Timewave PK-232MBX, Operating Manual, Page: 111 / 231

PK-232 MBX – OPERATING MANUAL SIAM AND TDM OPERATION
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The complete information from the PK-232 signal analysis will look something like the follow-
ing:
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 analy-
sis, 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 BI-
TINV 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 en-
code a Baudot signal. If only simple bit-inversion is being used, one of the settings of BI-
TINV should cause the transmission to print in plain text. If however, none of the 32 pos-
sibilities 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 char-
acter sets. Look up the CODE command in the Command Summary Appendix for informa-
tion on some of the other character sets you may encounter on the HF bands.
10.4 TDM Receive Operation
The aforementioned SIAM mode will recognize and decode TDM signals for receive only. The
TDM receive mode can be entered directly simply by typing TDM at the PK-232 command
prompt.