Teach you to identify and choose coaxial cable and twisted pair

author: Zhejiang Linquick Technology Co., Ltd.

2023-08-22

Coaxial cable

A coaxial cable is a cable that consists of layers of insulated wire wrapped around a central copper conductor. It is characterized by good anti-interference ability, stable transmission data, and cheap price, and is also widely used, such as closed-circuit television lines. The general market price of coaxial fine cable is a few yuan a meter, which is not too expensive. Coaxial cable is used to connect with the BNC head, and the coaxial cable sold on the market is generally the finished product that has been connected with the BNC head and can be directly selected. Coaxial cable is widely used in Ethernet to transmit low-loss high-frequency electrical signals.

In the early days of Ethernet, the standard 10Base-5, 10Base-2, and 10Broad-36 were designed to regulate Ethernet over coaxial cables. In the latest IEEE 802.3z, full-duplex Ethernet over coaxial cable and fiber achieves 1000Mbps transmission.

In the current network, coaxial cable is almost eliminated by twisted pair and optical fiber, because according to the analysis of the characteristics of the coaxial cable itself, when the signal is transmitted in the coaxial cable, its attenuation is related to the transmission distance and the frequency of the signal itself. Generally speaking, the higher the signal frequency, the greater the attenuation. The bandwidth of the video signal is very large, reaching 6MHz, and the color part of the image is modulated at the high end of the frequency so that the video signal is transmitted in the coaxial cable not only the overall amplitude of the signal is attenuated, but also the attenuation of each frequency component is very different, especially the maximum attenuation of the color part. Therefore, coaxial cable is only suitable for close-range transmission of image signals, when the transmission distance reaches about 200 meters, the image quality will be significantly reduced, especially the color becomes dim, and there is a sense of distortion.

Twisted Pair (TP)

CAT5, CAT5E, Network Cable Manufacturer in China

The twisted pair is the most widely used cable in Ethernet, including both unshielded twisted pair (UTP) and shielded Twisted pair (STP). STP also includes two types, STP and FTP (foil Twisted pair).

The shielding layer can reduce radiation, prevent information from being eavesdropped, and also prevent the entry of external electromagnetic interference. Therefore, compared with UTP, STP, including FTP, can transmit higher bandwidth.

According to the speed of the twisted pair, the twisted pair is labeled CAT. For example, in LAN networks, CAT5 and CAT5e are widely used. Although both CAT5 and CAT5e cables are used in 1Gbps Ethernet networks, CAT5e has a better SNR than CAT5, which helps CAT5e provide better service than CAT5. CAT5e offers up to 2.5G bandwidth even over short distances.

In fact, the use of twisted pair has a long history, telephone transmission is the used of twisted pair, in many industrial control systems and interference in larger places and long-distance transmission are used in twisted pair, we are widely used today in the local area network is also the use of twisted pair. The reason why twisted pair is so widely used is that it has many advantages such as strong anti-interference ability, long transmission distance, easy wiring, low price, and so on. Since the twisted pair also has a large attenuation of the signal, the frequency of the signal can not be too high when the transmission distance is far, and the high-speed signal such as Ethernet can only be limited to within 100m.

For the video signal, the bandwidth reaches 6MHz, if it is transmitted directly in the twisted pair, it will also attenuate greatly, so the video signal must be amplified and compensated on the twisted pair to achieve long-distance transmission, and the twisted pair video transmission equipment is to complete this function. With a pair of twisted pair video transceiver equipment, the image can be transmitted to 1 to 2km. The price of twisted pair and twisted pair video transmission equipment is very cheap, not only does not increase the cost of the system, but its cost decreases a lot compared with coaxial cable when the distance increases. Therefore, the monitoring system with twisted pair transmission has obvious advantages.