Radio remains to these days one of the most widespread and popular communication media in spite of the growing popularity of television and, more recently, of the Internet. Unlike these, it doesn’t require expensive equipment and, since the introduction of transistor radios in the mid-1950s, can even operate independently of the electricity grid, a major benefit for millions in many countries in which access to electricity is difficult or sporadic. Radio is experiencing a revival with increasing numbers of devices being designed to receive it and as digital radio widens its reach.
IEC Standards central to development of radio equipment
Radio depends entirely on electricity as a source of power for transmission and reception, and on electrical and electronic components for its broadcast equipment and receivers. A multitude of IEC TCs (Technical Committees) and SCs (Subcommittees) develop International Standards for such components and systems. In 1926, shortly after radio broadcasting was introduced, the IEC created TC 12: Radiocommunications, which was disbanded later. Nowadays, IEC standardization work for radio broadcast and receiving equipment is carried out by TC 100: Audio, video and multimedia systems and equipment, TC 103: Transmitting equipment for radiocommunication, and TC 108: Safety of electronic equipment within the field of audio/video, information technology and communication technology.
Radio reception can be subject to interference from a variety of sources, including electrical equipment. As early as the 1930s it was decided to deal with the subject of radio interference at an international level. Following an ad hoc conference of interested international organizations held in Paris in 1933, CISPR (International Special Committee on Radio Interference) was created and first met in 1934. CISPR is an organization within the IEC that brings together experts who come from radio regulatory authorities, test houses, manufacturers, other IEC committees, and other groups not associated with IEC National Committees.
The initial frequency range specified to deal with radio interference extended from 150 kHz to 30 MHz, thereby covering long-, medium- and short-waves. CISPR work led to a reduction in interference to radio (and later TV) broadcasts by the means of defining permissible limits from domestic, industrial and commercial appliances as well as from ignition systems in the automotive field and from fluorescent lighting fixtures. Different CISPR SCs deal with interference from various other sources, including power lines and ICT (Information and Communications Technology) equipment.
Securing the future of radio
The radio frequency spectrum is a valuable and limited resource. The desire to optimize its use and to benefit from other advantages, such as increasing the number of programmes in a given bandwidth, improving audio quality and reducing transmission power, led to the introduction of digital radio broadcasting. This technology requires audio signals to be digitized and compressed before transmission. Digital audio compression has been developed by MPEG (Moving Picture Experts Group) a working group of experts formed by IEC and ISO (International Organization for Standardization) to set Standards for audio and video compression and transmission.
The four international digital radio systems recognized by ITU (International Telecommunication Union), namely DAB/DAB+ (Digital Audio Broadcasting), DMB (Digital Multimedia Broadcasting), DRM (Digital Radio Mondiale) and IBOC (in-band on-channel), rely on digital audio compression Standards developed by MPEG. They include MPEG-1 Audio Layer II or MPEG-2 Audio Layer II (or MP2), defined by ISO/IEC 11172-3:1993, and various codecs based on MPEG-4 Audio profile, such as HE-AAC (High-Efficiency Advanced Audio Coding), defined by ISO/IEC 14496-3:2009. Through its standardization work in the fields of radio equipment, prevention of radio interference and digital audio compression, the IEC has been at the forefront of developments in radio broadcasting for nearly 90 years and will continue to prove central to the vitality of the industry.