The Rock Island Argus and daily union. (Rock Island, Ill.) 1920-1923, 1922-05-27
By DAVID SARNOFF.
General manager of the Radio Corr
poratiOn of America
Principles OF Tuning.

Principles of Tuning.
The next problem presenting it
self was TO arrange matters so that
if more than one emission of cleo
tro-magnetic waves was carrying
dots and dashes through the air,
the receiving apparatus would net
get the connictIng and simultane-
Gus messages in the form OF jun
BILE of signals; in other words,
there arose the problem of inter-
ference. The answer to that was,
tuning. Implied by that single WORD
are many of the familiar terms
appearing in the daily press, such
as wave lengths, tuning apparatus
and tuning coils, variometers, con-
densers and many other pieces of
electrical apparatus that resolve
themselves into associated devices
to accomplish the end. Yet the
principle of tuning is simple. Con-
sider-by way of analogy-the ef-
feet of resonance in music. 1t is
common knowledge, for example,
that using violin, when one string
is tuned to a certain pitch and
played upon, another string attun
ed to the same pitch will be set
into sympathetic and powerful vi
bration; that it will of itself re-
spond and give out music, or
single note OF music. In music,
this effect is known as syntony or
resonance. We call it the same
thing in radio The receiving ap
paratus is electrically tuned to the
sending apparatus, and vice versa
and a condition of resonance is set
up between the two circuits. Only
then do we get a resopnse.
The electromagnetic waves OF
radio travel outward from the
transmitter in all directions. TO
use another simple analogy: When
a stone is thrown into the water,
an overwhelming series of ripples
radiate outward; those waves die
out gradually, and the length OF
them and their character depend
upon the size of the stone and the
force with which it was thrown
Just so with radio. A stream OF
waves is sent out.
and its character and its length are
regulated by the kind of apparatus
used. Travelling in all directions,
radio can do that which is pos
sible with no other means of com
munication; it passes through ev-
erything; the message IL carries
practically cannot be stopped
So much for the fundamentals of
radio communication, which it has
been attempted to set down without
a bewildering array of technical
terms.
Ship to Shore Communication.
Quite naturally, radio was first
employed in ship to shore traffic,
for prior to that time there was no
way of communicating with NOV
ing vessel. Marconi had taken his
invention to England, where he had
been greatly encouraged by the
British postoffce; there had been
placed at his disposal every avail
able facility, and a number of tests
were made which proved that wire
less could travel, first, a mile. then
five miles, then so miles, and so
on. Then a ship was equipped with
wireless apparatus and sent out to
sea.
The first American vessel to
carry radio was the steamer "Phila-
delphia" of the American Line. a
ship still in existence. The install
lation comprised the induction coil
and the coherer receiving appar-
atus. Marconi himself made trip
for experimentation; and commu-
ufcation was established with a
coastal station erected on shore in
England. the ship maintaining con-
tact with the shore. first over a
very short distance. and then over
increasingly larger distances. until
the practicability of this method of
communication between ship and
-