Facts on HD

The first European high definition TV test transmissions were made at the IBC exhibition ten years ago. It has taken a while, but nowadays every organization involved in the broadcast industry is renewing or updating its equipment to HD.

So what exactly is HD? Its full name is actually HD-SDI, and it is a sub-set of the SDI (Serial Digital Interface) family of video interfaces standardized by the Society of Motion Picture and Television Engineers (SMPTE). SDI, which is covered by the SMPTE standard 259M, comes in many versions, the most common being  4×3 image, 270 Mbps (135 MHz clock), 480p (progressive).

HD-SDI itself is covered by SMPTE 292M, and comes in two versions, 1080i (interlaced) or 720p, both with a 16×9 image. But the next step is already on its way:1080p/60 (1080p/50 in Europe), which is covered in SMPTE 424M.


No old coaxial cable (8281 or below) has been tested or verified to HD or 1080p. Belden though has designed and developed HD coaxial cables tested to 4.5 GHz to cover 1080p.

In HD-SDI, every element in the transmission chain is critical: cable, patch panels, patch cords, adaptors, even the connectors on equipment and the traces on the circuit boards. Everything needs to be as close to 75 ohms impedance as possible–and tested for return loss too.

Belden’s guarantee for HD-SDI cable is -23 dB (5 MHz-850MHz), -21 dB (850MHz – 3 GHz); our guarantee on 1080p/50-60 is -23 dB (5 MHz-1.6 GHz), -21 dB (1.6GHz – 4.5 GHz).

In 2008, the European Broadcast Union (EBU) decided to support both 720p/50 Hz and 1080 /50 Hz high definition (HD) formats, which results in a clock of 750 MHz and a data rate of 1.5 Gbits/second. 1080p/50 Hz with a clock of 1.5 GHz and a data rate of 3 Gbits/second is an attractive production format for high-quality sport production, and as a master format that will convert into 1080i/720p with minimal transfer artifact.

For the end user, a critical question is: “How far can I run my coaxial cable within all those formats?” The answer can be found on our broadcast microsite.

But why should the end user take our HD coaxial cables? Here are ten good reasons:

  1. the cables are purpose-designed (high-density nitrogen-gas-injected foam dielectric, with small, closed-cell bubbles);
  2. Belden guarantees return loss;
  3. Belden provides installable performance: the high-density nitrogen-gas-injected foam resists deformation when bent or crushed, giving stable impedance as well as low return loss;
  4. attenuation is very low;
  5. matte finished outer jackets are available in 10 colors for easy identification (green for video, red for camera, etc);
  6. cable lengths are longer than those from other  providers (1080i/SMPTE 292M: 179DT goes 40m, 1855A goes 80m, 1855ENH goes 100m, 1505A goes 120m, 1694A goes 140m, 7731A goes 230m);
  7. available superflex cables (1865A, 1505F, and 1694F) are ideal for live events, as they are easy to de-and respool and to pass around obstacles;
  8. bundled versions (VideoFlex™ & BananaPeel™) are available too (179DT, 1855ENH, 1505A, and 1694A), facilitating installation and providing for a clean installation (all the coaxes are in one jacket);
  9. all cables are available in halogen-free (direct burial, UV-resistant);
  10. lightweight 179DT is designed for OB vans, where space is at a premium. 

To provide our end users with a complete solution, we recently added the connectivity part to our HD coaxial cables including a 25 year guarantee when they install our HD BNCs together with our HD video cables in fixed installations.

If you need more details about our solutions let me know. E-mail me at werner.eich@belden.com


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