application note Overview Successful signal management in headends of the future will be determined in large part by one issue: the ability to manage the dynamic environment of the return path. New services such as the addition of multiple channel lineups or narrowcast insertion of telephony, PCS, network management or data services, demand two-way signaling and the development of a robust reverse path. At the same time, providing excellent customer service requires a high level of network reliability, often achieved through headend redundancy. To meet these needs, the RF distribution and management infrastructure must be flexible, reliable, and capable of future growth. ADC’s traditional splitter/combiner product line meets these requirements, solves many of the headend signal management problems encountered by design engineers, and offers a robust solution that prepares the headend for future requirements. This application note will discuss ADC’s traditional splitter/combiner and describe its use in basic, cabinet, and open rack cable management applications. Product Description ADC’s traditional splitter/combiner products mount in a universal horizontal chassis configuration. As shown in Figure 1, the universal chassis accommodates 2x1, 4x1, and 8x1 splitter/combiner or directional coupler modules, and can be any desired combination. All chassis are 1.75 inches high and mount in 19-inch equipment racks or 23-inch equipment racks with extender brackets (ordered separately). Figure 1 Universal Panel Mounting Space Required Per Module 2:1 Splitter/ Combiner or Directional Coupler 4:1 Splitter/ Combiner 8:1 Splitter/ Combiner Rear View Although not shown in Figure 1, a cable tie bar is located at the rear of the chassis. There are 75 Ohm F or BNC connectors mounted on the rear of the modules that, when installed into the universal chassis, provide the interface for all coaxial connections to the network elements. The universal chassis can support a mixed complement of splitter/combiners and directional couplers. The directional coupler occupies the same space as the 2x1 splitter/combiner. RF Signal Management Traditional Splitter/Combiner Installation and Cable Management 2 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Basic Chassis Installation Small or Stand-Alone Applications Since the universal chassis is equipped with a cable tie bar at the rear of the chassis, all necessary hardware to completely install the chassis in a 19-inch rack and manage the coaxial cables is provided. When installing the universal chassis, first determine what type of mounting environment it is to be installed in. If mounting the chassis in a 23-inch equipment rack, attach extender brackets (ordered separately) to the chassis prior to installing the chassis in the equipment rack (see Figure 2). Figure 2 Chassis Equipment Rack Mounting Cable Tie Bar Mounting Screws (2) Mounting Screws (2) TOP VIEW 23-inch Equipment Rack Mounting Extender Bracket Mounting Screws (2) Extender Bracket Mounting Screws (2) Cable Tie Bar Mounting Screws (2) Mounting Screws (2) TOP VIEW 19-inch Equipment Rack Mounting 3 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Basic Chassis Installation Figure 3 Typical Splitter/Combiner Cable Routing Rear View Once the extender brackets have been attached to the universal chassis, position the chassis in its assigned rack location and secure with four mounting screws (provided), two on each side. Next, install the required type of splitter/combiner module(s) into the universal chassis. Lastly, cable the network elements to the splitter/combiner modules. When routing the coaxial cables into the universal chassis, it is recommended that the cabling be split between the left and right sides of the equipment rack (see Figure 3). Figure 3 depicts a sample installation in which two 8x1 splitter/combiner modules have been installed in the universal chassis. As shown, signal coaxial cable enters/exits each individual 8x1 module and is routed up the equipment rack uprights. 4 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Cabinet Cable Management For Larger Applications Figure 4 Cabinet Cable Ring Kit SVC-CBL-KIT-C Cable Ring Kit Figure 5 Cabinet Cable Management Cable Management Utilizing SCV-CBL-KIT-C Kit In using this cabinet cable management kit, it is important to understand the type of cable routing practice used within the office. If cables enter/exit the cabinet at the top of the cabinet and run in overhead cable ladder, the largest 6-inch ring must be placed at the top of the bay. The 5-inch ring should be installed in the middle of the bay with the smallest 4-inch ring towards the bottom (see Figure 4). If cabling enters/exits the cabinet through a raised computer floor, for example, the ring locations must be inverted. Assuming that overhead cable routing is used, cable the uppermost chassis first; route the cables through the top cable ring closest to the top of the cabinet (see Figure 5). Cables from the next-lower chassis exit the rack through either the top 6-inch ring or the 5-inch, depending on chassis versus ring placement. Continue working down the cabinet, routing cables through the ring most appropriate for the chassis location. Route the cables from the lower chassis through the cable ring at the middle of the rack, then through the uppermost ring at the top of the rack as shown. Tie all cables into a bundle before routing them through the cable management rings at the top of the rack. All cables must exit the rack through the 6-inch by 6-inch ring at the top of the cabinet. 5 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Open Rack Cable Management 84" 12" 23" For Larger Applications Figure 6 Open Rack Cable Tie Bar/Ring Kit SCV-CBL-KIT-E Cable Tie Bar/ Ring Figure 7 Typical Unequal Flange Rack with 5" Front Guard Box Before the use of this cable management kit is discussed, a review of a few basic cable management practices for open racks is important. Unlike an equipment cabinet which can have a footprint of 24 inches to 30 inches in depth, an open unequal flange frame typically only provides a 12-inch or 15-inch deep footprint (see Figure 7), including the 2-inch or 5-inch guard box. 6 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Ordering Guide 10" For Larger Applications When installing equipment in this type of rack, ADC recommends a minimum of 10 inches of bay separation to accommodate the vertical routing of cable. As shown in Figure 8, all coaxial cables vertically entering/exiting the universal chassis are routed up the sides of the unequal flange equipment rack. Therefore, when two racks are placed side by side, additional room for cable routing must be allowed. Note in Figure 7 that the cable bundle at the top of the equipment rack is substantially larger than at the bottom of the bay. Had the equipment rack been mounted on a raised floor, the situation would be inverted with the large bundle mass at the bottom of the rack. For aesthetic considerations, rack filler kits can be purchased to hide the cable bundles when viewed from the front of the equipment racks (see Figure 8). Figure 7 Rear View/Coaxial Cable Routing For Larger Applications Note that the universal chassis cable tie bars have been removed for clarity. The six cable tie bar/ring assemblies should be evenly spaced to provide for adequate bay coverage for cable management. Once installed on the bay, the cable tie bar/ring assemblies provide two separate channels for routing of coaxial cables within the bay. First, the cable tie bar portion of the assembly mimics the cable tie bar that ships with the universal chassis and provides cable management for coaxial cable entering/exiting the rack. Secondly, the rings attached to the cable tie bar provide excellent cable management of coaxial cable routing between universal chassis within the rack. Figure 9 provides a top-down view depicting how coaxial cables are routed when using the cable tie bar/ring assembly. As with all cable management practices outlined in this document, the universal chassis divides the connections on the rear of the universal chassis into two planes – left and right. Each cable bundle is then routed either to the left or the right hand side of the chassis. At that point, coaxial cables entering/exiting the rack are routed via the interbay cable routing channel, as created by the rack uprights. Coaxial cables needing to connect to other universal chassis modules are routed through the intrabay cable channel, as provided by the cable rings. Figure 10 shows a side view of the cable routing. 7 www.adc.com • +1-952-938-8080 • 1-800-366-3891 5/01 • 1267 Traditional Splitter/Combiner Traditional Splitter/Combiner Open Rack Cable Management Side View REAR 12" 5" 5" Cable Tie Bar/Ring Assembly Figure 8 Open Rack Cable Management Intrabay Cable Routing Interbay Cable Routing Traditional Splitter/Combiner Open Rack Cable Management Conclusion ADC’s RF Signal Management products meet the needs of today’s broadband RF service provider. Quality of service to the customer is quickly becoming the major differentiating factor between various service providers – and is key to retaining current business as well as gaining additional business. Excellent cable management practices take the worry out of lengthy troubleshooting and problem resolution. Figure 9 Top View – Open Rack Cable Management Detail Figure 10 Side View – Open Rack Cable Management Detail Cable Tie Bar/Ring Assembly Universal Chassis Unequal Flange Rack Upright ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 1267 5/01 Revision © 2000, 2001 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891, Ext. 63475 • Outside of North America: +1-952-938-8080 Fax: +1-952-946-3292 For a complete listing of ADC's global sales office locations, please refer to our web site. . Rack Cable Management Intrabay Cable Routing Interbay Cable Routing Traditional Splitter/Combiner Open Rack Cable Management Conclusion ADC’s RF Signal Management. occupies the same space as the 2x1 splitter/combiner. RF Signal Management Traditional Splitter/Combiner Installation and Cable Management 2 www.adc.com • +1-952-938-8080