Exploiting HDMI - a versatile standard?

Launched at CES in 2003 and included in over 70 products at CES 2004, it's undeniable that HDMI has achieved early market acceptance Tim Parker, product specialist - interconnect at Micromark, takes a closer look at this developing market.HDMI, or high-definition multimedia interface has achieved early market acceptance. This year's CES gave an insight into the application of HDMI connectors in alternative consumer products. The potential is there to exploit HDMI in broadcast, production and recording studios, as well as virtual classrooms, video conferencing and medical imaging.

In fact, any industrial application dealing with audio and video data can benefit from this technology.

HDMI

Backed by the industry heavyweights - Sony, Hitachi, Panasonic, Philips and Toshiba to name but a few - HDMI is a fast, uncompressed digital link for audio and video data. It was developed as a superior alternative to DVI to connect high definition video sources to digital displays in consumer electronics equipment such as dvd players, set-top boxes and a/v monitors, as well as handheld devices running Windows CE.

Capable of transmitting up to 5Gbps uncompressed digital video and audio over a single cable, HDMI is a derivative of DVI. It also replaces the maze of cabling usually associated with home cinema products. In addition, it enables the transmission of high-definition content along with 8-channel digital audio with bandwidth to spare.

The bulk of products now benefiting from HDMI, unsurprisingly, come from the home cinema and traditional a/v markets and include digital tvs, plasma displays, LCDs, dvd players and recorders, a/v receivers and set-top boxes.

Essentially, applications traditionally requiring several separate audio and visual leads.

On one level, HDMI is eliminating the cost and complexity of multiple cables used to connect current a/v systems, but HDMI also offers a number of advantages over DVI.

Connectors

HDMI uses a compact, reliable and user-friendly connector, similar to a USB connector, and offers a number of advantages over the bulky SCART socket and connector.

SCART leads and sockets are used to provide stereo sound from a stereo vcr, set-top box or satellite receiver to a tv or display. In addition, it can also provide rgb signals for connecting video game consoles or digital tv set-top boxes. SCART connectors, however, are not very sturdy, and in practice tend to give a fair few problems.

In vcrs, for example, the socket is often mounted solely by its soldered connections, and frequent use can make these become loose, creating intermittent problems. If the lead isn't sufficiently well screened this can give rise to picture problems, as can excessive cable length, and many users have experienced the disabling of teletext functions.

In contrast, HDMI connectors are much smaller and save about 40 percent of the pcb space. Surface mount sockets are available with a panel mounting flange, which sits flush within the unit like other consumer i/o components, and has springs on the side and bottom for grounding and mating retention.

The smt connectors are fully shielded for esd protection, gold-plated for reliability and produced with 100 percent lead-free processing. An easy-to-use friction lock design blends in well with home entertainment equipment while providing secure electrical contact with smooth cable insertion and extraction.

Cables

HDMI has been designed to use standard copper cable construction at long lengths. In order to allow cable manufacturers to improve their products through the use of new technologies, HDMI specifies the required performance of a cable, but does not specify a maximum cable length.

Cable manufacturers are keen to tap into the expanding HDMI market and suitable connectors and cable assemblies are now widely available. Most manufacturers offer HDMI-to-HDMI cables in lengths of 1, 2, 3, 5, 10 and 15m. Lengths in excess of 20m have been tested and are regarded as reliable, and as semiconductor technology improves, lengths over 100m can be reached with fibre optic cables and active cable technologies such as amplifiers or repeaters.

Cable assemblies are available in HDMI-to-HDMI styles for true digital connectivity and HDMI-to-DVI versions to accommodate the transition of equipment still using DVI connectors.

In summary

The uptake of HDMI by the CE industry in just the first year has shown that there is a requirement for an alternative to existing standards, especially in relation to HDTV and digital equipment. Although in its infancy, HDMI is still capable of greater things and we are likely to see its implementation in a growing number of handheld a/v devices and wider industrial applications.

Micromark C&CD

Source: http://www.cieonline.co.uk