The Technology Behind HDMI Cables


With the development and availability of High Definition televisions, HDMI (High definition multimedia interface) cables are being used to connect the signal source to the display device, usually a television or computer display. These cables carry both the audio and video signal in digital format, eliminating signal loss which are common in DVI and analog cables. As a result the images obtained using HDMI cables are clearly defined and do not have the blurs or fuzzy edges which analog video cables have. Since these cables carry digital signals, they also can be used for carrying Consumer electronic controls (CEC) digital signals for switching devices on or off.

HDMI technology has been developed by some of the largest consumer electronic companies in the world such as Panasonic, Hitachi, Philips, Sony and Toshiba and were initially used for television. Today many of these companies use HDMI as the default standard. The latest HDMI standard is 1.3 based on consumer requirements.This standard allows for cables with a bandwidth of 340 MHz (1.2 Gbps) allowing much higher image resolutions. It supports 10 bit, 12 bit or 16 bit color depths allowing the display to render up to one billion different colors on the screen. HDMI standard 1.3 also makes a provision for a connector with a smaller form factor, which can be used for connecting to compact devices such as HD camcorders and cameras.

This technology can also be classified as standard HDMI cables (category 1) with a bandwidth of 75 Mhz used for home entertainment systems and high speed HDMI cables (category 2) with a bandwidth of 340 MHz. The high speed cables are used for applications where a higher resolution and refresh rates are required like cinema theaters.

HDMI cables use copper conductors and are recommended for connecting devices at a distance of up to ten meters. For longer distances, there may be some signal degradation, so HDMI repeaters may be needed, though the quality of the transmitter and receiver in the HDTV and Device may also determine the signal quality. These cables are compatible with DVI devices, and can be used interchangeably. For short distances of less than five meters, there is little difference in the quality of images for HDMI cables of different quality. However, for longer distances, the cables quality and connectors used may make a difference.

There may be some variations in the quality of material used for cable sheath or covering. A thicker cable cover, made from fire resistant polymer compound will be more expensive. This technology has greatly simplified the installation of many audio and video devices, as the number of cables to be used is consolidated into a single cable.