Comtech EF Data SLM-5650A - Manual (Page 30)

SLM-5650A Satellite Modem Revision 8
Introduction MN-SLM5650AMN-SLM5650A
1–2
1.2 Functional Description
Figure 1-2. SLM-5650A Block Diagram
Figure 1-2 depicts the functional block diagram for the SLM-5650A. The modem has been
designed to accommodate a wide range of currently required features, and to support both near-
and far-term advances in software-defined radio technology as well as advances in FEC
technology. It is designed for installation in fixed or mobile Earth Terminal (ET) facilities (sites)
using Defense Satellite Communications System III (DSCS III), DSCS III/Satellite Life
Enhancement Program (SLEP), Wideband Gap filler System (WGS), and commercial satellites.
The user has the ability to:
• Add or change modular data interfaces and FEC assemblies;
• Utilize an extensive array of built-in test capabilities;
• Easily upgrade the modem’s operational capabilities in the field;
• Easily update the modem’s firmware in the field;
• Use a wide range of flexible remote control options.
As shown in Figure 1-2, the modem accepts signals from a selected digital signal source and
modulates either a 70/140 MHz or L-Band Intermediate Frequency (IF) carrier with these signals.
The demodulator receives the Rx signal from either the 70/140 MHz or L-Band IF input interface,
then demodulates the IF carrier. Clock and data are recovered and output on a selected data
interface.
The Tx and Rx functions are independent with respect to coding, interleaving, overhead, and
scrambling. The modem does not allow simplex operation in the 70/140 and the L-Band IF
interfaces at the same time. The modem allows duplex operation in either one of the two IF
interfaces.