Mocomtech CDM-QX - Manual (Page 60)

CDM-Qx/QxL Multi-Channel Satellite Modem with DoubleTalk™ Carrier-in-Carrier® Revision 7
Rear Panel Connectors MN/CDMQX.IOM
3–10
3.3.6 HSSI Interface and Connectors
This data interface is a plug-in module that inserts into the rear of the CDM-Qx/QxL’s Modulators
or Demodulators. 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 it.
The plug-in interface has full duplex capability.
The HSSI Card Data Interface Module plugs into the rear of the Modulator or Demodulator.
Figure 3-2 shows a block diagram of the interface.
The HSSI interface provides:
• A single HSSI interface;
• A DCE Connection:
o
ST clock is sourced to the terrestrial interface for use as reference by DTE
o
TT is treated as an incoming External Clock, and the interface phase locks to it
o TA / CA is supported
Additionally, the module is automatically configured for simplex-transmit or simplex-receive
operation when the module is plugged into a Modulator and Demodulator. When the
CDM-Qx/QxL is configured as a modem, only the Demodulator is required to have a HSSI
Interface and the Modulator is assigned a blank panel with the Alarms output only, as shown in
Figure 3-3 on the next page.
Figure 3-2. HSSI Interface Block Diagram
A summary of specifications for the interface is provided in Sect. 3.3.6.1; the HSSI connector pin
assignments are provided in Sect. 3.3.6.2 (see Sect. 3.3.1 for more information on the Alarms
connector).
Processor
Mux /
Demux
PLL
Rx
Buffer
Interface
Loopback
Control
Processor
Mux /
Demux
PLL
Rx
Buffer
Interface
Loopback
Control
Modem
Interface
Clk
&
Data
μC
HSSI Interface
TT
SD
ST
Common
J1
Rx Clock
Rx Data
50
P
in
H
S
SI
F
em
ale
TA
CA
(RTS)
(CTS)
Tx Clock Input (External)
Tx Data
Output Clock (Rate Programmable)
RT
RD