- Use the FM or TV Query to retrieve broadcast station coverage maps. At the FM Query or TV Query search form, enter your search parameters, and select the longer, detailed Query output. When the records are retrieved, look under each record for a series of links. Click on the "Service Area Map" link to retrieve the map page.
These maps display the service contour for the FM or TV station that is generally protected from interference caused by other stations under the present FCC rules. However, interference-free reception is not guaranteed at all locations within this contour. Local conditions (for example buildings, terrain, receiver quality, type of receive antenna used, car radio or mobile operation) can influence reception of a radio signal.
Service does not stop at this contour line. In many cases, FM or TV stations can be received at locations well beyond the location of the mapped contour, with interference-free reception becoming less likely at greater distances. FM stations in particular can often provide service to a substantially greater area than depicted by this contour. However, radio or TV reception in areas outside of this service contour is not protected from interference caused by other authorized stations.
- Contour distances less than 1.5 km. The smallest curve on the FCC's FM and TV propagation curves calculates the contour location at a distance of 1.5 km. For distances which are predicted to be less than 1.5 km using the propagation curves, the curves program uses the free space equation to calculate the distance to the contour. Near 1.5 km, these two methods do not agree: the free space equation calculates a larger distance to the contour than do the FCC's propagation curves. This shows up as an apparent discontinuity or jump in the contour at certain azimuths. To minimize the visual effect of this discontinuity on the maps, distances calculated by the free space equation that are in excess of 1.5 km have been set to 1.5 km. This phenomenon will be seen most often on maps for lower-power directional FM or TV translator stations.
- Terrain affects FM and TV signals. Land features can affect the shape of an FM or TV station's service area. For example, a mountain may truncate service in certain directions, reducing the service contour. A valley may cause a bulge in the contour because the terrain is lower in that direction, allowing the signal to extend further. FM and TV stations will often locate on a tall tower or mountaintop to reduce the effects of intervening terrain.
- Maps vary in scale to allow both large and small contours to be displayed with clarity. Presently, the FM and TV service contour maps are plotted on Bing Maps (or alternatively and if locally installed, Google Earth), which gives users the flexibility to zoom in or out as needed. Maps will not be provided based on one display scale only.
- Maps are not stored, but are generated on demand using map data points. There is no option for a user to download all the service contour maps associated with broadcast radio or television stations.
- Map Data Points. We provide service contour data points for public download. These zipped text files may be downloaded at:
Be aware that these are LARGE FILES (approximately 65 MB for FM, and 30 MB for TV, zipped) and may take some time to download. Files are generally updated each day.
Additional infoFM and TV Service Contour maps and data are provided for general use. No restriction is placed on the use of these maps and data. Any use is at the user's sole risk. The FCC does not guarantee the accuracy of the generated maps. Maps may not correspond precisely to data used by the staff to evaluate applications. We do not have AM broadcast station service contors available at the present time.
We regret that we cannot provide source code or assistance to persons or groups looking to generate their own maps. Nor can we honor requests for special maps or additional service or interfering contours, or computations of area or population within these service contours.
Maps are generated from data extracted from the Media Bureau's Consolidated Database System (CDBS). The accuracy of the maps is in part dependent on the accuracy of the data contained in that database.
Data errors in the FM records may be brought to the attention of Dale Bickel, email@example.com.
Data errors in the TV records may be brought to the attention of Mark Colombo, firstname.lastname@example.org.