Television Sight-and-sound broadcasters to send more and brighter 1946 June

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Television Sight-and-sound broadcasters
to send more and brighter 1946 June Issue
By WILLIAM P. VOGEL, JR.

THIS month television star ts its pos twar
campaign for public acclaim. After years
in the laboratory and months of limited
commercial operation, it is now out to conquer
an audience.
Those who already own television sets
(at a guess, about 10,000 families) will get
at least four hours of sight-and-sound each
week this month. The televising of the
Louis-Conn fight at Yankee Stadium on June
19 will be the stellar event; boxing will
provide some of television’s most compact,
action-filed, suspense-crammed programs.
Next month, unless FCC grants a further
postponement, every commercial station will
have to put at least 28 hours a week of
sports, news, special events and live or
screened shows on the air to hold its license.
Television holds such promise today that
30 feet has been added to the Empire State
Building. The National Broadcasting Company
has doubled the power of Station
VVNBT by perching a new and taller antenna
on top of the world’s tallest building.
This antenna is so designed that it flattens
the signals in the direction of the horizon
instead of letting them squirt upward as
wel as outward, and thereby increases the
reception radius from 60 to 70 miles.
Since its fumbling start during the New
York World’s Fair, television has fallen heir
to a fortune in radar research. When frozen
for the duration, it was standardized on
pictures moving 30 frames per second with
a definition of 525 lines. (This means that
the electron beam in a television pick-up
tube—the “eye” that sees the image—cuts
up each picture into 525 horizontal lines
and scans those lines, moving from left to
right and from top to bottom, in one-thirtieth
of a second.) This is still the standard,
but the quality of television has become
much better.
Out of the war came huge improvements
in the cathode-ray tube, which produces the pictures to bigger audience.
received image. The glass was made with
better optical qualities; its curvature was
lessened, so that when viewed sideways the
image would not be distorted like a reflection
in a Coney Island mirror. The phosphors—
chemicals that blaze into light when
bombarded by electrons—were changed to
double and triple the brightness of the
picture.
In a new RCA cathode-ray tube, soon to
be mass-produced, a microscopic film of
aluminum, about four-millionths of an inch
thick, is ingeniously deposited on the inside
of the phosphor coating. The electrons pass
through it, striking the phosphors and converting
the television image into light. But
the light, mirrored by the aluminum film,
cannot go back into the tube. In uncoated
tubes, the light loss inside runs as high as
50 to 60 percent; in the new tube the light
is al projected outward. Increased voltages,
12,000 to 15,000 instead of 7,500, also produce
brighter pictures. Even at these voltages,
however, there is no danger from
shock, because the current is measured in
microamperes—just about what you generate
when you scuf your foot on a thick rug in
a cold room.
In a television picture with more light,
more tones of gray can be crowded in.
Prewar television had a contrast ratio of
about 15 to 1, but soon contrast will be as
good as in the average movie screen (40
to 1)—possibly even better.
You will be able to see television pictures
in roughly three diferent grades, depending
upon the cost of the set. Probably the
most popular grade will be the cheapest
(estimate: $150 to $250), which will feature
small cathode-ray tubes, say five or
seven inches in diameter, and produce
pictures 3 by 4 or 4% by 6. Sets in the next
price bracket will have cathode-ray tubes
up to 12 or 15 inches across. In the highest
price range you will see pictures on 20-inch
tubes, and projected television in which an
intensely bright high-voltage tube sends its image through lenses onto a ground glass
the size of a home movie screen.
Persons accustomed to good radio reception
with skimpy antennas will have to be
re-educated for television; good antennas
will be needed regardless of the quality of
sets. The weakness of signals 40 to 60 miles
from the stations wil necessitate good antennas
in suburban areas; and in cities,
where signals are stronger, good antennas
will be needed to get clear pictures free
from ghosts—those troublesome multipath
images that make a television screen look
like a double exposure. Ghosts, created by
reflected signals, are annoying—especially
when they make an otherwise nice-looking
actress appear to have four arms, two
mouths, and several extra eyes and ears—
but we must be grateful to them, even so,
for they are the basis of radar.
Sight-and-sound has been assigned channels
in the short-wave band from 44 to 218
megacycles. The shorter the radio wave,
the more like light it behaves. Television
waves can be aimed by transmitting antennas very much as light waves are aimed
by searchlights. And they can be reflected
by buildings; trees and even airplanes. In
general, radio waves begin to be capable
of reflection when they are smaller than
objects in their path. That is why the
waves used in sound broadcasting do not
bounce and ricochet—for they are far larger
than almost anything they encounter.
Antennas for the public will most likely
be dipoles—tall vertical standards with two
horizontal pick-up rods measuring about
nine feet across. The dipole should be installed
at right angles to the line of transmission,
so that the spread of the antenna
is broadside to the television station. It
should be carefully rotated to find the exact
azimuthal setting that produces ghost-free
reception. There may be several such settings—
and there may be none. In the latter
case, the set owner is out of luck, for at the present state of television development
a rotating antenna is the only means of
eliminating ghosts. The lead-in from the
aerial to the set is also important. It will
probably be a matched or twisted pair of
wires specially designed to keep down loss
of the signal. The trick in television lead-ins
is to have the two wires a certain distance
apart and to keep them always at that distance
lest the signal vanish.
The broadcasters are also having their
troubles. Most cameras and transmitter rigs
now in use need rebuilding or total replacement.
New equipment has been held up
by the slow pace of reconversion. Studios
need enlargement, but building materials
are scarce. Broadcasters may not get them
at al, because of a recent government order
curtailing commercial construction in favor
of the veterans’ housing program.
Since television can be received only in line-of-sight transmission, approximately as
far as the horizon, rural dwelers will not
be able to gather around a ‘scope for an
evening’s entertainment until networks are
established. Because television wave-lengths
are too short to be carried on the usual
telephone circuits that handle sound broadcasting,
television will have to be carried
from station to station either by coaxial cable
or radio relay links. A national network is
planned, to be built within the next five
years, using a combination of both methods
Economic and technical details of proposals
to use airplanes flying at high altitudes as
television sources, covering wide segments
of the country, must yet be tested. For the
time being, television will be confined to the
big cities, chiefly those on the east coast.
A typical station operating 28 hours a
week will probably ofer 12 hours of “mobile”
shows (news, special events, sports,
etc.), 10 hours of “live” entertainment
(plays, short spots, skits, song-and-dance
acts, news comment with maps, and similar
stunts) and six hours of movies. Unfortunately,
the movies, which ofer the best
possibilities for elegance, are likely to be old stuf unless the big movie companies,
forever fearful of the efects of television on
their big-money industry, bury the hatchet
with television and furnish new films.
By fall, broadcasters will be able to use
one of the most important inventions in electronic
science: the new Image Orthicon
camera tube (see accompanying drawitigs)
developed by Drs. Albert Rose, Paul K.
Weimer, and Harold B. Law, of RCA. It
is 100 times more sensitive to light than
prewar pick-up tubes.
Three of the five cameras that will cover
the Louis-Conn fight this month will use
the Image Orthicon. Two cameras will be
mounted on a special platform, two in the
NBC television box on the stadium’s mezzanine,
between first base and home plate,
and the fifth beside the ring. Signals will
be carried by wire to an ultra-high-frequency
radio relay link, beamed from there to a
receiving antenna on the RCA Building,
fed through NBC’s master control board for
television, mid finally carried by coaxial
cable to the Empire State Building for
transmission.
Bright lights produce intense heat, and
it is no joke to be working near them on
a cramped television stage. Such lights will
not be needed when the Image Orthicon
is in mass production, but until then studios
will have to rely on several wrinkles to keep
their actors cool. Sheets of special glass
will absorb 87 percent of the heat and pass
93 percent of the light. A mercury vapor
lamp rated at three kilowatts is said to be
as cool at four feet as an ordinary desk
lamp. Studio brightness eventually will decrease
from several hundred foot-lamberts
to around 50. For mobile broadcast, the
Image Orthicon does away with bulky equipment
and vastly broadens television’s scope.
It will be able to take almost any kind of
spot-news event, regardless of the kind of light in which it occurs. When turret lenses
are also available for television cameras,
quick switching from long shot to close-up
will be possible; and breaks in the show,
such as occurred at the U.N. broadcasts,
will no longer be necessary.
No one knows how many sets will be in
use by the end of the year, and no one can
tell how many television stations will be
operating. One big manufacturer who hoped
to build 4,000,000 radios and 60,000 television
sets has been forced to cut his estimates
in half. It’s anybody’s guess if 50,000
or 200,000 television sets will be made this
year, although everyone seems certain that
in 1947 around a quarter of a million sightand-
sound receivers will be on the market.
The black-and-white versus color controversy
has clouded the broadcasting picture.
NBC, backed by RCA, has locked horns
with CBS over this isue. CBS, intensely
proud of the accomplishments of its research
engineer, Dr. Peter C. Goldmark, takes the
position that al television should be standardized
on the basis of its system. This would mean scrapping the black-and-white
developments, moving television from its
present band in the spectrum to a higher
frequency, and re-engineering everything
now ready for commercial use. If the industry
would cooperate, says CBS, there is
no reason why commercial color should not
be a reality by next year.
NBC and RCA, as well as others who
have lavished both time and money on television
since it was merely a dream of the
laboratory men, resent Columbia’s insistence
on the virtues of its system. They want a
return on their investment and believe that
the public should be alowed to see blackand-
white shows now, no matter how bright
the promises are for color next year. They
argue that color television still needs years
of basic research before it becomes commercially
practical.
All wrapped up in the color fight are the
intense personalities and the misty economics
of the radio industry. In the opinion of the
best minds in radio, the injection of the
color isue at this time is certain to have

 

 

 

 

 

 

 

 

 

 

 

a deterrent efect on the development of
black-and-white. Already some 30 applicants
for licenses to operate television stations
have withdrawn their petitions from
FCC. This would indicate that some of the
men who want to invest from $400,000 to
$1,000,000 in television would rather wait
and see what happens.
But more important than the immediate
controversy is the ultimate decision on where
television should be placed in the radio
spectrum. CBS, working on its color experiments
in the region of 480 megacycles,
believes that al television should be in that
band. Others believe that an eventual move
into that region or higher is inevitable—
because there is more room there for individual
broadcasters. The higher the frequency, the broader the transmission band
can be; in the present television band from
44 to 216 megacycles the air is already so
crowded that only six-megacycle channels
are available. In the higher reaches, a 16-
megacycle channel can be used. The width
of the channel is extremely important; if
standards are ever to be raised, in the direction
of more picture frames per second and
more lines of scansion, the channels will

 

 

 

 

have to be wider. Obviously a faster transmission
rate and a picture scanned with
more lines produce more “information” in
the television image, and bring to the viewer
a picture of greater detail and exactness.
It is quite likely that even before color is
oficially sanctioned for commercial operation,
television will move up into the UHF
(ultra-high-frequency) region or higher.
This summer FCC will hold hearings on
a CBS petition to license color television
commercially. Television is bound to move
up some day. Today’s band, where you
can see National’s WNBT at 66-72 on your
dial; Columbia’s WCB W (for black-andwhite)
at 54 to 60, and DuMont’s WABD
at 76 to 82, is simply a halfway house for
the art. But it is a halfway house that
promises a good period of occupancy. Regardless
of the speeches and the fighting,
commercial operation has begun. It will
not be obsoleted any more than standardband
broadcasting was obsoleted by frequency
modulation.

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පෙර ලිපියෙන්THE History of Television 1946
ඊළඟ ලිපියRUTH ETIING Radio Star 1929
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