Comtech EF Data CDM-750 High-Speed Trunking Modem

The Comtech EF Data CDM-750 Advanced High-Speed Trunking Modem was designed to be the most efficient, highest throughput, point-to-point trunking modem available. The CDM-750 accommodates the most demanding Internet Service Provider (ISP) and telco backhaul links by offering users the most advanced combination of space segment saving capabilities while minimizing the need for unnecessary overhead. With the ability to process packets at line speed, the CDM-750 will not throttle throughput due to processing limitations.

Beginning with the most efficient coding and modulation available, the CDM-750 leverages the DVB-S2 EN 302 307 LDPC/BCH standard to provide the best possible combination of coding and foreword error correction ensuring that the maximum amount of satellite traffic is transported for a given signal to noise capacity.

Implementing Adaptive Coding and Modulation (ACM) operation (in packet-based applications) allows link margin to be converted to user capacity during non-faded conditions by taking advantage of the actual signal to noise ratio rather than calculated worst case signal to noise. This technology transforms link margin, implementation margin and margin for antenna pointing directly to improved throughput.

By using the best encapsulation methods, the CDM-750 further increases throughput by using minimal overhead. In G.703 synchronous mode, users can implement monitor and control over the satellite with no additional overhead. When using Ethernet bridge mode, less than 1% overhead is used for encapsulation.

Additionally, the CDM-750 leverages Comtech EF Data’s powerful DoubleTalk® Carrier-in-Carrier® “Adaptive Cancellation” technology. With the ability to overlay TX and RX carriers, Carrier-in-Carrier enables the operator to establish the perfect balance between bandwidth and power, enabling the best possible use of the satellite resource and reducing operating expenses (OPEX).

These technologies alone offer enormous savings to the ISP and telco operator. When used in combination, however, the savings are astronomical.

The innovative high-performance architecture of the CDM-750 allows efficient networking and transport over satellite links while supporting a wide range of applications and network topologies.

CDM-750 Applications IP Trunking G.703 Trunking High-Speed Content Delivery Disaster Recovery & Emergency Communications

Typical Users Mobile Operators Telecom Operators ISPs Government & Military

Doubletalk Carrier-in-Carrier

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 reference only.