Figure 5-4. Demodulator Block Diagram - Comtech EF Data SDM-9000 Installation And Operation Manual

Theory of Operation
From
RF Demod
I
Σ
I and Q
Nyquist Filter
Daughter-
Q
Σ
board
20MHZREF
To Host
M&C
Local
5–12
I Channel
A/D
Offset
Control
Soft
Decision
LUT
(SRAM)
A/D
SYMBCK
DIVIDER
( ÷ 2,4,8,16)
Clock Loop
M&C
Costas Loop
AOC/AGC

Figure 5-4. Demodulator Block Diagram

AMB
OUT OF SYNC
2
Viterbi
Decoder
6
Commutator,
13 6
Viterbi
Rate
Decoder
Exchange,
Depuncture,
6
Viterbi
Decoder
Ambiguity
Resolver,
3
Digital Delay Line
Decoder
3-Bit x 526 Deep
Order Detect
SCLK
2/3 SCLK
EN13
PLL
1/2 DDS DAC
1/2 DDS DAC
I-OFFSET
Q-OFFSET
SDM-9000 Satellite Modem
To
3
Interface
8-PSK Parallel
to Serial,
3
TTL DATA
3
3 x 3 Barrel
to
Shifter,
DATCLK/3
ECL
x3 Parallel
3
Differential
Decoder,
Extended E /N
b 0
Monitor
÷
2
DATCLK/3
PLL
( x 8 )
SYNTHREF
To RF Demod
AGC
Rev. 4