Modulator; Figure 4-2. Modulator Block Diagram - Comtech EF Data SLM-3650 Installation And Operation Manual

SLM-3650 Satellite Modem
Theory of Operation
4.2

Modulator

The modulator provides PSK modulated carriers within the 50 to 180 MHz range. The
types of modulation that encode the transmitted baseband data from the interface PCB
are:
•
BPSK
•
QPSK
•
OQPSK
•
8PSK
Refer to 4.2.3 for a description of each modulation type.
A block diagram of the modulator is shown in Figure 4-2.
DATA
INTERFACE
CLK
SCT
REFERENCE
LO
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OPTIONAL
OPTIONAL
FRAMING UNIT
REED-SOLOMON
IBS/IDR, ASYNC/AUPC
ENCODER
DROP & INSERT
SCT
PLL
OPTIONAL
BPF

Figure 4-2. Modulator Block Diagram

4–8
MUX
CONVOLUTIONAL
ENCODER
DIGITAL
BPF SIGNAL
PROCESSING
POWER LEVEL
CONTROL
Revision 3
MN/SLM3650.IOM
MONITOR
&
CONTROL
RF
LPF
OUTPUT
RF LOOPBACK
OUTPUT