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Mouse-over
the below questions to see
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How far away can an AM advisory radio signal be heard?
Licensed systems: Though the standard signal can usually be detected 5-10 miles away over open country, the strongest signal area is normally present in a 3-5 miles radius. Most operators position their "tune-to" signs within a 3-mile distance.
Exceptions:
The RadioSAFE Wide Area Broadcast System can operate above and beyond the conventional FCC signal limitations. Review the specific RadioSAFE system to discover its potential range and FCC licensing considerations.
License-free radio systems designed to operate outdoors such as the InfOspot system (Talking House/iAM Radio with the Range Extender) will commonly have a much shorter range, up to ½ mile. License free transmitters with indoor antennas will have ranges in the hundreds of feet, depending on their immediate environment.
See the estimated signal range for the radio system that is under consideration.
In general, signal distances will be less in areas with very hilly or mountainous terrain or very poor soil. Distances can also appear to be less in areas where interference is present from other radio stations on or near the operating frequency or where high voltage overhead power wires or AM-broadcast towers are immediately present. At night and in the hours immediately before sundown and after sunrise, intermittent AM “skywave” interference can become a factor and make a station’s signal appear to have less range.
Another variable that affects listeners' ability to hear the signal at greater distances is the quality of the radio receiver. Especially for car radios, sensitivity varies widely. Additionally, certain car engines and onboard computers produce varying amounts of their own interference, which can negatively affect reception especially in areas where radio signals are not strong.
In general, however, the in-car radio receiver is the best instrument for AM radio reception.
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Can
I hear the signal in
homes as well as
cars?
Most communities do
not promote this,
because home
reception varies
widely with many
factors, including:
- Distance from the
home to the AM
transmitting antenna
(AM signal level);
- Quality of the AM
receiver in the
home;
- Presence of an AM
receiver that will
work on loss of
power (battery
operated);
- Structure of the
building and
interference sources
that it may contain.
With a maximum of 10
watts of AM power,
your transmitter is
optimized for
in-vehicle
listening.
See our TechTalk
article on signal
penetration.
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May
I put the AM antenna
on our 100+ foot
tower, building,
silo (or other
extremely tall
structure)?
We don’t recommend
it, though it can be
done when required.
Your antenna is
likely to work best
on its own support
structure over open
ground. If you do
want to consider an
existing structure,
the antenna-height
restriction is 15
meters (49.2 feet)
from tip to ground.
So don't select a
structure that is
too tall. To
function well,
however, the antenna
must be mounted at
the top (not side)
of the structure you
do choose and must
have the opportunity
for a groundplane at
the bottom.
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What
may be broadcast on
my AM Information
Station?
Generally speaking,
this class of
service is voice
only, noncommercial
in nature. You are
not allowed to
transmit music,
mention commercial
names (except in a
noncommercial way,
e.g., you may use
air carrier names to
provide directions
at airport
facilities) or
provide any kind of
commercial
announcement.
Although these radio
stations operate in
the AM broadcast
band, they are
licensed under
public safety radio
regulations; and
decisions about
content must be made
with that in mind.
The stations are not
in any way meant to
compete with
full-power broadcast
services. Broadcast
content should be
targeted to people
in vehicles
and should comply
with FCC Rules Part
90.242.
For more on this
topic, please see
our page on
permitted broadcast
content.
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Which frequency is
the best to use at
my AM Information
Radio Station?
There is no single
right answer for
everyone, partly
because, in
different areas of
the country, all AM
frequencies are not
available due to FCC
separation
regulations.
Generally, however,
the conventional
wisdom is as
follows.
The favorite is
1610. Here's why: - It is known by
listeners as a
common information
radio frequency.
- ts short antenna
and small
groundplane are somewhat
more convenient to
locate and install.
- There are no
commercial radio
stations in the US
on that frequency,
which means that
interference,
especially at night,
is usually less.
- The short
wavelength means
less interference
with power lines.
The second favorite
is 1620-1700:- Very few
commercial radio
stations are
permitted on these
frequencies, which
lessens interference
and produces good
signal range for
information radio
stations using them.
- Short antennas and
small groundplanes are
somewhat more
convenient to locate
and install.
- The short wavelength
means less
interference with
power lines.
The third favorite
is 530: - It is known by
listeners as a
common information
radio frequency.
- There are no
commercial radio
stations in the US
on 530 to cause
interference, the
only source of night
interference being
Caribbean and
Canadian stations in
the eastern US after
dark.
- 530's
long wavelength
signal fades slowly
and can produce a
large fringe
coverage area.
The fourth favorite
is 540-1600: Almost every car
radio receives these
frequencies, but
there is often more
nighttime noise and
interference in this
original AM
frequency band.
See our TechTalk
article on skywave.
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How
can I determine the
right frequency for
may information
radio service?
We offer a Frequency
Planning Package (FPP)
you may order to
allow you to
determine the right
frequency. It
includes a Frequency
Search Service that
produces a list of
possible frequencies
that the FCC will
assign, a Signal
Monitor Radio
Receiver to allow
you to monitor the
frequencies and
quantify the
results, and the FCC
License Application
Service, which gets
your application
prepared and filed.
The cost of the
Frequency Planning
Package is 100%
subtractable from
the price of the
information radio
station you order.
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May
I use low power FM
instead?
LPFM has been fraught with misunderstanding about its complexity and cost. Public safety agencies, in particular, are wary of LPFM, because...
- The FCC rarely opens LPFM license-application filing windows and then just for brief periods.
- FCC separation rules for LPFM make obtaining frequencies near populated areas extremely difficult.
- The FCC allows more types of entities to apply for LPFM licenses, such as non-profits, fostering more competition for licenses making them harder to get.
- If applicants from this larger pool are granted license to popular frequencies, they are required by the FCC to share operation with other equally qualified applicants in the area.
- Running LPFM stations can be costly:
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Can
any field tests be
done to see how well
an AM Information
Radio Station would
perform at a given
location?
Yes, but these tests
are commonly done
only where the exact
coverage pattern or
range needs to be
determined. They are
not often required,
because transmitter
power can be set
anywhere in the 0-10
watt range to
produce a
standardized signal
level at the
FCC-mandated 1.5 km
distance from the
antenna. This means
that unless there is
severe terrain, very
poor soil or there
is an interference
potential, almost
all TIS stations
will produce the
same coverage
pattern. As a
result, pre-testing
isn't often
required. If it is
desired, however,
we offer a
self-test service
called
EventCAST
.
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What
if I don’t have room
for my groundplane
beneath my antenna?
Assuming your
antenna will be
mounted on the
ground, Information Station Specialists can
offer a number of
"vertical
groundplane"
solutions that
require no more
physical space than
the pole itself
requires. There is
some additional
cost. Inquire at the
time that you are
planning your
installation.
See our Vertical Profile Antenna Support and Grounding System.
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Can
this system be used
for the AMBER Alert
Program?
AMBER Alerts
were not anticipated
by the FCC when the
service was
introduced, but
AMBER Alerts are a
perfect addition to
content that is now
allowed, under the
heading "imminent
danger."
See our Permitted
Content webpage, which
gives you a formula
for analyzing
content.
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Why
might I not want to
place my AM antenna
on the roof of my
building?
We do not
recommend installing
antennas on rooftops
or otherwise within
50 feet of buildings
or other locations
that contain
telecom/AV systems
because of the
potential for
interference.
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What does an
information radio
station call sign
mean and may I
choose it? Why are
there seven
characters, three of
them numbers? How
often must I
broadcast my call
sign?
Federal Communication Commission Rules (part 90) govern the licensing of information radio stations (TIS) issued to local government entities such as states, cities and counties. The Commission assigns 7-character call signs to all - 4 alpha letters, followed by 3 numbers.
Modern TIS call signs that are issued by the FCC begin with a “W” (though many years ago some were issued that started with a “K”). The next 3 letters and 3 numbers are sequential, based on when the Commission grants each license.
Although the Commission does not permit applicants to request specific call signs, in a few instances (when licensees indicated certain call signs were objectionable), the FCC granted changes.
The FCC requires that the full 7-character call sign be broadcast every 30 minutes (or more) in English. Sometimes station operators inadvertently drop off the three numbers of the call sign, probably because standard broadcast stations (licensed under FCC Part 73 Rules) don't have numbers in their call signs and have only three or four characters (WGN, WABC, etc.).
Information Stations operated by federal government agencies are licensed through the NTIA (National Telecommunication Information Agency) rather than the FCC and do not necessarily follow the same format. In some instances, these call signs may begin with a "K," may have only three letters or may have no numbers.
Information Stations authorized by branches of the military are not issued call signs.
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