Brownsville herald. [volume] (Brownsville, Tex.) 1910-current, 1929-09-15
INTERFERENCE COMING FROM
UNDESIRABLE STATIONS Is
ANALYZED BY RADIO EXPERT

4, bles II To discriminate between two
incoming signals on neighboring
f~reuuencies, passing one and exciud-
ing other. IL involves q progressively
Increasing attenuation Of the radio
Frequency Tor intermediate frequen-
cy.) tuning system toward frequen-
cies increasingly removed the desired
signal frequency.
II should be noted in this connec-
tion that the sensitivity Of a receiver
will apparently influence its work
ing seiectivity. Highly sensitive re-
ceivers. which give extremely power
FIJI sounds from the loud speaker
when actuated by feeble incoming
waves, will correspondingly give an
audible response from an interior
ing signal under circumstances N
which a less sensitive receiver. while
giving a weaker loud speaker sound,
viii not seem 10 produce any inter
fering signal because the interfering
signal has been dropped below the
%audibility limit. The obvious rem
edy for interference which accom-
panies excessively loud signals from
weak stations. produces by an ultra
sensitive receiver. Is 10 reduce the
receiver sensitivity by volume con-
troll manipulation assuming that
the selectivity Of the receiver Is in
dependent OF It's sensivity, which Is
sometimes not the case.)
interference Analogous
"Of analogous nature is the in
reference resulting from the use Of
antenna or pickup system OF ex-
ceSsive dimensions whereby an IN
appropriately large signal voltage
Is impressed upon the receiver, per-
haps overlooking one or more stages
OF amplifier tubes. Under such cir-
cumstances. even feeble interfering
signal voltages viii cause an audible
response in the loud speaker and
normal signal voltages will cause I'M
desirably loud or distorted signals.
In this case the indicated remedy
IS a reduction in the size Of the wave
pick up system.
1T Is clear that the practical use
fulness of feebly ~selective receivers
is limited 10 locations where there
are only weak signals. on consider
ably separated fr~equencies. Such
signals from distant or low power
stations are generally found exclus-
lively in rural districts.
by contrast. hirhly s~elective re-
ceivers have a wider land In fact,
practically UNIVERSAL sphere Of use
fulness. They are capable Of re-
ceiving weak signals from compare
lively distant low power stations
without interference even though
there are nearly powerful stations
in operation.
In regard to the Psychological In
fluences interference is astonishing
IL odious TO the average broadcast
listener despite the absence OF direct
financial participation by him IN
the expense activities of the broad
casting stations which attempt 70
serve him. A listener may receive
II stations perfectly. but fail TO re-
ceive the 18th because Of interfer-
ence from a 18th station. Under
these conditions characterization in
the extreme case is somewhat as fol-
lows: the III stations which he can
receive become interesting to him.
and are neglected. The 18th station
which he cannot receive regardless
Of its intrinsic merits. becomes the
grimly desired goal Of his radio am
billions. The 18th. or interfering
station. also regardless of its pro-
gram Of mission. merits and tone