What is the difference between coaxial cable assemblies and twisted pair - difference in transmission characteristics
The transmission characteristics of coaxial and twisted pairs are specified by the national standard and cannot be changed. For example, the upper frequency of the video signal is 6M, for a transmission distance of 2000 meters, the attenuation of the SYWV-75-5 cable is 40db, that is, the voltage attenuation is 100 times, and the 6M video signal of 1Vp-p is attenuated to 10mv, or 80db microvolts, at this level For video restoration, a high signal-to-noise ratio can be guaranteed. Engineers with experience in cable TV system design are very clear about this; for unshielded twisted pair cables, the attenuation of 6M at 2km is 92db, which is nearly 40,000 times, and 52db (nearly 400 times) larger than 75-5 coaxial cables;
What is the difference between coaxial cable assemblies and twisted pair ---- the difference in working principle
The coaxial cable assemblies confines the electromagnetic field of the transmission signal to the inside of the shielding layer, and does not radiate outward. According to the principle of reversibility of sending and receiving, the external electromagnetic field cannot pass through the shielding layer and enter the interior. 【ZOMWAVE Provide High Performance SMP Cable Assemblies WIth Low price.】
The coaxial cable assemblies is divided into four layers from the inside out: the central copper wire, the plastic insulator, the mesh conductive layer and the wire sheath. Electric current conducts the loop formed by the central copper wire and the meshed conductive layer. It is named because the central copper wire and the mesh conductive layer are in a coaxial relationship.
Coaxial cable assemblies conduct alternating current rather than direct current, which means that the direction of the current is reversed several times per second.
If a normal wire is used to transmit high-frequency currents, the wire acts as an antenna that emits radio outward, an effect that dissipates the power of the signal and reduces the received signal strength.
Coaxial cable assemblies are designed to solve this problem. The radio emitted by the center wire is isolated by the mesh conductive layer, which can control the emitted radio by grounding.
There is also a problem with coaxial cable assembly, that is, if a certain section of the cable is squeezed or twisted, the distance between the center wire and the mesh conductive layer is not consistent, which will cause the internal radio waves to be blocked. reflected back to the source of the signal. This effect reduces the acceptable signal power. To overcome this problem, a plastic insulator is added between the center wire and the mesh conductive layer to ensure a consistent distance between them. This also causes the cable to be relatively stiff and not easy to bend. 【ZOMWAVE Provide High Performance SMP Cable Assemblies WIth Low price.】
The principle of coaxial interference is another matter. The twisted pair is different. Its signal transmission electromagnetic field is theoretically distributed in infinite space. According to the principle of reversible transmission and reception, the electromagnetic field in the external space can also directly enter the twisted pair. The twisted pair cannot prevent the entry of the external electromagnetic field, but the method of helical twisting is adopted to make the signals received by the two wires "as exactly the same as possible", and the balanced differential signal processing technology is used to convert this exact same "common mode signal". "Suppress. The key here is the "balance" characteristic of the twisted pair. Once the "balance" is different, interference will take advantage of it, and external objects will also affect the balance. In engineering, "balance" is relative, not absolute, and the "common mode rejection" performance of the circuit has a certain range. These two practical problems determine the anti-interference ability of twisted pair, which is limited. In the case of strong interference stipulated in the integrated network wiring rules, shielded twisted pair must be used. This is the reason.
What is the difference between coaxial cable assemblies and twisted pair?
Twisted pair is a general-purpose wiring made of two mutually insulated wires twisted together according to a certain specification (usually clockwise). It belongs to the information communication network transmission medium, which can reduce the degree of signal interference. The waves radiated by one wire during transmission are canceled by the waves emitted by the other wire. Twisted pair was mainly used to transmit analog signals in the past, but now it is also suitable for the transmission of digital signals.
Coaxial cable assemblies can be divided into baseband coaxial cables and broadband coaxial cables (ie network coaxial cables and video coaxial cables). Coaxial cables are divided into 50Ω baseband cables and 75Ω broadband cables. Baseband cables are further divided into thin coaxial cables and thick coaxial cables. Baseband cables are only used for digital transmission, with data rates up to 10Mbps. Coaxial cable (Coaxial) refers to a cable with two concentric conductors, and the conductor and the shield share the same axis. The most common coaxial cable consists of copper wire conductors separated by insulating material.
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