PK-232 MBX Operating Manual - N3UJJ

PK-232 OPERATING MANUAL
SIAM AND TDM OPERATION
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.
TDM is an immediate command that places the PK-232 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 TD-M 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 key to enter the TDM mode. The PK-232 responds by
displaying the previous mode:
Oprnode
Oprnode
was PAcket
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-232 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-232 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-232 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 4channel 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
10.4.3 Where to Find TDM Sianals
We have heard TDM signals on the following frequencies which should be
used as a starting point when looking for TDM signals.
9.125.9 LSB 11.246.5 USB 12.061.7 USB 14.623.3 USB
14.956.7 USB 18.983.6 USB 19.101.9 LSB 19.647.4 LSB
The above signals were using several different shifts. Remember to set
WIDESHFT for the frequency shift of the signal you are tuning.
4/91 10-4
From The N3UJJ.COM Document Library