Comtech EF Data’s DMD2050 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) and the IESS-308, IESS-309,
IESS-310 IESS–315 & DVB-S commercial standards.
The DMD2050 provides highly advanced and bandwidth-efficient forward error correction (FEC). Advanced
FEC options include Turbo Product Codes (TPCs) and Low Density Parity Check (LDPC). 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, 8-PSK,
8-QAM, and 16-QAM.
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
Data rates range from 2.4 kbps to 52 Mbps and symbol rates range from 4.8 ksps to 30 Msps. The modem provides a standard
MIL-STD-188-114 (EIA-530 / RS-422) serial interface. It can optionally be configured with EIA-613 (HSSI), G.703 (T1/E1/T2/E2 &
T3/E3), DVB ASI/SPI and 10/100/1000Base-T Ethernet interfaces. Drop & insert functionality is supported on the G.703 interface. A
dual IF interface supports low IF (52-88, 104-176 MHz), and L-Band (950-2000 MHz) frequency ranges. Cost-effective, ultra-high reliable
systems are enabled in conjunction with the RCS-11 1:1 redundancy switch, and/or the RCS-20 M:N redundancy switch.
The DMD2050 is interoperable with the DMD20,
DMD50, DMD15/15L SLM-5650/5650A, SLM-8650,
SLM-7650, SLM-3650/3650A, SDM-300/300A, CLM-
9600, CDM-625, CDM-600/600L, CDM-570/570L,
CDM-700, CDM-Qx, and OM 73 satellite modems.
The DMD2050 is compatible with competing modems
that are compliant with MIL-STD-188-165A and/or open
DoubleTalk Carrier-in-Carrier is based on patented bandwidth compression technology originally developed by Applied Signal
Technology, Inc. Using “Adaptive Cancellation” it allows transmit and receive carriers of a two-way link to share the same transponder
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:
Spread the signal by switching to a lower order modulation and/or FEC code –
say QPSK, TPC 7/8. This increases the total transponder bandwidth, while
reducing the total transponder power:
Now using DoubleTalk Carrier-in-Carrier, the second QPSK, TPC 7/8 carrier can be moved over the first carrier – thereby 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.
Flow Control & QoS
Pause Frame flow control is supported on the Ethernet interfaces. QoS is also supported, with both strict priority and fair weighted
BER Performance Guaranteed (Typical) at BERs Shown:
BPSK, QPSK, and OQPSK, 8PSK, 16QAM
IF Tuning Range
70 ±18 MHz and 140 ±36 MHz in 1 Hz Steps
L-Band Tuning Range
1350 ±400 MHz and 1500 ± 500 MHz in 1Hz Steps
IF: 50 Ohm (75 Ohm Optional)
L-Band: 50 Ohm
TNC: 50 Ohm
SMA: 50 Ohm, L-Band
IF < 1.5:1, L-Band < 2.0:1
0 to -25 dBm
IF: ±0.5 dB Over Frequency and Temperature
L-Band: ±.5 dB Over Frequency and Temperature
Selectable and Meets MIL-188-165A or IESS 308/309/310
Power Spectral Mask (DVB-S Optional)
-55 dBc In-Band (50 to 90 MHz, 100 to 180 MHz, 950 to 2050
-45 dBc Out-of-Band
On/Off Power Ratio
OM-73, CCITT V.35 or IBS
Viterbi, K = 7 at 1/2, 3/4 and 7/8
Turbo Product Code (Optional)
QPSK/OQPSK 1/2, 3/4, 7/8
8PSK/16QAM 3/4, 7/8
Legacy Rates: 0.495, 0.793