Kantronics KPC-4 - NAVTEX;AMTEX Theory

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NAVTEX/AMTEX Mode
KAM only
NAVTEX/AMTEX Theory
Navtex
transmissions
are,
in
reality,
Mode
B
AMTOR
(FEC).
What
makes
Navtex
unique
however,
is
the
actual message
format.
NAVTEX
stations
always
transmit
on
518 KHz
LSB,
and
are
typically
located
on
the
coast
lines. The
same
format is now
being used
by the
American
Radio Relay
League
(ARRL)
to
transmit
their bulletins
on
a
daily
basis.
These
are
transmitted
during
their
scheduled
teleprinter
bulletins.
At
the
beginning
of
a
NAVTEX
(or
AMTEX)
transmission,
the
sending
station
will
send
a
preamble,
identifying
the
station
that
is
transmitting,
the
type
of
message,
and
the
message
sequence
number.
The
preamble
would
look
like
this:
ZCZC AG25
The
ZCZC
is
always
present,
and
the
receiving
unit
sees
this
as
the
indication
that
the
identifier
is
coming
next.
The
components
of
the
identifier,
as
defined
in
the
NAVTEX
'
documentation
are:
B1 B2 B3 B4
B1
is
used
to
identify
the
station
that
is
transmitting
and
consists
of
the
letters
A
through
Z.
B2
indicates
the
message
class
(A
through
Z).
Note
that
class
A,
B
and
D
messages
must
always
be
printed
once.
B3
and
B4
are
the
sequence
number
for
the
message,
and
will
have
values
from
00
through
99.
Messages
with
sequence
number
00
are
always
printed.
When
the
message
numbers
reach
99,
they
wrap
to
01
as
the
next
number.
Currently operating NAVTEX stations are:
Halifax, Nova Scotia Guam
Boston, MA Honolulu, HI
New Orleans, LA Kodiak, AK
Miami, FL Astoria, OR
San Juan, P.R. Long Beach, CA
Chesapeake, VA San Francisco, CA
For
NAVTEX
messages,
the
currently
assigned
message
classes
are:
Navigational warnings
Meteorological
warnings
(storm
warnings)
Ice reports
Search and Rescue Information
Meteorological forecasts
Pilot messages
Decca message
LORAN-C message
Omega message
differential Omega message
QRU — no message on hand
K-Y Reserved
NOTE:
K
has
been
proposed
for
"other
electronic
navigational
aid
system
message”
No Ta Bu0ad»>
€qx-—
===
NANTEX/AMTEX
50
A
O
Copyright
1990,
Kantronics,
Inc.
All
Rights
Reserved.
:
Duplication
of
this
manual
or
the
firmware
without
Aug.
13,
1990
>
Version
3.0
permission
of
Kantronics,
Inc.
is
prohibited.
f
Operations
Manual