Comtech EF Data CDM-550T - Manual (Page 23)

CDM-550T Satellite Modem Revision 3
Introduction MN/CDM550T.IOM
1.3 Options
As an external option, a G.703 interface (Comtech EF Data Model Number CIC-50), operating at
T1 (1544 kbps) and E1 (2048 kbps) is available.
Two optional Forward Error Correction (FEC) Codecs can be supplied.
• The first, a Reed-Solomon (R-S) Codec (a plug-in daughter card, field upgradeable),
significantly enhances the bit error performance of the modem.
• The second is the Comtech EF Data Turbo Product Codec (TPC), representing a very
significant development in the area of FEC. Like the R-S Codec, it is a plug-in daughter
card, field upgradeable. It provides the best level of BER improvement currently
available, and in Rate 3/4 QPSK mode, simultaneously conserves bandwidth.
1.4 Compatibility
For 1:1 applications the CDM-550T is supported by a low-cost external switch, the
CRS-100. For Hub applications, the CDM-550T is supported by a low-cost 1:N switch, the CRS-
200. Its fast acquisition time makes it attractive for both demand-assigned and fixed-assigned
SCPC applications.
The CDM-550T is a companion product for the Comtech EF Data line of Radio Frequncy (RF)
Transceivers. The Modem incorporates an Frequency Shift Keyong (FSK) serial link that can be
activated on the Receive Intermediate Frequency (IF) port for the purpose of communicating with
a Transceiver, if connected. In this manner, a user may monitor, configure, and control the
Transceiver, using the front panel display and keypad of the Modem. The EDMAC channel may
also be used to convey Monitor & Control (M&C) data to a Transceiver at the distant end of a
satellite link, if it is connected to a CDM-550T.
The CDM-550T is fully backwards-compatible with the Comtech EF Data CDM-500 and
CDM-550 modems.
1.5 Manual Release Notes
Revision 3 incorporates the following MN/CDM550T.IOM updates:
• Update Customer Service and Warranty information (see Preface)
• Update FEC End-to-End Processing Delay specifications table (see Sect. 7.5.1)
• Update FEC Turbo Product CODEC Figure 7-7
• Update Demodulator Specification table, Turbo Product CODEC BER (see Sect. 14.2)
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