SCOTT NARDELLI /
12.01.2011 12:00 PM
Making light work
Fiber optics prove a versatile tool for broadcast distribution.

The telecommunications industry has used fiber-optic technology since the 1970s to revolutionize data transfer and help usher in the digital information age. The broadcast industry began to adapt the technology in earnest only in the mid 1990s, as part of the move toward DTV and HD production. Since then, the use of fiber optics for content production and delivery has gone from long-distance applications only to every aspect of the production and delivery process.

Remote productions have benefitted greatly from fiber optics, as venues have installed fiber networks for easy interfacing with OB vans and production equipment. Fiber connections are now routinely found everywhere on production and post-production equipment across the board, including cameras, support gear and audio consoles, streamlining the setup and operational process while lowering its cost. The broadcast industry has come a long way in adopting fiber, and the new generation of fiber-optic cables and connectors will continue to bring enhanced benefits far into the future. This article will examine infrastructure, the adaptation of fiber in equipment, connectors and new cables that impact the production side of the broadcast equation.

Shedding light on the topic

Fiber-optic transmission of digital signals has been with us for nearly four decades, but the guiding of light by refraction — the basis of fiber optics — has been around since the early 1840s. That is when people began experimenting with light passing through a stream of water. This early experimentation evolved into image transmission through glass tubes in the 1920s, with refinements over the next two decades yielding the modern glass optical fiber with a suitable refractive index to accurately carry information. Development then moved into fiber bundles for image transmission. From that point, refinements in chemical makeup and manufacturing techniques — in which, for example, a fused quartz ingot could be stretched for up to 40km per strand — led to the creation of telecommunications fiber infrastructure suitable for digital transmission.

The advantages of an optical-based infrastructure are legion over a copper-based one in almost every way, from significant transmission loss improvements to eliminating EMI and RF interference. For the broadcast industry, the bandwidth demanded by HD production necessitated the move into fiber to overcome the limitations of copper.

The new infrastructure

Live sports and remote events present two excellent examples of how fiber has impacted the broadcast industry. Fifteen years ago, a company seeking to use fiber at a football game would need to run its own cable throughout the stadium. Fiber optics are significantly lighter and easier to run than copper but, at that time, venues had not yet embraced fiber to the same extent as the telecommunications industry. What was de rigueur for telecommunications was still considered unproven for the broadcast industry.

Today, however, this gap has completely closed, as all new arenas and stadiums include fiber as a standard component of everyday construction practice. The older venues, which previously would have been a one-off installation, have now upgraded with a fiber infrastructure to stay competitive.

Also, in the early days, companies chose fiber technologies originally intended for military or other applications. These seemed safe and reliable, but there was no technical ability to support them. An example of this is an early fiber connector used by the military, a 12-channel hermaphroditic type for field applications. No one on the broadcast side had the experience to service something like that in the field. Judging by those experiences, the industry viewed fiber optics as expensive and somewhat unreliable, as broadcasters did not know how to maintain or repair a fiber infrastructure. There was also a manpower issue because in the industry at that time, there was a shortage of engineers who understood how to work with fiber.

Fortunately, this piece of the fiber puzzle has been solved, as today's design and integration companies offer a new generation of fiber-informed, broadcast-savvy individuals who understand the needs of the broadcaster and also know about fiber data transfer protocols and installation practices. This new generation of engineers understands the unique requirements and aspects of broadcast television and live remotes, which is a significantly different environment from traditional telecom, with its own broadcast-speak such as “EVS network,” “tie-run” or “using an HDC1500” — terms that would leave a telecom engineer at a loss.

Equipment advances

In today's coverage of live sports and other events via fiber, fiber technology has proliferated, and the manufacturing sector has moved to optically enable its equipment. Although the basic makeup of a glass fiber hasn't changed much over the decades, the availability of equipment specifically designed for broadcast has increased significantly. Fifteen years ago, the industry was trying to use telecommunications-style products for broadcast applications. Now, nearly all major broadcast suppliers are working in the optical domain to some extent.

Ten years ago, the only router a company could buy had BNC connectors on the back. Today routers are optically enabled and move signals via fiber. Ten years ago, moving those signals out of the router required a different manufacturer's device that was made specifically for the broadcast industry to convert electronic signals to optical. Today an OB van has dedicated, fiber-enabled routing capabilities and cameras connected by fiber. As a result, the signal path and workflow have been simplified, complications have been reduced significantly, and the knowledge level regarding fiber has risen. Further, fiber has simplified the infrastructure because it is an agnostic medium, meaning that it does not matter if the signal is carrying video, audio or metadata. Fiber can handle any type of data. In the past, cabling came down to decisions about what kind of coax connector, audio cable or camera cable was needed to wire the system. With fiber, the equipment defines the signal type.

Making the connection

Once installed and a part of a production workflow, the passive aspects of a fiber-optic installation do not change from day to day. With little maintenance, a fiber line can function for decades. However, there is a difference between connectors that are ideally suited for the rigors of the live event broadcast and their telco counterparts. For instance, running fiber for a golf tournament requires a robust connection. Various connector formats have been tried over the years, including everything from hermaphroditic multi-pin connectors to ultra-robust expanded-beam connectors.

In the end, many broadcasters still rely heavily on the ST connector, a technology that has existed for more than a quarter century. The advantage of the ST connector is that a technician anywhere in the world can easily install one on a fiber, the parts are extremely inexpensive, and it is a positive-locking bayonet style, such as the familiar BNC connector used in broadcast applications. The popularity of the ST connector also demonstrates the necessity of having an engineer and crew that understand the challenges involved in wiring a live, one-off event such as a golf tournament.

Another benefit of fiber is that different types of connectors can be used on either end of the cable run. For example, audio over copper has several types of connectors, with equipment dedicated to such connectors as male and female XLR. An engineer probably would never have occasion to create a wire with XLR on one side and BNC on the other. With fiber, a relatively fragile LC-type connector found on a piece of equipment safely racked in an OB van can be used on a cable with the more robust ST connector on the other end that is out in the field.

One of the biggest revolutions with connecting equipment is the development of the small form-factor pluggable (SFP) or Mini-GBIC transceiver. Essentially, this device allows a digital signal to go from a fiber to a copper Ethernet line. SFP transceivers support SONET, GigE, Fibre Channel and other communications standards, making the jump to another medium extremely easy. SFP allows a company to buy a box that does what is needed for a job from a signal transport or aggregation standpoint and then use SFP to decide what medium is necessary to best complete the setup. Unfortunately, SFP uses the more fragile LC connector, so attention must be given to protecting the fiber connection going into SFP.

Tying everything together

During the 1980s, the AT&Ts and Level 3s of the world put down what became a glut of underground fiber for long-haul installation between states and countries, making fiber hard to come by for the smaller company. The benefit, however, was that the cost of fiber came down and different types of cables began to be created specifically for the broadcast industry. Several companies built the SMPTE hybrid cable for cameras that had both the AC power wires and the fiber-optic line in one cable.

The cable industry has gone from older, gel-filled cables to what is known as dry tape, which uses a powder instead of gel for more permanent placement outside. It has also developed tight buffered fiber, allowing for a quicker, easier installation. This technology is predominantly used in military tactical cables, which are nearly indestructible and were adopted for temporary installation applications.

These military-style cables now come in double-jacketed varieties to provide even more protection. One variation features a noxious chemical between the layers to discourage rodents from biting through the cable. Military tactical cables are ideal for outdoor events covering everything from golf to world cup skiing.

Bright future

The implementation of fiber for the live event industry has many benefits, including reduced setup time, improved distribution of signals, long cable runs without transmission loss and dramatically reduced weight. As signals continually require more bandwidth and equipment continues to aggregate more signals into a single transmission path, optical fiber will continue to be a reliable and robust method of transmission and distribution of broadcast signals.

Over the next several years expect to see more and more equipment fiber enabled right out of the box, to some extent reducing the complexity even further by eliminating the need to convert signals after the fact. It is a bright future for broadcasters and optical manufacturers as optical transmission and equipment have proven their worth to an industry that has no tolerance for unreliable technologies.

Scott Nardelli is senior vice president at Bexel.



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