Getting More Fiber in Your Diet
As the last few weeks of 2016 wind into obscurity, Kramer has been teaching some classes on AV transport over IP networks – you know, the “AV−IT convergence,” which according to our calculations already happened over a decade ago.
But the pro AV industry is, as usual, reluctant to change and adopt many new facets of technology. And one in particular is the use of optical fiber cable. We’re not sure what it is about fiber that causes people to turn and run away at the drop of the word.
Is it the connectors− Shouldn’t be; you can now terminate fiber connectors in a little over a minute. Is it pulling and fishing the cables− Is it a fear of dust (a definite problem with fiber if you don’t keep the connections clean)− Or is it just a general lack of understanding about fiber signal transmission−
Whatever the excuse, there are plenty of compelling reasons to start using fiber in your next installation. For one thing, bandwidth isn’t really an issue with fiber – we’re talking about modulated light waves with frequencies in the Terahertz (THz) range and bandwidths insanely large enough to accommodate multiple high bit−rate signals with zero compression.
There’s a reason why 1 Gb and 10 Gb network switches incorporate optical ports – their bandwidth far exceeds the capacity of the switch, which is just good design practice. And to successfully implement an AV−over−IP installation that streams multiple channels of HD (1080p) video, you will need every bit of that bandwidth; especially if you are multiplexing TCP/IP traffic with your real−time AV traffic.
Here’s another example. The longest practical cable length for an HDMI signal is in the range of 50 feet, with 25 feet being more like the norm. Yet, if we convert the HDMI TMDS signal to pulsed light – easily done with LEDs – and couple that into multimode optical cable, we can now extend the HDMI signal as far as 300 feet.
Kramer’s Active Optical Cable (AOC) system is a good example of an easy way to extend HDMI. It uses a modular slip−on plug to facilitate pulling through conduit and plenum spaces, and requires just 250 milliwatts of power to operate its LED lasers – power taken right from the HDMI jack. And optical cable offers a high degree of isolation from radio frequency interference (RFI) and electromagnetic impulse noise that conventional coaxial and twisted−pair cables can’t match.
As far as transmission distance goes, multimode fiber is good for several kilometers even at the highest clock rates, while single−mode fiber can transport connections almost 20 miles before running out of energy. That blows by the 200−feet to 300−feet distance limitations we now have using twisted−pair signal extender formats.
Another interesting thing about optical fiber is that it can be purchased pre−terminated in long runs. Signal attenuation (per foot) is so low that, if you only need a 65−foot run and don’t want to bother with installing the optical connectors, you can just buy a 100−foot ready−to−go cable and coil up the extra 40 feet. (No muss, no fuss!)
And let’s face it – the only ‘future−proof’ cable choice we have is optical fiber. Yes, we can migrate from Category 5 to 6 and even 7 as network speeds zoom by 1 Gb/s to 10 Gb/s and then on to 40 Gb/s (100 Gb/s, anyone). And there have been some amazing advances in copper−based network switches in recent years.
But at some point it becomes impractical to use copper for such high data rates, and fiber is the only option left to us. Consider that an 8K display has 7680x4320 pixels, and if all of them were refreshed 60 times per second with an RGB (4:4:4) signal, we’d need to support an uncompressed data rate of 96 gigabits per second (Gb/s). For high frame rate display (120 Hz), that would double to 192 Gb/s!
That’s more than ten times as fast as the latest version of HDMI and almost nine times faster than the current version of DisplayPort. 8K displays aren’t that far off in the future – more than a half−dozen were shown at the 2016 CES – and they already require multiple DisplayPort or HDMI connections to demo. Yet, one optical port can do the entire job and do it without breathing hard.
Can you run optical fiber to wallplates and pop−up interfaces− Sure, and it’s been done already. Will it work with any signal type− The answer is yes, as long as that signal type can be converted to pulses of light. Do you need to be especially careful when installing fiber− Well, you don’t want to bend it, nor do you want to loop it onto a small bend radius – but that’s just common sense. You wouldn’t want to abuse copper cables that way, either.
And now that our industry finally appears to be embracing the concept of AV over an IT network, we’re going to have to learn to deal with optical fiber connections. Layer 2 and Layer 3 managed switches suitable for AV signal transport often have one or two optical ports alongside their category wire ports, and the signals they’ll be carrying won’t be traveling as display formats. Rather, these signals will be encoded in the JPEG and MPEG formats with TCP/IP wrappers.
In just over a month, it will be 2017. Think about that – we’re already 17 years into the next century, and it will be 52 years after the first practical demonstration of data transmissions over optical fiber in Germany. (For reference, RS−232 will be 55 years old!)
Maybe it’s finally time for us to get more fiber into our diet