What are the classifications and characteristics of twisted pairs

Category 4 twisted pair and Category 5 twisted pair.

Twisted pairs are divided into shielded twisted pair and unshielded twisted pair.

1. Shielded twisted pair has a metal shield between the twisted pair and the outer insulating envelope. Shielded twisted pair wires are divided into STP and FTP, STP means that each wire has its own shielding layer, while FTP only works when the entire cable is shielded and both ends are properly grounded. Therefore, the whole system is required to be shielded devices, including cables, information points, crystal heads and distribution frames, etc., and the building needs to have a good grounding system.

2. Unshielded twisted pair cable is a kind of data transmission line, which is composed of four pairs of transmission lines of different colors, which is widely used in Ethernet and first-class cables.

The characteristics of twisted pair are long transmission distance, high transmission quality, convenient wiring, high cable utilization, strong anti-interference ability, high reliability, easy to use, and cheap, and the material is also very convenient. Twisted pair is the most commonly used transmission medium in the excavation or bending of a kind of integrated wiring project, which is composed of two copper wires with an insulating protective layer.

Two insulated copper wires are twisted together according to a certain density, and the radio waves radiated by each wire during transmission will be canceled by the radio waves emitted by the other wire, which can effectively reduce the degree of signal interference.

Twisted pair is generally made of two 22-26 insulated copper wires wound with each other, from which the name twisted pair comes from. In practice, twisted pair wires are made up of multiple pairs of twisted pairs wrapped together in an insulated cable sleeve.

In daily life, the "twisted pair cable chain" is directly called "twisted pair". Compared with other transmission media, twisted pair is limited in terms of transmission distance, channel width and data transmission speed, but it is relatively cheap.

1) Class 1 line (cat1):

The maximum frequency bandwidth of the cable is 750kHz, which is used for alarm systems, or only for voice transmission (a class of standards is mainly used for ** cables before the early eighties) and is not used for data transmission.

2) Class 2 line (cat2):

The maximum frequency bandwidth of the cable is 1MHz and is used for voice transmission and data transmission at a maximum transmission rate of 4Mbps, which is common in older token networks that use the 4Mbps specification token passing protocol.

3) Category 3 line (cat3):

Refers to the cable specified in the ANSI and EIA TIA568 standards, the cable has a transmission frequency of 16MHz, a maximum transmission rate of 10Mbps (10Mbits), mainly used in voice, 10Mbit S Ethernet (10Base-T) and 4Mbit S Token Ring, the maximum network segment length is 100M, and the connector in the form of RJ has been faded out of the market.

4) Category 4 line (cat4):

This type of cable has a transmission frequency of 20MHz and is used for voice transmission and data transmission at a maximum transmission rate of 16Mbps (referring to the 16Mbit S Token Ring), mainly for token-based LANs and 10BASE-T 100BASE-T. The maximum network segment length is 100 m, and the connector in the form of RJ is not widely used.

5) Cat5 line (cat5):

This kind of cable increases the winding density, the jacket is a high-quality insulating material, the highest frequency bandwidth of the cable is 100MHz, the maximum transmission rate is 100Mbps, for voice transmission and the maximum transmission rate of 100Mbps data transmission, mainly used for 100BASE-T and 1000BASE-T networks, the maximum network segment length is 100M, and the connector in the form of RJ.

6) Cat5e line:

Category 5 has reduced attenuation, less crosstalk, and has a higher attenuation-to-crosstalk ratio (ACR) and signal-to-noise ratio (SNR), and a smaller time delay difference, and the performance has been greatly improved. Category 5 cables are mainly used for Gigabit Ethernet (1000Mbps).

7) Category 6 line (cat6):

The transmission frequency of this type of cable is 1MHz 250MHz, and the Category 6 cabling system should have a large margin for the Combined Attenuation Crosstalk Ratio (PS-ACR) at 200MHz, which provides 2 times the bandwidth of Category 5e. The transmission performance of Category 6 cabling is much higher than that of Category 5e standards, and it is most suitable for applications with transmission rates higher than 1Gbps.

8) Super Class 6A or 6A (Cat6A):

The transmission bandwidth of this type of product is between Category 6 and Category 7, the transmission frequency is 500MHz, the transmission speed is 10Gbps, and the standard outer diameter is 6mm. Like the seven types of products, the country has not yet issued a formal testing standard, but there are such products in the industry, and each manufacturer announces a test value.

9) Category 7 line (cat7):

The transmission frequency is 600MHz, the transmission speed is 10Gbps, the standard outer diameter of a single wire is 8mm, and the standard outer diameter of a multi-core wire is 6mm.