After another 15 seconds or so, the PK-232 should respond with one of
the following signal classes and tell whether or not the signal is
reversed by giving the status of the command RXREV:
ASCII AMTOR ALIST Baudot Unknown noise 6-bit TDM
The complete information from the PK-232 signal analysis will look
something like the following:
0.47 50 Baud, Baudot, RXREV OFF
This means that the PK-232 has determined the signal to be a 50-Baud
Baudot signal that is not inverted (since RXREV is OFF). The 0.47
means that the PK-232 is only 47% sure that this analysis is correct.
SIAM can identify and copy ASCII, ARQ and FEC AMTOR, Baudot and TDM
signals. To begin printing one of these signals, all that must be
done is to type the command OK after the analysis has been completed.
You should immediately begin to see text appear on your screen.
If the PK-232 determined the signal to be Unknown, 6-bit or noise
which it cannot decode, typing OK will cause the response:
?bad
The SIGNAL routine will run repeatedly until the operating mode is
changed either by typing OK, or forcing a change to another mode. If
you tune to a different signal during an analysis, simply type SIGNAL
again to restart the analysis routine.
10.3.1 Copying Encoded RTTY Transmissions
In the Short Wave bands many RTTY stations can be found that are not
transmitting in plain text. Most of these stations are using
sophisticated encryption techniques that make receiving them almost
impossible. There are a few stations however that use a relatively
simple bit-inversion technique to make them hard to copy. For these
stations, the PK-232 has included the BITINV command.
If the text is not plain, but appears to be encoded, you can try
different settings of the BITINV command. BITINV will Exclusive-OR a
number from $00 to $1F with the received character of a Baudot signal
thus inverting specific bits. By varying BITINV f rom 0 through 31,
you will test all the different bit-inversion possibilities that may
be used to encode a Baudot signal. If only simple bit-inversion is
being used, one of the settings of BITINV should cause the
transmission to print in plain text. If however, none of the 32
possibilities reveal plain text, then the transmitting station is
likely using a more sophisticated encryption technique. Computer
programmers may be interested in the 5BIT and 6BIT commands.
10.3.2 The CODE command for International RTTY Compatibility
The CODE command allows the PK-232 to receive (and sometimes send)
other RTTY character sets. Look up the CODE command in the Command
Summary Appendix for information on some of the other character sets
you may encounter on the HF bands.
4/91 10-3
