The inside of the cable is a copper core wire; the inside of the fiber optic cable is glass fiber. A cable is usually a rope-like cable that is twisted with several or groups of wires at least two in each group. An optical cable is a communication line in which a certain number of optical fibers form a cable core according to a certain method, and is sheathed with an outer sheath, and some are also covered with an outer sheath for optical signal transmission.

When the phone converts the acoustic signal into an electric signal and then transmits it to the switch via the line, the switch then transmits the electric signal directly to the other phone to answer. The line transmitted during this call is the cable.

When the phone converts the acoustic signal into an electrical signal and transmits it to the switch via the line, the switch then transmits this electrical signal to the photoelectric conversion device (converts the electrical signal into an optical signal) and transmits it to another photoelectric conversion device (the optical The signal is converted into an electrical signal), and then to the switching equipment, to the other phone to answer. The line between the two photoelectric conversion devices is an optical cable.

Inside the cable are mainly copper core wires. The diameter of the core wire is divided into 0.32mm, 0.4mm and 0.5mm, the larger the diameter, the stronger the communication ability; there are also divided according to the number of core wires: 5 pairs, 10 pairs, 20 pairs, 50 pairs, 100 pairs, 200 Wait a minute. Optical cables are only divided into the number of core wires. The number of core wires are: 4, 6, 8, 12 pairs, and so on.

Cable: Its volume, weight and communication ability are poor, and it can only be used for short-distance communication. Optical cable: its volume, small weight, low cost, large communication capacity, strong communication capabilities, etc. Due to many factors, it is currently only used for long-distance and point-to-point (ie, two exchange rooms) communication transmission.

In fact, the difference between cables and optical cables is mainly manifested in three aspects.

First: there are differences in materials. The cable is made of metal (mostly copper, aluminum) as the conductor; the optical cable is made of glass fiber as the conductor.

Second: there is a difference in the transmitted signal. The cable transmits electrical signals. Optical cables transmit optical signals.

Third: there are differences in the scope of application. Cables are mostly used for energy transmission and low-end data information transmission (such as telephones). Optical cables are mostly used for data transmission.

It can be known in practical applications that optical cables have greater transmission capacity than copper cables, long distances, small size, light weight, and no electromagnetic interference. They have now developed trunk roads, city trunks, offshore and cross-country cables. The backbone of wired transmission lines such as ocean and subsea communications, as well as local area networks and private networks, has begun to develop into the field of user loop distribution networks in the city, providing transmission lines for fiber-to-the-home and wide-generation integrated service digital networks.