| Design Considerations Optical/Coaxial Cable System The cable system layout shall be in accordance with the following requirements: Cable system configuration involves determination of : 1. The location of major cable system features such as the headend. 2. The route of the trunk and distribution cables. 3. Cable system redundancy. 4. The location along the distribution cable of the cable taps which allows connection of communication devices. Effective cable system layout requires that the system designer understand the objectives for the cable system, the physical characteristics and limitations of the environment in which the cable system is to be installed, and basic principles of broadband cable system design. A prerequisite of the cable system layout design is a, complete set of drawings of the route, site, and/or buildings in which the cable system is to installed and plats of the areas to be served. Drawings will have the following characteristics: a) Cover the entire area in which the cable system will be installed. b) Show all facility features through which the cable will be routed, including buildings, structures, underground tunnels, conduits, exterior pole lines, cable trays, utility corridors, etc. c) Drawn to a scale allowing clear delineation and scaling of dimensions of building features, streets, building, etc. Physical Environment Two elements of the physical environment through which the cable is routed need to be included in the design data under certain conditions. The first is the temperature range of the areas the cables are routed in. This is important in large systems where the cable temperature can very widely. Under these conditions, automatic level control amplifiers may be required in the trunk cable. To design a cable system for these conditions both the lowest and highest possible ambient temperatures must be specified. The second element is the routing of the cable through areas containing a corrosive environment. In this condition special components and surface coverings must be used. System Layout Drawings The cable system layout drawings shall consist of building and outside plant drawings showing the location of all cable system components and the routing of the trunk and distribution cables. The drawings shall have the following minimum characteristics: a) Drawn to scale and detail sufficient to permit location of the components in the network. b) Drawn in reproducible from. c) Use the standard symbols defined by the Society of Cable Television Engineers and the National Cable Television Association. d) Each cable system component contained in each drawing shall be assigned a unique node number to correlate the component to the corresponding component in the Cable System Design Table. |