PK-232 MBX – OPERATING MANUAL AMTOR AND NAVTEX OPERATION
4/91 7-14 99
The ARRL has also adopted this format for transmitting bulletins. In amateur radio this same
format is starting to be referred to as AMTEX.
AMTEX transmissions can be found on ARRL bulletin frequencies.
NAVTEX is broadcast in Mode-B AMTOR (SITOR) on a frequency of 518 kHz.
NAVTEX may be selectively monitored, so you will see only information of interest and never
see the same message twice. It is this unique feature of NAVTEX that the PK-232 uses with
the NAVSTN and NAVMSG commands to allow the user to monitor only messages of impor-
tance.
NAVTEX/AMTEX messages are prefaced by the characters "ZCZC" and then a four character
Preamble as diagrammed below.
ZCZC AA99
3333
333@DSerial Number 2nd DigitDD?
33@DDSerial Number 1st DigitDDY
3@DDDMessage Classification (A to Z)
@DDDDNAVTEX Station Identification (A to Z)
The first character of the Preamble is a letter that identifies the NAVTEX transmitter. Trans-
mitter Identification letters can be any of the characters A through Z. This limits the number
of NAVTEX stations in an area to 26. The NAVSTN Command can be used to selectively mon-
itor or reject certain NAVTEX transmitters.
The second character of the Preamble is the Message Classification. The NAVMSG command
is used to selectively monitor or reject any of the NAVTEX message classes shown below:
A. Navigational Warnings
B. Meteorological Warnings (Storm Warnings)
C. Ice Reports
D. Search and Rescue Information
E. Weather Forecasts
F. Pilot Service Messages
G. DECCA System Information
H. LORAN-C System Information
I. Omega Systems Messages
J. SATNAV System Messages
K.-Z. Reserved for future use
The exception to this is that message classes A, B and D CANNOT be excluded and will al-
ways be copied if the transmitting station is enabled by NAVSTN.
The last two numbers form a serial number from 00 through 99 that is different for each
message. The PK-232 remembers the Preamble of the 200 most recent messages and will
not re-print a message that has the same preamble if it has already been received without
many errors.
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