Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-04-12
SHARPER TUNING
ORDER is ISSUED
Radio Commission Doubles
Short. Channels by
New Edict.
BY MARTIN coDEL.

Sharper tuning, or narrower spacing
between radio short-wave lengths, has
been ordered by the Federal Radio COM
mission. This Is expected to result in
making at least twice a many of the
precious high-frequency channels avail
able for use.
The order is designed to impose mod
ern methods upon all short-wave sta
lions for the conservation Of the por-
ton of the radio spectrum that has
attracted so much attention of late
because of It's actual and potential use
for radio-telegraph service.
In technical parlance the commission
has ordered that stations working the
frequencies above $500 kilocycles GOO
meters) shall not deviate more than
their assigned frequencies, or one
| twentieth Of per cent on either side
of given channel To the layman
this means that wave webbing" on the
short waves must be reduced, just as 1t
has been on the intermediate broadcast
ing channels.
The practical effect of the order,
which is effective at once, Is to double
the number of high frequencies avail
able for transoceanic operation and for
the domestic radio-telegraph systems
that have been projected by the Uni
versal Wireless Communications Co.,
inc; the Radio Corporation of America
and the Mackay radio systems. For
merly this country accepted the two
tenths per cent separation, which Is
still fha if1fAPna fi0nAI standard
Applies to Many Uses.
The order applies also to high-speed
telegraphy, facsimile transmission, radio
telephony, multiplex meditation, poly
phase transmission and multiple ennis
sion on separate frequencies closely
spaced. All these uses are recognized
by the commission and will be encour-
aged, says the order. Present license
holders on two-tenth per cent channels
are authorized to retain such channels,
but to reduce their width and to use
them to full capacity, or else share the
channels on part-time basis with
others.
Sharp tuning on the short waves Is
not new. 1t will be recalled that the
grant of 40 frequencies to the Universal
wireless project for its proposed nation
wide radio-telegraph network was made
upon its representations that 1t could
utilize each frequency to fivefold Its
normal capacity. In other words, II
claimed 1t could send and receive Ave
messages simultaneously within the
space ordinarily assigned for one.
1t Is understood that the Radio Cor
poration of America and Mackay COM
panies are agreeable to the narrower
spacing, the former proposing to use
many OF the extra channels for inland
extensions of its vast transoceanic sys-
tenn In the interchangeable network,
covering about 80 cities, which 1t plans
to establish. Neither OF these COM
panies, however, has claimed to be able
to effect as sharp tuning as the uni
Fversal project contemplates.
Limits Visual Channel.
The same commission order limits a
visual broadcasting channel, which In
cludes television, to 100 kilocycles In
width. a commercial telephone channel
to 8 kilocycles and certain relay broad :
casting channels to 20 kilocycies. It is
generally accepted that it takes at least
10 times as much ether space" for
television as for ordinary broadcasting
OF speech and music. The normal
broadcast wave length over which the
AASeCACA ACaAo HIS pIOBI6IuS OCCUPIES
space" for at least 10 code message
transmissions, and with sharper tuning
perhaps many more.
Wave webbing" on the short waves
has not presented as many serious In
reference problems since the continue
Gus wave method rendered spark trans
mission obsolete. SparS is still used
aboard many ships Of foreign nations,
and frequently causes an overlapping of
code into the broadcasting wave band,
to the annoyance Of liste ners residing
along the seaboards. Ali spark must be
displaced soon under the international
treaty.
While the narrowed deviations are be-
ing ordered on the short wave to keep
American radio abreast Of the growth
Of the art, further l.mite I'll ons on broad
casting channels are being considered
by the Federal Radio Commission.
In order to hedge in the cause of a
great amount Of interference even more.
the commission may soon require ali
broadcasting stations to keep from
straying more than so cycles either way
from their assigned channels. At pres
ent the deviation permitted is 500 cycles,
or " kilocycle.
(Copyright, 1929 by North American News
paper Alliance0