Because the effect of dispersion increases with the length of the fiber, a fiber transmission system is often characterized by its bandwidth–distance product, usually expressed in units of ·km. This value is a product of bandwidth and distance because there is a trade-off between the bandwidth of the signal and the distance over which it can be carried. For example, a common multi-mode fiber with a bandwidth–distance product of 500 MHz·km could carry a 500 MHz signal for 1 km or a 1000 MHz sig. The fiber optic network extends from the cable operators' master, sometimes to regional headends, and out to a neighborhood's hubsite, and finally to an optical to coaxial cable node which typically serves 25 to 2000 homes. A master headend will usually have for reception of distant video signals as well as aggregation. Some master headends also house equipment (such a.
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