[GreenKeys] Random memory about surplus TTY equipment

[Bob McConnell]

Jeffrey Angus wrote:
> Back in the eary '70s I acquired a double wide rack cabinet full of RTTY
> equipment. AN/FCC something I think. 
> 
> All tube euipment, sealed audio filters at some useless combination of
> frequencies. This was supposed to be a multiplex TTY system with I
> think 15 or so pair in one audio bandwidth channel.
> 
> Does this ring a bell (ahem) with anyone?
> 

I don't know about the shore based units. But the AN/UCC-1 multi-channel 
RTTY demultiplexor we had aboard ship may have been its replacement. 
There were 16 channels available, 75 Hz shift with 75 Hz between the 
upper freq on one channel and the lower freq on the next. The bottom 
channel started somewhere just above 300 Hz. Different ships had 
different sets of channels. NFIT (USS Cochrane) had only  channels 1-8, 
but four modules for each channel. Always encrypted, it would push 107 
wpm into a M-28 printer through each channel.

UCC-1 could do channel diversity (1+5, 2+6, etc.) as well as multiple 
receiver diversity. Signals were normally transmitted on USB. Each shore 
station transmitted on a handful of frequencies spaced through the HF 
bands. Each ship would tune the two strongest signals, moving one at a 
time when a frequency faded out. There was sometimes an LF option with 
only 8 channels, but that was normally ground wave and could only be 
copied within 100-160 miles.

Bob McConnell
N2SPP