11–1
Chapter 11. ASYNCHRONOUS
INTERFACE/AUPC
11.1
Asynchronous Interface/AUPC
The asynchronous (ASYNC) interface option provides the interface for terrestrial data
and a single ASYNC overhead channel. Typically used for earth-station-to-earth-station
communication, the overhead channel is MUXed onto the data and transmitted at an
overhead rate of 16/15 of the main channel. The AUPC feature works with the ASYNC
option to allow remote communication between a local modem and a remote modem.
Refer to Figure 11-1 for a modem block diagram with the ASYNC/AUPC interface
option.
G.703, EIA-422, or V.35 interfaces are available for terrestrial data input and output.
These interfaces can be selected via the front panel.
EIA-485 or EIA-232 interfaces are available for ASYNC channel input and output. These
interfaces can also be selected from the front panel. Fixed 1/15 overhead is added to the
data when an ASYNC channel is being used. With the ASYNC channel enabled, the
terrestrial data rate can be from 8 to 2048 kbps. The ASYNC channel I/O protocol can be
as follows:
Baud
110 to 38400
Data Bits
5 to 8
Parity
odd, even, or none
Stop Bits
1 or 2
Note:
Certain combinations of baud rate, data rate, parity, and stop bits will limit the
maximum baud rate allowed for continuous throughput based on terrestrial data rate.
