The CDM-650 Satellite Modem is designed for use by foreign government entities that need a

modem which employs state-of-the-art modulation and coding techniques to optimize satellite

transponder bandwidth usage while retaining backward compatibility with a wide range of

Comtech EF Data modems currently in use. The CDM-650 leverages the heritage and feature

set of our very successful SLM-5650B/C, CDM-625A and CDM-425 modems. The CDM-650

supports backwards compatibility / interoperability in certain modes of operation with the SLM-

5650B/C, CDM-625A and CDM-425 modems.

The CDM-650 offers data rates from 18 kbps to 155 Mbps and symbol rates from 32 ksps to

64 Msps (coding / FEC dependent). The modem supports an Ethernet 10/100/1000T user

traffic data interface that can be used in Bridge mode or Routed mode offering Quality of

Service protocols and traffic shaping / congestion control methods.

Advanced forward error correction (FEC) capabilities are a Comtech EF Data standard feature. Turbo Product Codes (TPC), and three

Low Density Parity Check codes (LDPC) families, VersaFEC®-2 high performance LDPCs short and long block and Direct Sequence

Spread Spectrum (DSSS) are all supported.

Direct sequence spread spectrum is available to support both point-to-point and point-to-multipoint applications as an option in

conjunction with LDPC-based FEC and BPSK. Spreading factors up to 64 are supported. Maximum supported chip rate is 64 Mcps.

Spread spectrum results in operation with ultra-low power spectral densities. This enables use of small antenna apertures when

adjacent satellite interference (ASI) is an important consideration.

The IF interface supports 950 to 2000 MHz frequency ranges.