Founded in 1983, Information Station Specialists is the nation's sole domestically owned source for Information Radio Station and Advisory Sign systems that allow public agencies to broadcast safety and service messages to motorists.
 

 

      FAQs    
 

Click on a question below to be taken to the answer farther down this page. Email ISS to submit a question.

 
 
  1. How far away can an AM Information Station signal be heard?

  2. Can I hear the signal in homes as well as cars?

  3. May I put the AM antenna on our 100+ foot tower, building, silo (or other extremely tall structure)?

  4. What may be broadcast on my AM Information Station?

  5. Which frequency is the best to use at my AM Information Station?

  6. May I use low-power FM instead?

  7. Can any field tests be done to see how well an AM Information Station would perform at a given location?

  8. Can this system be used for the AMBER Alert Program?

  9. What if I don’t have room for my groundplane beneath my antenna?

  10. How can an AM Information Station tie in with our outdoor warning sirens?

  11. Why might I not want to place my AM antenna on the roof of my building?

  12. What does an Information Station call sign mean and may I choose it? Why are there seven characters, three of them numbers? How often must I broadcast it?

 

1. How far away can an AM advisory radio signal be heard?

Though the signal can usually be "heard" 5-10 miles away over open country, the strongest signal area is normally 3-5 miles in radius, regardless of the frequency being used. Most operators position their "tune-to" signs within a 3-mile distance. Signal distances can 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 (especially at night) on or near the operating frequency or where high voltage overhead power wires or AM-broadcast towers are immediately present. Another factor that affects listeners' ability to hear the signal at greater distances is the car radio. Sensitivity of automobile radios vary, and different cars produce different amounts of their own engine interference, which can affect radio reception especially in areas where AM signals are not strong. But in general, the AM car receiver is the best instrument for reception.

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2. 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.

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3. 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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4. 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 decision 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 their vehicles and should comply with FCC Rules Part 90.242. For more on this topic, please see our page “What May Be Broadcast on AM Advisory Radio.”

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5. Which frequency is the best to use at my AM Information 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.
Its short antenna and smaller groundplane are somewhat more convenient to locate and install.
There are no radio stations in the US on that frequency, which means that interference, especially at night, is usually less.
The short wavelength is interfered with less by 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 antenna and smaller groundplane are somewhat more convenient to locate and install.
The short wavelength is interfered with less by 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 the frequencies, but there is often more nighttime noise and interference in this original AM frequency band.

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6.  May I use low-power FM instead?

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 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, mandated 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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7.  Can any field tests be done to see how well an AM Information 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, ISS offers a self-test service called Radio Express.

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8.  Can this system be used for the AMBER Alert Program?

AMBER Alerts were not anticipated by the FCC when they instituted this service in the 1970s. It is generally thought, however, that AMBER Alerts are a perfect addition to the content that's allowed, perhaps under the heading "travel advisories" or as an emergency broadcast.

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9What if I don’t have room for my groundplane beneath my antenna?

Assuming your antenna will be mounted on the ground, ISS 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.

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10.  How can an AM Information Station tie in with our outdoor warning sirens?

The ALERT AM system can. There are contacts on the ALERT AM system you can use to make a specific pattern of pre-recorded messages trigger in conjunction with a specific siren activation. Some communities simply assign a siren controller to the ALERT AM system, and the radio system gets the same cue that the sirens get when they are activated. Other communities put pushbuttons in the EOC that the dispatcher can push, when certain situations occur, to immediately broadcast messages pre-recorded for those situations.

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11.  Why might I not want to place my AM antenna on the roof of my building?

ISS does 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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12.  What does an Information Station call sign mean and may 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 call signs 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 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.


* Some older TIS call signs issued by the FCC begin with a "K".

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This page was last updated: March 01, 2010.

 
 
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