[GreenKeys] Teletype on 4.004 Revisted

[NNN7DXB at aol.com]

All:
 
Thanks to all who responded to my question regarding the apparent teletype  
signals
on 4.004 (4.003.5) a few days back, and the recommendations on what types  
of
software and equipment to use in copying any of this traffic. As my HF  
radio gear
consists mostly of resurrected antiques these days, it is not likely  that 
I will spend any great
deal of money on any of it in this lifetime. 
 
Some interesting further observations noted:
 
a. the signals start (come online) at exactly 5:00 PM (Eastern) (2200Z  
(UTC)) every day.
 
b. There are no preliminary or start-up processes, nor is there a carrier  
signal before
transmission begins. It is as if someone throws a switch, and the TTY  
signals begin
immediately, and continue unending late into the night. I do not know when  
they
stop, as the transmission continues long after my bedtime. When morning  
arrives,
the signals are gone and the frequency is clear - and quiet.
 
c. The traffic is continuous with no breaks whatsoever in the bit stream.  
This leads
me to believe it is some form of automated data or telemetry, as there are  
none of
the usual audible "machine functions" that one could discern by ear, such  
as
End of Machine Functions (8 LFs, NNNN, blanks, pause, etc between  
messages).
 
I mention audible "machine functions" because, if you have ever worked  
CommCenters
or RATTs for many years as I have when teletype equipment was still  common,
there were certain "characteristics" that an operator could eventually  
learn both
by "ear" and by "sight", particularly in regard to tape operations (tape  
relay in
reading tape) and RATT by listening for certain "sequences" to know when  
one
message ended and another was about to begin. Lost art today I think.
 
Inverted bits, encrypted or something other than Baudot? Either way, it  
appears
to be a very good replication of reasonably slow-speed Baudot code to my  
ear.
 
Most RATT traffic began with a carrier tone a second or two before the  
traffic
(tape) was sent. This was followed by a few "blanks" and then the  data.
This was true of both military and most Press traffic.
 
In a tape relay operation, one could always tell the start and end of a  
message
(at least in the military system) be the opening (visual) machine functions 
 which always
began with 5 spaces, 2 CR, and 1 LF (and most of us could read the ZCZC  
characters).
The ZCZC was called the Start Of Message (SOM) Indicator.
 
You could then tell the end of the message (EOM) functions by the  (visual) 
8 LFs,
and 4 NNNN, usually followed by 12 LTRS keys. Tape relay operators  were
generally called "Expediters" (aka: "tape apes"). Most of these types of  
stations
were high-volume, so you picked this stuff fairly quickly.(Tape relays did  
not
use printers as part of the relay work; it was ALL tape).
 
Thanks for the interest. All comments welcome,
 
Dave
Greenville, SC
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20131124/d2c55fd6/attachment.html>