MN/SMS758 Rev. 3
1–1
Chapter 1.
INTRODUCTION
1.1 Scope
This manual describes the SMS-758 modem protection switch (Figure 1-1), hereafter
called “the switch.”
The switch is a rack-mounted unit that provides independent backup control for
modulators and demodulators, or simultaneous modulator and demodulator (modem)
switching.
If a primary modem element failure occurs, the switch limits the loss of communication.
1.2 Purpose and Function
The switch is a fully automated, self-contained switching unit for many EFData satellite
data modems, including:
•
SDM-650B
•
SDM-308B
•
SDM-309B
•
SDM-8000
•
SDM-100
•
SLM-4650
•
SLM-8650
The switch, with one or two backup modems, provides redundancy for up to eight
primary modems.
The switch will automatically or manually switch one of two backup modulators online
to take the place of any of eight primary modulators. Also, one of two backup
demodulators may be switched online to receive any one of four possible downlinks.
