Channel Types - Furuno FELCOM 12 Service Manual

Chapter 2 Channel Types and Signal

2.1 Channel Types

A MES uses the following channels for the communications.
1) NCS Common Channel (NCS CC)
2) CES TDM Channel
3) SES Signalling Channel
4) SES Message Channel
Details of each channel are tabulated below.
Use
Contents
TX method
Speed
Packet
Bulletin Board
Scrambling
Encoding
Signal Unique word
process (TX)
Permuting
Preamble
Interleaving
Number of Symbols
TDM: Time division multiplex. A process for transmitting two or more channel
signals simultaneously to MES over a common channel path by using
successive time intervals (time slots) for different channels.
TDMA:Time division multiplex access. A system which allows a plural number of
MES to access an LES (NCS) over a single transmission line by assigning
each MES a time slot on the TDM channel in which to transmit over.
SCPC: Single channel per carrier. Enables assignment of channel for a call.
NCS
NCS Common CES TDM
Channel Channel
MES signalling MES signalling
(Line control), (Line control), LES
EGC, etc. to MES message
(Time Division
Continuous
Multiplex),
TDM
Continuous or on
8.64sec/frame
8.64sec/frame
1200
1200 symbols/sec
symbols/sec
640 bytes 640 bytes
Every frame Every frame
128 symbols 128 symbols
-
10368 symbols 10368 symbols
Satellite
MES
LES
2-1
Processing
SES Signalling
Channel
NCS, LES
signalling
(Line control)
Refer to section 1.3.
TDM
TDMA
(Time Division
Multiplex Access)
demand
1200 symbols/sec,
28 slots
(2nd Gen.SV)
15 bytes
64 symbols
-
316 symbols
SES Message
Channel
MES to LES
message
SCPC (Single
Channel Per
Carrier)
1200
symbols/sec
(2nd Gen.SV)
128 bytes
- -
128 symbols
-
- (192bits)
-
10368
Figure 2-1