Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-06-01
NJ RADIO IN THE HOME
by HENRY NJ. NEELY
Those Queer Code Noises You Hear

oRM.
Do you know what that means? In
these days of radio craze. QRM ought
almost to be adopted into our colloQuial
language. Every body is being QRM d.
s IL you could understand the CONT
mental code used by wireless operators
and could listen in and read some Of
the stuff that is constantly flying
through the ether, there would not be
a night that you would not hear one
of the men send. "Pls rpt QRM.
In ordinary English. that means.
"Plcase repeat. Another stations sig
nails are interfering and | cannot read
your message.
QRM means Il am being intcrfered
with And, with most of the sets
now on the market, designed for ease
of operation rather than sharpness Of
tuning, QRM is "A constant occurrence.
You will be listening peacefully to
the "Samson and Delilah' aria, per
haps. when suddenly it will b" broken
np by something that sounds lik" somr-
body saving wood or filing iron or per
haps It will be one Of those funny itit'c
squeaky limitations Of canary bird on
lag or n sort of liquid sing song. ri>-
ing and falling rapidly like Il whistler
practiCing n trill.
These are code signals and Il is in
teresting to know tho difference between
them even though you cannot read the
signs.
The rasping, buzzing. usually low
toned notes are spark" stations. We
have already learned how condensers
discharge their electric energy In sud-
den punches. vibrating Mt almost incon-
ceivable rapidity. The spark station
uses an apparatus that has gap or
opening in the circuit. When III" cleo
trio energy piles up in the condenser to
q certain strength it suddenly dis
charges with powerful surge that is
strong enough 10 make the electric cur
rent jump across this gap or opening IN
the form of n spark.
The current swings first one way
and then the other. charging the con-
denser each time, first with positive.
then negative and again positive. alter
mating thus until the energy dies down.
each time sending II in the form Of Il
spark across the gap until the energy
used up in the form of the light and heat
of the spark entirely empties the con-
denser.
But these alterations are so incon-
ceiyably rapid that there are thousands
of them during the time Of the shortest
little spark that a mans hand can make
and perhaps several million of them in
q second.
These spark signals use what radio
experts call "damped waves'--that is,
the original energy sent out by the dis
charge of the condenser dies down just
as the sound of big bell dies down
oft &c ctr yrif hn m ms
all is silent again. The resistance Of
the air and the natural resistance Of
the metal damp the sounds Of the
bell and you hear the noise gradually
trail off into nothing.
So the spark "damps'' the electric
energy. but it does It couple OF mil
Hon times second.
The little chirpy, canary bird noises
and the gurglng. liquid sounding dots
and dashes are usually made by what
operators call continuous wave sta
tions, referred to in all the radio maga-
zines as &C. W."
This form of radio energy is sent out
by an audion bulb. The little audon
bulb that you use as a deteCtor in your
receiving set is all the time sending out
stream of radio waves while YOU are
listening to concert These waves are
extremely weak. but, il you had an
other aerial within lew feet or YOUR
own. you would hear them in the form
of a steady little hum in the phones.
Radio engineers have developed spe
cial forms of bulbs or tubes for sending
purposes and these tubes send ont radio
energy not damped. as the spark signal
Is damped. bur continuous and with
radio waves of the same size and DOwss
all the time.
The broadcast concerts are sent out
IN this way. All radio telephone work
Is done on this &C. w" and it is also
used for the Continental code messages
BY means Of special devices in the send.
ing station. &c. W." is a favorite
form of radio among skilled amateurs
and by means of 1t. amateur messages
have been sent all the way across the
United States and from the United
States to Great Britain and the Con-
tinent.
Then there is the QRM that sounds
like a whistler trillng. There are two
distinct notes, one higher than the other
and they back slap" like rubber ball
bouncing rapidly between two surfaces
These are arc" sending stations