Comtech EF Data C5 - Manual (Page 220)

Theory of Operation C5/K1/K3 Integrated Satellite Terminal System
5-10 Rev. 0
5.4 Demodulator
A block diagram of the demodulator is shown in Figure 5-3.
The demodulator converts PSK modulated carriers (refer to Chapter 2, Specifications) to
a demodulated baseband data stream. The converted modulation types are BPSK and
QPSK (refer to Section 5.2.3 for a description of modulation types). The demodulator
then performs FEC on the data stream using Viterbi or Sequential decoding algorithms.
DIGITAL
SIGNAL
PROCESSING
DIGITAL
CLOCK
RECOVERY-
LOOP
SWITCH
REF
VCXO
REF
OSC
AGC LPF BPF
LO #2
LOOPBACK
RF INPUT
RF INPUT
950 TO 1700 MHz
BPF
A TO D
CONVERTER
LO #1
REFERENCE
VITERBI
DECODER
SEQUENTIAL
DECODER
OPTIONAL
REED-SOLOMON
CODEC
DOPPLER/
PLESIOCHRONOUS
BUFFER
MUX
INTERFACE
OPTIONAL
OVERHEAD DEFRAMING
ASYNC/AUPC
Figure 5-3. Demodulator Block Diagram