Introduction - Comtech EF Data CDM-700 Installation And Operation Manual

C.1

Introduction

The CDI-50 data interface is a plug-in module that inserts into the rear of the CDM-700 series
modem chassis. It provides physical and electrical connection between the external terrestrial
device and the internal circuitry of the modulator or demodulator. By convention, a modem is
Data Communications Equipment (DCE) where Tx data enters the data interface and Rx data
exits. The plug-in interface has full duplex capability.
In addition, the module is automatically configured for simplex-transmit or simplex-receive
operation when the module is plugged into a simplex chassis configured for 'modulator only' or
'demodulator only' operation. Slot 1 of the modem – located to the right center of the rear panel –
is filled with a data interface module first; Slot 2 – located to the right side edge of the chassis – is
assigned a blank panel or another interface depending upon configurations allowed at time of
order (i.e., when an OC-3 / STM-1 module is installed in Slot 1, Slot 2 is a blank panel).
Initially, the modem is available in Duplex and Rx only configurations.
Two types of OC-3 / STM-1 modules area available; one is selected at the time of order. Each
module has two interfaces: one optical, and the other copper (coaxial); the user programs the
active interface.
Figure C-1 depicts a block diagram of the interface. Figure C-2 shows the module, looking at
the rear panel of the interface.
Appendix C. OC-3 / STM-1
INTERFACE (CDI-50)
Interface
Single Mode Fiber
CDI-50-1
OC-3 / STM-1
Multi-Mode Fiber
CDI-50-2
OC-3 / STM-1
Optical Coaxial
G.703
G.703
C–1
Data Rate
155.52 Mbps
155.52 Mbps