Comtech Radyne's DMD2050E Satellite Modem is designed to comply with the widest possible range of U.S. Government
and commercial standards and is compatible with the largest number of satellite modems in the industry. It
is fully compliant with MIL-STD-188-165A (all terminal types), fully complies with STANAG 4486 Edition 3,
the draft standard MIL-STD-188-165B, as well as the IESS-308, IESS-309, IESS-310 & IESS–315
The DMD2050E provides highly advanced and bandwidth efficient forward error correction (FEC).
Advanced FEC options include Low Density Parity Check (LDPC), Turbo Product Codes (TPCs) and 165B
Turbo Codes. Legacy support for Viterbi, Trellis, Concatenated Viterbi Reed-Solomon, and Sequential FEC
are also included. A complete range of modulation types is supported including BPSK, QPSK, OQPSK,
8PSK, 8-QAM, 16-QAM and 16APSK.
Advanced FEC and modulation capabilities are integrated with the revolutionary DoubleTalk® Carrier-in-
Carrier® bandwidth compression allowing for maximum state-of-the-art performance under all conditions.
This combination of advanced technologies enables multi-dimensional optimization, allowing satellite
communications users to:
Minimize required satellite bandwidth
Maximize throughput without using additional transponder resources
Maximize availability (margin) without using additional transponder resources
Enable use of a smaller BUC/HPA and/or antenna
Or, a combination of the above to meet specific mission needs
The DMD2050E also supports Information Throughput Adaptation (ITA). Also referred to as Adaptive Coding and Modulation (ACM), ITA
enables modems on each side of a point-to-point link to use the modulation and coding combination that maximizes throughput, and
automatically adapts the optimum operating point as conditions (such as weather) change.
Data rates range from 2.4 kbps to 52 Mbps and symbol rates from 4.8 ksps to 30 Msps. The modem provides standard
MIL-STD-188-114 (EIA-530 / RS-422), and EIA-613 (HSSI) serial interfaces and 10/100/1000Base-T Gigabit Ethernet interfaces. A dual
IF interface supports low IF (52-88, 104-176 MHz), and L-Band (950-2000 MHz) frequency ranges.
The DMD2050E is interoperable with the DMD2050, DMD20, DMD50, DMD1050, SLM-5650/5650A, CDM-625, CDM-600/600L, CDM-
570/570L, as well as many other Comtech satellite modems. It is also compatible with modems from other vendors that are compliant
with MIL-STD-188-165A/B or IESS-308/309/310 open standards.
DoubleTalk Carrier-in-Carrier, based on patented “Adaptive Cancellation” technology, allows transmit and receive carriers of a duplex link
to share the same transponder space.
Figure 1 shows the typical full duplex satellite link, where the
two carriers are adjacent to each other. Figure 2 shows the
typical DoubleTalk Carrier-in-Carrier operation, where the two
carriers are overlapping, thus sharing the same spectrum.
When observed on a spectrum analyzer, only the Composite
is visible. Carrier 1 and Carrier 2 are shown in Figure 2 for
DoubleTalk Carrier-in-Carrier is complementary to all advances
in modem technology, including advanced FEC and modulation
techniques. As these technologies approach theoretical limits of
power and bandwidth efficiency, DoubleTalk Carrier-in-Carrier
utilizing advanced signal processing techniques provides a new
dimension in bandwidth and power efficiency.
DoubleTalk Carrier-in-Carrier allows satellite users to achieve spectral efficiencies (i.e. bps/Hz) that cannot be achieved with traditional
links. For example, DoubleTalk Carrier-in-Carrier when used with 16-QAM approaches the bandwidth efficiency of 256-QAM (8bps/Hz).
As DoubleTalk Carrier-in-Carrier allows equivalent spectral efficiency using a lower order Modulation and/or FEC Code, it can
simultaneously reduce CAPEX by allowing a smaller BUC/HPA and/or antenna.
DoubleTalk Carrier-in-Carrier can be used to save transponder
bandwidth and/or transponder power thereby allowing successful
deployment in bandwidth-limited as well as power-limited
scenarios. The following example illustrates the typical process
for implementing DoubleTalk Carrier-in-Carrier in a power-limited
The conventional link is using 8-PSK, TPC 3/4:
Switching to LDPC and using a lower code rate – for example 8-QAM, LDPC
2/3 increases the total transponder bandwidth, while reducing the total
Now using DoubleTalk Carrier-in-Carrier, the second carrier can be placed over the first carrier – thereby significantly reducing the total
transponder bandwidth and total transponder power when compared to the original side-by-side 8PSK, TPC 3/4 carriers:
Ultra high reliability redundant configurations are supported in conjunction with Comtech EF Data’s RCS-11 and RCS-20 redundancy
switches. The RCS-11 can be configured to support 1:1 redundancy for any DMD-2050 configuration. The RCS-20 provides the same
functionality for M:N redundant system architectures.
TRANSEC / Key Loader
A transmission security (TRANSEC) module provides bulk AES-256 encryption/decryption in accordance with STANAG 4486 Edition 3
and the Federal Information Processing Standards (FIPS)-140-2 Level 2 specifications. A key loader interface is available to reduce
configuration complexity and simplify TRANSEC key management (Key Loader device is sold separately).
Flow Control & QoS
Pause Frame flow control is supported on the Ethernet interfaces. QoS is also supported, with both strict priority and fair weighted
Information Throughput Adaption
In ITA mode, modems automatically communicate the maximum efficiency modulation and coding mode to be used by the distant end
modem, maximizing throughput and link availability under all conditions. Modulation and coding changes are made seamlessly, so there
is no reacquisition time or data loss when modems change parameters to maintain optimum performance.