SDM-300L3 Satellite Modem
Revision 1
Asynchronous Interface/AUPC MN/SDM300L3.IOM
11–7
Notes:
1. Comtech EF Data does not recommend increasing the power to the satellite
without consulting with the satellite controller.
2. Be careful not to set carrier output too high when there is a loss of carrier due to
severe weather and the CL loss action is set to Maximum.
3. Do not use the distant end RX signal to compensate for local rain fade unless
allowances are made for a narrow window for TX level changes.
11.3
ASYNC
The modem supports terrestrial data interfaces and the ASYNC Overhead interfaces.
11.3.1
Terrestrial Data Interfaces
Two I/O interfaces are provided for the terrestrial data source: EIA-422 and V.35. The
operator must select the terrestrial interface type from the front panel under the Utility
Interface menu. Once selected, I/O data is routed to and from the appropriate drivers and
receivers.
11.3.2
ASYNC Data Interfaces
The EIA-485 and EIA-232 I/O interfaces are provided for the ASYNC data source. The
operator must select the ASYNC data interface type from the front panel under the Utility
Interface menu. Once selected, the I/O data is routed to and from the appropriate drivers
and receivers.
EIA-485 (2-wire) requires connecting the TX + and RX + as one wire and tying TX and
RX for the second wire at the Data I/O/ This connection is not facilitated inside the
modem with relays.
Example:
BOP
MODEM
E
S
C
50-PIN
TX
RX
