Evening star., 1923-11-10
ACHIEVED
IN RADIO MESSAGES
Received on "Stock-Ticker''
Device While Garbled on
Other Machines.
BY the Associa ted Press.

CHICAGO, November 10.-Privacy In
| radio communication by means OF
standard land line printer telegraph
| machine. was demonstrated yesterday
by Chicago experts before the annual
convention Of the Association OF Rail
way Electrical Engineers. The nrst
public demonstration OF the system,
which radio engineers predict will mark
| the beginning of a new era in wireless
communication, was made as a result OF
| series of experimental tests extending
over virtually year. The designers OF
portant possibilities in the direction OF
extended commercial use OF the ether
waves for private communication, com
mercial. telegraph and press reporting.
| Before the 500 assembled engineers,
a message from a standard broad
| casting station five miles from the
convention room was typed In the
meeting hall on an ordinary STOCK
| ticker" device at the rate of approx
! mately thirty words a minute. Be-
| cause of purposely jumbled connec-
| tions in the sending and receiving
| machines, which, however, were CO.
ordinated as between the two sta
tions, signals which were rendered In
the convention hall as aAclearly in
telligible. neatly typed dispatch were
simultaneously recorded on other sets
as an indecipherable conglomeration
Of meaningless letters. figures and
punctuation marks, all devoid OF
The key device of the new system
Is small instrument weighing less
than twenty pounds. known as the
Dunmore relay. the invention OF
Francis w. Dunmore. a staff engineer
of the bureau Of standards.
This instrument transmutes the
radio impulses into a specially divided
turn. is recorded by the printer or
ticket. In addition to the selectivity
function as regards wave lengths. the
relay also responds to definite tones.
so that interference by sending sta
tions with corresponding wave lengths
is reduced virtually to the zero point.
The extremely close tuning afforded
by the tonal resonance works also
for the elimination of static inter-
ference. according to the demonsta-
tors.
The signals received in the stand
ard radio set are passed to the relay
and then transmitted to the printing
telegraph machine. The primary
sending and the receiving equipment
are identical TO that used in printer
telegraphy over land wires. the diff
ference between the two being that
the signals of one are transmitted
by ether waves and those of the
wire system moved over physical
connections between the two stations.
we have demonstrated the relia-
bility of the radio printing telegraphy
by tests between ground stations and
maneuverlng aircraft and between
moving ships, but yesterdays exhi-
! bition marks the first demonstration
Of the system which insures privacy"
said L. X. Schmidt, radio expert of
the Morkrum company, pioneers In the
printer wire equipment.
"Typewritten news by radio is one
of the many important things the
Dunmore system makes possible
The privacy trick is turned by
merely placing the wires Of the send
ing keyboard in improper relation
ships with the broadcasting pulsator.
Then by arranging the same order
of pulsations at the desired receiving
station private commuHi cation Is pos
sible. Elsewhere, even to stations
tuned into the proper wave length,
the pulsations register an uncanny
signals give the code expert a prob
lem which several have not been able
to solve.
The broadcastirg may be made
available to many co-ordinated re-
ceivins stations simultaneously or held
for a single station. ~, b..
The first long distance experimental
test of the Dunmore -Morkrum sys-
tenn in news transmission was made
last February between Chicago and
Milwaukee. The Morkrum company.
cooperating with the Associated
Press and the Milwaukee Journal,
tested the system first by moving the
Associated Press dispatches into the
Journal Offices in typewritten form.
The results were satisfactory to the
radio experts and the news men. but
because of several minor problems
suggested by the trial. the engineers
requested additional time for perfect
ing the system for commercial install
lation.
'It is hoped that distribution of
news by wireless will solve the prob
towns" said a statement made public
yesterday by Sterling Morton, presi-
dent OF the Morkrum company.
Application to the federal govern
ment for the radio-typing wave
length and its assignment to a GER
tain band under the Department
of Commerce regulations will be the
next step in the development of the
new system, Mr.. Morton said. Yes
terday's demonstration was on the
130O-meter wave length