Comtech EF Data SDM-650B - Manual (Page 126)

Theory of Operation SDM-650B Satellite Modem
5–2 Rev. 6
A block diagram of the modulator is shown in Figure 5-1.
INPUT
DATA
DATA
SCRAMBLER
DIFFERENTIAL
ENCODER
FORWARD ERROR
ENCODER
CORRECTION
I CHANNEL
NYQUIST FILTERS
COMBINER
POWER
NYQUIST FILTERS
Q CHANNEL CLOCK
GENERATOR
CLOCK OUTPUT
INPUT
CLOCK
CLOCK SYNTHESIZER
IF
MULTIPLE LOOP
SYNTHESIZER
BANDPASS
IF OUTPUT
50 to 90 MHz
or
OUTPUT LEVEL
CONTROL
100 to 180 MHz
FILTER FILTER
MICRO-COMPUTER
BUS INTERFACE
PROCESSOR
BUS
Figure 5-1. Modulator Block Diagram
Refer to Section 5.1.2 for a detailed description of the modulator.