Evening star., 1936-01-05
Mystery" Signal Barred.

A PURSUIT during the past few
"A weeks through the radio spectrum
by Government observers. broadcast
ing and communication engineers and
ham" operators has tracked to its
lair the shadow" of the ether-mys-
terious, low-pitched 60-cycle raucous
signals which have been interfering
recently with high frequency wireless
transmission, including international
short-wave broadcasting programs.
The search of the ether by the
radio observers with direction finders
and cathode ray oscillographs reSpec'
lively, to locate the source Of the sig.
nals and to determine its frequency
phase and meditation, disclosed that
the mystery signals had been emanst-
ing from sources entirely innocent OF
their effect upon radio transmission
the leading hospitals Of the United
States and foreign countries. using the
recently developed high-voltage elec-
trio apparatus for physio-therapeutic
treatments. AS result of the dis
covery the Federal Communications
Commission is undertaking confer
ences with the manufacturers Of this
apparatus to the end that these medi-
cal devices can be shielded against
sending forth their radio emissions
and so that their transmission lines
can be protected through frequency
chokes" against sending out interfer-
ing radiations.
The entire field force Of the r. c. c.
throughout the United States has been
ordered to observe the signals from
this medical apparatus, and at present
the F. G. c. monitoring station at
Grand Island, Nebr, is conducting a
Joint observation of the signals with
the American Telephone g. Telegraph
Co.'S radio-telephone station at Ne
toong, N. j., to ascertain whether the
emissions from the medical apparatus
of Eastern hospitals are heard in the
Middle West. Similar tests are being
conducted by F. c. c. observers with
the stations Of r. c. A. Communica.
tions, Inc, and Mackay Radio &
Telegraph Co. on both the Atlantic
and Pacific coasts in an attempt to
find out whether the signals from this
high-frequency hospital apparatus are
confined to local areas or are heard
throughout the country. Photographic
recordings of the signals are being
made simultaneously both in the 2.
c. C. monitoring and inspection sta
tions and by these communications
companies and then the results Of the
observations are Immediately ex-
changed.
AS a result of the mysterious sig.
mails, jumping from frequency to fire.
quency at irregular intervals-appar.
emily whenever these machines were
in use in hospitals or doctors Offices
radio engineers while they We're
searching for its origin had dubbed
the signals the shadow" These sig
mails had burst forth over q wide
range of frequencies from 5000 to
10000 kilocycles. They were heard
as raucous sounds. not unlike the in
reference caused by the operations Of
elevators and vacuum cleaners close to
radio receiving sets. AS result Of the
mysterious character Of the signals,
the radio observers at firSt had spec
ulated that they might have been
confidential code messages from some
foreign nations high-powered station
but this theory was soon discarded be-
cause the signals were unvarying In
tone and modulation and were in.
telligible for communication purposes.
The Navy Department, through its
research station at Bellevue and
through leading amateur operators
who are members Of the Naval Re.
serve communication service. was re-
ported to have been the first agency
10 locate the source In the medical
apparatus after it had received con-
siderable cooperation, in the search
from the Cruft Radio Laboratory at
Harvard University. The Navy then
reported its findings to the F. c. G.