According to the presence or absence of a shielding layer, the twisted pair is divided into a Shielded Twisted Pair (STP) and an Unshielded Twisted Pair (UTP).
The shielded twisted pair has a metal shield between the twisted pair and the outer insulating envelope. Shielded twisted pair is divided into STP and FTP (Foil Twisted-Pair). STP means that each line has its own shielding layer, and FTP only works when the entire cable has shielding and both ends are properly grounded. Therefore, the entire system is required to be a shielding device, including cables, information points, crystal heads and distribution frames, and the building needs to have a good grounding system. The shielding layer can reduce radiation, prevent information from being eavesdropped, and prevent external electromagnetic interference from entering, so that the shielded twisted pair has a higher transmission rate than the similar unshielded twisted pair.
Unshielded Twisted Pair (UTP) is a data transmission line consisting of four pairs of different color transmission lines, widely used in Ethernet and telephone lines. Unshielded twisted pair cable has the following advantages: 1. Unshielded jacket, small diameter, saving space and low cost; 2. Light weight, easy to bend, easy to install; 3. Minimize or eliminate crosstalk; 4. It has flame retardancy; 5. It has independence and flexibility and is suitable for structured integrated wiring. Therefore, unshielded twisted pair is widely used in integrated wiring systems.