Specifications

10.3.2 The CODE command for International RTTY Compatibility
The CODE command allows the PK-900 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.
10.4 TDM Receive Operation
The SIAM mode described above will recognize and decode TDM signals
for receive only. The TDM receive mode can be entered directly simply
by typing TDM at the PK-900 command prompt.
TDM is an immediate command that places the PK-900 in the TDM
receive mode. TDM stands for Time Division Multiplexing, also known
as Moore code and is the implementation of CCIR Recommendation 342.
The following describes the TDM mode and commands in detail.
10.4.1 TDM Parameters
If you are using an AEA PAKRATT program, follow the instructions in
the program manual to enter the TDM mode.
If you are using a terminal, simply type "TDM" from the Command Mode
followed by the <Enter> key to enter the TDM mode. The PK-900
responds by displaying the previous mode:
Opmode was PAcket
Opmode now TDm
10.4.2 Monitoring TDM Signals
The TDM command forces bit phasing; do this when changing frequency to
another TDM signal. This is also useful when the PK-900
synchronizes on the wrong bit in the character stream, which is likely
on a signal which is idling. TDM stations idle MOST of the time, so
you may have to leave the PK-900 monitoring for an hour or two
before any data is received.
TDM signals allow multiple data streams to share the same RF channel.
The PK-900 can receive either 1, 2 or 4 channel TDM signals. When
monitoring 2 or 4 channel TDM, the TDCHAN command allows you to select
which channels will be displayed. The TDCHAN command takes an
argument from 0 to 3 to allow any one of the four channels of a
4-channel TDM station to be monitored.
TDM signals operate at different data rates. The TDBAUD command
allows any data rate from 0 to 200 baud to be selected, but only the
values in the following list are valid.
1-channel: 48, 72, 96
2-channel: 86, 96, 100
4-channel: 171, 192, 200
1/93 10-5