Fiber Figuring in More Hybrid Solutions
Nov 27, 2006 8:00 AM
Although fiber-optic networks are becoming increasingly vital to the success of large-scale AV installations, it remains rare for any install to rely entirely on fiber. Instead, AV integrators and their clients often design and work in hybrid environments, where data moves from fiber to copper and back again, and facilitating this movement challenges the knowledge and skills of the integrator.
Modern healthcare facilities, including hospitals, are a prime example, says Tim Adams, associate director of engineering and compliance at the American Society for Healthcare Engineering. Adams recently briefed members of the Construction Management Association of America (CMAA) on the growing role of IT in healthcare facility design and construction.
A typical hospital setting may rely extensively on fiber to move large images and other files around, but the latest in copper and wireless transmission are also likely to be highly visible, Adams notes. The latest copper Ethernet cabling, including Categories 5, 6, and 7, has achieved substantial increases in data-carrying capacity, including up to 10Gb on Cat-7 cable.
Similarly, hospitals are rolling out more sophisticated wireless systems to enable patients, nurses, and doctors to communicate instantly regardless of where they are in the facility. Data must be able to flow freely among copper, fiber, and wireless vehicles.
Due to the distance limitations on Cat-5 and Cat-6 cables—roughly 100m maximum— much of this communication will move through intermediate data frames, or IDFs, located throughout the facility. The IDFs will generally be connected to a main data frame (MDF) by means of fiber lines, Adams said, and fiber will also be called into service to support redundant backup MDFs and similar resources.
”Different buildings or locations may be linked by dedicated fiber, T1 lines, rented ‘dark fiber’, or copper connections, he adds.
Where fiber is concerned, the performance of the system boils down to the quality of the termination. “Usually, when there is a performance problem with fiber-optic cable, it’s due to the termination,” he says.
Here is where issues may arise for the AV professional, says Jim Colquhoun, vice president of technical services at Audio-Visual Innovations . “[Fiber] is typically not something that the industry as a whole has been trained for. It’s getting easier, but ... if you don’t treat it right, it will bite you.”
Many AV integrators prefer to convert signal propagation back to copper when possible, so as to work in a more familiar environment—and he believes Cat-5 or Cat-6 cable can feasibly be extended over distances of 1,000ft. or more without loss of performance.
“It’s atypical circumstances that drive us to fiber,” Colquhoun says. One factor arguing for reliance on fiber is the distance to be covered. Another is fiber’s resistance to electronic interference. “In a medical setting, we are having to put displays in the neighborhood of MRIs,” he says. “How can I keep that from impacting my pictures?”
Colquhoun also notes that it is often necessary to route images from the MRI or other imaging system to an operating room. “If the doctor wants to see those images immediately, we get into moving some huge files,” he says. “The existing infrastructure just can’t handle it.”