Harris Atlas DVL400, Technical Manual

Page: 27 / 180

2/25/03 888-2473-001 1-13
WARNING: Disconnect primary power prior to servicing.
Section 1 Introduction
ATLAS Series™
1.2.7 V-XCAST™ Exciter
The ITIS V-XCAST™ COFDM (Coded Orthogonal Frequency Division Multiplex)
exciter is used with the Atlas Series™ transmitter. This exciter is described in a
separate instruction book. A second hot standby exciter/driver and drive chain
switcher is available as an option. The exciter is controlled and configured using an
RS-232 serial connection. Software is provided with the exciter. A serial diagnostic
and monitoring port is also provided.
The COFDM exciter V-XCAST is a fully compliant DVB-T (Digital Video
Broadcast - Terrestrial) exciter and up-converter supporting both 2K and 8K
operations, specifically designed for commercial networks. This device performs
channel coding and OFDM modulation of a MPEG2 transport stream. One single
unit drives the Atlas Series™ transmitter with a fully modulated RF DVB-T
channel. The excellent quality and stability of analogue UHF signal output
maximises the TV transmitter efficiency, decreasing global cost. Thanks to its ASI
(Asynchronous Serial Interface) standardised interface, the V-XCAST exciter can
be used with any DVB compliant source equipment.
A flexible Bit Rate Adaptation mechanism, with PCR (Program Clock Reference)
restamping, is provided, giving an independence between the multiplexer rate and
the DVB-T rate.
Test generators are included, which allow easier BER (Bit Error Rate) measurement
with the optional V-TER, professional test receiver.
The V-XCAST COFDM exciter accepts a SFN (Single Frequency Network) option
which allows to set up single frequency networks with use of a SFN adapter at the
DVB multiplexer site. In SFN mode, the COFDM modulation and RF up-converter
are locked on a stable 10 MHz external reference coming from GPS (Global
Positioning System). With the optional internal GPS receiver, the V-XCAST offers
a compact and reliable SFN modulation solution.
The full device remote control can be performed via the MIP channel (remote
control from network head-end), or via an RS232 port and the PC software (local
control or remote control via modem) or via a standard SNMP (Simple Network
Management Protocol) manager, allowing a very fast integration with most Control
Systems.
The same PC software can be used for easy logging and maintenance, thanks to an
accessible rear panel RS-232 connector. It will be used to adjust digital
precorrection curves.
Alarms are monitored on front panel leds and on a rear side connector as relay
contacts. Alarms are optionally controlled and monitored by standard SNMP
managers.