08.16.2005 03:18 PM
How To Buy: A Routing Switcher
Routing switchers have been around for nearly 50 years, and during this time manufacturers have made significant technological advances and improvements in their design.
During its infancy, the technology of routing consisted of little more than basic crosspoint switch requirements. Now, as the industry migrates from analog to digital and on to HD, facilities must begin to address signal distribution for legacy equipment, distribution for digital and HD, data distribution, networking, compression and conversion.
Trying to take all of this into consideration can be intimidating, so a few key criteria need to be understood when going into the selection and purchase of a routing system for a facility today.
Planning For A New A/V Distribution Solution
As with any improvement to a facility, the deployment of a routing switcher requires a budget and time frame. Physical considerations such as space requirements, efficient studio and control layouts, and necessary interconnects should be identified ahead of time. The needs of every part of the facility should be brought to the table during this planning phase to ensure a comprehensive, future-proof routing solution.
Obviously, format support must be considered. An evaluation of a facility’s existing systems and systems that may be integrated in the future is key in assessing just how robust and flexible a switcher is required. Likewise, compatibility with existing systems will narrow the field in terms of the switcher that is right for a particular facility. Reliability of the routing system and redundancy for power and control are important features to be considered upfront. Early routing systems were architecturally configured as “output oriented” switchers essentially inputting many signals into one printed circuit matrix card that provided only one output path. If a card failed, only one output would be affected. Today, larger matrix cards are available based on more reliable components, and smaller architectural footprints. The net result is that less power and space is required and pricing is lower. Redundancy in the matrix cards is now technically feasible where absolute redundancy is a prime consideration. PESA Switching Systems pioneered this technology for a specific application during the 1988 Olympics for use by NBC. This technology has been replicated for use in the Cheetah routing systems.
The network required for signal transmission is also critical, as it forms the foundation for moving audio and video. Existing wiring can be put to use to keep costs down, but the soundest strategy is to run more cable or fiber than is strictly necessary, thereby ensuring adequate capacity for future interconnects. If HD signals are to be used, an eventuality for most facilities, the benefits of installing a fiber network are invaluable—even if the up-front investment is higher than for coaxial cable. Fiber handles long runs much better than cable and provides greater versatility in incorporating IT-based broadcast systems.
Ensuring Required Format Support & Functionality
The first major requirement to consider in a routing switcher is its ability to handle all of the signals and formats that will be managed within the facility. The switcher must also have the capacity to handle the necessary signal volume—with the means of easy expansion in terms of signal number and format.
In making the transition to digital, the question arises: Do you throw out your current analog equipment, or is there a way to protect your investment by effectively continuing to use analog? With the move to digital, many facilities are finding that they must now be capable of handling both analog and digital equipment side-by-side. True flexibility in routing allows a facility to retain its use of analog equipment while converting to digital operations.
Analog-to-digital conversion products (A/D and D/A converters) make sense, economically speaking, for some applications, but they cannot completely replace a routing switcher. Routing switcher manufacturers address this issue by providing plug-in output modules that enable signal conversion within the router, thus eliminating the need for outboard conversion products. Current routing switchers are able to switch not only like signals; they can also convert analog signals into digital format at the inputs or back to analog at the outputs. The use of digital audio within a facility also demands a common reference to handle audio-delay issues. In this case, the router must also be able to accommodate multiple sync signals.
One of the biggest unknowns today is how to standardize a facility on a digital format, and which standard to choose. Although SDI makes the most cost-effective choice for now, there is no doubt that HD will increasingly be adopted—alongside other digital formats—by most facilities.
Before making such a large and important infrastructure investment, it is important to consider all the other possible data rates allowed to pass through the router. Given all of these considerations, the router selected by a facility should allow the advantage, and more importantly, the flexibility of passing analog, SD, HD and data through the same frame. Prior to purchasing a routing switcher, the user must envision the way in which HD and SD signals will be used and integrated.
Router manufacturers are exploiting new routing technologies such as time division multiplexing (TDM) and fiber optic switching. Certainly not new to this industry, they are seeing much more interest as products become more affordable. So though traditional crosspoint architecture is holding its ground for now, future routing requirements are likely to be met by a combination of data switches and other network solutions.
Establishing Effective Routing Control
The second major consideration in specifying a routing switcher is its control system. In the beginning, the router control system was based primarily on a simple microprocessor board connected to the routing switcher via some type of serial connection. Today, most control systems are Windows-based systems with the ability to connect through both serial and/or Ethernet connections. The user interface now consists of a variety of control panels that provide specific functionality to manipulate the router. Versatility of the router is gained through the different types of panels. As an example, in mobile applications a smaller panel footprint is desired, together with dynamic change capability from the panels. Configurations of redundant information can be moved around with a drop-and-drag feature minimizing set up time. Control of the router can now also be accessed from the Web through browser portals complete with password protection and user limitations.
The chief area of interest today is employing network connectivity for routing control. Leveraging the standard Ethernet-based networking found in virtually every facility, this technology is now the most widely accepted form of audio and video distribution control. Future control systems are migrating toward an open-architecture concept, which allows maximum flexibility in interfacing and control. Up-and-coming solutions include control systems featuring their own software development kits (SDKs) to make customization easier.
Monitoring and control via simple network management protocol (SNMP) is also something that more and more facilities are considering. Using the Internet and wireless connections are other methods destined to become standard for routing switcher control. This trend becomes apparent as PC-based control systems are more widely accepted as the principal control system, in large part because they operate at speeds many times faster than similar systems did just two or three years ago. Open Ethernet-based design allows video professionals to tailor their control systems in accordance with their particular needs.
Looking Forward in Router Implementation
Multi-format signal handling capability and scalability are key requirements for any routing switcher system. While most routers available today are very much alike, it is only when a router is combined with a control system that a true solution begins to take shape. The IT and broadcast worlds continue their convergence, and the routing switcher is and will remain central to this process. It is the key link enabling broadcast equipment to communicate across local and wide area networks.
The next-generation routing system will be able to provide broadcasters with centralized and distributed routing and remote monitoring and diagnostic capabilities, as well as signal-integrity analysis that is expected to expand functionality and control over LAN, WAN and video networks. With responsibility for moving valuable video and audio assets across an enterprise, routing switcher technology will continue to serve as the heart of facility infrastructures for many years to come.
Bob McAlpine is senior vice president of sales and marketing for PESA. He can be reached at (631) 845-5020, or firstname.lastname@example.org.