Telepresence
you.” Why not “I need you?” Maybe he was wishing
that his new device was a bit closer to what we now
call telepresence. Some of Bell’s technical notes from
April 1891 indicate that he was thinking about an
‘electrical radiophone’ when he recorded “... the
possibility of seeing by electricity.” He mentioned
using “specks of” selenium as part of the vision
imaging elements. He wrote: “Should it be found ...
[that the image sensor] is illuminated, then an
apparatus might be constructed in which each piece
of selenium is a mere speck, like the head of a small
pin; the smaller the better. The darkened selenium
should be placed in a cup-like receiver which can fit
over the eye … Then, when the first selenium speck is
presented to an illuminated object, it may be possible
that the eye in the darkened receiver should perceive, not
merely light, but an image of the object… “
It was easy to see that light-sensing devices developed
from using these elements could send an electrical signal
proportional to the amount of light shining upon it.
However, a complex image was beyond the capabilities of
these sensors. Even the crudest image would require many
hundreds of separate pixels or specks of selenium to sense
one scene and form that scene at another location. He had
no idea of how to address each line of specks and how to
receive the varying electrical signals from each of the
specks, then transmit them, and then re-arrange them at
the other end into a picture. Would he have to divide each
image into a line of pixels and then scan each line
individually or does each illuminated pixel need to send a
bit of information to its respective pixel at the other end?
With the success of his telephone that transmitted
verbal information, Bell predicted that: “... the day would
come when the man at the telephone would be able to see
the distant person to whom he was speaking.” Figure 1
shows an artist’s conception of ‘Videotelephony’ as
imagined in 1910 — 20 years after Bell’s prediction.
FIGURE 1. Artist’s conception of Videotelephony,
as imagined in 1910.
main means of home entertainment.
Regular television transmissions began in 1929, and the
1939 New York World’s Fair introduced it to the American
public. World War II kept wide acceptance and availability
from the public until 1948. Color television appeared in the
NTSC form in the US in 1953. TV resolution in the US
started below 300 lines of scanning for the picture, but
soon standardized at 525 lines. Most European countries
used the higher 625 lines with 30 frames per second
interlaced to provide 60 lines. Solid-state electronics, LCD,
projection sets, and high definition brought us to where we
are in this new millennium.
Telepresence Starts with
Video Phones
With the transmission of audio and video over wire and
RF, Bell’s wish for true telepresence was possible, but not
quite to the extent that we have it in 2011. I remember
seeing a video phone at Disneyland when I was a kid and
Television Makes the Scene
Basic telepresence got its true start with the
invention of television. When the cameras and
monitors were first available, inventors immediately
interconnected them in pairs to provide remote two-way television communications. Of course, thoughts
about developing the viewing and transmission of
visible images started back in the 19th century with
Bell’s and other’s ideas — well before what we now
call television. The telephonoscope was first envisaged
in 1878 with some crude sketches by science fiction
writers. The idea of scanning the image used a
swinging pendulum in 1881, but the best idea of the
era was using a spinning disc with a series of holes in
it, spiraling towards the center to create a raster scan.
With the development of vacuum tube amplifiers and
other circuitry, radio wave transmission, and the
cathode ray tube (CRT), television became one of the
FIGURE 2. The Jetson’s video phone.
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