Description; Rev. - Comtech EF Data SDM-100A Installation And Operation Manual

SDM-100A Satellite Modem
The modem interfaces with IF converter equipment operating in a 50 to 180 MHz band.
The data interface options consist of RS-449/422, V.35, RS-232-C, ASYNC, and
Adaptive Differential Pulse Code Modulation (ADPCM) voice. Changes in connectors
for the various interfaces are accomplished by small, field-changeable connector
modules.
Recent advances in Digital Signal Processing (DSP) have been incorporated into the
modem's design. Examples of high density components employed in the modem are:
•
•
•
•
Utilization of these state-of-the-art components and surface mount technology provides
maximum modem processing power in a minimum amount of space.

1.2 Description

The modem is a complete, self-contained unit in a standard 1 Unit (1U) 19"
rack-mountable enclosure weighing approximately 10 lbs. A dimensional drawing of the
modem is shown in Figure 1-3.
All monitor and control functions and indicators for operation of the modem are located
on the front panel. The display Printed Circuit Board (PCB) is mounted on the front
panel.
The chassis also contains the power supply. A fan is located on the rear panel.
The modem consists of the following assemblies:
Chassis with Power Supply
PCB, Demod/M&C
PCB, Interface Daughter (RS-422)
PCB, Interface Daughter (V.35)
PCB, Interface Daughter (RS232)
PCB, Interface Daughter (ASYNC)
PCB, Interface Daughter (ADPCM)
PCB, Modulator
ASIC, Sequential Decoder
PCB, Mod RF
PCB, Demod RF
PCB, Reed-Solomon (SDM-100)
Where X = various options available on the modulator and demodulator boards.
Refer to Table 5-2 for more information on the options available for each board.
Note: Only one interface option is shipped per modem.

Rev. 0

Embedded microprocessor
Viterbi Large Scale Integration (LSI) processors
Direct Digital Synthesis (DDS)
Field programmable gate arrays for logic processing
Assembly Drawing #
AS/5281-X
AS/4973
AS/2524
(See note below)
AS/2532 or AS/4326
(See note below)
AS/2533
(See note below)
AS/4089
(See note below)
AS/3916
(See note below)
AS/2522
IC/EFD 8858 (optional)
AS/3995-X
AS/4401-X
AS/3708-2
Introduction
1–3