Comtech EF Data SDM-300A - Manual (Page 30)

SDM-300A Satellite Modem Revision 6
Introduction MN/SDM300A.IOM
1–4
1.1.3 Description of Interface Functions
An interface consists of a device having the following functions:
• Terrestrial Data Interface or a Terrestrial Voice Interface including terrestrial interface
to Engineering Service Channels (ESC).
• Multiplex various types of ESCs into the data.
• Demultiplex various types of ESCs from the data.
• Buffer the RX data.
• Monitor and display the interface status without interrupting service.
• Perform Self-Test.
1.1.4 Modes of Operation
The following modes of operation are supported:
• ASYNC Overhead Interface with AUPC (see Note 1) • SDM-100 Emulation
• CDM Compatibile
• SDM-650 Emulation
• Custom (see Note 2) • SDM-6000 Emulation
• Drop & Insert (D&I)
• SDM-300 Emulation
• EFD Closed Network • SDM-308 Emulation
• IDR • SDM-309 Emulation
• IBS • CDM Compatible
Notes:
1. The ASYNC/AUPC option allows an additional overhead channel to be multiplexed
and demultiplexed from the data carrier.
2. The Custom mode of operation enables the programming of the modem for emulating
most proprietary modems.
Two mechanisms are provided for uplink power control within a closed network.
• One method, which requires the optional ASYNC/AUPC interface card, is used for
control between two links to sustain sufficient transmit power to maintain a
programmed Eb/No at both ends.
• The second method is used for self-monitoring the carrier from the same uplink with the
local demodulator, requires no additional hardware, and is software-selectable. This
method is appropriate for applications such as paging networks, where the uplink is
transmitting to receive-only devices.
The modem interfaces between the channel unit or Multiplexer (MUX) and Intermediate
Frequency (IF) converter equipment operating in a 50 to 180 MHz band. An internal channel
unit, conforming to IESS-308, -309, and -310 emulation specifications, provides overhead
designated for an ESC.