With the rapid development of optical communication technology, optical cables have been widely used in the backbone networks and inter-office trunk lines of China's wireline communication networks, and the entry of optical fibers into access networks has become an inevitable trend. However, the cost of cable laying is too high, and the cost of joints and the cost of terminal optical-to-electrical conversion are expensive. Therefore, for a long period of time before the popularity of fiber-opticization, the subscriber line of the access network will still be dominated by metal cables. Metal cables mainly include all-plastic cable, coaxial cable and data cable. Among them, the data cable is the ideal transmission medium for the broadband access network. It has the advantages of low manufacturing cost, simple structure, good expandability and easy network upgrade. It is mainly used for building integrated wiring, community computer integrated wiring, etc. .
There are two main types of data cables: one is the 100Ω cable implemented in the Americas, mainly for unshielded Twisted Pairs (UTP); the other is the 150Ω cable implemented in Europe, mainly for shielding doubles. STP: Shielded Twisted Pair.