broadcasting.
In this contest, the use of repeaters for digital TV broadcasting becomes a key issue for commercial
terrestrial distribution of digital TV.
In addition, 8VSB signal characteristics avert well known adjacent channel interference problems of
analogue TV broadcasting. This leads to the SFN network planning: a single frequency is used all over the
coverage territory, increasing spectrum efficiency.
Therefore, in digital TV SFN netwotrks iso-frequency repeaters are needed. An On-channel repeater is,
basically, a radiofrequency repeater that receiver and transmits using the same frequency.
Traditional On-channel repeater use is limited by a hard design constraint: coupling between transmitter and
receiver antenna limits the allowed maximum gain for the on-channel repeater, leading to a reduction of the
coverage area: a traditional on-channel repeater installation is only possible if hard isolation conditions are
complied.
A on-channel repater, with coupling echo cancellation system, allows operations at higher power levels
under normal tower isolation conditions.
2.2 INTRODUCTION
SDT ARK-1 ECHO is a Multi-standard Television Transposer. Based on Software Defined technology, SDTX
ECHO allows the definition of different operative modes on the same hardware platform.
At the state of the art SDT ARK-1 ECHO has the following possible working modes:
 Analog Television Heterodyne Transposer;
 Digital Television Heterodyne Transposer;
 Digital Television Heterodyne Transposer with echo canceller;
 Re-broadcasting ATSC Modulator.
Analog and Digital Television Heterodyne Transposers receive and re-transmit Analog or Digital TV signals
allowing the software setting of input and output channels.
Re-broadcasting ATSC Modulator receives and de-modulates ATSC signals and re-modulates them.
Auxiliary inputs and outputs allow to import and export TS contents on ASI and GBE interfaces.
The single software controller allows the switching between working modes and different settings for each
operative mode using the same platform.
A brief description of the main features and potentialities of each operative mode follows.
2.2.1 ANALOG/DIGITAL TELEVISION HETERODYNE TRANSPOSER
Heterodyne Transposer with Digital Filtering at Intermediate Frequency for Analog and Digital Television
standards.
Capable of:
 Agile UHF input Down-converter (from 470 MHz up to 862 MHz)
 Agile UHF output Up-converter (from 470 MHz up to 862 MHz)
 Input Analog/Digital signal level monitoring with quality measurement for ATSC
 Digital Filtering at Intermediate Frequency
 Echo canceller for Digital signal
 AM/PM Software Pre-correction power and frequency calibrated for Digital and Analog signal