[GreenKeys] 132A2 subscriber set (TT-10/FG) and TTY book on line

[Jim Haynes]

On Thu, 23 May 2013, Nick England wrote:

> I picked up a manual for the 132A2 at Fair Radio last week - it is an
> interesting gadget - essentially a model 14 RT (reperf plus TD) with
> synchronizer circuitry to insert missing pulses. Intended for radio
> teletype service where a start pulse or character pulse might get
> dropped, but where an entire missing (as opposed to simply wrong)
> character plays havoc with the crypto system.

I've been wishing I could read somewhere a report on how effective the
thing was.

As for a Model 28 version, I don't know of one but that doesn't mean
much.  The 132A2 was a Bell Labs item rather than Teletype.

One thing I do know about is that Teletype made a "monoplex" that was
used on the DEW line.  They called it a monoplex because it was a single
channel system built using some of the hardware from the AN/FGC-5
time-division multiplex.  They converted the 5-level start-stop code to
6-level synchronous and back.  This was successful enough that they used
it, tho again I wish I knew how effective it really was.  The reason for
6-level code in the multiplex and monoplex was that all 32 5-bit 
characters were considered legitimate.  The blank character was not 
available for use as an idle character as it was on the older Western 
Union time-division multiplex systems.  So the 6th bit distinguished
between a real character and a fill character sent to keep the system
in synchronism when there was no real character to send.

Jim W6JVE