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Answers to
Frequently Asked Questions |
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Why are most
low-power radio stations AM instead
of FM?
At present, the FCC is not
taking applications for a low power
FM service (LPFM), though it did as
recently as 2001. At that time, the
Commission granted a handful of FM
low power stations, each with about
100 watts of power (about 5 miles of
range). The FCC has not indicated
that it will again offer the service
for another round of applications.
Of special note: first-round
grantees discovered that LPFM
stations are not ideal as pure
information sources because of
FCC-imposed operating parameters,
which, for example, mandate that
LPFM station operation be more like
commercial FM stations in terms of
hours of operation, content
restrictions and equipment
requirements.
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BACK TO QUESTIONS |
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What are other technical
limitations on Information
Stations?
The license is valid for 10
years and can be renewed.
The stations are secondary
to regular broadcast
stations and must make way
if a new broadcast station
comes on the air.
Information Stations'
antennas must be vertical
and can be only 15 meters
(49 feet) above ground;
transmitters must be type
accepted and can only
broadcast with a maximum of
10 watts, as long as a field
intensity of 2.0 mV/ is not
exceeded at 1.5 km (0.93
miles) away. The
transmitters have a filter
to limit their bandwidth to
6 kHz and their dynamic
range to 3000 Hz. They may
only operate on a given AM
frequency if separated from
the signals of co-channel
and adjacent broadcast
stations by specified
distances spelled out in
FCC Rules Part 90.242.
BACK TO QUESTIONS |
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What about
unlicensed stations?
Unlicensed stations are similar to
Information Stations, but have much
less power and much less range
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typically a fraction of a mile.
Their antennas are limited to 3
meters, and they have no protection
from licensed stations and can give
licensed operators no interference.
But unlicensed stations can
broadcast a wider array of content,
including music and commercials.
Unlicensed stations still require
transmitter certification to operate
legally.
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What does an
Information Station callsign mean
and can I choose it? Why are there
seven characters, three of them
numbers? How often must I broadcast
it?
Federal Communication Commission
Rules (part 90) govern the licensing
of Information Stations (TIS) issued
to local government entities such as
states, cities and counties. The
Commission assigns 7-character
callsigns to all - 4 alpha letters,
followed by 3 numbers.
Only the first character (the "W")
has any particular significance,
however.* 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 callsigns, in a few
instances (when licensees indicated
certain callsigns were
objectionable), the FCC granted
changes.
The FCC requires that the full
7-character callsign be broadcast
every 30 minutes (or more) in
English. Sometimes station operators
inadvertently drop off the three
numbers of the callsign, probably
because standard broadcast stations
(licensed under FCC Part 73 Rules)
don't have numbers in their
callsigns 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
callsigns 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 callsigns.
* Some older TIS callsigns issued by
the FCC begin with a "K".
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Copyright 2008-2010 • American Association of Information
Radio Operators • All Rights Reserved
PO Box 41, Zeeland, Michigan, USA,
49464-0051
Phone 616.772.2300, Fax 2966,
Email AAIRO
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