Specifications

SDM-300L3 Satellite Modem Revision 0
Introduction MN/SDM300L3.IOM
1–10
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,
OQPSK, and 8PSK. The demodulator then performs FEC decoding on the data stream to
produce the error corrected data output to the data interface.
Figure 1-2
. Demodulator Block Diagram
DIGITAL
SIGNAL
PROCESSING
DIGITAL
CLOCK
RECOVERY-
LOOP
SWITCH
REF
VCXO
REF
PLL
OC XO
OPT
HIGH
STABILITY
AGC
LPF BPF
LO #2
LOOPBACK
L-BAND INPUT
L-BAND INPUT
BPF
ATO D
CONVERTER
LO #1
REFERENCE
VITERBI
DECODER
SEQUENTIAL
DECODER
OPTIONAL
REED-SOLOMON
CODEC
DOPPLER/
PLESIOCHRONOUS
BUFFER
MUX
INTERFACE
OPTIONAL
OVERHEAD DEFRAMING
IBS/IDR, ASYNC/AUPC
DROP & INSERT
EXT REFERENCE
OPTIONAL
TURBO
CODEC