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SDM-2020 Satellite Demodulator
A.2
RS-422 Parallel/Serial Interface
The following paragraphs describe the RS-422 parallel and serial interface. The interface
operates at RS-422 signal levels. It accommodates a variety of MPEG2 framing formats
and EIA-530 serial data.
A.2.1
Applicable Documents
Applicable specifications, as referenced herein, include:
TM1449
TIA/EIA-644
RS-422
EIA-530
A.2.2
Description
The RS-422 interface has two data connectors and an auxiliary connector supporting
various operating modes.
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The appropriate interface control is automatically enabled when the interface module is
installed in the Demodulator. The plug-in data interface is programmable for serial or
parallel operation from either the front panel keypad or the remote port on the rear panel.
Rev.3
Interfaces for CATV/SMATV Headends and Similar Professional Equipment.
Telecommunications Industry Standard, Electrical Characteristics Of Low Voltage
Differential Signaling (LVDS) Interface Circuits (originally Standards Proposal
SP-3357)
Electrical Characteristics of Balanced Voltage Digital Interface Circuits
High Speed 25-Position Interface for Data Circuit - Terminating Equipment
J3 Parallel/Serial DVB Connector (25-pin D, female):
!
Parallel mode - In this mode, the interface functions like a DVB parallel
synchronous interface, but with RS-422 levels. The input is at the byte rate.
!
Serial mode - An alternate form of operation is possible, where the MSB is
used for serial input at the bit rate.
J4 Serial EIA-530 Connector (25-pin D, female):
!
Serial mode only - RS-422 levels with pinout and operation per EIA-530 at a
serial clock rate.
J5 Auxiliary Connector (9-pin D, female):
!
Provides an additional ST Clock (output), plus open collector fault signals.
Data Interfaces
A–5
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