Getting Started
Caution
With LNB power enabled, there is a potentially damaging dc voltage applied to the
Demodulator input. When connecting test equipment, or a local modulator (or any dc
coupled devices), always use appropriate dc blocks, and disable LNB powering.
The following commands are available to provide dc, tone or reference to the LNB/BDC:
1.2
Summary of Features
1.2.1
Overview
The SBD75e Demodulator supports all the major satellite standards, both Intelsat and DVB, in a
one rack unit chassis, if the appropriate options are enabled.
Receiver and Radio
Frequency (RF) to
Intermediate
Frequency (IF)
carrier frequency
conversion.
IF
BB
RF
Demux
Recovers data
symbols and
timing from the
IF carrier.
Ensures signal
reception/
synchronisation.
Descrambles
randomized
data to assure
energy
dispersal and
assist timing
recovery
circuits.
Uses Forward Error
Correction (FEC)
code bits, added to
data symbols, to
check and correct
errors in the
received data
symbols.
De-multiplexes
the data signal
into required
streams for the
output interface.
RF Input Channel 2
(L-Band)
RF Input Channel 1
(L-Band)
ASI 1
Data interface
to terrestrial
equipment,
depending on
system
requirements.
RS232 M&C
ASI 2
ASI 3
ASI 4
Down
converter
Demodulator
(BPSK/QPSK/
8PSK/QAM/
16QAM)
FEC Decoder
Reed-
Soloman/
LDPC/TCM/
Sequential
Differential
Decoder
Descrambler
Data Terminal
Equipment (DTE)
Interfaces
ASI (270 Mbit/s)
M&C DEMOD
ALARM
RS232
Demodulator
Figure 1.1: SBD75e Demodulator Block Diagram
1.3
Guided Tour
1.3.1
Enclosure
The SBD75e Demodulator can be fitted into a 1U high enclosure and may be used on a desktop
or rack mounted.
1.3.2
Front Panel
The SBD75e Demodulator is provided with a Vacuum Fluorescent Display (VFD), 7 status LEDs and
a 16 button keypad. An RS-232 port is also provided and further details of this connector can be
found in
Chapter 2, Installation
.
SBD75e Series Demodulator Installation and Operation Manual
1-3