Comtech EF Data SDM-9000 - Manual (Page 140)

Theory of Operation SDM-9000 Satellite Modem
5–12 Rev. 4
I and Q
Nyquist Filter
Daughter-
board Σ
A/D
A/D
Commutator,
Rate
Exchange,
Depuncture,
Ambiguity
Resolver,
Decoder
Order Detect
Soft
Decision
LUT
(SRAM)
Viterbi
Decoder
Viterbi
Decoder
Viterbi
Decoder
8-PSK Parallel
to Serial,
3 x 3 Barrel
Shifter,
x3 Parallel
Differential
Decoder,
Extended E
b
/N
0
Monitor Digital Delay Line
3-Bit x 526 Deep
TTL
to
ECL
Clock Loop
Costas Loop
AOC/AGC
1/2 DDS
1/2 DDS DAC
DAC
To RF Demod
PLL
( x 8 )
÷ 2
I-OFFSET
Q-OFFSET
AGC
SYNTHREF
DATCLK/3
Local
M&C
To Host
M&C
20MHZREF
I
Q
From
RF Demod
To
Interface
DATCLK/3
DATA 3
6
6
6
2
3
Σ
PLL
SYMBCK
DIVIDER
( ÷ 2,4,8,16)
13
I Channel
Offset
Control
OUT OF SYNC
3
3
3
SCLK
2/3 SCLK
EN13
AMB
Figure 5-4. Demodulator Block Diagram