Kantronics KPC-4 - AMTOR Operation

Once you have entered your MYSEL7 and MYSEL4, the KAM will automatically
respond to either SELCAL for a mode A (ARQ) qso, or (if AUTOSTRT is ON) for a
SELFEC mode B (FEC) transmission.
If you want to initiate a call to another station using the 625 form of AMTOR, simply
use the AMTOR command with the appropriate SELCAL:
AMTOR XDBUXAS
or
AMTOR 123456789
AMTOR ARQ (Mode A) operation requires that both station transmit alternately.
First the information sending station (the station actually sending data) sends three
characters. This requires 210 milliseconds. This station then enters the receive mode
and listens for the acknowledgment from the information receiving station. The
sending station will wait 240 milliseconds for the acknowledge. After this 240
millisecond delay, the sending station will again enter transmit and send the next
(or the same) three characters.
Since both stations are constantly switching from receive to transmit and back again,
fast switching times are required for AMTOR ARQ operation. You can adjust
TXDAMTOR to allow for the time required for your station to change from receive to
transmit, but you should allow a small extra time for the other station to switch from
transmit to receive. Regardless of the setting of this parameter, the total turn around
time for one AMTOR data/ack cycle remains 450 milliseconds. `
AMTOR Operation
There are three methods of entering AMTOR Mode of operation from the cmd: prompt,
depending on which mode of AMTOR operation you wish to use.
Entering LAMTOR at the cmd: prompt will allow you to receive Mode A (ARQ) and
Mode B (FEC) AMTOR signals, but this mode does not support transmitting. If you
are receiving Mode AAMTOR, you may see repeated characters, or miss characters
completely, since you are not a part of the link. The two stations which are linked may
be requesting retransmission (thus you see repeated characters) or they may have
received the characters and you didn't due to band conditions. In this listen only mode,
you may receive characters which do not meet the 4/3 space/mark ratio, or characters
which do not properly decode in the AMTOR character set. These will be displayed on
your screen as the MISSCHAR which is defined in your KAM.
The second method to enter AMTOR operation is to use the FEC command, which
places you in the Mode B receive. In this mode you may receive FEC transmissions,
and you can enter the transmit mode by issuing the Ctrl-C T directive. You can then
enter any text you wish sent from the keyboard, and return to receive mode with the
Ctrl-C E directive.
The FEC command is also used to initiate a SELFEC transmission. Entering FEC with
a SELCAL (Fec xxxx[xxx]) will automatically enter the transmit mode of FEC and
send the xxxx[xxx] SELCAL to start the designated stations receive system. You would
then send your message, returning to receive with the Ctrl-C E directive. In order to
enable your unit to receive only SELFEC signals, you must turn AUTOSTRT ON. Once
you have started receiving, you will stop upon the end of the transmission, or upon
losing lock with the FEC signal.
48 AMTOR
R © Copyright 1989, 1990, Kantronics, Inc. All Rights Reserved.
Version 3.0 Aug. 13, 1990 Duplication of this manual or the firmware without
Operations Manual permission of Kantronics, Inc. is prohibited.