A Look at New Coaxial Cable Design for “True” 4K

Multi-cable formats (dual and quad links) can be used today because the bandwidth on each cable is the same as HD or 3G bandwidths currently used.  This is possible because recent video cards contain chips that will separate the video data misc. sign 9_Original_22638into two or four signals. The signals then run over separate coax cables at a maximum speed of 3GHz (3GHz for 3G and 1.5 GHz for HD) and at the receiver, they will be transformed back to 6GHz or 12 GHz. Belden believes that its current line of cables will work to 6 GHz, but 12 GHz will require re-design and new cables.

New Cable Design

There are a number of things that can be done to improve performance of the 4K versions listed above. First is to increase Velocity of Propagation (Vp) by means of nitrogen gas injection. The limits of this technique are closely guarded secrets for most manufacturers. So can we get much higher? The problem is, as more nitrogen gas is added, dimensional stability suffers. This leads to impedance variations or “return loss”, which negatively affects performance. The solution is to reduce the size of the bubbles in the foam. Belden already offers better Vp in its well-known RF cable line with a Velocity of Propagation of 86% – 1694A has currently 82%. Unfortunately these RF cables are 50 ohm and not 75 ohm as needed in the broadcast world. So, there is still some work to be done. Thankfully Belden has both the technology and the experience, so we will be able to develop the correct cable for this new 12 GHz requirement. Improvements in shield design, such as multi-layer shielding, are also possible, although these improvements are not tied to the raw performance, such as attenuation. But shielding is certainly tied to noise immunity, which speaks to signal integrity in longer runs or noisy environments.

What About Connectors?

We see a trend towards DIN 1.0/2.3 connectors instead of BNC connectors at those high frequencies needed for “true” 4K. The outer diameter of a DIN 1.0/2.3 connector is much smaller compared to traditional BNC types. The smaller DIN 1.0/2.3 connectors (secure locking with push/pull) are less stressed than traditional BNCs, and they do not require a tight bending radius. This contributes to a better RF launch profile, and a better return loss. The smaller dimension of a DIN connector is an advantage: because of their specific design, DIN connectors for such high frequencies (up to 12 GHz) are easier to manufacture than traditional BNC connectors. Which design will ultimately take the lead? The future will tell.

Conclusion

If the revised distance formula, -40 dB at ½ the clock, is adopted, and if performance improvements are made, such as higher Velocity of Propagation, single-link coaxial cable for 4K formats will be able to provide the right performance for future video transmission.

If you need more details about our solutions let me know and Email me at werner.eich@belden.com

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.

                    Chart

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.

Read more »

See Belden at IBC 2013 – and be amazed by our scope

Mail-Attachment_IBC

Preparations are well underway for our booth at IBC 2013.  I have always enjoyed being at the show, focusing on Belden’s cable and connectivity products (“the most trusted brand for Broadcast cables”).

This year, however, we have so much more to offer. Since Belden’s acquisition of Miranda Technologies, we are now also able to provide hardware and software solutions for television broadcast, cable, satellite and IPTV.

Our booth will reflect our expanded capability to deliver world-class solutions for immediate and uninterrupted transmission, flawless HD, 3G and 4K audio and video streams. We will also be introducing some new products.

To highlight just two of them, our new Duobond® Plus HD Digital Video Cables with bonded foil over the dielectric will make the termination of Belden’s 1-Piece HD BNC very easy and much faster than traditional methods with 3-Piece BNCs. It is the absolute reliable combination to deliver the needed performance!

Moreover we will be launching our extremely rugged and flexible Belden CatSnake® Tactical Heavy Duty Category 6A shielded data cables, which are designed for use in high traffic areas in a broadcast studio or for use out of doors, in broadcast truck applications, and for portable, professional audio/video use.

And if that is not enough, visitors to our booth have the opportunity to meet Steve Lampen, Belden’s Manager for Multimedia Technology and Product Line – Entertainment Products. Steve is a prolific blogger, public speaker and writer, and was named “Educator of the Year” by the Society of Broadcast Engineers in 2011.

So if you are looking for maximum reliability and performance in your broadcasts, be sure to visit our booth and see for yourself what Belden has to offer.  My team and I will be delighted to see you at the show.

Splitting Digital Video

Back in the old days of analog audio, splitting a signal was no big deal. Just use a ‘Y’ adaptor. Or if you’re punching down wires, just punch another pair on top of the first. Of course, each signal will be 3 dB lower than the original, but that’s not a worry. That’s because the wavelength of audio is miles long (quarter-wavelength at 20 kHz is more than 2 miles!).

While adding wires might change the impedance, it didn’t matter. You couldn’t go far enough for it to matter. But when it came to video, it was a different story. The signal is a lot higher frequency, so the wavelength is shorter. While you might get by with a BNC ‘T’, this would cause a mismatch on the two splits and could result in some reflected signals.   Read more »

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