A practical case for fiber - TvTechnology

A practical case for fiber

As your 4K decision looms, fiber’s benefits are clear.
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The multiple benefits to be had by the implementation of fiber-based cabling and connectivity in a broadcast infrastructure are well documented, but they are not always fully understood. The cost benefits alone would seem to be a clincher, but there are technical advantages that actually make the cost advantages seem almost secondary, but no less appealing.

So, if you have so far had only a passing interest in fiber, read on. It’s time to get on the fast train, particularly if 4K production is on your near- or longer-term horizon. A broadcast audio/video/data infrastructure will extend faster; carry multiple, bi-directional signals on each fiber strand; and be able to handle almost unlimited bandwidth — all of which is a definable improvement on current capabilities of traditional triax.

Despite the most obvious advantages, there is still some reticence in some quarters to adopt fiber. Questions of fragility, cost and reliability are, however, largely resolved and rapidly diminishing. What five years ago may have been seen as a rational reason to defer a decision to take up fiber is no longer valid.

HD is almost the “new normal,” and if you need to transmit HD quality, unless you’re using fiber, those images will be on a pretty short leash. Routers also need to handle HD, and it’s fair to say that the majority still use legacy coax cables, which is perfectly serviceable for short distances, of course. Increasingly, though, that is seen as more CD than download, to use the analogy. Bundled fiber does tend to generate slightly more heat than coax, but router manufacturers have developed cooling systems that make it a non-issue, and a considerably less bulky one. There are good reasons why many stadiums, arenas and other production facilities around the world (usually driven by the go-to catalyst of sport) are threading fiber through facilities today. The ability to future-proof such venues is dependent on fiber to ensure that everything from HD production to in-house monitors and big-screen displays are able to take advantage of a fiber-optic infrastructure and adapt to expanding bandwidth requirements. Multiple signals from sound systems, radio booths, microphones and a virtually limitless number of cameras are easily managed through fiber-optic cables and interfaces.

That said, in some quarters, there is still some hesitation in making a decision on fiber. However, more often than not, it’s just a matter of waiting for a CAPEX budget to cycle its way back to the upgrade wheelhouse. Granted, the spokes on that wheel have turned more slowly in recent years, but the pressures placed on facilities to deliver vast amounts of content to multiple devices is like aiming an open fire hose at those spokes. Consumers expect their content when they want it, where they want it, and they expect it to be high-quality. Setting spokes in motion with a high-pressure hose is great fun when you’re a youngster. But, it is a considerable concern when your revenue-generating broadcast spokes are slowed by copper, and your fiber-based competitors are effortlessly flashing past you under no pressure at all.

But, which cables should you cut?

A decision on fiber can also come down to the perplexing prospect of working out which cables to cut — perhaps within a multi-story infrastructure that has been in place for decades — without crippling the entire broadcast operation. There are elegant ways around that now. Being thin, flexible and now ultra-resilient, fiber is easy to manipulate and deploy. In some cases, it is entirely possible to leave most or all of the old coax in place. It is still useful, not least as a guide for threading new fiber.

This approach is typically part of a phased transition, which is an entirely viable option, particularly for structural situations where the disruption would be far too complicated and disruptive to contemplate without a carefully planned, incremental transition. Whatever the choice, and whatever the timescale, fiber should be on your near-term decision, preferably to-do, list.

Fiber-only systems

There is, however, something professionals involved in ENG or SNG in any capacity (including executives, station managers, news directors, field producers and on-air reporters) can do right now and are already exploiting with great success. Many high-end camera manufacturers have already opted to manufacture fiber-based-only systems and are offering exciting new connectivity options. In fact, they highly recommend that broadcast facilities of any kind follow suit. So, once you have fiber from camera to truck or studio, why not go the rest of the way?

Make all relevant infrastructure fiber ready, and deploy fiber connections between them and every camera within 30km. With fiber, out of sight is not out of mind. It enables you to get even closer to the action without the burden of transporting, storing and laying multiple lengths of heavy triax. New camera angles, robotic controls and single-unit deployments can all be used to truly get to the heart of the action without the burden of bulky lengths of cable.

The only possible restriction is total available bandwidth, which costs money. However, bandwidth is rarely an issue with ENG/SNG. Copper systems need a cable, and connector, for each individual data stream. That requires extra cable, extra connections and, ultimately, extra cost. With single-mode fiber, multiple wavelengths of light can easily be multiplexed onto one fiber core, even at extremely high data rates, which means it costs less to move. Broadcast quality coax cable can require an expenditure of up to 7X more than the fiber equivalent. If you take into consideration the thousands of meters of cabling typically required for a broadcast facility, the savings to be realized by implementing fiber are self-evident.

SPP

To make it even easier for production facilities and broadcasters to take advantage of fiber, Small Form-factor Pluggable (SFP) fiber modules are now available. These hot-pluggable devices provide fiber connectivity to 3Gb/s/HD/SD devices, and by using single-mode fiber instead of coaxial cables, these devices further extend distances over which fiber cabling can be used without any degradation in signal quality.

Similarly, SFP cartridges designed specifically for video can slide directly into any product that includes video SFP connectivity. These cartridges can provide either one or two fiber connections and are available as single Tx or Rx, dual Rx, dual Tx or as a bi-directional Rx/Tx.

For more demanding applications, say, for example, building-to-building or truck-to-truck, multiple channels can be multiplexed onto a single fiber by using a Course Wavelength Division Multiplexing (CWDM) unit, which can carry multiple and, significantly, different signals such as AES, MADI, DVB-ASI, 3G/HD/SD SDI or Ethernet, across long distances. A CWDM mux unit combines up to 18 different-wavelength signals from different optical fibers into a single fiber. The CWDM demux unit can separate those differing wavelength signals from a single fiber back to 18 separate fibers. What makes this possible is that the units are completely agnostic to the signal type.

A key advantage of the SFP approach is that it vastly simplifies the migration to fiber. Equipment can be purchased with integrated fiber connectivity, or fiber can be added easily in the field, without any disruption to existing coaxial services. This allows the building of future-proof infrastructures, while minimizing costs associated with the transition.

Of course, decisions on what approach to take and how much power it will require to transmit the signals are, to some degree, dependent on a careful calculation of the distance an optical signal needs to travel, which requires an examination of several key factors, namely: optical output power, optical frequency of the transmitter and optical receive sensitivity or optical range of the receiver. It is also important to determine the length of fiber, number of connection points, splice points and passive optical devices (such as optical multiplexers and splitters) that it will encounter along the way. Once those calculations have been made, a solution can be readily and confidently tailored to ensure peak efficiency and performance.

Those who have implemented fiber systems have not only remarked on the compelling new coverage options now available to them, but also a decrease in storage and transportation expenditures. As we’ve already discussed, fiber cables are small and light compared to their copper equivalents, which can weigh up to 20X as much when bundled for ENG/SNG camera applications. What kind of mileage does your OB truck get with cable 20X heavier than it needs to be? Throw in the weight of copper shielding to protect the coax from its inherent susceptibility to EMI and RFI noise, and the problem is compounded.

Moreover, a fiber system has the advantage of being able to transmit bi-directional signals simultaneously. Coax, on the other hand, is a one-way street. Bi-directional communication can be mimicked with copper, but you’ve just thrown away half of your available bandwidth to do it.

4K

And, let’s not forget 4K. No matter where you are on the 4K opinion spectrum, it’s getting traction. At NAB this year, it was all about being 4K-ready here and now. But, what was a bit obscured in the hail of hardware is that fiber will underpin the whole prospect of eventually going 4K.

While you may now think fiber is the way to move your existing video, audio and data signals, until you’re ready to up the ante to 4K, it may still be a matter of convincing those upstairs. So, I suggest you go to your next meeting having first talked with experts in the field.

David Cohen is director of marketing communications at Miranda Technologies.