Common Terminology Used in Part 15 Broadcasting
- Description of "Part 15"
- Part 15 is a portion of the Title 47 Code of Federal Regulations that covers a variety of electronic equipment that generates or emits radio frequency energy. These regulations define how unlicensed devices may be operated within the radio frequency spectrum. It is the responsibility of the Federal Communications Commission (FCC) to enforce these regulations within the United States. These regulations outline specifics such as the maximum allowed transmit power for a given frequency and transmission method, the type of radiating element or elements that may be employed as well as any field strength limitations.
- Industry Canada, the regulatory body for Canada, has regulations similar to Part 15 in the U.S. RSS-210 are their regulations for "Low Power License-Exempt Radiocommunication Devices (All Frequency Bands)".
- Description of "Part 15 Certification"
- Certification is given to a piece of equipment by the FCC when a manufacturer has successfully proven via lab testing that the equipment in question operates in compliance to applicable Part 15 rules. Devices that receive Part 15 certification must have their certification identification number attached to the unit.
- Description of "Part 15 Compliant"
- Some manufacturers may state that their assembled or kit transmitters comply with Part 15 regulations. This is not a guarantee that the equipment has been tested as there is usually no certification data submitted to the FCC. While the equipment may indeed operate within the parameters dictated by Part 15 regulations this does not necessarily mean the equipment will pass a field inspection from an FCC inspector.
- Description of "Cable FM" broadcasting
- While technically not classified as Part 15 broadcasting, this is where a very low power FM broadcast modulator (transmitter) is connected into the cable television's distribution center, or "headend", and an FM broadcast signal is injected into the cable distribution system. Radio receivers connected to the cable system can receive the station as a normal FM broadcast signal. While nowhere as common today as it had been in the 1980's and 1990's, Cable FM had been commonplace in corporate and school campus cable installations.
- Description of "Cable TV Audio" broadcasting
- More common today than the Cable FM transmission method, this is where a station's audio is added to accompany a video-only television channel on a cable television distribution system. This is often utilized in on-campus broadcasting where the video is an informational video bulletin board and a corporate or campus station's audio is utilized as supplemental programming.
- Description of "Cafeteria" broadcasting
- A non-broadcast program distribution method where a station's audio is piped into a sound system feeding a cafeteria, lobby and/or other public areas without the use of radio transmission techniques.
- Description of "Carrier Current" broadcasting
- Carrier current broadcasting is a method where a low power AM broadcast transmitter utilizes the AC power lines as the radiating element instead of a conventional antenna. Commonly used in campus-limited broadcasting, carrier current allows a controlled broadcast environment, as the radio frequency (RF) signal is usually unable to pass through the power transformers of the electric utility. Special methods are employed to couple the RF signal to the power lines.
- Description of "Free Radiate" transmission
- This is referred to radio transmission using an intentional radiator element (i.e., antenna) to transmit the radio frequency energy into the air. This is a common transmission technique used in Part 15 radio.
- Description of "Radiating Coax" or "Leaky Coax" transmission
- Leaky coax is a special type of coaxial cable that is designed to radiate or leak the RF signal traveling within it. In essence the cable is the antenna or radiator. This cable is designed to radiate the signal by a controlled amount, allowing nearby radios to receive the signal radiating from it. Leaky coax systems are usually designed by engineers to insure compliance with Part 15 regulations.
- Description of "Campus Limited" broadcasting
- Campus-limited broadcasting refers to Part 15 stations whose coverage area is limited to the grounds of an academic institution, be it a K-12 school, college or university. These campus Part 15 stations are engineered to both provide coverage to campus buildings while limiting the signal radiating off the campus. This is most often done utilizing a "carrier current" system but it may also be accomplished with leaky coax or radiating antenna transmission methods.
- Description of "Class D" FN Station
- A now-defunct broadcast license classification no longer being issued by the FCC, Class D stations were stations licensed to educational institutions with a power output of 10 watts. There are some Class D stations that had been grandfathered but many were forced to migrate to a minimum power of 100 watts or risk losing their station license.
- Description of "LPAM" broadcasting
- Some people refer to Part 15 AM broadcasting as low power AM radio broadcasting or as LPAM. While there is an FCC licensed low power FM (LPFM) radio service, currently there is no FCC licensed LPAM service. This site will limit the reference to Part 15 AM broadcasting with the acronym "LPAM" since it is possible the FCC may consider or implement an actual LPAM broadcasting service in the future.
- Description of "LPFM" broadcasting
- Low power FM (LPFM) is a FCC licensed broadcast service which currently utilizes a minimum transmission power of 100 watts. LPFM is not a Part 15 transmission technique and is outside the focus of this site.
- Description of "TIS" or "HAR" broadcasting
- While not specifically called LPAM, this is the only form of low power AM radio broadcasting currently approved and licensed by the FCC, Traveler's Information Service radio (TIS) as well as Highway Advisory Radio (HAR) systems are often licensed to government agencies and are operated to warn motorists about road construction and other traffic information along highways. Music broadcasting is not allowed on these services.
- Description of "Pirate" broadcasting
- Pirate broadcasting is the act of unlicensed broadcasting with transmitter power and field strength exceeding that allowed in the Part 15 regulations. Quite often pirate broadcasters cause harmful interference to other radio services due to the lack of competent engineering or a lack of regard for licensed broadcasters. Pirate broadcasting is illegal in the United States and is outside the scope of this site.
Why Broadcast?
Part 15 broadcasting lends itself to many different uses. A few examples that lend themselves to low power broadcasting include:
- On Campus Radio Station
- Real Estate Drive-by Advertising
- Campground Radio
- Resort and Tourist Attractions
- Elder Community Radio
- Church Ministry Outreach
- Neighborhood Radio
- Play OTR On Antique Radios
- Outdoor Sound Reinforcement
The fun is only limited by your own imagination. The hobby of Part 15 broadcasting may allow you to learn not only about radio broadcasting, but electronics theory as well.
Get ready to have some fun!
Coverage Area
Your legal coverage may span from a handful of feet to upwards of several miles. Determining factors include the number of transmitters employed, transmit power, antenna length : height as well as the broadcast frequency. The limits imposed under Part 15 greatly restrict the legal coverage attainable on the FM band. To obtain the maximum legal coverage it is recommended that you consider one of the many Part 15 AM band transmitters available for purchase. While you're free to use transmitters available in kit form, kit transmitters do not carry FCC certification and should you ever have a visit from an FCC field agent your operation may be more likely to be questioned. Operating with a certified Part 15 transmitter may prove to be an asset should you happen to get a visit from a field agent.
