User's Manual

Digital ATSC Exciter-Modulator System Chapter 1, Introduction
Axcera Axciter, Rev. 0 1
Chapter 1: Introduction
This manual explains the installation, setup, operation, alignment and
maintenance for the Axciter 8VSB digital television modulator. It is
intended that persons installing, operating, or maintaining the Axciter read
this manual for important safety and operational instructions.
Manual Overview
This instruction manual is divided in 5 chapters and four supporting
appendices. Chapter 1, Introduction, contains information on safety,
general maintenance, product return procedures, and warranties.
Chapter 2, Installation and Operating Instructions, describes the system
installation and setup of the Axciter. Chapter 3, Detailed Alignment,
contains alignment instructions for each circuit card that contains
alignment controls. Chapter 4, Upconverter/Downconverter Tray or
Module Assemblies, contains descriptions of the tray and module
assemblies and the boards and subassemblies that make up the tray and
module assemblies. Chapter 5, Maintenance, contains maintenance
instructions. Appendix A, System & Modulator Drawings, contains the
System Drawings for both the stand alone and the sled based Axciter
systems. Appendix B, Upconverter/Downconverter Tray Drawings,
contains the tray interconnect, board schematics and assembly drawings.
Appendix C, Upconverter and Downconverter Module Assembly
Drawings, contains the interconnects of the module assemblies, and the
schematics and assembly drawings of the boards that make up the
module assemblies. Appendix D contains a glossary of acronyms that is
provided for reference.
Axciter Overview
The Axciter represents the most up-to-date technology available in digital
television (DTV) modulators. The Axciter DTV exciter was designed to
address many of the problems facing digital television transmitter
engineers. The Axciter accepts SMPTE-310M encoded digital video and
performs all processing necessary to create an ATSC compatible RF output.
The exciter is equipped with high speed digital signal processing systems
that monitor not only the incoming digital video signal but the transmitted
signal as well. Critical information about the incoming digital video is
provided to aid in trouble-shooting the digital video chain leading up to the
exciter. On the output side, the Axciter monitors the RF output of the
transmitter power amplifier and automatically computes precorrection
information that is used to produce the highest quality over-the-air 8VSB
signal possible. This system is called Adaptive Digital Equalization and
throughout this manual is referred to as simply ADE. Optional software
called DTVision is available for viewing the performance of the adaptive
system directly on the self-contained color LCD of the Axciter.
While the Axciter performs all of these tasks automatically it is important to
understand how the Axciter operates. There are no controls inside the
Axciter due to its digital nature and it is quite likely that the transmitter
engineer will never have to even open the cover. Even so there are several
selections and options that must be made from the front panel of the