Making the right connections

Room for many solutions to many messages

By Morand Fachot

Multimedia content and computer data can be accessed through a variety of channels. In recent years the wireless distribution and reception of audio, video signals and other kinds of data have undergone remarkable developments. However, cables and connectors still remain an essential link of the entire production, transmission and reception chain. Several IEC TCs (Technical Committees) and their SCs (Subcommittees) prepare International Standards for these.

Coaxial cables are still extensively used in the broadcasting and audiovisual industries Coaxial cables are still extensively used in the broadcasting and audiovisual industries

Cables standing their ground

The spectacular expansion of the number of connected devices, in particular portable ones such as mobile phones or tablet computers, has been made possible by improvements in wireless communication.

In most consumers' homes, wireless connectivity has become the predominant networking technology for computer and multimedia devices. However, new high-efficiency coding technologies allowing the transmission of higher volumes of data over copper wires and the expansion of fibre optic-based systems have ensured that wired solutions continue to stand their ground.

Higher up the chain, at the production and transmission levels, cables and connectors are still essential, even when signals and content are disseminated via electromagnetic wave propagation or using satellite technology.

Perfect sound

In audiovisual or computer equipment the most commonplace applications for cables are in carrying sound, image or data from an analogue or digital receiving or processing unit to other components, loudspeakers, a display or any other terminal. 

As many technologies are in use, as signal production has gradually shifted from analogue to digital sources and as use of metal wires and cables has given way to optical fibre-based systems, International Standards are essential to ensure that equipment from different manufacturers can be interconnected and work seamlessly with the right interfaces and connectors. Several IEC TCs and SCs prepare these International Standards to guarantee that this is what actually happens.

In the beginning there was copper…

RF or r.f. (radio frequency) signals, used to carry multimedia, voice or, more recently, data content, have long relied on copper cables, essentially coaxial cables, as distribution channels.
A coaxial cable is an electric cable that acts as a waveguide for RF signals. It consists of an inner conductor (single solid or stranded wires), surrounded by a dielectric (non-conducting) insulator that separates it from an outer metallic conductor made up of metal tubing or braided strands. These elements are contained within an outer sheath that protects them from the environment; they are all aligned along the same axis, hence the term coaxial.

IEC TC 46 prepares International Standards for cables, wires, waveguides, RF connectors, RF and microwave passive components and accessories.

…then came light

For many applications, coaxial cables and copper wires have been replaced by optical fibres for the transmission of RF, voice and data signals and multimedia content. Optical fibre-based systems present many benefits as they allow large amounts of data to be transmitted over long distances almost instantaneously. Optical fibres are made up of a transparent core surrounded by a transparent but less refractive material that keeps light in the core, allowing it to act as a waveguide.

Electrical signals such as RF signals are changed into optical signals using an electrical to optical fibre converter. They are then transmitted down optical fibres. If required, repeaters are used to regenerate the signal over distance.

Hundreds of fibres can be bundled in a single cable, allowing large amounts of data to be transmitted simultaneously at great speed. This makes fibre an ideal medium for multimedia, telecommunication and ICT (Information and Communication Technology) applications.

Optical fibres are highly adaptable: they can be fitted nearly anywhere indoors or outdoors. They may be laid in ducts, sewer networks, water pipes, high-pressure gas pipes, along or inside power cables. They can be buried in the ground, in the pavement, used in self-supporting cables or submerged in the sea…

The fibre optic market is expanding rapidly. IEC TC 86 and its SCs prepare International Standards for fibre optic-based systems. SC 86B, in particular, deals with "fibre optic interconnecting devices and passive components".

Multimedia world

One sector that relies extensively on both coaxial and fibre optic-based systems is the broadcast and entertainment industry. Everything from content production to signal distribution may be carried via satellite, terrestrial broadcast or cable networks.

The dramatic rise in the number of TV channels has driven the need for increased transmission capacity. The number of national channels in Europe had swollen from 47 in 1990 to 9 800 by 2010, a trend also observed elsewhere in the world. The introduction of interactive and data services, of HDTV (high-definition television) and of 3D TV has further increased the search for even higher capacity.

The signal distribution infrastructure in satellite ground stations and CATV (cable TV) head-ends still relies heavily on coaxial cables. HFC (hybrid fibre-coaxial) networks, employing a combination of optical fibre and coaxial cable, have been widely deployed for broadband networks by CATV operators since the early 1990s. In HFC networks, the initial distribution is ensured by optical signals. These are converted by fibre optic nodes into electrical signals which reach the end users' equipment via coaxial cables.

Converging formats and physical interfaces

Computer and multimedia systems have been able to exchange content and use the same distribution channels following their convergence when the broadcasting and entertainment industry migrated from analogue to digital formats. Computer networks then started distributing multimedia content.

Nowadays both worlds use the same interfaces. Computers hook up to and power peripherals using USB (Universal Serial Bus) connections and send digital content to displays or TV sets via HDMI (High-Definition Multimedia Interface). In turn, TV sets link up to DVD players, set-top boxes or satellite receivers, also using USB or HDMI connections.

A single HDMI cable combines video and multichannel audio. If analogue leads were used, provision of the same connection would require three component video cables, plus six audio cables… (see article on HDMI in e-tech, January 2012).

USB ports replace serial, parallel, PS/2 and other interfaces, allowing different computer peripherals and electronic devices to be conjoined using the same cables and connectors.

The IEC has just endorsed four USB-IF (Implementers Forum) specifications. USB-IF specifications are recognized around the world as the de facto USB standards (see article on IEC endorsement of USB-IF specifications in this e-tech).

Wireless in; cables and connectors not out

In spite of its spectacular and recent expansion, the wireless distribution of content has not replaced cables in the computing and multimedia environments, and is unlikely to do so in the near future.

New and constantly evolving connections and interfaces have given a new lease of life to cabled connections. The work of many IEC TCs and SCs to improve existing standards and to incorporate industry specifications like USB and HDMI into their International Standards will ensure continuing extensive usage of cabled connections in multimedia and computer equipment.

Coaxial cables are still extensively used in the broadcasting and audiovisual industries Coaxial cables are still extensively used in the broadcasting and audiovisual industries
tech-1_hdmi_lrg HDMI connectors can replace several other types of connectors
One HDMI connectors (left) can replace replace several other types of connectors (Photo: Yamaha) One HDMI connectors (left) can replace replace several other types of connectors (Photo: Yamaha)