The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1924-05-28
RADIO PICTURES
DIFFICULT TO
OBTAIN
Engineers See Little Hope OF
Success for Wireless
Photography

Photographs sent 523 miles over
telephone wires between Cleveland
and New York so clearly that they
were reproduced in newspapers IN
New York last Tuesday, prompted
radio followers to ask, Can the
same process be applied to radiu?"
Engineers in answering this qies.
ton point out that anything capable
Of being sent over telephone or
telegraph wires can be carried
through the ether on the carrier
wave Of. a broadcasting station,
since the carrier acts as an invisible
telephone line In space. However,
radio is not as refined as the tele.
phone. The ether is far more diff
ficult to work with and control
than copper wires. There are many
obstacles to be overcome in radio
before pictures can be successfully
crisscrossed through the air.
Steady Current.
To send picture over a wire the
current must be steady because II
governs the amount of light that
passes through a revolving film.
The light constantly increases and
decreases according to the black
and white that make the picture
Where the film is transparent, light
passes through without loss, and
this causes comparatively strong
current from a photo.electric cell,
an instrument which responds so
perfectly to light variations that
variations in an electric current can
be made practically identical. Where
the film is dark, the light il cor
respondinglS reduced and so 10 the
current
Radio waves transmitted dis
tances over 100 miles are subject to
fading. For this reason radio can
not be depended upon to furnish d
steady current necessary for trans
mission Of clear photographs. The
slightest waxing and waning Of sig
nails would distort the photograph.
Fading is not the only obstacle.
Static Interferes.
Static and interference from other
stations, although operating on
other wave lengths, would be likely
to make the picture unrecognizable.
II a certain channel through the
ether could be made absolutely
quiet and the waves did not fade,
a picture could undoubtedly be sent
and received. It is understood THAT
the process was tested over wave
lengths between Washington and
New York, but the pictures were
spoiled by interference, and, further.
more, a loud hum from the trans.
hitting apparatus interfered with
the regular broadcast programs.
Radio contributed to the success of
the wire pictures by means of the
vacuum tube. <. They served as am
plfiers along the line to strengthen
the current and thus make good
losses in transmission.
Earlier in the week an announce.
ment from Rome told of the success
OF a new radio system invented by
John Hays Hammond, jr., by means
OF which several messages can be
sent at once and only the stations
knowing the combinations of wave
lengths can understand them. The
great Importance of such a system
Is secrecy and the transmission and
reception of more than one message
on one wave length.
OF Military Value.
FOR military purposes and corn-
merclal communication 1t is valu-
able, but the system is not likely 10
transmit photographs any more
EFFICIENTLY than the regular radio
methods. Static, interference from
other stations and fading are still
to be contended with, because of
the characteristics of the ether.
Danger of interference between sta
tons would undoubtedly be greatly
minimized by the Hammond system.
but static prevails on all wave
lengths, although it may not be OF
the same intensity.
Radio operators know how easy
1t Is to piece words together al.
though a few letters may be lost
because of interference. In radio
photography reception must be
clear. Interference registers as a
bad line or blot on the picture, and
for that reason an extraneous sound
cannot be tolerated.
A good wireless operator can
read through static or other inter.
ference largely due to concentration
on the particular pitch Of the si,r.
nal and broadcast listeners can On.
joy concerts, although a little in.
reference may creep in. But a
good radio Photographic machine
would record the slightest interior.
ence and would not let it pass by
unheeded.