Isn’t it millons of teeny tiny reconnections?
In: Engineering
There’s a fairly nice story about this they used to teach us about the importance of line impedence
” At the time, undersea cables were unreliable. It was not uncommon for the signal on a cable to fade and then die completely, most often due to a short circuit caused by failure of the [gutta-percha](https://en.wikipedia.org/wiki/Gutta-percha) insulation between the copper conductor and the iron sheath surrounding it. When a cable failed, there was no alternative but to send out a ship which would find the cable with a grappling hook, haul it up to the surface, cut it, and test whether the short was to the east or west of the ship’s position (the cable would work in the good direction but fail in that containing the short. Then the cable would be re-spliced, dropped back to the bottom, and the ship would set off in the direction of the short to repeat the exercise over and over until, by a process similar to [binary search](https://en.wikipedia.org/wiki/Binary_search_algorithm), the location of the fault was narrowed down and that section of the cable replaced. This was time consuming and potentially hazardous given the North Sea’s propensity for storms, and while the cable remained out of service it made no money for the telegraph company.
Heaviside, who continued his self-study and frequented the library when not at work, realised that knowing the resistance and length of the functioning cable, which could be easily measured, it would be possible to estimate the location of the short simply by measuring the resistance of the cable from each end after the short appeared. He was able to cancel out the resistance of the fault, creating a quadratic equation which could be solved for its location. The first time he applied this technique his bosses were sceptical, but when the ship was sent out to the location he predicted, 114 miles from the English coast, they quickly found the short circuit.”
[https://www.fourmilab.ch/fourmilog/archives/2018-11/001795.html](https://www.fourmilab.ch/fourmilog/archives/2018-11/001795.html)
Latest Answers