[GreenKeys] A little more on regenerative repeaters

[w9ddd at tapr.org]

Darn autocorrect.  Let's try this.  How was the sixth bit defined?

John, W9DDD


> On Oct 12, 2019, at 9:13 PM, "w9ddd at tapr.org" <w9ddd at tapr.org> wrote:
> 
> 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
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