Evening star. [volume] (Washington, D.C.) 1854-1972, 1948-08-15
For Radio Listeners
By Harry Macarthur

changes the new setup would bring.
WTTG, which is on the air IS to 40
hours week, what with baseball
games, plans not to expand its
schedule, but to add to it number
of new network productions. Among
the newcomers are wrestling and
boxing from Jamaica, Key to the
Missing" "Tele Fashions, The
Leytons" and so on. WTTG also
promises a Zero Mostel comedy show
tCome autumn.
Since one of the first questions
many ask is why television can't
be sent along an ordinary wire like
AM radio, Kenneth r. Berkeley,
vice president of The Evening Star
Brodacasting Co., thought an ex-
PLANTATION might be in order when
he was announcing the new cable
situation early in the week. He had
the above Earl Hilburn
do the explaining and if you will
hang onto your hat you may come
along. If this comes out at all
understandable, Mr.. Hilburn can
call himself a genius.
The first thing you have to have
is rough idea of the way ordinary
AM radio brings you sound. A
man speaks and his larynx vibrates
the air in sound waves. The micro
I nh WV iy,f<
electrical impulses. The transmitter
imposes the impulses representing
the sound wave on the radio wave
it is sending out. Your receiver
plucks the impulses off the radio
wave. applies them to speaker and
the result is sound matching the
words spoken into the microphone
Frequencies of sound waves range
roughly from Is to $4,000 cycles.
Speakers in most moderately priced
radios do not pass anything above
1000 or 5000 cycles, however, which
is acceptable until you become &C
customed to FIN, which we're not
going into here. Ordinary telephone
lines will carry impulses represent
ing these low frequencies satisfac-
torily.
Comes now television, though,
which is something else. The
method by which the picture gets to
your living room is basically the
same as that by which radio brings
you sound. Light waves reflected
from the object being televised
strike the horoscope, which is a
sort of electronic eye. 1t turns the
light waves into electronic impulses.
These are imposed on a radio wave,
broadcast and then your receiver
catches the radio wave, plucks the
impulses of and passes them along
to the picture tube. This turns
them into light waves again for you
to see.
These electronic impulses are not
those low frequency ones we had
back there in ordinary radio. how
ever. To scan a scene and broad
cast an entire picture instantane-
ously requires a flock of very high
frequency electronic impulses work
ing like mad. Frequencies of the
sight portion Of television run up
to As megacycles, or 100000 cycles.
~ Xxx
This is where the transmission
problem comes in. AS the frequency
increases, loss of energy along the
line increases. These high fire.
quency waves dissipate if you try
to send them along an ordinary pair
of wires and little, if any, of their
energy reaches the other end.
Part of the solution is better in
sulation, to cut down on the loss Of
energy through dissipation. The
Navy helped here, by developing a
plastic called polyetheline during the
war for radar equipment. The en-
ergy loss can be further cut down,
it was discovered, by insulating one
wire and wrapping the other around
it. This, basically, is the coaxial
cable, so named because both wires
have the same axis. 1t is a wire. a
layer of insulation, the other wire,
which has became tube of copper
mesh, and more insulation.
One link of the television network,
say between New York and Wash
ington, is a lot more complicated
than this, of course. In addition
to the coaxial line for the sight por-
ton of the television show, the cable
carries lines for the sound portion,
which is FIN, and for the control of
it's amplifiers. There's remote con-
troll amplifier every five miles, with
an amplifier manned by an operator
every SO miles. The mechanics of a
television network are both exten-
sive and expensive.
There already is considerable
network of coaxial cables over the
country, used for carrying multiple
telephone conversations. They are
being released for television by
A. T. & T. as fast as possible and
the video network should be we'll
into the Middle West in time for
telecasts of the inaugural. Trains
continental television in two years
is the estimate most often encount-
cred for that.