[GreenKeys] Fwd: Why 1.42 ?

[Charles Ring W3NU]

Maybe 1.42 was the closest approximation of 1.5 conveniently possible 
with the geometry of early selectors?

73 de W3NU


Don Robert House wrote:
>
> Many thanks Ben!
> Hope to see you when the weather gets better.
> Don
>
>
> -----Original Message-----
> From: Don Robert House <drhouse at nadcomm.com>
> To: Ben Stephens <K9kom at aol.com>
> Sent: Tue, 28 Mar 2006 14:56:04 -0600
> Subject: Fwd: Why 1.42 ?
>
> Charles Ring wrote:
> I remember printing 65 wpm (not 66) on a 15 with no problems and no 
> adjustments; that is 60 wpm/45.45 baud with one stop bit rather than 
> 1.42. I have no doubt a 28 could do it even better. I'd consider two 
> stop bits to be too much so I would use 1.5. I know the extra length 
> for the stop bit is a "catch-up" safety margin but I have forgotten 
> why it is 1.42 rather than 1.5 on the mechanical printers.
>
> 73 de W3NU
>
> Ben,
> Now I cannot remember.  Can you refresh my memory?
> Thanks,
> Don
> =
>
> Don,
>
> I once heard the detailed reason for the 1.42 stop bit length, but 
> that was decades ago and I have forgotton it.  However, it went back a 
> long way to the very beginnings of printing telegraphy, with two 
> different and potentially competitive firms competing on a reliable 
> system of machine telegraphy.
>
> The first group was out at Bell Labs in New Jersey, and they were 
> working with some sort of a system where the transmitting and 
> receiving shafts ran at the same speed.  With a 1.0 stop bit, the 
> machine would transmit in a sort of synchronous manner as long at 
> everything went well.
>
> Out in Chicago, the Krum boys were working with a system where the 
> receiving shaft went faster than the transmitting shaft, with the 
> receiver actually coming to a complete stop briefly before starting 
> again at the leading edge of the next start pulse.
>
> Of course, the two systems were incompatible.  Bell Labs had the edge 
> in being part of the American Telephone and Telegraph Company, with 
> Western Electric and the Operating Companies as a captive market.  
> Morkrum wanted to sell into this huge market, and the 1.42 stop bit 
> was a compromise which enabled its products to work on a circuit with 
> the Bell Labs equipment on the other end.  I don't recall the 
> technical details which led to 1.42 as the compromise solution.
>
> Anyway, the Morkrum system quickly proved itself superior, and the 
> Bell Labs system was dropped and forgotton, but the 1.42 stop bit had 
> established itself as a Bell System standard.  As we all know so well, 
> a lot of current effort in common carrier communications is to retain 
> smooth operation with the older legacy equipment.
>
> 73, Ben Stephens K9KOM
> NNNN
>
>
>
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