Comtech EF Data SDM-300A - Manual (Page 45)

SDM-300A Satellite Modem Revision 6
Functional Description MN/SDM300A.IOM
2–5
2.2 Description of the 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
• Offset QPSK
• 8-PSK
Refer to Section 2.2.2 for a description of each modulation type.
A block diagram of the modulator is shown in Figure 2-2.
INTERFACE MUX
OPTIONAL
FRAMING UNIT
IBS/IDR, ASYNC/AUPC
DROP & INSERT
OPTIONAL
REED-SOLOMON
ENCODER
MONITOR
&
CONTROL
CONVOLUTIONAL
ENCODER
DIGITAL
SIGNAL
PROCESSING
BPF
BPF
REFERENCE
LO
SCT
PLL
OPTIONAL
DATA
CLK
SCT
POWER LEVEL
CONTROL
LPF
OUTPUT
RF
RF LOOPBACK
OUTPUT
Figure 2-2. Modulator Block Diagram