Next to the DTV transmitter, a central router is one of the biggest capital expenditures a broadcast station will make. Large routing systems with all of the associated control panels and wiring can carry seven-figure price tags, not including costs associated with the design and installation of the router.
Once installed, the router is expected to work reliably in a 24-hour-a-day operation, typically for 15 to 20 years. Routers installed 15 years ago have withstood a dramatic revolution from analog television with stereo audio to a world of multiple HDTV and SDTV standards, DTV multicasting, and 5.1 channels of Dolby surround sound.
Routers installed today must be prepared for the inevitable changes in signal formats, channel counts and interface connectivity that will occur in the future. For example, while no broadcaster is currently broadcasting in 1080/60p, at NAB2007, 3Gb/s-capable routers will be one of the hot new technologies to watch. Not only are they a natural progression from today's 1080/60i and 720/60p HD broadcasts, but also we are seeing evidence that motion picture production is moving in the direction of 1080/60p, and many display devices are already capable of supporting 1080p natively.
Planning for 3Gb/s routers
Transmission at 3Gb/s is nowhere on the horizon, and production equipment is limited in terms of 3Gb/s cameras, switchers and servers. But, the issue of 3Gb/s capability is something that is going to slowly integrate into broadcast facilities over the next five years. The key questions:
- Will the router you buy today be capable of withstanding and supporting the technology changes to come?
- If the purchase is for a big “house” router, how long do you expect it to be at the core of your facility?
If the answer is 10 to 15 years, which is common, you need to look at future technology trends. A facility may just be converting to 1.5Gb/s HD-SDI now and have absolutely no current plan for 3Gb/s. However, wouldn't it be nice to know that as the 3Gb/s standard becomes viable for content creation, distribution and transmission over the next five years, your house router will be able to handle it without the need to throw out the frame or undergo a major redesign?
If the purchase is for a small black box-type router, say 32 × 32, buying something 3Gb/s-capable may not be as important because they are less expensive and don't necessarily have the same life cycle as a large router. Also, it is not uncommon to add a small router when dealing with a small number of sources/destinations in a new format.
Customers will most likely base their production equipment needs, switchers and cameras on their current infrastructure. Because the distribution backbone of a facility tends to be in service for longer periods of time, a move to 3Gb/s probably needs to be planned for earlier.
The key questions for customers considering a large router purchase that is going to last 10 years:
- Are the routers 3Gb/s-capable?
- If yes, how is that achieved?
- Do current modules have the ability, or is it going to be handled in their upgrade path?
- What does that upgrade path entail?
- If it does not support 3Gb/s, what are their plans?
Because many router vendors are already touting in their ads that they have 3Gb/s capability, this is something customers will increasingly be exposed to and need to start considering today.
Growing router demands
Another quantum leap on the horizon is the transport of multiple signals over IP or hybrid baseband/IP infrastructures. Audio demands also will be expanding dramatically. While analog and AES/EBU two-channel audio are currently the dominant audio formats, high-profile sporting events, entertainment shows and prime-time TV shows increasingly offer 5.1 channel surround sound. And many of today's digital audio consoles tout that they are already 7.1 and 10.1 Surround Sound-capable.
While all of the processing modules and other components in the broadcast infrastructure are not yet ready to support 3Gb/s, prospective buyers must ask vendors whether their product's architecture offers provisions for these technological advances on the horizon. It's highly likely that they will come to fruition in the router's lifetime.
With the advent of 3Gb/s routers and hybrid baseband/IP routers, we'll see more fiber-optic I/Os and cabling. The use of multiple transport streams over ASI via coax or fiber or IP via RJ-45 or fiber will also become more predominant. The need to save on wiring and connectivity costs will also lead to wider use of multiplexed signals between remote routers across a facility, city and country, as well as between mobile trucks.
The ins and outs of routing
Large central routers will be expected to deal with analog, SDTV and HDTV simultaneously, along with many popular new formats. The key questions:
- What type of converters should the router support?
- Should these converters be internal to the router or configured as a bank of external devices? (See Figures 1 and 2.)
- Or, should the broadcaster opt to add a level onto the router to handle new demands, such as adding a level of HD routing to a SD router?
While it's true that video servers and nonlinear editing systems can do format conversion, the router must step up to the plate to handle any up-, down- and crossconversion requests intelligently and automatically. This signal processing and management must be done with minimal effort on the part of the user. And the router's internal signal processing has become more complex to support new formats.
Whether these digital signal processes are internal or external to the router, that additional signal processing will introduce a slight delay into the audio that causes it to go out of sync with the video. Frame synchronization should be considered for the overall system, either externally or on the router's inputs to correct for this timing delay.
Also, with centralcasting and remote station monitoring, we're seeing more signals transmitted via fiber-optic cable, where discreet signals are combined into a multiplex and demultiplexed back into discreet signals. This audio conversion and delay issue is becoming an increasingly common occurrence.
A bit about audio
In buying new routers, audio needs must be considered carefully. Some of the questions to ask when buying a new large router:
- What do my current and future audio requirements look like?
- Do I currently have discreet audio, and do I plan to keep all future audio additions discreet?
- How many channels of discreet audio will I need? (If it is a lot, you may want to buy a frame just for current audio needs that is big enough to add inputs/outputs, as well as add channel count.)
- If your desire is to have embedded audio, do you have need to process the audio?
- If so, is the router capable of processing audio (e.g., channel swapping, summing, muting, level adjustments) internally?
- If not, or if the customer prefers to keep that out of the router, they need to make a list of the external muxes and demuxes that will need to be on the router's inputs and outputs.
Framing the issues
Overall, prospective customers should fully evaluate their own needs and the architecture of the router to determine if the investment they make today will be flexible enough to meet their facilities' changing needs tomorrow. Among the questions that a prospective buyer should ask:
- What has the router's architecture been designed for?
- Have the modularity, frame layout, power and cooling systems been designed for what the future may or may not hold?
- Can it meet the facility's requirements today, as well as adapt to what the future will be?
While baseband routing is the primary focus today, IP routing will likely become a reality in the future. So, we must ask:
- Has the router been designed in a way so that it will be able to route future signals, such as IP?
- If so, how will that be accomplished?
- Will it simply involve adding new I/O modules and updating a database?
- Or will it require a separate frame?
This is a bit of an unknown, but it is not unlike asking the old “is it future proofed?” question.
Getting in control
With large routers, there are many choices to make. Large routing systems often offer different types of control panels that can be located throughout the facility, depending upon the unique requirements of each work area. Router control panels can be X-Y, multi bus, single bus or button per source in function, and hardware, software or Web-based in type. Prices are going to vary depending upon size, type and quantity of the control panels that are chosen, and that's something the broadcaster and systems integrator will have to consider.
With a Web-based interface, control, configuration and diagnostics can be accessed from PCs that can log into a facility's LAN or WAN, thus making it easier to control routers that are on site locally as well as remotely.
Also, different areas of the facility have control requirements that call for different types of panels. They may also vary as to the accessibility of numbers of sources and destinations. Thought needs to be put in to analyze job function to determine the type of panel required, as well as user and group access rights and privileges.
Because control panels are not typically on a large router's frame itself, it must use a communications protocol to talk to the central router. Today, these connections can be made via serial port or coax, Ethernet and connection via the Web.
Control questions
The selection of control panels is an area that requires careful consideration. Among the issues that a prospective buyer must consider:
- How do different user groups need to view the sources and destinations on the router?
- How often do their particular list of sources and destinations change?
- What is their work location in relation to the frame's location?
There is a wide range of panels to choose from, and they vary by physical size, layout, menu structure, method of communications and price. There is no one-size-fits-all, and facilities will almost always have a combination of them. A designer needs to interview the various user groups to determine what their needs are so he or she can select the right panel for that job function. This is an important point. This is the user interface to the router. The system may run great, but a clunky interface will leave the engineering staff having to defend its decision.
Planning for growth
Planning for growth means anticipating changes and planning for how those changes will be handled. Questions to ask before buying:
- What are my control requirements?
- How is the router configured, and how easy is it to change?
- If you need to make changes, such as modify a database or add any I/Os, how does the system incorporate those changes?
- Can these modifications be done in the background, with little or no disruption, or do they require having the system to go down for a period of time?
The user needs to pick a frame size that will handle their current needs as well as future requirements. If a customer needs a 128 × 128 HD router with no expansion, that could most likely be put in a fairly small frame, say 10RU or smaller. If, however, the customer needs to expand, by how much does he or she need to expand? Is it just that particular format, or will the customer be adding additional formats over the life of the router?
Also, you don't have to buy a completely full frame right off the bat. Different manufacturers have different I/O granularity. Consider the cost to upgrade. A smaller I/O size potentially means it will be cheaper per board, which in today's world means adding a board or two for a few inputs doesn't have to go through the capital process.
The bottom line
Five years ago, many installations involved a separate video and audio router, but with advances in technology, it now makes sense to combine video and audio routing in the same system. For a television broadcast facility, a smaller router is beneficial because it leaves space for other things. But on today's space-challenged mobile production units used for HDTV telecasts of sports and entertainment, space is a critical concern.
A few years ago, many 256 × 256 SDI routers with AES audio would have required multiple frames for each format, all with their own power supplies, fans and controllers. Today, comparable functionality is available in a single frame that is 30RU or smaller.
This progress is owing to advances in the internal circuitry on the components; improved I/O layouts; improvements in power consumption and cooling; and smaller, faster processing components. This drastically reduces the physical size of the cards.
This consolidation has, in turn, reduced the footprint of the router itself, as well as the number of power supplies that must be used. The drastically reduced power consumption and cooling requirements lower the cost of operation, as well as extend the life of the system components.
For owners of older routers, the savings on the electricity bill and the cost of replacing bad power supplies can be significant over many years of operation. And that is money that could be applied towards the purchase of a newer, more energy-efficient router.
A house router has to work. So we need to ask:
- How reliable is it?
- Are the critical parts hot swappable?
- How easy is it to get to those parts if there is a failure?
- What is the power draw of the frame, and how does it cool?
That may sound trivial, but electricity bills come every month. It's part of the cost of ownership. A router that draws less power will cost less over its lifetime, while one that cools well will not require as much air conditioning. And those factors, combined in an efficient system, will allow for a longer life span of the individual components in the frame.
Final key points
In a cost analysis of a major router purchase, consider that internal converters will piggy-back on the router's existing cable and power supplies, whereas external routers will require additional cabling and power. Because of the complexities involved with the purchase, design and installation of a large central router, as well as the relatively lean engineering staffs at most facilities, many broadcasters and mobile truck companies must enlist the help of systems integrators.
However, once the system has been installed, broadcasters must plan for repairs, configuration changes and upgrades because these will be inevitable. Therefore, choose a router that provides as much easy accessibility from the front of the router, so you don't have to move equipment or pull it forward to access it from a rear panel.
Fans, control panels, power supplies and other key components all need to be hot-swappable parts. And there should be back-up components ready to take over should the main units fail. After all, fail-safe operation is the broadcasters' primary goal.
Todd Riggs is product marketing manager for Harris Broadcast Communications, Router Systems Division.
