How do cable lines on telephone poles transmit and receive data along thousands of houses and not get interference?
In: Engineering
This primarily only applies when discussing *coaxial* cable. Some pretty good explanations have been given about how that works.
Bear in mind, if you’re talking about copper telephone lines, each end point has its own pair of (very small, like 24ga) cables. Thus, each house has its own + and – wires over which signal is transmitted to the nearest node (point at which signals are converted to fiber, generally) or CO (building that houses telephone equipment).
While this technology is growing much less common, some ISPs have, in some areas, taken to bringing fiber closer to clusters of houses, where a new node is installed so that they can send DSL over copper very short distances. At such distances, because DSL speeds are heavily dependent on the length of the copper cable, DSL bandwidth can reach speeds as high as 100Mbps.
If you’re talking about fiber optics, there *is* an analogue to the way coax works. Generally speaking, with fiber optic cable, each end point/home gets its own fiber which runs continuously to the nearest node or CO. That fiber may—and usually is—spliced at various points, so what you often have is, for example, a cable with 4 or 6 fibers running from the house to the “pedestal,” where it’s spliced to another cable which might have 12 or 24 or even 288 fibers, and these generally progress toward larger fiber-count trunk lines until reaching the CO.
However, when you need more fibers than you have, say a development is built at the end of an existing fiber line that’s already mostly or entirely in use, and installing a new line is cost prohibitive, you can install a fiber “splitter,” which allows you to send multiple (up to hundreds) of signals down the same fiber, by splitting into different wavelengths of light. Those signals are re-split at a node site to separate fibers and then sent off to the various new end points.
An example of this is the fact that the entire small town of 800ish people where I live is fed entirely by a 12 fiber cable.
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