[Qcwa] Memory Lane !!

[qcwa@mailman.qth.net]

Thanks very much to Harvey Chase W4TG for the history of Morse Code and=20
Morse's contribution to the telegraph industry.  This brought back memories=20
of my days with Xerox Corp. in the mid to late 1960s when I was writing=20
patent applications on the 'new' technology of facsimile transmission.  It=20
was new in the 60s for fax transmission over telephone lines, but fax=20
antedates the telephone!  Everyone nowadays thinks that fax and phone lines=20
are intermarried, but phone lines just happen to be the economical and=20
widespread medium on which fax transmissions are made today.

While heavily involved in Xerox's Telecopier=AE facsimile program for seven=20
years, I wanted to get as much background prior art that I could so as to=20
build our knowledge of this burgeoning field.  Everyone on this reflector=20
remembers wire photos, and RCA and Western Electric had that industry tied=20
u[p for years in the 1930s and 40s.  But facsimile transmission owes its=20
beginning to telegraph lines.  If memory serves me right, a curved platen wa=
s=20
used together with a pendulum stylus to scan a document.  If the pendulum co=
mp
letes a circuit at the transmitting end, and a like pendulum at the receivin=
g=20
end uses the interrupted D.C. current on the line to burn a similar pattern=20
on a document at the receiving end, then a 'facsimile'' of the transmitted=20
document appears on the received document which 'resembles' the transmitted=20
document.  Very crude, but a fax nevertheless.  I remember at least two=20
systems used in the late 1840s (no I was not an eyeball observer!).  One use=
d=20
a damp chemically coated document at the sending end with raised letters,=20
which closed a circuit while the pendulum (in a raster scan, either move the=
=20
pendulum or move the document) scanned the document.  A similar chemically=20
coated document was used at the receiving end, which changed color slightly=20
when current flowed through it in sync with the sending pendulum.  The secon=
d=20
technique used a thin metal document with open spaces cut into the metal=20
sheet in the form of information to be sent (think of a big X cut out of the=
=20
middle of the thin sheet).  When the scanning pendulum was in contact with=20
the metal, a circuit was closed and the information sent to the receiving en=
d=20
where either a similar thin metal sheet had holes burned into it in the form=
=20
of the information cut into the sending sheet.  Or the same chemically coate=
d=20
paper document could be used to chemically change color when current flowed=20
through it.

All this back in the 1840s!

Sorry to bore you if you got this far, but it was a good memory lane trip fo=
r=20
me!

73

Frank K6FCW


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