Various types of cabling

Twisted Pair wires use a pair of metal wires that are insulated from each other to withstand external electromagnetic interference. Twisting the two insulated copper wires together at a certain density can reduce signal interference, the electric waves emitted by each wire during transmission are offset by the electric waves sent from the other wire. The "Twisted Pair" name also comes from this. Twisted Pair wires are generally wound up by two insulated copper wires 2-26. In actual use, twisted pair wires are wrapped together in an insulated cable casing. There are four pairs of typical twisted pair wires, and more pairs of twisted pair wires are placed in one cable casing. These are called twisted pair cables. In a twisted pair cable, also known as a twisted pair cable), different pairs have different twist lengths. Generally speaking, the twist length is within 1cm to 14cm, and is twisted in the clockwise direction. The twist length of the adjacent line is more than 7cm. Generally, the closer the twist line is, the stronger its anti-interference capability. Compared with other transmission media, the twisted pair is at the transmission distance, channel width and data transmission speed are limited, but the price is relatively low. Twisted pair cables (referred to as twisted pair cables) are the most common transmission medium in the Integrated Wiring System. In the star network topology, twisted pair cables are essential for cabling. Twisted Pair wires can be divided into two categories: unshielded twisted pair UTP and shielded twisted pair STP. STP is divided into three categories and five categories, while UTP is divided into three categories, four categories, five categories, over five categories, and the latest six categories.
I. Differences between unshielded twisted pair wires and shielded twisted pair wires

The maximum transmission distance of twisted pair wires is generally 100 meters. The shielded twisted pair cable is enclosed by a layer of metal material to reduce the radiation. At the same time, it has a high data transmission rate of up to 100 Mbps for 5 kinds of STP within 155, while UTP can only reach 100 Mbps ). However, the price of shielded twisted pair cables is relatively high. installation is more difficult than unshielded twisted pair cables. Special connectors must be used and the technical requirements are higher than unshielded twisted pair cables. Compared with the shielded twisted pair cable, the unshielded twisted pair Cable only needs one layer of insulation rubber, so it is light, easy to bend, easy to install, flexible networking, and very suitable for structured wiring, therefore, unshielded twisted pair cables are often used in computer network cabling without special requirements.
Ii. Technical Performance of twisted pair wires

Due to the fact that many manufacturers of twisted pair cables exist on the market, there may be great differences in the performance of products with the same standard and specification. In order to facilitate your selection, the main performance indicators of twisted pair cables are described as follows:
1. attenuation. Attenuation is the degree of loss along the line signal. The attenuation has a great impact on the network transmission distance and reliability. In general, the attenuation increases with the increase in frequency.
2. crosstalk. Crosstalk is mainly used for unshielded twisted pair cables, including near-end crosstalk and remote crosstalk. Among them, the main role of network transmission performance is the near-end crosstalk. Near-end crosstalk refers to the degree of interference between one pair of twisted pair wires and the other pair of twisted pair wires. This value varies with the length of the cable. Generally, the longer the cable, the smaller the value.
3. impedance. The impedance in a twisted pair cable mainly refers to the characteristic impedance, which includes the resistance, inductance, and capacitance impedance of the material. It is generally divided into 100 ohm, 120 Ohm and 150 ohm.
4. attenuation crosstalk ratio ACR ). It refers to the ratio of attenuation to crosstalk in some frequency ranges. The greater the value of ACR, the stronger the anti-interference capability of the cable. For the above performance parameters, see the twisted pair Cable documentation. If necessary, they can be measured by a dedicated instrument.
Iii. Transmission Characteristics and usage of twisted pair wires
1) Category 3 lines. The maximum transmission frequency of the three types of cables is 16 MHz and the maximum transmission rate is 10 Mbps. It is used for voice and 10 Mbps data transmission.
2) 4 lines. This type of twisted pair has a maximum transmission frequency of 20 MHz and a maximum transmission rate of 16 Mbps. It can be used for voice transmission and 16 Mbps data transmission.
3) Category 5 lines. Category 5 twisted pair cables use special insulation materials to achieve a maximum transmission frequency of 100 MHz and a maximum transmission rate of 100 Mbps. These cables can be used for voice and data transmission with a maximum transmission rate of Mbps.
4) over 5 lines. Compared with Category 5 twisted pair wires, cat5 twisted pair wires have less attenuation and Crosstalk, providing a more solid network foundation to meet the needs of most applications, especially supporting Gigabit Ethernet BASE-T cabling ), it facilitates network installation and testing and has become a good solution for network applications. The transmission characteristics of Category 5 cables are the same as that of Category 5 cables. However, according to the standard of Category 5 cabling, all the four pairs of Category 5 cables can achieve full duplex communication.
5) cat6 cables: the transmission frequency of these cables is 1 MHz ~ 250 MHz, cat6 cabling system at MHz integrated attenuation crosstalk than PS-ACR) should have a larger margin, it provides 2 times the bandwidth of cat5e. The transmission performance of cat6 cabling is much higher than that of cat5e, which is most suitable for applications with a transmission rate higher than 1 Gbps. An important difference between Category 6 and Category 5 is that it improves the performance in crosstalk and return loss. for a new generation of full-duplex high-speed network applications, the excellent return loss performance is very important. The basic link model is removed from Category 6 standards. The cabling standard adopts a star-shaped topological structure. The required cabling distance is: the permanent link length cannot exceed 90 m, and the channel length cannot exceed 100 m.