It is estimated that approximately 1.5Mmiles of cable plant is now deployed in theUnited States. The majority of existing HFCnetworks have active 5-42 MHz reverse pathin place. Much discussion has occurredduring the past year relative to expandingreverse path network capacity on existingnetworks and how that expansion mightproceed. Various ideas on the subject haveincluded increasing the reverse pass band to85 MHz, to 200 MHz, or even higher; addinga tri-split filter configuration with a secondreverse path above 1GHz; relying upon nodesplitting and fiber deep migration toaccomplish the goal; and incorporating acombination of solutions. Each approach hasboth technical and financial merits as well asdisadvantages which need seriousconsideration.To evaluate the costs of extending theupstream to 85 MHz or to 200 MHz (orgreater) we will look at the issues involved inoperating an HFC network upstream to thosefrequencies, including RF gain requirements,slope and AGC requirements and requiredlaser performance. The cost of each of thesecomponents increases as the upstreambandwidth increases.
展开▼
