12
Saturn Bm Mk2 Marine – Technical Manual
Listens to NCS common
channel.
LES
Land Earth Station
NCS
Network
Coordination
Station
NCS Common Channel
OFF-HOOK
MES operator dials
subscriber’s international
telephone number.
Transmits "Access Request"
SU.
MES
Mobile Earth Station
MESRQ
Adds MES to NCS
busy list.
Transmits "Channel
Assignment" SU.
NCSA:
Once for maritime
MES. Three times for
Land mobile MES.
Adds MES to LES
busy list.
"Request for Channel
Assignment" SU
NCSI
NCSA
Sets SCPC channel in "In-
band Signalling" mode.
Transmits "Service Address"
SUs and "Scrambling Vector
Advice" SU alternately.
MES-SIG
Returns "Scrambling
Vector Acknowledge"
SU.
LES-SIG
MES-SIG
Changes to
LESV/SUB mode.
"Return Carrier Identifier"
SUs
Changes to MESV/SUB
mode
Transmits "Ringing
Tone" & "Fill-in" SUs.
"Ringing tones"
Sends answer signal
& "LES Connect" SUs.
"Fill-in" SUs when
quiet.
Maintains burst SU
every 5 secs to
prevent clearing by
MES.
Transmits "MES
Connect" SUs.
Transmits speech
and "MES Connect"
SUs continuously.
LESV & SUB
SUB
LES Voice Channel
and sub-band
signalling
LESI
SUB
Terrestrial call set-up
procedure.
For call release, see
separate diagram
SUB
INMARSAT-B
MES-originated Duplex Telephone Call
Set-up
SCPC In-band Signalling Mode
SCPC V
oice Mode
✳
Saturn B
Set-up
SCPC In-band Signalling
SCPC V
oice Mode
Listens to NCS common
channel.
NCS Common Channel
MES number from
telephone network.
Validates MES
authorization.
Adds MES to LES
busy list. "Request
for Call
Announcement" SU.
NCSI
NCSA
Sets SCPC channel in "In-
band Signalling" mode.
Transmits "Scrambling
Vector Advice" SU
repeatedly.
MES-SIG
Returns
"Scrambling Vector
Acknowledge" SUs
repeatedly.
LES-SIG
RINGING
LESI
NCSC
Ringing tone
(generated by LES)
MES-SIG
Transmits "Return Carrier
Identifier" SUs.
Switches to MESV/SUB
mode
Transmits "Channel
Assignment" SU.
NSCA: Once for
maritime MES. Three
times for Land mobile
MES.
MESRP
Transmits "MES
Response" SU on the
TDMA channel.
Adds MES to NCS
busy list.
"Call Announcement"
SU. Repeated once if
no response from
Land Mobile MES.
MES
Mobile Earth Station
LES
Land Earth Station
NCS
Network
Coordination
Station
OFF-HOOK
Transmits "Connect" SUs
For call release, see
separate diagram
"Fill-in" SUs when
quiet.
Maintains burst SU
every 5 secs to
prevent clearing by
LES.
Transmits speech
and "MES Connect"
SUs continuously.
SUB
SUB
INMARSAT-B
Fixed-originated Duplex Telephone Call
✳
✳
Saturn B
S y s t e m D e s c r i p t i o n
S y s t e m D e s c r i p t i o n
S y s t e m D e s c r i p t i o n
Communication Sequences
-- 15 of 30
LRC Prüfung
