Comtech EF Data SDM-300A - Manual (Page 309)

SDM-300A Satellite Modem Revision 6
Asymmetrical Loop Timing MN/SDM300A.IOM
12–3
PLL
DDS
TXD
TXC
EXT
REF
INT
RXC
S2
S1
MC
ST
TT
TXD
S4
S3
OUTPUT
Clock Selection S1 set to: S2 set to: S3 set to: S4 set to:
TX TERR (TT) DDS INT TT
INT (SCT) DDS INT ST
SCT (INT) DDS EXT REF (See Note 2) ST
SCT (LOOP) DDS EXT REF (See Note 2) ST
INT (LOOP)
(See Note 1) RXC PLL ST
EXT CLOCK MC PLL ST
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 12-1. Transmit Section of the Asymmetrical Loop Timing Block Diagram