Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

Radio
Broadcast
Belin announced the successful conclusion of
his efforts to transmit pictures by radio.
Now we have pictures across the Atlantic.
The Radio Corporation of America has succeeded
in sending some quite recognizable portraits
from Carnarvon, Wales, to Riverhead,
Long Island. High power
is used so that the
signal received in America is reasonably large
compared with static disturbances, and in this
way the blotchy appearance which is sometimes
caused by atmospheric disturbances has
been practically eliminated.
The general scheme used is the same as before:
light from (or through) the portrait to
be transmitted falls on a sensitive photoelectric
cell. The action of this cell controls
the intensity of the signal sent from the transmitting
antenna. The light beam used is very
small (only about one hundredth of an inch
square) so that it covers only a very small
THE u.s.s.
"TEXAS"
Showing the elaborate radio antenna system, which is used to dispatch the
very considerable radio traffic necessary on practically every naval vessel
part of the portrait at one time. By moving
the picture past the light beam back and forth
and having quite similar receiving apparatus
actuated from the received signal, a picture
is formed by packing together a series of
shaded lines. It takes about three seconds
to draw one line completely across the picture,
and as there are about 100 lines per inch it
may be figured out that to transmit a picture
about three inches square requires twent
minutes.
Fixing the charge for picture service by the
amount a station could earn in a similar time
by transmitting telegraph signals, each picture
would cost about $50. Most of us will evidently
send our pictures by mail for quite some
time to come, but newspapers may well use
this picture service. The same apparatus
can be used for sending the written or printed
word, and it may turn out that, with the improvements
which
are sure to come,
one can send a
message faster by
this photographic
scheme than it is.
by the present dot
and dash code.
It is not quite
clear from the announcement
made
by the Company
just what its engineers
have contributed
to this photograph
transmission
development.
Practically the
same process as
that outlined has
been used before
for picture transmission,
but it is
quite possible that
valuable additions
to the progress of
the art have been
made in synchronizing
the sending
and receiving apparatus,
and in
eliminating the
blotches caused by
atmospheric disturbances.
After
the transmission
has once started, it
is essential in anv