Figure 6-8. Transmit Section Of The Asymmetrical Loop Timing Block Diagram - Comtech EF Data SDM-300L3 Installation And Operation Manual

SDM-300L3 Satellite Modem
Clocking Options
MC
ST
TT
TXD
Clock Selection
TX TERR (TT)
INT (SCT)
SCT (INT)
SCT (LOOP)
INT (LOOP)
(See Note 1)
EXT CLOCK
Notes:
1. When CONFIGURATION INTERFACE → LOOP TIMING is set to ON, SCT
(INT) will change to read: SCT (LOOP).
2. When CONFIGURATION MOD → MOD REF is set to EXT MOD, S3 will
switch to the EXT REF position.

Figure 6-8. Transmit Section of the Asymmetrical Loop Timing Block Diagram

S1
S4
S1 set to: S2 set to:
DDS
DDS
DDS
DDS
RXC PLL
MC PLL
6–15
PLL
S2
DDS
S3 set to:
INT
INT
EXT REF (See Note 2)
EXT REF (See Note 2)
Revision 1
MN/SDM300L3.IOM
RXC
INT
S3
EXT
REF
OUTPUT
TXC
TXD
S4 set to:
TT
ST
ST
ST
ST
ST