[GreenKeys] Continuing, nothing about Teletype art

[Jim Haynes]

During the college years I had frequent contacts with Bob Weitbrecht,
W6NRM/W9TCJ who was then at Yerkes Observatory in Wisconsin.  A good
friend of his was a professor at Arkansas, "Charley" Fan, who had
recently left Yerkes, so I got them together on RTTY several times.
Bob was one of the great pioneers and promoters of RTTY, devising a
lot of equipment and traveling great distances to help hams get
started.  There was one period when he and BeeP W0BP traveled together
for a long distance, stopping to visit RTTY-ers all along the way from
Minnesota to Texas and beyond.  Bob was deaf, so ham radio was a great
social outlet for him, and RTTY made his communication a lot faster
than he could do with CW.  He decided to leave Yerkes and came to visit
us and the Fan family in Arkansas before returning to California and
resuming use of his W6NRM call sign.

I enjoyed operating the RTTY contests in those early years.  There were
only two a year, and the number of RTTY operators was so small that many
of us were acquainted with one another outside of the contest periods.
Also W5YM was the only RTTY station in Arkansas, so everybody wanted to
work us for the section multiplier.

When I told Merrill I had a summer job at Teletype he told me to look up
Bob Reek there.  He and Bob had been roommates at some summer short course
on transistors put on by some university not long before.  As it turned
out Bob was my immediate supervisor both summers when I worked there.
He is still living and we are still in touch.

Although Teletype Corp. was not in the radioteletype business we were
working on time-division multiplex equipment for the Navy to use on RTTY.
This was my first chance to work with transistors in large quantities.
I didn't take to transistors very well in linear circuits since they were
so hard to bias and stabilize.  But we were using them as switches in
digital circuits where they really excelled.  At the time transistors
were too slow to use in digital computers, so we were working with and
manufacturing logic circuits ahead of the computer industry.

As to the original subject matter of this posting, RTTY art, I never
paid much attention to it because on HF there are enough hits and dropouts
to spoil just about any attempt to transmit pictures.  Plus it takes up a
lot of time that could be spent in conversation about RTTY.  I guess
RTTY art was more practical in areas where there were a lot of hams 
operating VHF where copy was consistently good.

Back then in addition to amateur RTTY there was a lot of other stuff on
the air we could copy.  I remember when Sputnik went up we were very
busy at W5YM copying all the press we could find and hanging it on the
door outside the ham shack for the passers-by to read.

In the Air Force I had my own RTTY station, first in the garage of a 
friend who was married and had a house on the base, and later in my room
in the BOQ.  I used the Model 15 I had put together from parts from W9GRW,
and an old BC-375 transmitter modified to use a Heathkit VFO.  Receiver
was initially a BC-348 and later a Drake 2B.  Later Bob W6NRM gave me
a transmitter, Royal Canadian Air Force I think, that was less ponderous
than the BC-375.  It was intended for use with an external modulator
for AM, so the transmitter alone was a fine CW and RTTY performer.

After the Air Force I went back to Teletype full time.  I set up my RTTY
station and had a lot of contacts with Irv Hoff who moved to California
sometime in that period, and with Vic Poor at Frederick Electronics Corp.
I didn't really contribute to the design of the ST-6 and the Frederick
demodulators, but it was interesting to keep abreast of what those guys
were doing.  We had a ham club at Teletype, and I occasionally attended
meetings, but for some reason I never got over to the building where the
club station was located.

After 3 years at Teletype in Skokie I went with G.E. when they were in
the computer business in Phoenix.  I learned a lot about computers, but
working for G.E. was a lot less fun than Teletype, at least for me.
After two years of that I landed a non-academic engineering job with
University of California, Santa Cruz and stayed there for 30 years.
On the faculty were Harry Huskey, a computing pioneer who had worked on
ENIAC, and David Huffman, famous for the Huffman codes and a lot of
other important things.  And continued RTTY in my spare time.  I had a
housemate WA6JYJ who was a friend of Bob Weitbrecht and whom the 
university hired when he got out of the Army.  Bob lived just about an
hour away in Redwood City, so we got to visit each other often.  By
that time Bob was quite absorbed in the modem he had invented for use
over phone lines by deaf people with TTY machines.  But that's another
story.

This was the period of time when integrated circuits became cheap, so
we could develop a lot of stuff for RTTY quickly and easily.  One thing
I built was a speed converter so that a Model 28 running at 100 wpm
could copy any of the standard speeds.  Larry WA6JYJ also built one with
a few changes from mine and wrote it up for Ham Radio magazine.

I was also interested in the possibility of improving RTTY reception
by using a more advanced detector, one taking advantage of synchronism
to know when the big boundaries were going to occur.  The FCC rules for
amateur RTTY had never permitted us to transmit anything other than
7.0-7.5 unit start-stop code.  After a while I realized that I could
transmit 7.0 unit code synchronously, putting in a fill character 
whenever there was nothing available in time from the keyboard or tape
reader.  I built a circuit to do this and started using it on the air.
I had a collaborator who was supposed to be working on a receiver for
the signals, but I don't know if he ever got it working.  In any event
the guys who were experimenting with and using two-tone demodulation
really liked it because it prevented the loss of space tone when a 
keyboard user quit typing.  I believe this is the origin of the "diddle"
style of RTTY signaling that is almost universally used today.

I was really tickled many years later when I read of K6STI and his RITTY
software that demodulated RTTY on a PC and that had what he called a
"digital flywheel" that would synchronize to a repetitive FSK signal
regardless of the length of the stop bit.  This was what I had hoped
to achieve with my diddler circuit and a purpose built hardware
synchronous demodulator.  Well RITTY was a very good demodulator, but
the improvement we were hoping for did not materialize - the synchronous
detection only helped a couple of dB of signal-to-noise ratio.  I found
an old government report where Stromberg-Carlson had developed a system
for the Army that was pretty close to what I had in mind, back in 1958.
The abstract to the paper reported a great improvement over standard
FSK operaton.  I was able to obtain a copy of this report - having to
use a FOIA request to get it.  It turned out that real synchronous
detection didn't seem to help at all, because propagation through the
ionosphere introduces so much variation in the arrival time of signals.

> I hope that my rambling is not boring to any or many.  It is great to think
> back to that time of my life and remember the 'good times'
> along with the bad times.  The nearly two years I spent on the USS Hancock
> were most interesting and educational for me. 
> 
Not boring to me, and I hope my attachments are not boring to the group as
well.

Jim W6JVE