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The National Radio Systems Committee (NRSC) is an organization sponsored by the Consumer Technology Association (CTA) and the National Association of Broadcasters (NAB). Its main purpose is to set industry technical standards for radio broadcasting in the United States. While regulatory authority rests with the FCC, it usually adopts NRSC recommendations, such as RBDS and spectral masks. For U.S. television, the NTSC sets standards.
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Digital Audio Broadcasting (DAB) is a digital radio standard for broadcasting digital audio radio services in many countries around the world but not in North America where HD Radio is the standard for digital radio.
AM broadcasting is a radio broadcasting technology, which employs amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave transmissions, but also on the longwave and shortwave radio bands.
Radio broadcasting is transmission of audio by radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both. Signals can be either analog audio or digital audio. Television broadcasting also uses radio frequencies, but includes video signals.
Radio Data System (RDS) is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardizes several types of information transmitted, including time, station identification and program information.
Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television, in which the television signal is transmitted to the receiver from an overhead satellite, cable television, in which the signal is carried to the receiver through a cable, and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is limited by the visual horizon to distances of 40–60 miles (64–97 km).
In-band on-channel (IBOC) is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency.
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast. There is no physical difference between a carrier and a subcarrier; the "sub" implies that it has been derived from a carrier, which has been amplitude modulated by a steady signal and has a constant frequency relation to it.
Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting, particularly shortwave, and FM broadcasting. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of bandwidth, using xHE-AAC audio coding format. Various other MPEG-4 and Opus codecs are also compatible, but the standard now specifies xHE-AAC.
Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services.
Code of Federal Regulations, Title 47, Part 15 is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting. Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.
AM stereo is a term given to a series of mutually incompatible techniques for radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers. There are two main classes of systems: independent sideband (ISB) systems, promoted principally by American broadcast engineer Leonard R. Kahn; and quadrature amplitude modulation (QAM) multiplexing systems.
HD Radio (HDR) is a trademarked term for the in-band on-channel (IBOC) digital radio technology used by AM and FM radio stations mostly in the United States, Canada and Mexico to transmit audio and data by using a digital signal embedded "on-frequency" immediately above and below a station's standard analog signal, providing the means to listen to the same program in either HD or as a standard broadcast. The HD format also provides the means for a single radio station to simultaneously broadcast one or more different programs in addition to the program being transmitted on the radio station's analog channel. iBiquity developed HD Radio, which was acquired by DTS in September 2015 bringing the HD Radio technology under the same banner as DTS' eponymous theater surround sound systems. The HD Radio technology and trademarks were subsequently acquired by Xperi in 2016.
Travelers Information Stations (TIS), also called Highway Advisory Radio (HAR) by the United States Department of Transportation, are licensed low-powered non-commercial radio stations, used to broadcast information to the general public, including for motorists regarding travel, destinations of interest, and situations of imminent danger and emergencies. They are commonly operated by transportation departments, national and local parks departments and historic sites, airport authorities, local governments, federal agencies, colleges and universities, hospitals and health agencies, and for special events and destinations.
In telecommunications, a spectral mask, also known as a channel mask or transmission mask, is a mathematically-defined set of lines applied to the levels of radio transmissions. The spectral mask is generally intended to reduce adjacent-channel interference by limiting excessive radiation at frequencies beyond the necessary bandwidth. Attenuation of these spurious emissions is usually done with a band-pass filter, tuned to allow through the correct center frequency of the carrier wave, as well as all necessary sidebands.
Radio broadcasting in the United States has been used since the early 1920s to distribute news and entertainment to a national audience. It was the first electronic "mass medium" technology, and its introduction, along with the subsequent development of sound movies, ended the print monopoly of mass media. During the Golden Age of Radio it had a major cultural and financial impact on the country. However, the rise of television broadcasting in the 1950s relegated radio to a secondary status, as much of its programming and audience shifted to the new "sight joined with sound" service.
FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is capable of higher fidelity—that is, more accurate reproduction of the original program sound—than other broadcasting technologies, such as AM broadcasting or DAB radio. Therefore, FM is used for most broadcasts of music or general audio. FM radio stations use the very high frequency range of radio frequencies.
Subsidiary Communications Authorization (SCA) in the United States, and Subsidiary Communications Multiplex Operation (SCMO) in Canada, is a subcarrier on a radio station, allowing the station to broadcast additional services as part of its signal.
HDC with SBR is a proprietary lossy audio compression codec developed by iBiquity for use with HD Radio. It replaced the earlier PAC codec in 2003. In June 2017, the format was reverse engineered and determined to be a variant of HE-AACv1. It uses a modified discrete cosine transform (MDCT) audio coding data compression algorithm.
AMAX is an American certification program developed by the Electronic Industries Association (EIA) and the National Association of Broadcasters (NAB) in 1993. This quality control program addressed both consumer receiver developments and air chains of broadcast AM transmission stations. Tuners and receivers offering AMAX Stereo were designed to capture the widest audio frequency response and stereo separation of AM stereo broadcasts, where available.
A sign-on is the beginning of operations for a radio or television station, generally at the start of each day. It is the opposite of a sign-off, which is the sequence of operations involved when a radio or television station shuts down its transmitters and goes off the air for a predetermined period; generally, this occurs during the overnight hours although a broadcaster's digital specialty or sub-channels may start up and closedown at significantly different times as its main channels.