Comtech CRS-500 1:N Modem Redundancy System

The Comtech CRS-500 1:N Modem Redundancy
is intended for hub applications, and provides automatic or manual protection for up to 10 Traffic (or prime) modems with one redundant (or standby) modem.

The CRS-500 supports the CDM-625 and CDM-750 modems for select interfaces. The CDM-625 is supported when using the 10/100 Packet Processor mode. The CDM-750 is supported when using the G.703 interface or the Gig-E interface in all modes.

As shown in the figure, the CRS-500 is a flexible, modular-type architecture, composed of a Control Switch Unit (CSU), Data Switch Unit (DSU) and
optional IF Switch Units (ISUs).

A key feature of the CRS-500 architecture is its ability to allow the redundant modem to ‘bridge’ a traffic modem. The CRS-500 controller automatically configures the redundant modem to match the bridged traffic modem’s configuration. The CRS-500 also provides a copy of the bridged traffic modem’s TX traffic data to the redundant modem. When using the IF Switch Units (ISUs), it additionally routes the bridged traffic modem’s RX IF.

CRS-500 Control Switch Unit (CSU)

The CSU is the controller of the CRS-500 Redundancy System and consumes only 1RU of rack space. It contains field-replaceable modules such as the CRS-530 controller and dual, hot-swappable Power Supply Units (PSUs).The configuration of each traffic modem is stored in the CRS-530 controller. This information is used to program the redundant modem if a traffic modem fails. The CSU contains an extensive M&C system and is fully controllable from the front panel or from external 10/100 Ethernet or EIA-232C/485 ports located on the back side of the CSU unit, (on the CRS-530 module). Ethernet is used by the switch to communicate to all modems. A 10/100 Ethernet M&C connection goes to/from each modem to the CSU.

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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.

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