Evening star., 1925-11-14
i. S. STATIONS USE
8S WAVE LENGTHS
Explanation Given of Vital
Subject Before Radio
Conference Here.

While the radio conferees here have
been discussing the use of radio broad
cast waves and frequenCieS some fans
may be wondering what ii IS all about,
or how the ether Is divided up SO
that the thousands of radio broad
casts and code messages on the air
are kept from taugling up into un-
intelligihle knots.
ActualIv there are SIS separate
channels through the ether reserved
for broadcastinG by the 81 United
States stations out Of a large num-
Der of wave lengths used by other
services
Although radio transmission is ac
compliShed without the aid of direct
ing wires. wireless emissions carry
ing either voice or code cannot he
projected into space in q haphazsIrd
manner. They must be classified and
sent III definite channels to avoid
interference. If we consider the ether
as composed of a mass of parallel
channels which lead everywhere in
stead of just in one direction as do
wires perhaps the layman can grasp
the method OF routing radio traffic.
The many ETHEREAL route groups may
be liliened to the cOlorS in the spec
trum, running from ultra violet on the
high or long wave side to infrared
on the lower edge. There are II
separate CulorS in the spectrum, but
only a dozen groups of wave bands
in the radio spectrum. The known
routes by which we may transmit
radio emanationS lit between the 23,.
450 and the .75-meter wave lengths,
or in frequencies. between 12.S kiIo-
cycles and 40l 900 kilocycles-meters
and kilocycles being merely related
units of measurement
l.. ). Uses High Wave Lines.
Dividing this radio spectrum up
roughly into groups or wave bands
we find that the highest wave lengths,
from the top down to ,304 meters. Rre
used by Government and commercial
land and ship stations. where only
code is employed The next lower
band is assigned to universities, and
the next to other Government and
commercial stations. Below lie three
bands allocated To Government ship.
radio compass and public ship and
coastal stations, which brings us down
to the 600-meter wave length reserv-
ed for calling and the SOS distress
signal 1t is just below this wave
length that the radiophone broadcast
ing band starts; 1t reaches from 545
meters to 202 meters. Beneath 1t are
teurs. the band from 200 to $50
meters. Further down there are some
commercial land stations: below lie
the experimental channels, and at the
lower end of this so-called spectrum
are found the short waves around IS
meters assigned to the amateurs for
experimental work. If We think OF
each hand as a single color of the reg
ular spectrum it is seen that the
dozen bands are composed of Il large
number of lines, as are the colors
Each of these lines is used as "a sep
arate radio channel available for traf.
ftc, and although used simuta neouS-
iy, the messages carried do not inter
fere, they are insulated as il We're.
This Is n rough exposition of the
method by which the ether routes are
laid out, technical experts will tell
why and how the waves travel. The
broadcast band. containing S8 sepa-
rate channels. is all that concerns the
discussion Of this article.
When broadcasting started in Sep
tember. 1921, the use of the 36O-mete~