Comtech EF Data SDM-2020 - Manual (Page 109)

SDM-2020 Satellite Modulator Revision 7
Low Voltage Differential Signal (LVDS) MN/SDM2020M.IOM
8-2
•
J4 Transmit In connector (25-pin D, female):
Parallel format: The interface is a DVB 8-bit parallel synchronous
interface. Data and clock are input to the connector and the input clock
(Clock A and Clock B) is at the byte rate.
Serial format: MSB (Data7) is used for serial input data and the input
clock (Clock A and Clock B) is at the bit rate.
• J5 Auxiliary connector (9-pin D, female):
Provides TX and RX clock references and open collector fault signals.
The TX In or RX 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 cables, or an equivalent computer grade cable incorporating twisted,
shielded pairs, are recommended:
• Belden type LV Computer M9768
• Belden 8175
The Belden 8175 has a 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 8-1.
Table 8-1. 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 TX data.
25-pin D female for RX data.
9-pin D female for reference clocks plus faults.
Electrical Properties Per TIA/EIA-644.