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SDM-300A Satellite Modem
1.1.3
Modem Construction
The modem contains:
Built-in scramblers/descramblers
Differential encoder/decoder
The modem is a complete, self-contained unit in a standard, one-rack unit (1 RU), 19-
inch (48 cm), rack-mountable enclosure weighing approximately 11 lbs (5 kg). The unit
was constructed using modular design (Figure 1-2), and consists of from two to five
Printed Circuit Boards (PCBs), depending on the configuration. The modem consists of
two major, replaceable assemblies as follows:
•
•
The front panel of the modem contains all Monitor and Control (M&C) function
indicators used for operating the modem. The modem can be operated remotely via the
M&C connection on the rear panel. Refer to
Appendix B for remote control operation information. Refer to Appendix C for modem
specifications.
Rev. 4
Rear panel, main PCB, and power supply
Upper and lower enclosures (chassis) and the front panel
Figure 1-2. Modular Design
TX and RX frequency synthesizers
Multi-rate FEC convolutional Viterbi and
Sequential Decoder
Chapter 2
for connector information and
Introduction
1–5
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