VP’s Corner

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This has been quite a mind expanding week as I listened to John
describe his favorite new digital mode, JS8. It runs on a laptop
computer and manages to copy at subterranean signal to noise
ratios. Wow, how does that work? And how did we get here?

Military version of the Model 15

Military version of the Model 15

No computer memory in those days. Messages were stored for transmission on 5 level punched paper tapes.

No computer memory in
those days. Messages were
stored for transmission on 5
level punched paper tapes.

The journey leading to seemingly magical
modes like JS8 began shortly after World
War I as growing demands for commercial and government communications rapidly exceeded
the capacity of manual telegraph circuits.
A small group of clever inventors proposed a solution known as a “printing telegraph” or teleprinter. Its electromechanical keyboard and printer combination used a 5 bit Baudot code to represent 64 possible alphanumeric characters.

Their invention was a resounding success and their company, the Teletype Corporation, went on to become a major supplier of telecommunications equipment during the 20th century. Both landline and radio teletype (RTTY) circuits commonly ran at speeds of
60 and later 100 wpm.

Clever operators sometimes exchanged teletype art during the midwatch.

Clever operators sometimes
exchanged teletype art during
the midwatch.

Surplus Teletype equipment became available
to the amateur radio community in quantity
shortly after WWII. Most ham activity used 60
wpm FSK on the HF bands. I can remember a
friend and I spending an all nighter to get an
old Model 15 working during my high school days.
Our demod was a 6AL5 discriminator (yes, those
were vacuum tubes). We were ecstatic when we
finally got Reuters news coming out of the
printer.
Time marches on. The invention of the PC
hastened the demise of the Teletype Corporation,
which went out of business in 1990. It also spawned some fascinating new sound card modes (below). Join us for a presentation on one of
the newest, JS8, by John KG4NXT at our March meeting. Hope to see you there

Jeff Fuller, WB6UIE

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