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HDTV Cables
HDTV cables are conduits of HDTV transmissions. There are two kinds of HDTV connections: analog or digital. Various HDTV cables are used for these connections. They should be of good quality and well installed to guarantee a fully reliable system.
Analog HDTV cables
Analog HDTV signals are either RGB (usually RGBHV) or component video (Y/Pb/Pr).
Component connections are made using RCA connectors. These connectors transfer SDTV NSTC signals from external devices such as DVD or VHS to HDTV displays. Component cables are usually color coded: green for Y, blue for Pb and red for Pr. Audio cables are also color-coded: red for Right audio and white for Left audio.
Seventy-five (75) ohm video coaxial cables are suitable for these applications. These HDTV cables end with RCA plugs, BNCs or VGA monitor plugs.
HDTV analog signals are ten times stronger than NTSC. HDTV signals scale up to 35 MHz while NTSC reaches only up to 3.5 MHz. It is important that HDTV cables which connect devices together maintain a consistent impedance of 75 ohms. HDTV cables which do not meet proper specifications will cause ghosting or "ringing" of projected images because portions of the signal issues back and forth within the cable instead of being smoothly delivered to the screen.
Before purchasing analog HDTV cables, make sure that the device has been sweep-tested at least up to 105 MHz. Also, check that the impedance tolerance is 75 ohms within +/- 1.5 ohms.
Digital HDTV cables
Digital HDTV cables exist in SDI or Serial Digital Interface. However, this very strong cable is still commercially unavailable. In the market are the DVI (Digital Visual Interface) and HDMI (High-Definition Multimedia Interface ).
Bi-directional connection between computers and monitors is possible through dual-channel versions of DVI. These connections carry only video. Audio must be carried by other HDTV cables.
HDMI carries digital uncompressed audio between devices such as an STB and a display. Smaller connectors are used with HDMI. The HDMI HDTV cable allows for bi-directional interface also. HDMI uses a 19 pin connector for single link or a larger 29 pin connector for dual link.
Cables to interconnect DVI and HDMI devices are also available.
DVI and HDMI are characterized by very short cable lengths because they designed to house a copy-protection scheme. Digital HDTV cables use twisted-pair cable not coaxial cables which analog HDTV cables use. DVI and HDMI work without problems over short distances but some low-quality cables falter beyond ten feet.
Practically no digital HDTV cable works beyond fifty feet. Pre-formed DVI cables up to 10 ft. in length are available. Longer lengths require specialized materials and are expensive. Although digital interconnections produce highest video and audio quality, running over long distances is the limitation of digital HDTV cables.
Other cables
S-Video Cables. are used in some televisions to improve picture quality of NTSC signals. Audio must be interconnected separately using RCA cables. S-Video cables are available in any length.
F Cables are coaxial cables with F-connectors used to connect to antennas or satellite dishes to the TV cable system. Several possible cables are selected depending on the length needed. RG-59 is acceptable for short lengths but a low-loss cable is needed for roof-top antennas.
Mini DB 15 RGB Monitor Cables are used to connect PC to HDTV displays with analog RGB interfaces. These cables extend up to 5 meters. Special cables are needed beyond this length. Screw locks secure the connectors to warrant a firm connection.
Firewire/1394 is designed for digital video connections. Audio and video are carried together. The four pin version is the most common but six pin versions are also available for some devices. Prefabricated HDTV cables like these are up to 3 meters.
Dolby Digital audio in SPDIF format is frequently transmitted in optical form. Fiber link, an optical fiber cable which is also called "optical audio output cable", may be employed to send these transmissions to the decoder in the audio system. Excessive bending or twisting of these cables must be avoided as not to break the fiber inside.
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