Baseband Processing Printed Circuit Card; Enhanced Interface Printed Circuit Card; Functional Block Diagram - Radyne DMD20 Installation And Operation Manual

DMD20/20LBST Universal Satellite Modem

3.1.2 Baseband Processing Printed Circuit Card

The advent of million-plus gate count FPGAs, advanced logic synthesis tools, and DSPs
providing hundreds of MIPs enabled the design of a software configurable modem. Large, fast
FPGAs now provide designers with what is essentially an on the fly programmable ASIC. High
speed, complex digital logic functions that previously could only be implemented in dedicated
integrated circuits are now downloaded from a micro-controller through a serial or peripheral
interface. When a new digital logic function is needed, a new configuration file is loaded into the
FPGA. There is no limit to the number of digital logic configurations available to the FPGA, aside
from the amount of Flash memory available to the system microprocessor for storage of
configuration files.
The Baseband Processing Printed Circuit Card provides a flexible architecture that allows many
different modes of terrestrial and satellite framing, various FEC options, digital voice processing,
and several different modulation/demodulation formats. Also included on the Baseband Printed
Circuit Card are three synchronous interfaces, an EIA-530 Interface supporting RS-422, V.35,
and RS-232. All three interfaces are provided on the same DB-25 Connector, and are selectable
from the front panel.
The Baseband Printed Circuit Card also contains the Monitor and Control (M&C) Circuitry
responsible for:
• Programmable part setup and initialization
• Continuous control and adjustment of some functions
• Calibration
• Monitoring fault status
• Calculating and displaying measurements
• User monitor and control interface including front panel and remote
• Units configuration and feature set
The M&C System is based on a powerful microprocessor with a large amount of Flash memory.
Several bus architectures are used to interconnect the M&C to all components of the modem.
Communication to the outside world is done via connections to the remote port, terminal port,
Ethernet port, and alarm ports. The M&C runs off of software programmed into its Flash memory.
The memory can be reprogrammed via the Ethernet port to facilitate changes in software.

3.1.3 Enhanced Interface Printed Circuit Card

The normal terrestrial data for the Baseband Processing Card can be re-routed to the enhanced
interface card. The enhanced interface card adds a variety of connections to the modem for
additional applications
3.2

Functional Block Diagram

Figure 3-3 represents the Functional Blocks. The modem is shown in a typical application with
customer data, Tx/Rx RF equipment and an antenna.
MN-DMD20-20LBST Revision 14
Theory of Operation
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