Information Station Specialists Website     

America's Source for Information Radio Systems   |   Related Products   |   Technical Services
 Limitations of Licensed Information Radio Stations
FCC Limits for TIS

Information radio stations may be licensed to governmental entities or to emergency medical/healthcare providers sanctioned by such entities. The legal name for the stations is Travelers' Information Stations, and the governing rule section within FCC Rules is Part 90.242 (linked at the bottom of this page).

Content Limitations

See our Permitted Broadcast Content webpage, which provides a formula for analyzing intended broadcasts to ensure they fit within FCC guidelines.

Technical Limitations

The audio bandwidth of information radio stations is limited to 5 kHz by new FCC rules, which is the same bandwidth many standard broadcast stations use. Before 2015, information stations were limited to 3 kHz of bandwidth. This is to prevent the stations from interfering with standard broadcast stations.

The height of information radio station antennas is limited to 49 feet above ground level.

Exposure risks from such stations are minimal, due to the relatively low RF power levels involved. Even so, it is prudent to maintain a one-meter separation from the antenna and its support structure, when it is in operation to be in compliance with FCC guidelines.

Signal Level Limitations

Information radio stations have 0-10 watt power levels that are significantly lower than standard broadcast stations, which is why their coverage areas are smaller. Because of this, their peripheral signals can be more vulnerable to interference from a variety of terrestrial sources, nighttime skywave interference and blockage by structures and terrain features.

…Power lines and bridges can distort (add hum) or temporarily block signals, when the receivers are in the immediate proximity.

…Nighttime “skywave” interference can create the perception of lower range by adding competing on-channel noise during the dark hours. This can be especially pronounced on AM frequencies that are shared with many standard broadcast stations.

…Terrain features such as mountains, steep cliffs and valleys, etc., can block signals when the listener is in the immediate proximity.

…Noise from active interference sources such as automobile engines, electrical systems and onboard computers can limit the range at which a particular vehicle can clearly receive radio signals. Likewise, passive sources such as the presence of a poor receiver or poor receiving antenna on the vehicle can produce the same effect.

…Information radio stations are designed specifically for in-vehicle listening. Receiving their signals inside of structures depends upon many variables, including the distance of the building from the information radio station antenna, the composition of the building walls, interference sources (computer systems) that might be present in the building and the type and placement of the receiver and receiving antenna with respect to the building.

Service Coordination Limitations

Information radio stations are a secondary service. Standard broadcast stations are primary, which means that Information stations must make way for any changes that standard broadcast stations make in their service. Such changes could include the introduction of a new broadcast station or an increase in the power or bandwidth of an existing AM broadcast station. Information stations must accommodate these changes, even if it would mean changing channels or ceasing to operate. Fortunately this rarely, if ever, happens due to the fact that the AM spectrum is nearly gridlocked on most channels and there is little room for change. In fact, to date, there has never been an instance of an information station being required to cease operation due to a change in service by a broadcast station, though there have been a few isolated instances in which an Information Station was required to change channels in order to continue operation.

Information radio stations licensed at fixed geographical points are protected by a 9.3-mile buffer. FCC rules prevent other fixed-point Information Stations from licensing on a given frequency within that distance.

Portable information stations licensed to roam on a temporary basis within a territory (because they are moveable) are not similarly protected from encroachment by fixed-point information stations. Additionally, portable stations must not operate within 9.3 miles of fixed point stations on the same frequency that are licensed within or near their operating territory, including those that might be licensed subsequent to the granting of their license to operate within the territory.

Related Links
FCC Part 90 Rules
Signal Penetration