Evening star., 1936-01-12
Bv the Radio Editor.

IL muCn cross cnduUeT, HuSii,
souealing and other inter-
~ ference when you tune in
those foreign short wave broadcasts
on your "all-wave" sets? Tune in
the annual report of the Federal
Communications Commission, sub
mitted to Congress last week. and
you will get the answer. It is the
simplest of all radio problems-un-
scientific ALLEGATIONS.
Apparently most of the European
nations, in their zeal to place as many
stations on the air as possible with
propaganda destined for foreign ears,
are disregarding engineering funda-
mentals and cluttering up the short
wave ether. In so doing, according
to the F. c. c., they are spiting
themselves, because what otherwise
would be good reception is being de-
stroyed.
In its report the F. c. C. points
out that many of the European and
South American stations as well as
those of other nations during the
last year were received with regularity
both day and night, subject to wide
variations in fading and interference.
But, the report adds, experience has
shown that channel widths of at least
20 kilocycles are required for reason
ably good reception and reproduction
on these short waves. This broad
"skyway" is required because of the
extreme and rapid fading. average
weakness of received signals, carrier
frequency tolerance required, average
receiver characteristics and other
considerations.
VET, say Uncle Sans radio moguls,
| assignments are being made by
some nations with separations of only
5 kilocycles, and other nations are
assigning odd channels with separa-
tions even less.
GAS a result" continues the F. C. c.,
'this international broadcast service
Is being greatly impaired by reason
of mutual interferences. 1t is very
important, therefore, that agreements
be made between the various par
ticipating nations of the world for
the shared use of these frequencies
during periods of time when inter-
ference may be caused. There are
times of the day and seasons when
relay stations on certain of the fire.
quencies can transmit and be re-
Ceived in one section of the world
but during which time it is imprac-
ticable or impossible for other Sec
tions of the world to employ salts
factorily the same frequencies because
the listening public is not available
due to the early morning hours, or
because of geographical separations,
daylight and darkness distributions,
and the seasonal and diurnal changes
in propagation characteristics.
On these channels, the F. c. c.
also has concluded, it Is necessary
for stations to transmit with not less
than 5000 or 10000 watts of power.
This Is necessary because of the great
distances to be covered and because
the average signals are always weak.
To solve this problem, which is
destined to become chaotic unless
steps are taken, the F. c. c. recon-
mends that sound engineering and
economic ALLEGATION of the frequencies
be worked out through close co-opera-
ton, mutual agreements and treaties
between the nations engaging in this
service.
THE F. c. c. also told Congress of
- the rather surprising develop
ments in local broadcasting in the
ultra high frequencies, above 10000
kilocycles. Already daily there are a
number Of applications filed for au-
thority to experiment in this band,
looking to the day when there may
be hundreds of low-powered local sta
tions broadcasting on them, but pro-
viding a purely local radio service.
The bulk of these applications are
from newspapers.
Interest in very high frequency
experimental broadcasting has con-
tinued to develop" the F. C. c.
stated. However, the full possibilities
of the frequencies for local broad
casting are developing slowly due to
the very limited number of broadcast
receivers that will tune to this band
Of frequencies.
'The very high frequencies above
80 megacycles have such character
istics that they serve a small area
and then beyond this range no inter-
ference will be caused to other sta
tions. This is different from the propa-
cation characteristics of the stations