The standard connection of twisted pairs is not strictl […]
The standard connection of twisted pairs is not strictly specified, but is made to keep the symmetry of the cable joint layout as much as possible, so as to minimize the interference of the cables in the joints, and at the same time minimize The differential signal values of the external interference are also made equal as much as possible so that the anti-interference circuit performs the subtraction operation to eliminate it. Therefore, when we usually make a network cable, if it is not made according to the standard, although the line can be connected sometimes, the interference between the lines inside the line cannot be effectively eliminated, so that the signal transmission error rate increases, and eventually the network performance is degraded.
In fact, the cable connection we used in this article is the EIA/TIA 568B standard, and there is also a standard for EIA/TIA 568A, which simply swaps the orange line pair and the green line pair in the figure (that is, green and white). -1, Green-2, Orange-3, Lan-4, Lanbai-5, Orange-6, Brown-7, Brown-8), the layout of the cable joint is still symmetrical. Comparing the above figure with the standard connection diagram, it can be found that the two actually exchange the green line pair and the orange line pair. The careful person will find that it just happens to be the EIA/TIA 568A standard, so the production of the direct twisted pair is said. The standard connection is to press EIA/TIA 568A at one end and EIA/TIA 568B to connect the other end. Both ends meet international standards, which is the benefit of doing the standard line.
What is the difference between Category 3, Category 5 and Category 5? First of all, let's say, why use twisted pairs instead of parallel lines? Are parallel lines not easier to produce?
This is because the high-frequency signal of >10MHz passes through the network line. At this time, the insulated wire between the wires is equivalent to a dielectric plate, and the capacitance formed by the wire and the wire form a bypass attenuation effect on the high-frequency signal (signal phase) It is delayed, because the signal frequency is high and cannot be ignored, so it is impossible to transmit high-frequency network signals by parallel lines. But if we twist the parallel pairs, we will form a series inductor at the same time as the capacitor is formed. According to the knowledge of the electronic circuit, the function of the inductor is just opposite to the capacitance. It makes the signal phase ahead, just adjust the winding of the wire. Degree, the inductance and capacitance formed by the pair can be exactly offset, and the effect of both increases with the increase of the length of the pair is equally increased. Ideally, the signal can be transmitted on the twisted pair without attenuation. .
From this we can know that although the 3, 5 and 5 types of lines on the market are basically similar in appearance, there are certainly some differences in the interior: First, the insulation material of the signal line is different, the better the line, it The lower the dielectric constant should be, so that the smaller the capacitance is formed, and the second is that the winding of the pair may be different (determined by the dielectric constant of the insulating material).