User's Manual

Page 1–21
18 September 2007
SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
eNfusion™ HSD-128 High-speed Data Terminal
The HSD-128 is the master of the system; it controls the overall operation of the
Multi-Channel HSD configuration. It keeps track of time and allocated power and
may command the HSD-X units to terminate calls under certain conditions, such
as an ocean region change. The HSD-X units are wired to the HSD-128 HPA
and therefore compete equally for HPA power allocation.
The transmit signal of each channel is fed through combiners/attenuators
combinations to the HPA located in the HSD and ultimately to the antenna.
Conversely, the receive signal from the antenna goes through a series of splitters
on its way to each channel.
On power-up, HSD-X channels go through an initialization process that identifies
and communicates the number of HSD-X channels and their position in the
system chain back to the HSD-128 master.
The block diagram in Figure 1–10 illustrates the system function of the HSD-128,
two HSD-Xs, and the antenna system.
(2) Pin and Connector Descriptions
Detailed pin and connector descriptions for both HSD and HSD-X transceivers are
provided for all installation modes and configurations in
"Installation" on page 3-1.
F. System Interface Descriptions
This section briefly describes the external HSD and HSD-X system interfaces. The system
interfaces are those required to control, monitor, maintain, and supplement the unit’s
functionality.
"Installation" on page 3-1 provides a detailed description of interface
connections.
(1) HSD System Interfaces
This section describes the system interfaces of HSD transceivers. Detailed
information on the splitter and combiner specifications and losses, as well as cabling
notes and system interconnections for all operational modes for HSD transceivers are
provided in
"Installation" on page 3-1.
(a) HSD Source Destination Identification (SDI)
1. Stand-Alone Mode and Multi-Channel Configuration
Source/Destination Identification (SDI) is provided to the HPA as per ARINC
741 specifications.
2. Non-Stand-Alone Mode
Source/Destination Identification (SDI) is provided to the HPA as per ARINC
741 specifications.
(b) HSD Forward and Return Address IDs
The HSD uses two 24-bit IDs called “Forward Link Pairs” (FRLPs): a Forward ID
(Fwd ID) and a Return (Rtn) ID per pair. The HSD reads the Fwd ID and performs
a look-up for the Rtn ID. For security reasons, each assembly contains an
encrypted look-up table with the whole addressing space assigned to the product
by Inmarsat. To minimize the risk of unauthorized use of its contents, the table
is not accessible to the user.