Editing Loading coil (section)

====Carrier systems====
American early and middle 20th century telephone cables had load coils at intervals of a mile (1.61&nbsp;km), usually in coil cases holding many. The coils had to be removed to pass higher frequencies, but the coil cases provided convenient places for repeaters of digital [[T-carrier]] systems, which could then transmit a 1.5&nbsp;Mbit/s signal that distance. Due to narrower streets and higher cost of copper, European cables had thinner wires and used closer spacing. Intervals of a kilometer allowed European systems to carry 2&nbsp;Mbit/s.