The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1903-08-05
SECRECY ASSURED BY
TESLA'S TUNING PLAN
An Advance in Wireless eIegraphy-Meddling
Impossible.
An Advance in Wireless
Impossible.

Anyone who has ever tried to per-
suade the inventor. Nicholas Tesla, 10
talk for publication about his expert
ments and projects knows how firm and
courteous are his refusals. Neverthe-
less, one source OF information about his
inventionns is open TO the public. His
patents are matters of record. Anyone
may obtain copies by proceeding in the
right manner, though familiarity with
legal phraseology and electricity is nee
essary fully TO understand them. Two
patents, almost identical in tenor, were
recently Issued to Mr.. Tesla. The in
vention which they cover seems TO CON
stitute a distinct improvement in wire
less telegraphy. and its character AMI
purpose are perfectly Ineligible.
Almost from the first It has been ap-
parent that that system of communica-
ton would have a limited application
unless secrecy could be insured. Hence.
several OF the most conspicuous workers
in this field have been studying how to
attain such a result. While their meth
DDS differ in detail, they all agree that
the problem is to be solved by tuning"
By that phrase electricians mean a reg
ulation or adjustment of the transmitter
which makes II send out waves Of q
certain frequency-say 500.0O0 a second
and a treatment OF the receiving APP
paratus which renders the latter more
susceptible to that number than to any
other. 1t has been assumed. rashly per-
haps, that unless a practically disposed
outsider either knew what frequency
was being used, or hit upon IL by acct
dent, he could not adjust his instru-
ments so that he could steal message
where tuning" had been employed. OF
course, where no attempt was made to
insure such agreement. wireless com
munications would not be private. IN
some kinds OF service. indeed-as be-
tween steamships meeting at sea - no
harm would result from overhearing.
In his patent specification Mr.. Tesla |
points out a difficulty which is expert
enced in the operation just described,
and which he has sought TO evade. A
phenomenon IS observed IN the genera, |
ton OF electric waves which parallels !
one IN music. II a given tone is produced |
by a violin string. several others. less |
tone be the one which IS caused by leo |
vibrations a second. the additional but /
fainter sounds Will be those resulting |
from 200. 800 and other frequencies. Such /
extra tones. or "harmonics," represent |
exact multiDIes Of the number OF vibra- |
lions requisite TO the lowest, or funda-
one. and there are usually six |
Of them. When a Hertz wave generator |
IS put in operation. that, too. produces |
"harmonics." Besides the one principal |
frequency which the operator aims to
employ. his apparatus will also give out
Mr.. Tesla declares tina. 4 re-
ceiver which has been regulated 10 re-
spond 70 one frequency is likely TO picl
up waves which are given off anywhere
from exactly twice to exactly seven
times as often. Hence II might receive
not intended for that station.
That system OF tuning therefore, seems
less secure than is desirable.
Mr.. Tesla 8 plan certainly appears dis
tinctly superior to this. What he pro
poses TO do is to generate two or more
sets of waves at once. and employ them
all simultaneously in sending. These
might have frequencies proportioned to
each other tn some such fashion as IS
and II, or 81 and 43, or 73, 80 and 1O1.
Only a receiver which had been tuned
10 respond to two or three selected
rates OF vibration, when all were in use.
would be able 10 pick up a message
nus sent. 1t Will be seen at q glance
hat this scheme differs from the other
5ery much as the many notched Yale
Key differs from an ordinary latch key.
Though Mr.. Tesla thinks that only two !
requencies would usually be enough ]
he system admits Of considerable null
iplicates. Moreover, 1t may be taken /