Router systems should minimize interruptions and maximize flexibility.
Nearly all modern TV facilities are built around a central routing switcher, and in recent years, these routers have been growing in size. Where just a few years ago a normal routing system would have been 128 inputs and 128 outputs, routers now are commonly 256 × 256 and larger. Specialized systems in large production facilities, uplink facilities and mobile production units often use routers that are at least 528 × 528, and systems of 1000 × 1000 and up are becoming more common.
As routing systems become larger, the design of the control system becomes more important. Large routers often require more frequent reprogramming, and the task of presenting source and destination labels to the operators in a useful and helpful way becomes quite challenging when thousands of labels are involved.
Well-designed control systems are crucial for another reason. Unlike other types of broadcast equipment, routing systems have a long service life. A typical routing system is expected to be in service for at least 10 years and often longer. This means that the router will serve multiple generations of source and destination equipment, a fact that makes it crucial that the router is readily upgradable to suit the working environment as it evolves.
The complexity of contemporary broadcast requires that today's routers, regardless of size, offer a wide range of features for improved signal-handling flexibility and greatly enhanced operational reliability. Features that are considered essential include 3G operation; control, crosspoint and power supply redundancy; a compact, space-saving physical design; and low power consumption for reduced heat loading and prolonged service life. (See Figure 1.)
As facilities' needs continue to evolve, equipment is added and removed from the routing system, and the technical crew must reconfigure it — usually while it remains online. Each configuration change requires sources and destinations to be relabeled or reconfigured, and control panels in all areas of the system have to be reprogrammed. (See Figure 2 on page 30.)
Size, complexity and evolution combine to make a well-designed control system a key component of the routing system and for the technical staff, which keeps the overall operation running smoothly. Such a control system automates repeated steps and performs error checking to ensure, for example, that a typing error doesn't have disproportionate consequences. The following control system features will make router setup and operation easier.
In most cases, the technical crew receives advance notice of changes to be made to the system. If the router control system allows for offline editing of configuration files, the entire system configuration can be prepared in advance and installed at the time of the changeover. This will not, of course, prevent the last-minute changes that will always occur, but it will give the technical crew a basis for testing the new configuration.
In every router control system, normal operation is interrupted when the system must be reprogrammed. In some systems, this process is quick enough that operators are not inconvenienced by the interruption. In other systems, the full reprogramming cycle means an interruption of several minutes. One way to reduce system downtime is to remove control-panel reprogramming from the system configuration process. The best systems do this by making it possible to reprogram individual panels or groups of panels, while the rest of the operation hums along unaffected. This is a big plus in reducing complaints from the production crew.
The most time-consuming part of setup is reprogramming dozens of control panels to reflect the new system configuration. This is where the design of the router control system is potentially helpful. Most control systems offer a GUI for panel programming, and the best ones allow the GUI to be customized, for example, to allow separate views of certain parts of the system, reducing on-screen clutter so the operator can focus on specific devices.
Another useful control system design feature is the ability to clone panels, i.e., to create a master panel of each type with all programming changes automatically reflected in each panel that is copied from the master. When the cloning feature is impracticable, a good system allows all or part of a panel's configuration to be used as a starting point when configuring other panels of that type. This can be a tremendous help when the system has multiple panels that require specific configuration for that operator's position.
Configuration management tools
During the setup of a complex routing system, there may be dozens of iterations of the control system configuration. A good control system must feature a full set of tools to reliably save and recall these various configurations and provide a fail-safe system to back them up. (See Figure 3 on page 32.)
Rigors of mobile production
A particularly demanding environment for router systems is mobile production. Whereas a TV station's router may be reconfigured or updated a few times per year, mobile systems typically are completely reprogrammed for every show. Over the years, this has provided plenty of challenges for the designers of these systems, but the improvements and enhancements that come out of mobile system applications have proven to be useful to all routing switcher users.
Monitoring system operation
In addition to the system configuration software, the router control system must provide a comprehensive toolbox to monitor the operation of the system. Alarm indicators such as power supply failure and temperature alerts must be presented in a clear and easily understandable form to the maintenance crew so corrective action can be taken.
The monitoring/maintenance utility is also the logical place to provide tools for operational supervision of the system, giving access to high-level functions such as tie-line management, releasing locks, and identifying and trouble-shooting hardware faults.
In a growing number of facilities, the routing switcher is tied into an overall network management system. These systems monitor the health of the overall operation by receiving messages from the individual subsystems via SNMP communications. The routing system must be able to provide alarm information via SNMP trap messages. Additional functionality such as loss of signal alarms on critical inputs and outputs can help the network management system trace the root cause of a service interruption through the various devices in the system.
Virtual control panels
Another category of software that is becoming increasingly important in today's facilities is a system to provide virtual control panels, which are GUI representations of router control panels displayed on the computer screens.
A good control panel system GUI will enable the design of an unlimited range of on-screen panels, from simple button-per-source panels to panels that support the setup of complex monitor walls. The ability to support multiple operating system platforms as well as browser-based panels can greatly extend the usefulness of the virtual control panel system.
Likewise, the ability to apply the panels throughout a network with specific access rights for users or groups of users can make the system much more useful. If the panel design process is closely linked to the control system configuration files, it will be possible to input source and destination labels with mouse clicks, eliminating the tedium and potential errors associated with typed entries.
External device interfaces
The final control system feature requiring consideration is its ability to interface with external devices. External control of the router by automation, scheduling systems, editors and production switchers is critically important when it comes to integrating the router into the overall system.
Equally important is the ability of the router control system to communicate router status to external systems such as tally management, under-monitor display devices and, in this day of the expanding use of flat-panel-based monitor walls, multiview image processors.
Traditionally, communication from the router control system to these external devices has been by a simple numeric interface. The router status was sent as a message that output XX is connected to input YY. This meant that the external system's programming needed to be reconfigured to match the router's labeling configuration every time the router was updated. In modern systems, it is possible to download the router's programming information directly to the external device, allowing the complete system to be automatically updated when changes are made to the router's configuration.
The increasing sophistication of router control systems has kept pace with the amazing growth of routers over the past few years. Modern systems are infinitely easier to configure, manage and maintain than their predecessors, making it increasingly practical to design systems based around a large central routing switcher.
Scott Bosen is director of marketing and international sales for Utah Scientific.