Furuno 16 Communications Network, LES TDM channel, MES message channel, MES signaling channel

INMARSAT C SYSTEM

Communications Network

The illustration below shows the Inmarsat C communications network.

NCS/LES Signaling Link

Network

Coordination

Station (NCS)

NCS/NCS Signaling Link

NCS Common Channel

Mobile Earth

Station (MES)

Data

Communications

Network

Land Earth

Station

(LES)

MES Signaling Channel

MES Message Channel

Data Circuit

Terminating

Equipment

(DCE)

Data Terminal

Equipment (DTE)

Enhanced Group

Telex Network

Terrestrial

Communications

Network

LES TDM Channel

Calling (EGC) Receiver

Inmarsat C communications network

NCS common channel The NCS has two major functions:

1)Transmitting information on a common channel.

2)Transmitting EGC messages to MESs.

NCS/LES signaling link This is the link between NCS and all LESs in its

LES TDM channel	region. All EGC messages pass through this link.
	This channel carries the circuit control signal for
MES message channel	MES and transmits messages from LES to MES.
	This channel carries messages from MES to LES.
MES signaling channel	This channel transmits requests, data reports, etc. In
	addition, it carries login and logout from MES to
NCS/NCS signaling link	NCS.
	This is the link between NCSs. It exchanges data
MES interface	between MESs operating in different ocean regions.
	The MES consists of the Data Circuit Terminating
	Equipment (DCE) and the Data Terminal Equipment
	(DTE). The DCE consists of the antenna unit, and
	the DTE consists of the communications unit and
Terrestrial network	terminal unit (PC).
	The major functions of the LESs are:
interface	1) Telex store-and-forward conversion
	2) Handling EGC messages
	3) Data Reporting and Polling
	4) Distress message processing

xiv