In daily life, we will be exposed to a variety of wires, such as video cable, audio cable, network cable, power cable. If you don't look at the connector, it is difficult for ordinary people to distinguish it. The most intuitive difference in the hand is that there is Thick, some thin, some hard, some soft.
It is better to understand the thick and thin, for example, if you need high-power power transmission, the wires will be much thicker, and you need to transfer more sets of data, such as USB 2.0 and USB 3.0, the number of data lines will be more, and the wire will be thicker.
Why are the same thick and thin lines, some are very hard, some are softer? This has a lot to do with the internal structure of the wire.
Signal lines on the market can be divided into Coaxial and twisted pair.
As the name suggests, The coaxial line is composed of a layer of insulating layer wrapped around the central copper conductor, and the metal mesh layer is wrapped around the insulating layer. Since the outer metal mesh and the central axis are on the same axis, it is called coaxial line. .
The metal mesh shields the electromagnetic interference of the outer layer, as shown in the following figure:
As can be seen from the anatomical view of the coaxial line, From the inside to the outside are: center wire, insulation layer, outer conductive layer (metal mesh), wire sheath.
The lightning data line is composed of multiple sets of coaxial lines plus independent power transmission lines.
The opposite of the coaxial line is the twisted pair, that is, two wires with an insulating protective layer are entangled with each other according to a certain degree of helix.
6 sets of signal lines composed of twisted pairs
What is the difference between these two lines?
Part of the interference from the data line comes from the external magnetic field, and the other part comes from the magnetic field generated by itself when transmitting the changing signal.
Due to the existence of the metal shielding mesh, the external magnetic field cannot pass through the shielding layer, and the internal magnetic field cannot pass through the shielding layer. When the signal is transmitted in the coaxial cable, the attenuation is related to the transmission distance and the frequency of the signal itself.
For high-frequency signals, the farther the transmission distance is, the greater the signal attenuation. In order to achieve the long-distance transmission of high-frequency signals, the coaxial amplifier is usually used to amplify and compensate the signal.
Intel's Thunder 3 data line uses coaxial line. Because of the high frequency attenuation of the coaxial line, for the lightning line 3 with a length of 0.5m, only the passive chip is needed. When it exceeds 0.5m, the active chip pair is needed. The signal is amplified, the price of the active chip and the passive chip are several times different, so the lightning 3 line generally does not exceed 0.5m.
Of course, Apple used a passive chip to make a 0.8m lightning 3 data line, which is already the limit.
CHOETECH's 2m Thunder 3 data line uses an active type of chip, priced at five or six hundred yuan.
The twisted pair lacks a metal shield and is intertwined. The internal and external electromagnetic interference signals cancel each other out, so it has the advantage of strong anti-interference ability.
If it is required to have strong anti-interference ability, it is necessary to use shielded twisted pair. Our common super six network cable is unshielded twisted pair, and the seventh type is shielded twisted pair.
In addition, the twisted pair has many advantages, such as long transmission distance, easy wiring, low price, etc. Of course, the hand is not like the axis.
