10 Essentials for Planning Your Fiber Optic System

•October 8, 2012 • Leave a Comment

10 Essentials for Planning Your Fiber Optic System


The design and planning of a fiber optic based A/V installation for professional A/V or Broadcast shouldn’t be a problem for the experienced system integrator or project engineer. But you need to keep in mind that working with fiber is different than working with copper distribution. Fiber has unique and beneficial characteristics that can only be exploited to your advantage if they are taken into account at the very beginning of the planning stages. Here are 10 essentials you need to consider when designing a fiber optic system for professional audio/video.

1) Start with a Clean Sheet of Paper    

One of the most common mistakes made when designing with fiber in an A/V or Broadcast system is to first design the system using traditional copper products and design techniques and then substitute and shoe-horn into it fiber optic elements. By doing so, you restrict your use of fiber to the technology limits of copper. Fiber optic technology and products are capable of being implemented in ways that copper cannot such as bidirectional transmission and multiplexing multiple, and dissimilar baseband signals on one fiber core.

2) Think A/V not Data

When designing with fiber you may have to work with the facility’s IT staff or their consultants. Remember one thing: when it comes to understanding how baseband A/V signals are communicated and the implication it has on any fiber infrastructure, IT folks are from Venus and A/V folks are from Mars. Even though modern baseband A/V signals over fiber are transmitted as 1’s and 0’s it is not data in the same sense that IT folks understand data as IP based packets using various compression schemes. The biggest difference is that baseband A/V, including SDI, are transmitted on a one-way basis with no error detection or correction protocols. This results in a need for much higher bandwidth and lower bit-error-rate for the end-to-end infrastructure.

3) Determine the Type of Fiber to Use

There are two types of fiber optic cabling called multimode (MM) and single mode (SM) and they are not compatible with each other. If you are given fiber to work with and have no choice it is imperative to know whether it is SM or MM and if it is MM, what type of MM such as 62.5u or 50u. Knowing what type of fiber is being used will be needed in specifying the electrical to optical converters for the signal types being communicated and other ancillary equipment in the system. It will also be used in calculating budget losses and estimating the maximum usable cable lengths. If given the choice, it is recommended that SM fiber always be used for its lower cost, superior bandwidth and low loss.

4) Determine the Lengths of Fiber Cable Segments

It is important to know the lengths of the individual fiber segments, especially if MM fiber is being used on a particular segment. When transmitting uncompressed baseband video signals, such as HD-SDI, the bandwidth required will severely limit the usable distance of MM fiber due to dispersion. As a practical matter, this is usually not a concern with SM fiber in all but the most exceptional cases such as inter-city communications.

If you are forced to work with fiber segments of different types, such as SM fiber between buildings and MM fiber within a building, don’t worry. There are active and passive equipment that can be deployed to interface between different fiber types successfully. And some products work with both fiber types right out of the box eliminating the concern all together.

5) Minimize the Total Amount of Fiber Used

It’s no secret that the cost of installing any cable infrastructure can be the largest cost component of a new system. Many times designers focus on the cost of the fiber optic converter boxes at each end of the fiber segments. But, with SM fiber you have the bandwidth to aggregate signals of all different types to reduce the number of cores to a minimum. Also, unlike copper distribution, multi-point distribution can be done downstream and does not have to be done at the source. For example, if you have a source on the first floor of a building that has to be distributed to multiple points on the 40th, then run just one fiber between the first and 40th floors and then use a passive or active optical splitter on the 40th floor to the destinations on that floor.

6) Understand this Term: “Link Budget”

Fiber is not a loss-free medium. There is attenuation of the light as a function of the type of fiber used, operating wavelength and length of the fiber. “Link Budget”, sometimes called the loss budget, is the maximum attenuation of light between the optical transmitter and receiver that can be tolerated before the receiver ceases to work properly.

The manufacturers of the “black boxes” that are placed at each end of the fiber to convert the electrical A/V signals into and from light specify, or at least they should specify, the link budget for their transmitters and receivers. Additionally, the manufacturer might also specify the individual transmitter launch power and receiver minimum sensitivity. This is particularly important for SMPTE compliant SDI products where interoperability with other manufacturer’s product may be necessary in your system design.

Knowing the optical loss in the fiber you are using and the link budget between the transmitter and receiver you can determine if you will operate with enough optical power margin so as not exceed the link budget.

7) Determine the Optical Connector to Use

There is a wide range of common and specialty fiber optic connectors that are used. Different manufacturers of “black boxes” will offer some, but not all, of the many different fiber connector types. In general, we have found LC connectors used in high-density rack installations and ST connectors used in desktop, throw-down and just about anywhere else. In outdoor and temporary field applications, often time specialty ruggedized connectors like those available from Neutrik and Lemo may be used. The fiber cable itself is usually sold in bulk with connector terminations usually done on site at the time of installation. This makes cable pulls easier. However, almost any distributor of fiber cable will offer pre-cut and terminated lengths on request.

The important thing to keep in mind is that you cannot assume that the fiber connector you have, or will get, on the fiber cable will match the connector that is standard on the product from the manufacturer. Some manufacturers offer more than one type of connector on their products. So be sure to specify, and verify, the connector type for both fiber cable runs and the equipment that will be at each end.

8) Think Bidirectionally

The bandwidth and nature of optical transmission allows full duplex bidirectional transmission over a single core of fiber. In fact, using multiple wavelengths in each direction, a great deal of information and A/V signals can be communicated. Audio, video, Ethernet and data can all coexist bidirectionally on one fiber core. This saves a tremendous amount of money, not only on the cable itself, but on related construction costs as the size of conduits and cable trays become minimal.

Normally, we do not transmit A/V signals bidirectionally over copper, especially when coax is used. But with fiber this can easily be done and signal types can be intermixed and aggregated.

9) Budget and Buy an Optical Power Meter

Your project is going to be expensive. And chances are good that the people who will be tasked to install and make it work will be new to fiber or have little experience with it. Perhaps this is your first fiber optic project too. Here’s a tip to save you time when it comes time to make it all happen: buy a fiber optic power meter. They are not expensive and they can be obtained for just a few hundred dollars, but they are essential to any installation and can save you their cost many times over on just the first job.

Small, compact and easy to use, the “power meter” measures the optical power or “brightness” of the light at the end of a fiber cable segment relative to the power when it is “launched” at the transmitting end of the fiber. The wavelength of the light on the fiber is invisible so the only way to measure its strength, or know if it is there at all, is to measure it electronically with a power meter. Segment by segment you can measure the integrity of your system and also get a first-order determination if your transmitting boxes are working as they should.

10) If You Don’t Understand, Just Ask!

Fiber optics isn’t complicated, it’s just not always clear. Different manufacturers specify their products in inconsistent or incomplete ways that make finding the information you need frustrating. This, together with the “folklore” that surrounds fiber optic communications, can make the system design task somewhat frustrating. But don’t be afraid to ask for help from those in the industry that have many years of practical experience with communicating professional A/V signals over fiber in a wide range of applications. We are always happy to help.

If you have any questions, feel free to contact us at info@commspecial.com or 1-631-273-0404. Alternatively, visit our website, http://www.commspecial.com for the latest product and educational information.


Fiberlink® 3620 Composite Video & Audio Series

•November 17, 2009 • Leave a Comment

The Fiberlink® 3620 Series transmits composite video and two independent audio channels over one multimode or single mode fiber. It is ideal for Videoconferencing, Broadcast and Cable TV and Digital Signage applications.


  • 10 MHz video bandwidth per channel
  • Video channel is compatible with NTSC, PAL or SECAM video standards
  • Two audio channels that may be user-configured for balanced or unbalanced inputs and outputs
  • Switch selectable audio output gain boost of +0 dB or +6 dB
  • Indicator LEDs monitor power, video and audio signals
  • Transmits over one multimode or single mode fiber
  • No adjustments; pure digital processing and transmission

  • Wide range power supply allows operation from both AC and DC sources

Card version fills one slot in 6000A card cage

Fiberlink® 3360 3G/HD/SD-SDI & 4 Pair AES Audio Series

•November 17, 2009 • Leave a Comment

The Fiberlink® 3360 Series allows you to transmit 3G, HD or SD-SDI as per SMPTE 424M-2006, 292 and 259 with the ability to embed up to 8 channels (4 pairs) of AES/EBU digital audio. Convenient switches on the 3360 Series transmitter allow the operator to embed each of the four pairs of audio independently, to strip previously serialized audio, or to pass it through without modification. At the receive end of the fiber optic link, the operator can decide which audio pairs they need de-embedded.

Audio signals are not required to operate the Fiberlink® 3360 link and it can be used as a stand-alone 3G/HD/SD-SDI optical link. Previously serialized data is left intact throughout the entire transmission process and the 3360 Series is immune to pathological signals over the entire budget link and operating temperature range.

Signals are equalized and re-clocked prior to fiber optic transmission and the 3361 receiver features a re-clocked SDI output.

The 3360 Series is compliant with SMPTE 297-2006 and has the ability to operate seamlessly with Fiberlink® Matrix and other SMPTE 297-2006 fiber optic compliant devices.

Available in card versions and a small footprint box version, it is ideal for broadcast or corporate studios, OB vans, rental and staging, auditoriums, stadiums and theaters, airport or transportation hubs, distance learning, surgical or medical imaging and more!

Fiberlink 3350 Series of 3G/HD/SD-SDI Fiber Optic Transmitters

•November 17, 2009 • Leave a Comment

The Fiberlink® 3350 Series allows you to transmit 3G, HD or SD-SDI as per SMPTE 424M-2006, 292 and 259, with or without embedded audio and data, as well as DVB-ASI over one single mode or multimode fiber. Signals are equalized and re-clocked prior to fiber optic transmission. The 3350 transmitter features a re-clocked and equalized SDI loop through and the 3351 receiver features two re-clocked and equalized SDI outputs.

The 3350 Series is compliant with SMPTE 297-2006 and has the ability to operate seamlessly with Fiberlink® Matrix and other SMPTE 297-2006 fiber optic compliant devices.

The 3350 Series is immune to pathological signals over the entire budget link and operating temperature range.

Available in card versions and a small footprint box version, it is ideal for broadcast or corporate studios, OB vans, rental and staging, auditoriums, stadiums and theaters, airport or transportation hubs, distance learning, surgical or medical imaging and more!

Embed and de-embed AES/EBU Audio with your SDI

Finally, an affordable optical matrix switcher: Fiberlink Matrix

•November 17, 2009 • Leave a Comment

Fiberlink® Matrix is a fully configurable and SMPTE compliant 32×32 optical router. The inputs and outputs can be ordered in quantities of one and the input and output quantities do not have to match providing you with the ability to build a Matrix that is ideal for your specific application and budget!

Available with LC or ST connectors, Fiberlink® Matrix is fully compliant with SMPTE 297-2006, supports up to 3G-SDI data rates and works with both single mode and multimode fiber. Redundant power supplies offer operational confidence. Best of all, the entire enclosure is only 3 RU high!

Multicolored and illuminated front panel push buttons make operation a snap and the status LEDs clearly reveal the current status of the matrix. Presets can be stored and recalled through the front panel or via RS-232 control or via the Ethernet HTML based GUI. A convenient USB port allows you to back-up and transport your preset configurations to another Fiberlink® Matrix. Ethernet HTML GUI facilitates firmware upgrades as well.

Winner of TVB Europe’s Editor’s Best of IBC 2009 Award and chosen as one of the top five products introduced at InfoComm 09 by Pro A/V Magazine!

The Standards Dilemma in AV

•December 11, 2008 • Leave a Comment

The problem is not that AV doesn’t have any standards – it’s that we use too many of them without knowing how or why.

How many times have you had a project that combined products from multiple manufacturers, and it “just worked” from both the mechanical interoperability and the signal compatibility perspectives? I didn’t think so. At the very least, connector gender changers are needed, or worse yet, boxes between boxes to perform some signal conversion magic to arrive at the desired result. Countless hours are spent tweaking, rethinking and resolving interfacing nightmares that plague the pro AV industry as a whole.

That is the life of a system integrator in the pro AV industry today. But, what remains unclear is why the industry endures this painstakingly difficult and costly methodology while other related industries such as Broadcast and IT, enjoy virtually seamless interoperability between their equipment. They can plan complex system designs with great accuracy, keep these system designs within budget and execute them with relative ease. They install components from an array of manufacturers and have them coexist predictably in relative harmony, both at the mechanical and electrical interface levels. And they do this repeatedly, confidently, every day. Isn’t this what the technology manager wants?

How do these industries achieve this? More importantly, can the pro AV industry follow suit? The short answer: they do it with standards and yes, pro AV too can enjoy the benefits of standards. The question is, how?

To understand the steps the pro AV industry must take in order to achieve a standards-based utopia, we must first understand why the problem exists and how both the equipment manufacturers, the system integrators and the technology managers are actually contributing to it.

One could argue that the pro AV industry does employ many of the available standards most of the time, and they would be absolutely correct. However, this is at the heart of the problem: we are using too many (if not all) of the standards available today in many situations and none at all in others. Manufacturers and users alike are utilizing standards with little or no guidance as to which standard to use, how to use them, and when to use them. When do you want an RCA or an XLR connector? Do you want an ST, SC, FC, or LC fiber optic connector? BNC or RCA for your video? Should S-Video be two BNC’s or two RCA’s or a 4-pin mini DIN? Should the audio screw terminals be fixed or removable? Are there true performance differences between them or is their choice based solely on preference? When do you use one or the other?

And these are just some of the mechanical interfaces available. The electrical interfaces between devices can quickly become more complex and unclear than their mechanical counterparts. What is the nominal level of line level audio? Is this level defined when terminated or unterminated, and under what load and source impedances? What exactly are the accepted data rates for RS-232? What are the accepted electrical levels and timings for RS-232? What is the accepted rise time for an HD-SDI signal? Should sync be terminated, and at what impedance and voltage levels?

And while mechanical interface incompatibilities may be easier for an integrator to circumvent, electrical interface incompatibilities can be virtually impossible to solve. This is especially true when we are faced with products that have implemented an interface that is similar to, but not exactly like the standard resulting in a new, incompatible iteration of what was once a well-defined, field proven standard.

Sadly, there are manufacturers that base their entire business model on this, ignoring the existing standards or, worse yet, creating their own. In many cases, this results in closed and proprietary systems that compel the system integrator to use only that manufacturer’s solution for most or all of the system design.

For example, consider the number of interface products that communicate using, what appears to be, standard RS-type data that are not compatible. If the product adhered to the standard, how could they be incompatible? These products are incompatible because the manufacturer deliberately chose to make subtle modifications to the electrical levels, timing levels, or other parts of the protocol to ensure that only their products would be compatible. The consequences of this are far reaching.

If any given manufacturer’s solution achieves some, but not all of the client’s requirements, the integrator must add additional hardware or services to the system. In a proprietary system it becomes very challenging if not impossible for an integrator to interface into this system using other components and for the technology manager to predict the results and cost. Rather than deciding upon and purchasing a product that offers the client the best performance and value, the integrator is often forced to install equipment because it is the only unit compatible. In other cases, they create ad hoc solutions to circumvent their interfacing problems that increase the system cost and the time to install and maintain that system… all while reducing its overall reliability and profitability.

The system integrator contributes to this by accepting, or at least, being complacent with these industry practices. Ultimately, manufacturers build what their customers ask for and standards compliance in pro AV hasn’t been a priority on that list.

As the pro a/v systems being installed continue to grow in complexity, the number of arbitrary components being installed continues to grow as well. Who is ultimately responsible for maintaining and troubleshooting these unnecessarily complex and often cumbersome systems?

After the system integrator completes the system installation, it falls upon the technology manager to keep the system running smooth and to respond immediately when it doesn’t. They have a clear picture of the overall signaling objectives and they know how it is all interconnected. What they may not realize is that there are additional components lurking in dark corners or ad hoc undocumented design changes that make the whole system work and it isn’t until a problem is reported that these interfaces and changes are discovered.

For example, they may know that DVI is being sent to the classrooms over fiber, but they may not realize that there are interface boxes performing an HDMI to DVI conversion prior to the fiber optic transmission. When the system goes down and the technology manager investigates the issue more closely, they are left to troubleshoot not only the fiber optic link, the expected component of the system, but the interface boxes at the ends of that link, the additional connections and cabling as well. Of course, this scenario becomes more difficult to manage and diagnose when working with the many products that require software in order to function properly.

This is a relatively new and painful experience to the technology manager who often has their roots in the IT and/or Broadcast industries.

If standards were employed in pro AV today, what benefits can we expect?

When manufacturers embrace the standards that define the solutions for common mechanical and electrical interfaces, manufacturers can then focus on the core of their product. They can innovate and develop products that offer more value, features and ease-of-use. And they can respond to industry trends more quickly with a lower cost-to-market. In short, manufacturers become successful because of what is in the box when they compete on value.

System integrators and technology managers can design and implement complex architectures with predictability and they can chose product based on its true merit, performance and value. They can eliminate the myriad of in-between boxes that have become essential components when interfacing incompatible products. This lowers equipment costs, installation times and labor fees. When working with proven and documented standards, the integrator is no longer challenged with solving complex signal and interface problems on their own. Instead, the integrator is left to do what they do best: integration.

Technology managers can enjoy increased reliability and respond more quickly when they no longer need to troubleshoot additional equipment, connections and cabling when diagnosing problems. They can achieve more of their pro a/v goals with less money and in less time, something that everyone appreciates.

So how does an industry become standards-based? It starts with the integrators and technology managers requesting, if not demanding, the seamless interoperability and system predictability that related industries like Broadcast and IT have been enjoying for decades.

But, which standards? The pro AV industry is not the Broadcast or IT industry. Should AV have it own standards or perhaps create recommended practices based on existing standards from related industries?

We certainly don’t need to develop any new standards; rather, we should choose from the plethora of proven electrical and mechanical standards that already exist. The existing standards are well documented and proven in the field. For example, the Society for Motion Picture and Television Engineers (SMPTE) is a standards development organization that has roots dating back to 1916, and has developed a standard for most of the signal types used in audiovisual technologies today. In fact, SMPTE is already developing standards for emerging technologies. These standards are very well defined and meticulously documented, making it easy for our industry to understand and embrace them.

Many in the pro AV industry believe that it’s on a collision course with Broadcast and IT. Embracing standards now ensures that AV can coexist in harmony when the merge happens in full effect.

That leaves the pro AV industry to choosing which standards are right for the unique applications that exist for pro AV. The industry needs a governing body that will embrace the community as a whole and technology managers can play an important role. In fact, small manufacturers as well as large, system integrators, consultants, technology managers should all participate in an open forum. As Broadcast, IT and pro AV are being homogenized, the technology managers are now in the unique position to demonstrate the benefits of standards and recommended practices that they enjoy when working within the Broadcast and IT industries to their fellow pro AV colleagues. The technology manager should dictate, where possible, a standards requirement for their facility, that the a/v systems they deploy have the same level of interoperability, reliability and manageability that they have when working with Broadcast and IT hardware and software.

Ultimately, the industry needs to discuss and select the standards that make sense for them and then, most importantly, stick to them when they choose them. For example, if we standardize on RS-232 or RS-485 type data for an application, then the manufacturer needs to strictly adhere to the standard that defines RS-232 and RS-485 data including the data rates, handshaking and connector types, not to mention the electrical levels and the timings defined within those standards. The industry simply cannot afford to embrace some, but not all, of any given standard.

Standards equal predictability. When you can predict results, complex system designs can be implemented with confidence, and installed on time and on budget. All of the standards we need already exist. We only need to choose them, embrace them and utilize them consistently. Once that’s been achieved, pro AV will be as efficient and profitable as the Broadcast and IT industries. And that’s good news for a changing industry and everyone in it.

By John Lopinto

John Lopinto is President & CEO of Communications Specialties, Inc.

Fiberlink Fiber Optic Termination

•December 11, 2008 • Leave a Comment

This video is a Fiberlink Fiber Optic Termination demonstration performed by Communications Specialties CEO John Lopinto. This demonstrates how easy it is to terminate a fiber optic cable without the use of glues, expoxies, grinding or polishing.

View the Fiberlink Fiber Optic Termination Video
learn about the Fiberlink Fiber Optic Termination Kit