1 INTRODUCTION Inmarsat B
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1.1 SYSTEM COMPONENTS
An Inmarsat B terminal can be supplied with various types of service and accessories. The drawing below
shows an installation with the various types of accessories.
ADE: The ADE (Above Deck Equipment) consists of a stabilised platform pointing the
antenna towards the satellite independent of the motion of the ship. Besides the
stabilisation including motors, sensors, tracking and stabilisation processor, the
platform also contains the main part of the RF equipment.
BDE: In the BDE (Below Deck Equipment) are placed the first/last part of the transmitter/
receiver consisting of a baseband UP and DOWN converter. Besides the interface
circuits for the various types of externally connected equipment, the BDE also
contains the signal processing, i.e. error correcting coding/decoding, voice coding/
decoding etc.
Handset: The control handset SC4345 is an integrated handset with display and keyboard used
when a voice call is in progress. A call is set up by entering the phone number from
the handset keyboard. A voice distress call can be started by removing the handset
from the hook and activating the distress button placed in the hook. Another function
of the handset is to use it as a control and set-up unit, where functions like the selection
of coast station and satellite can be carried out.
Control unit: The control unit SC4350 is a desk/bulkhead mounted keyboard and display with an
additional handset without keyboard and display.
Distress button: The distress button can be used to activate a voice or a telex distress alert. The kind
of distress alert the button is used for is selected during installation.
Connection
box: If there is a need for the connection of more than one handset or control unit, the
connection box is used. A maximum of five handsets or control units can be connected
to one transceiver unit which is possible by using four connection boxes.
Veritas: The Veritas connection box can be used as an interconnection box between the
transceiver unit and other system units using ship installation cables. Cables of that
type cannot be connected directly to the relatively small SUB-D connectors at the rear
panel of the transceiver unit.
Inside the Veritas connection box, to interface with ship installation cables, there is a
single printed circuit board containing SUB-D connectors to interface with the
transceiver unit and wire terminal blocks. Besides interfacing between transceiver
unit and ship installations, a gyro repeater is also included. The gyro repeater can be
used if there is no NMEA signal from the gyro of the ship.
