4K: How to Meet the Single Link Challenge?

One of the greatest challenges presented by the arrival of 4K video is in the ability of this signal to be carried by a single copper coaxial cable, commonly called “single link”.

Proposed Change in Distance Calculations

It is most important for a broadcaster to know how far he can transmit a signal over a single coax cable. In recent years Belden has proven that the recommended SMPTE distance calculation for HD signals can be outperformed. The original distance formula, -20 dB at ½ clock, was a reasonable “safe” value for 1990 and the technology then available. However, we believe that more than 20 years of improvements in chip design and active equipment has enabled us to surpass this calculation. Therefore, we think that a new formula, -40 dB at ½ clock, is an appropriate “safe” distance. And in the ‘real world’, Belden can go considerably further than that.


Let’s have a look at the green squares in the chart: Belden’s 1694A for example can run a minimum 113 meter with HD. With 2K signals 1694A runs a minimum of 78 meters, or 35 meters less when compared to HD. In general, all these lengths can be improved on by using our HD coaxial cables and BNC connectors. See for example the 140 meter at HD with 1694A.

If you remember that the bandwidth of 4K is 8 times HD and 4 times 2K, everyone would expect the minimum distance of a 4K signal to be less than HD or 2K. But look at the red squares. The chart clearly shows how Belden’s 1694A runs 106 meter with QuadFull-HD on a single-link! In other words: 28 meters further than 2K.

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POV cameras take outside broadcasts to the next level

Editor’s Note: This is the last part of a three part series.

In previous articles, I have covered the cabling infrastructure of HD broadcast studio and portable cameras. Another very exciting camera design is POV (point-of-view). With its standardization on HD, usage of 3G, and its pioneering of 3D, there is nowadays serious competition in sports broadcasting between different kinds of sports. TV viewers like to see thrilling moments, and TV networks need high ratings to grow their advertising revenues. POV cameras are able to help sports events become an even more spectacular viewing experience than ever. 

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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.


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