[GreenKeys] A little more on regenerative repeaters

[w9ddd at tapr.org]

So how was the sixth pulse defended?  The blank character becomes the synch character?

John, W9DDD


> On Oct 12, 2019, at 8:36 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> 
> As I said a little earlier, I was totally wrong when I said a regenerative
> repeater would not help things if your TTY machine is property adjusted.
> That would be true of a mechanical regenerative repeater.  Teletype made
> such a thing in the 1930s for the Bell System TWX service.  Much later
> Bell Labs designed an electronic (vacuum tube) regenerator to replace the
> mechanical ones.  I saw a design for a transistor regenerator at Teletype
> in about 1958, but it was never produced, so far as I know.
> 
> Something Teletype did make was called a monoplex, which was basically
> a single channel device using some parts from the AN/FGC-5 four-channel
> time-division tube-type multiplex.  The monoplex converted start-stop
> code to 6-level synchronous code and was used on the DEW line defense
> project.  Because it was synchronous it got around the false start
> and mutilated stop pulse problems that are so common in radioteletype.
> The reason the monoplex and the AN/FGC-5 multiplex and its descendants
> used 6-level code was so that all 32 combinations in 5 level code could
> be transmitted.  In 5-level multiplex the blank character has to be used
> as an idle character when there is no traffic character to send.
> 
> For the past 40 years or so we have had UART ICs which make it easy to
> make electronic regenerative repeaters and speed converters.  And I am
> now a strong advocate of using them in radio work for the false start
> and mutilated stop correction.  They are also good for speed conversion,
> so why bother with mechanical gear shifting when you can run the printer
> at 100 wpm and adapt to various input speeds electronically?
> 
> Before UARTS WA6JYJ (now W7JYJ) and I designed a speed converter using
> ordinary TTL ICs, and this circuit also acts as a regenerative repeater.
> 
>    ---
> 
>    "Ya can argue all ya wanna, but it's dif'rent than it was."
>    "No it ain't! No it ain't!  But ya gotta know the territory."
>        Meredith Willson, The Music Man
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
> 
> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to w9ddd at tapr.org