网线与水晶头的接法分为几种（The connection method of wire mesh and crystal head is divided into several kinds）.docVIP

网线与水晶头的接法分为几种（The connection method of wire mesh and crystal head is divided into several kinds） Types and selection of twisted pairs: Twisted pair (Twisted-Pair Cable; TP) The twisted pair of LANs can be divided into two categories: unshielded twisted pair (Unshielded, Twisted, Pair, UTP) and shielded twisted pair (Shielded, Twisted, Pair), or STP. STP there is a layer of metal material wrapped around it. The use of the metal shielding layer to reduce electromagnetic interference (EMI), when the shielding layer is properly grounded after the current signal of electromagnetic interference in the received signal and interference signal into the reverse current is formed in the twisted pair. As long as the two currents are symmetrical, they can be offset without causing noise to the receiver. However, when the shielding layer is discontinuous or the shielding layer current is asymmetrical, it will reduce or even completely lose the shielding effect and lead to noise. STP cables can only protect against electromagnetic radiation and interference only when the full end-to-end link is completely shielded and properly earthed. To minimize noise and improve signal to noise ratio, the ability to resist interference and radiation is called electromagnetic compatibility (EMC). STP can reduce radiation, prevent information eavesdropping, and have higher data transmission rate, but the price is relatively expensive, installation is more complicated. Outside the UTP, there is only one layer of insulating rubber wrapped in eight strands of plastic insulation, each of which is twisted into four pairs of twisted pairs, each resulting in a pair of twisted pairs. The purpose of twisted wires is to counteract the interference of adjacent lines and reduce interference from the outside by using electromagnetic field generated by the current in the copper wire. The number of lines in each winding each other every inch of the length determines the quality of anti-interference ability and