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Comtech EF Data SDM-8000 Satellite Modem

Comtech EF Data SDM-8000 Satellite Modem
  • 8PSK and 16QAM Modulation (Optional)
  • Concatenated Reed-Solomon Coding (Optional)
  • 9.6 Kbps to 9.312 Mbps
  • Closed Network

The single-chassis SDM-8000 satellite modem meets all requirements of the IESS-308 and 309 specifications for the Intermediate Data Rate (IDR), INTELSAT Business Specifications (IBS), and EUTELSAT SMS requirements.

Switching from one open network application to another is very simple with the SDM-8000. In most cases, switching can be done from the front panel.

The SDM-8000 can also be used for any closed network application.

An optional sequential decoder is available to complement the SDM-8000. Multiple filter masks, selected at the front panel, ensure end-to-end compatibility with other manufacturer's modems in closed network environments.


The SDM-8000 can be configured to any data rate ranging from 9.6 Kbps to 9.312 Mbps, in 1 bit/s steps. Each rate meets standard FEC code rates. Selection of data rates can be done from the front panel. The modem contains an internal channel unit that includes both IDR and IBS overhead framing units.

The framing unit, with D&I option installed, is fully functional at all specified rates for IDR (64 to 8448 Kbps) and IBS (64 to 2048 Kbps) data rates.


A full range of industry standard digital interfaces (G.703, V.35, or MIL-188/EIA-422) is built into the modem. Interface selection is a simple matter of moving jumpers. Optional breakout panels provide convenient access to all components of the IDR and IBS Engineering Service Channels (ESC) via built-in standard connectors and terminal blocks.


The SDM-8000 has been equipped with an improved, more extensive M&C system than its predecessors. Each modem subsystem has its own M&C microprocessor controlled by the host processor located on the M&C board. The microprocessor/host processor greatly enhances the flexibility of the SDM-8000. The M&C is compatible with the software versions of other Comtech EFData modems currently in the field.

All M&C functions controlled and monitored at the front panel keyboard are also programmable through the remote EIA-232 or EIA-485 serial interface. Modems can be individually addressed from 1 to 255. Address 0 is reserved for global addressing. Modem configuration is stored in non-volatile memory that is maintained for at least one year without external power.


Forward error correction, utilizing convolutional encoding and soft decision Viterbi K=7 decoding, yields high performance at low Eb/N0 levels while occupying minimal bandwidth.

Options available for the SDM-8000 include 8PSK and 16QAM modulation methods. These modulation techniques provide maximum bandwidth efficiency, particularly when used in conjunction with the concatenated Reed-Solomon Codec.


Different types of protection switches are available to satisfy all installation configurations. Fully automatic 1:1 redundancy and M:N protection (M = 1 or 2, N = 1 to 8) are available. These systems are capable of backing up to eight modems operating on different transponders. Switches and modems are also available in completely assembled and tested racks. The SDM-8000 also will interoperate in a redundant system with other models of Comtech EFData modems.