Coaxial cable is composed of two conductors. The center wire of the Coaxial cable is used for transmit signals. The metal shielding net plays two roles: one is the common ground wire as a signal to provide a current loop for the signal; the other is the shielding net as a signal to suppress the interference of electromagnetic noise to the signal.The center conductor and the shield mesh are between a semi-foamed polypropylene insulating layer, which determines the transmission characteristics of the cable and effectively protects the middle conductor.
Coaxial cables are widely used for audio-video or RF transmission. The transmission impedance is generally 75_, which has become the standard impedance for video transmission (in the early days, 50_ impedance was also used for video transmission).Premium standard coaxial cable is generally more expensive than twisted-pair cable due to its reliable physical properties and superior audio and video performance.The frequency, resolution of the signal and the effective transmission distance of the cable play a decisive role in audio and video system.
In addition, it should be noted that in order to maintain the correct electrical characteristics of the coaxial cable, the cable shielding layer must be grounded.At the same time, there should be terminals at both ends to weaken the signal reflection effect.
Coaxial cables are generally installed between equipment.A connector is equipped at each user location to provide an interface for the user.The interface is installed as follows:
(1) the fine line
Cut the cable and attach BNC ends to both ends of the cable, then connect to both ends of the T connector.
(2) the thick rope
The thick cable is typically installed using a splint-like TAP device, which uses a guide pin on the TAP to penetrate the insulation layer of the cable and connect directly to the conductor.Terminators are arranged at both ends of the cable to reduce the reflection of signals.