Comtech EF Data SDM-2020 - Manual (Page 138)

SDM-2020 Satellite Demodulator Revision 4
LVDS Data Interface MN/SDM2020D.IOM
8–2
8.1.2 Description
The LVDS interface has dedicated transmit and receive connectors and an auxiliary
connector. The RX Out connector is used with the demodulator while the TX In
connector is used with the modulator:
• J3 RX Out connector (25-pin D, female). This connector supports the following
data formats:
Parallel format: The interface is a DVB 8-bit parallel synchronous interface.
Data and clock exit the connector and the output clock (Clock A and Clock
B) is at the byte rate.
Serial format: MSB (Data7) is used for serial output data and the output
clock (Clock A and Clock B) is at the bit rate.
• J4 TX 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 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 8-1.