Comtech EF Data SDM-300A - Manual (Page 221)

7-1
Chapter 7. Clocking Options
7.1 Clocking Options
Clocking of the data from the terrestrial equipment to the satellite (and vice
versa) will depend on the application.
7.1.1 EIA-232, EIA-422, or V.35 Master/Master
Refer to Figure 7-1 for:
• Clocking block diagram
• Transmit clock options
• Buffer clock options
• V.35 timing signals
• EIA-422 timing signals
7.1.2 EIA-232, EIA-422, or V.35 Master/Slave
Refer to Figure 7-2 for:
• Clocking block diagram
• Transmit clock options
• Buffer clock options
• V.35 timing signals
• EIA-422 timing signals
The use of loop timing in the modem is an option for both EIA-422 and V.35
operation.
SCT (LOOP): SCT (INTERNAL) clock no longer applies when the modem has loop timing on
The TX clock source is now recovered from the RX satellite data. This recovered
clock is put out on the ST line and is used to clock the terrestrial equipment. The
TX terrestrial clock is now essentially the same as the RX satellite clock, except
that it has been buffered by the terrestrial equipment.