DMD2050 MIL-STD-188-165A Compliant Universal Satellite Modem

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.

Compatibility

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 network IESS-308/-309-310.

Doubletalk Carrier-in-Carrier

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 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 reference only.

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 scenario:

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:

Redundancy

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 queuing options.