Product specifications

Chapter 10. CDI-40 ASI
Data Interface
10.1 Introduction
This data interface is a plug-in module that inserts into the rear of the 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 transmit data enters the data interface and receive data exits it. The plug-in interface
has full duplex capability for the ASI interface. 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. The module will operate
when plugged into either Slot 1 or Slot 2 of the modem. (Slot 1 is located near the center of the
rear panel, and Slot 2 is next to the outside edge.)
The ASI Interface combines two electrical and physical interfaces into a single assembly. The ASI
section provides DVB compliant interface with BNC connectors.
Operation for either ASI is selected by programming the unit from the front panel keypad/display
or from the remote communications ports. Refer to
Figure 10-1 through Figure 10-5 for card
diagrams. There are two ASI Interface Cards:
ASI Interface Usage By Application
PL/10881-3 Standard non-redundant applications:
• Tx only 1:1 redundancy. Rx output (J2 and J3) is the standard ASI level
• Full duplex 1:N redundancy. Rx output (J2 and J3) is the standard ASI
level
PL/10881-4 Standard non-redundant applications (excluding J3):
• Tx only, Rx only or full duplex (Tx and Rx) 1:1 redundancy (see
Figure 10-5).
♦ Rx output J2 is standard ASI level
♦ Rx output J3 is higher so the standard level is delivered after a 3 dB
combiner (see Figure 10-5).
• Full duplex 1:N redundancy (excluding J3).
10–1