Comtech EF Data SDM-2020, Installation And Operation Manual

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Data Interfaces SDM-2020 Satellite Demodulator
A–14 Rev.3
•
J5 Auxiliary connector (9-pin D, female):
! Provides transmit and receive clock references and open collector fault
signals.
The Transmit In or Receive Out interface is automatically enabled when the interface
module is installed in the modulator or 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.
The following cable, or an equivalent computer-grade cable incorporating twisted,
shielded pairs, is recommended:
•
Belden 8175
The Belden 8175 has lower capacitance, however it has a larger diameter and requires the
selection of an appropriate connector shell.
The typical cable length for the serial/parallel interfaces is
≤
5 meters (16.405 feet).
The interface operates to the specifications described in Table A-7.
Table A-7. LVDS Specifications
General Specifications
Interface Type LVDS/DVB Synchronous, Serial/Parallel.
Data Rate 1.5 to 32 Mbit/s, serial.
1.5 to 100 Mbit/s, parallel.
Data Framing Formats 188, 204 byte packets per ETS 300 421, and None.
Connectors 25-pin D female for transmit data.
25-pin D female for receive data.
9-pin D female for reference clocks plus faults.
Electrical Properties Per TIA/EIA-644.
Signal Types TX: TX Clock, TX Data, Data Valid, and Sync per TM1449.
The modulator does not require Sync or Data Valid with the 188 or 204 byte
patterns.
Voltage Levels
290 ± 40 mV differential into 100
Ω