Ap1.3 Channel Types And Signal Processing; Ap1.3.1 Channel Types - Nera Inmarsat-c Service Manual

AP1.3 Channel types and Signal processing

AP1.3.1 Channel types

A MES uses the following channels for the communications.
1) NCS Common Channel (NCS CC)
2) LES TDM Channel
3) MES Signaling Channel
4) MES Message Channel
Details of each channel are tabulated below.
Use
Contents
TX method
Speed
Packet
Bulletin Board
Scrambling
Encoding
Signal
Unique word
process
Permuting
(TX)
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 Common LES TDM
Channel
MES signalling
MES signalling
(Line control),
(Line control),
LES to MES
EGC, etc.
message
Refer to section AP1.1.5
TDM
(Time Division
Continuous
Multiplex),
TDM
Continuous or
on demand
8.64sec/frame 8.64sec/frame
1200 1200
symbols/sec symbols/sec
640 bytes 640 bytes
Every frame Every frame
Yes
Yes
128 symbols 128 symbols
Yes
-
Yes
10368 symbols 10368 symbols 316 symbols
AP1-17
AP1.3 Channel types and Signal processing
MES Signalling
Channel Channel
NCS, LES
signalling
(Line control)
TDMA
(Time Division
Multiplex
Access)
1200
symbols/sec,
28 slots
(2nd Gen.SV)
15 bytes
Yes Yes
Yes Yes
64 symbols
Yes
-
Yes
Table AP1.3.1
MES Message
Channel
MES to LES
message
SCPC (Single
Channel Per
Carrier)
1200
symbols/sec
(2nd Gen.SV)
128 bytes
- -
Yes
Yes
128 symbols
- Yes
- Yes (192bits)
- Yes
10368 symbols