Comtech EF Data SDM-2020 - Manual (Page 136)

11-1
Chapter 11. G.703 DATA INTERFACE
11.1 G
ENERAL
The following paragraphs describe the G.703 data interface. This plug-in module
provides the physical and electrical interface between external terrestrial data equipment
and the modulator and demodulator.
11.1.1 D
ESCRIPTION
The G.703 data interface is a plug-in module that inserts into the rear of the modulator
chassis. This interface is designed for full duplex capability and is automatically
configured for simplex TX operation installed in a modulator chassis. The data interface
operates at the digital hierarchy bit rates as defined by ITU-T G.703, except as noted:
• 1.544 Mbps (T1 or E1) • 2.048 Mbps (T1 or E1
• 6.312 Mbps • 8.448 Mbps
• 32.064 Mbps • 34.368 Mbps
• 44.736 Mbps • 51.840 Mbps (as defined by SONET STS-
1)
Figure 11-1 is a block diagram of the G.703 data interface.
Connection to external terrestrial data equipment is facilitated by three BNC connectors
and a 9-pin auxiliary connector. The three BNC connectors are Send Data (SD), RX Data
(RD), and External Clock (EXT CLK).
• The Send Data (SD) input provides TX data to the modulator.
• The RX Data (RD) output provides RX data from the demodulator.
• The External Clock (EXT CLK) input provides an external reference for
clocking RX data out of the integrated plesiochronous/Doppler buffer.
The auxiliary connector provides for control and status monitoring when used with
external equipment such as a redundancy switch or monitor/control system.