Classification by structure:
① The covered wire is composed of a plurality of copper wires and steel wires mixed into a conductive wire core, which is wrapped with insulating materials. It is tensile and wear-resistant, which is convenient for retraction and repeated use. Generally, it can be used for audio telephone, Telegraph and single carrier telephone communication within 25 km under field conditions.
② Overhead open wire refers to the bare metal conductor for communication on the pole road, including galvanized steel wire, hard copper wire, copper clad steel wire, aluminum silicon magnesium alloy wire, steel cored aluminum stranded wire [1], etc. The transmission attenuation of galvanized steel wire is large, which is only used for audio or short-distance three-way carrier telephone. The other four types of wires are used for carrier phones with 12 or more channels. The overhead open line communication line has larger communication capacity and longer communication distance than the field covered line, but the target is obvious and is easy to be damaged. In case of ice, lightning, flood and storm, the communication quality will be seriously reduced and even the communication will be interrupted.
③ Communication cable is usually composed of cable core, sheath and sheath. According to the different structure of cable core, it can be divided into symmetrical cable and coaxial cable. The mutually insulated conductors in the former cable core adopt the structural form of two-wire pair twisted group or four wire star twisted group, and the latter adopts the structural form of mutual insulation and coaxial sleeve of cylindrical inner and outer conductors. The cable core with both symmetrical wire pairs and coaxial tube body is called integrated cable.
④ Communication optical cable is usually composed of several optical fibers and reinforcements. Compared with cable communication, optical fiber communication has the advantages of large communication capacity, small volume, light weight, anti-interference, strong confidentiality and non-ferrous metal saving. Since the 1970s, many countries are making use of the above advantages of optical fiber to actively develop a variety of communication optical cables for different purposes.
Classification according to use requirements:
It can also be divided into audio (low frequency) cable, digital cable and carrier frequency (high frequency) cable.
Audio cable is mainly used for urban or short-range communication; Digital cable is specially used for digital communication; Carrier frequency cable is mainly used for long-distance multi-channel carrier communication, in which symmetrical star twisted carrier frequency cable is used to open 12, 60 and 120 carrier phones; The small coaxial cable can open 120, 300, 960 and 3600 carrier phones; The medium coaxial cable can open up to 10800 or 13200 carrier phones.
Coaxial cable can also be used for digital communication. In order to meet different needs, there are field communication cables and submarine communication cables. The field communication cable uses one to several pairs of mutually insulated conductors or micro coaxial tubes as the cable core and is wrapped with rubber or plastic closed sheath. It is relatively light, has strong tensile resistance and can be retracted and released repeatedly. It can be used for audio, carrier telephone or digital communication within tens of kilometers. It is suitable for field communication. Submarine communication cables are divided into shallow sea type and deep sea type. Shallow water cable is used in the sea area with a water depth of less than 500 meters. Its cable core is a symmetrical structure or coaxial structure of solid insulator. The cable core is externally sheathed and wound with steel wire armor, so that it has strong tensile capacity and anti damage performance of foreign objects. The deep-sea cable is used in the sea area with a water depth of more than 500 meters. It adopts the coaxial structure of solid insulator. The coaxial inner conductor is equipped with high-strength steel strand to bear the tensile force of the whole section of cable during laying or fishing. Submarine communication cable is used for multi-channel carrier and digital communication. In addition, there is an underwater communication cable used to pass through rivers, rivers and lakes, which has a thickened lead or aluminum closed sheath wrapped with a steel wire armored protective layer.
【Baidu Encyclopedia】
