Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-10-20
|STENODE ASSURES
| HIGH SELECTIWTY
Britisher Demonstrates Ra.
dioStat-CIaims II Retains
All Tones.
BY ROBERT MACK.

The Old Worlds claim TO radio fame
q receiving set gadget that eliminates
inter station interference and can
double the station capacity Of the
broadcast spectrum--has been Demon
strated for the first time In this coun-
try, but with the public as much IN
the dark Is ever.
Before a group Of eminent radio
engineers and radio offiaials the stenode
radloStat was exhibited last week at the
Mafiower Hotel. It hrs aroused great
interest, because Of the claims made
for it, but American technical experts
feel that the demonstration was by no
means conclusive. None would say that
It could not reduce the separation Pc
tween stations in the broadcast band
10 five-kilocycles, or one-half the pres.
ent width, and none would say that IL
could.
DR.. James Robinson Of London.
former chief OF radio research OF the
British Royal Air Force. and one OF the
outstanding figures in world radio, Is
the inventor of the radiostat. he came
to this country to demonstrate MS IN
vention and prove his claims, wnicn
Principle Relieves Congestion.
The demonstration was quite simple.
Oscillations were set up which created
a high-pitch beat note" or squeal on
the conventional type of receiving set'
and married the program being re.
ceived from a local station. Ine
stenode set then was turned 70 tns
local station, but the beat note was IN
emSIhle THAT meant. DR.. Robinson ex-
planned. that the set was tuning 2
much narrower band and would not
pick up the heterodyne.. -, -
This newly developed principle, the
| inventor claimed, opens the way LOT
relieving congestion in the broadcast
band where stations are craI1imed, with
resultant interference. BY narrowing
the paths of radio transmission, ne saio,
this development will make way In the
ether for television, now retarded by
the limited number OF channels avail
| able.
''My invention" DR.. Robinson said,
"ennploys super-Selective receiving
| circuit of an order Of selectivtty up to
| now considered impracticable without
(, complete destruction of tone quality.
The purpose Of my visit to America -
to show TO American engineers what
we have already been able to prove TO
the satisfaction of European scientists;
namely, that super-selectivity is &C
complished by the stenode with COM
plete retention of all tones.
'The demonstration of the stenode
has proved that 1t is not necessary to
be bound by the accepted theory Of
sideband transmission which hereto
fore has prevented broadcasting chan
nels for being closer than 10 kilo-
cycles apart from the retention of all
audio frequencies. A closer examinA-
ton of the sideband theory proves that
it : possible by the application of stem
ode circuits to accomplish much
closer separation"
Picks Up Low Band.
American engineers admit it Is pos
sible to transmit on channels mar
hover than 10 kilocycles, but say that
the development of a receiver so sensi.
| tive that 1t will pick up stations on
narrower channels is the problem. The
| demonstration did not show that this
| could be done because the transmitting
end Of the demonstration was lacking.
The stenode set itself was not exhibited
so as to divtfige its circuits, because Of
| patent considerations.
DR.. Robinson and his party went to
Chicago to demonstrate the radiostat
to membersF=of the Radio Manufac~
turers' Association during the Chicago
Radio Show
(Copyfisht, 1880 By the Consolidated press,l