Comtech EF Data SDM-300A - Manual (Page 51)

SDM-300A Satellite Modem Revision 6
Functional Description MN/SDM300A.IOM
2–11
2.5 Description of the Interface
The terrestrial interface functions include:
• MUX various types of ESC into the data
• Buffering the receive data
• DEMUX various types of ESC from the data
• Monitoring and displaying the interface status without interruption of service
The interface block diagram is shown in Figure 2-4.
The terrestrial interfaces for the modem are defined by data communication standards RS-
530/RS-449, RS-232, or V.35. The interface receivers and drivers for these standards, as well as
the handshake signals for all formats, are selectable through the front panel menus.
Overhead can be added to the terrestrial data for other modes of operation. The format of the
overhead data is dependent on the mode of operation and requires one of the following options
used with the interface PCB:
• ASYNC/AUPC
• D&I
• IBS
• IDR