Description Of The Demodulator; Overview; Figure 1-2. Demodulator Block Diagram - Comtech EF Data SNM-1001L Installation And Operation Manual

SNM-1001L Satellite Modem
Introduction
1.7

Description of the Demodulator

A block diagram of the demodulator is shown in Figure 1-2.
1.7.1

Overview

The demodulator converts PSK modulated carriers within the 950 to 1750 MHz range to
a demodulated baseband data stream. The converted modulation types are BPSK, QPSK,
Offset QPSK, and 8-PSK. The demodulator then performs FEC decoding on the data
stream to produce the error corrected data output to the data interface.
L O O P B A C K
L-BAND INPUT
S W I T C H
L-BAND INPUT
R E F
V C X O
O C X O
O P T
H I G H
S T A B I L I T Y
E X T R E F E R E N C E
L PF
A G C
L O #1
REFERENCE
R E F
S EQUENTIAL
P L L
DECODER
OPTIONAL
REED-SOLOMON
CODEC

Figure 1-2. Demodulator Block Diagram

BPF
LO #2
OPTIONAL
VITERBI
TURBO
DECODER
CODEC
MUX
PLESIOCHRO N O U S
1–9
Revision 1
MN/SNM1001L.IOM
B P F
A T O D
CONV E R T E R
DIG I T A L
SIG N A L
PROC E S S I N G
DIG I T A L
CL O C K
RECO V E R Y -
LO O P
DOPPLER /
I N T E RFACE
BUFFER