RTTY / ASCII
41
AUTOLF ON causes the
KAM
to insert a line feed after every carriage return which is received from
the distance station. If received RTTY or ASCII signal appear double-spaced on your screen, you
want to turn this command OFF.
The AUTOSTRT command is useful if you wish to leave your station in the automatic mode, in
which you can receive messages from other stations, even when you are not present. With
AUTOSTRT ON, a station can cause you to start receiving data by sending the callsign in your
MYAUTOST parameter (will accept up to 7 characters allowing for MARS callsigns) prior to sending
his message to you. The
KAM
will stop receiving when it receives
NNNN
from the other station, or
when there is no signal present for approximately 30 seconds.
The CCITT command controls which RTTY character code will be used in the RTTY Mode. When
this command is OFF (the default) the US RTTY code will be used, and when ON, the European
code (ITA2) will be used. These two codes differ only on four characters and the differences are
shown here:
ITA2 US TTY's
BELL
'
+
=
'
BELL
"
;
A standard operation practice in RTTY is to send a CR CR LF at the end of each line to allow the re-
ceiving station time to return the carriage of the mechanical RTTY machine to the far left edge of
the paper before sending the next character. This can be accomplished by setting the CRADD com-
mand to ON. This causes the
KAM
to send an extra CR after every CR transmitted. This command
applies to ASCII and RTTY Modes of operation, as well as AMTOR.
The DIDDLE command will cause the
KAM
to send a special diddle character whenever you are in
the transmit mode and no data is being sent. The default for the DIDDLE command is OFF. This is
used to allow the receiving station to tune your signal prior to you sending data since it causes
both mark and space signals to be transmitted. The standard diddle character in the RTTY Mode is
the LTRS shift, and in ASCII a NULL is sent as the diddle character.
The ECHO command allows the TNC to send any character you enter from the keyboard back to
your terminal. If you are using a split-screen terminal program, your terminal program may provide
this local echo for you and you will then want to turn ECHO OFF. This would then allow what you
send to appear in your transmit window and the data you receive, would appear in the receive
windows of your terminal. (See XMITECHO for more information.)
The FSKINV command (default OFF) will determine the polarity of the signals sent from the
KAM
to the FSK input of your transceiver. In the OFF state, a MARK is open collector (open circuit) and
a SPACE is ground (closed circuit). Since transceiver manufacturers have not implemented a stan-
dard for FSK operation, it may be necessary to invert your transmitted signal using this command.
You cannot invert the transmitted signal once you are in the RTTY or ASCII Mode, but only by the
use of this command prior to entering either of these modes. In order to invert your transmitted
signal using AFSK, you will need to use modem shift (see SHIFT command or
Ctrl-C S
directive)
and set your MARK and SPACE tones using the MARK and SPACE command.
If INVERT is OFF, the
KAM
will decode RTTY, ASCII and AMTOR signal as sent (i.e. mark is de-
coded as mark and space is decoded as space). Most RTTY on the HF bands is sent in lower side-
band, but if your radio is upper sideband only, you may want to set the INVERT command ON. The
decoding of the mark and space signals may be inverted after you've entered the RTTY, ASCII or
