[GreenKeys] Kleinschmidt History (was Teletype Corp. History circa 1960)

[Jim Haynes]

On Sat, 18 Mar 2023, Duncanancy wrote:

>  Back in the 1920s , they did experiments with RTTY. 

I guess that would have been Morkrum-Kleinschmidt back then.

Patent 1,705,211  Lawrence R. Schmitt Radio Telegraph System, 1929 and
Patent 2,012,407  Lawrence R. Schmitt Radio Telegraph System, 1935
a two-tone demodulator scheme.  The latter patent modifies it to work
with single-tone keying.

I learned fairly recently from Mischa Schwartz that E. H. Armstrong
also was proposing FSK for radio telegraphy about the same time.
"Methods of Reducing the Effect of Atmospheric Disturbances", Proceedings
of the I.R.E., January 1928, p 15.  That was before Armstrong got into
limiter-discriminator FM demodulation, and was also a two tone system.
I gather both those men hoped that noise bursts would affect the mark
and space channels equally and could be canceled out.  Carson of AT&T
explained why that would not work in Proc. I.R.E. July 1928, p. 966.
However Armstrong's ink recorder traces showed a definite advantage for
the two-tone system.  Perhaps the difference was made by effective
transmitter power rather than by noise cancellation.  Two tone would
have about twice the transmitter power of single tone since the
transmitter is on all the time rather than being on-off keyed.

Patent 1,485,212 to John B. Brady, Radiotelegraph System, 1924,
Patent 1,523,377 to John B. Brady, Radiotelegraph System, 1925, and
Patent 1,562,820 to John B. Brady, Radio Receiving System, 1925 were
assigned to Morkrum Kleinschmidt though Brady was apparently not an
employee of the company.  He reported on patents in Proceedings of the
I.R.E.

Somewhere I've seen mention of experimental radio transmissions
between Teletype's Wrightwood plant and Lake Geneva, WI and Sterling
Morton's home in the Chicago suburbs.

When Teletype was acquired by AT&T the radio work presumably stopped.
At that point AT&T wanted a manufacturer of printing telegraph machinery,
was not interested in developing products for markets outside their
own system.