Fabrication and principle of super five twisted pair wire

I've seen a lot of people these days. There is a lack of understanding and misunderstanding on the various technical problems of twisted pair wires. To solve everyone's doubts and repeated questions, special writing this paste, I hope to learn more about the Super five-type twisted pair (wire) and its standards and electrical principles to bring help.

First, let's have a concrete understanding of what is twisted pair

1, twisted pair: As a transmission medium it is composed of two of thin copper wire wrapped in insulating materials at a certain ratio of each other entangled.

Super five twisted pair, consisting of four pairs of twisted pairs of wires, total eight lines.

2. Why do you want to put two strands of twisted pair?

Because this entanglement changes the original electrical characteristics of the cable. This will not only reduce their crosstalk, but also to the maximum extent to prevent other cables on the cable on the signal interference.

3, twisted pair line classification:

1 twisted pair can be divided into: 2 pairs, 4 pairs, 25 pairs according to their stranded wires. (such as 2 pairs for telephone, 4 pairs for network transmission, 25 pairs for telecommunications communications large log cable)

2) According to whether there are shielding layer can be divided into: shielded twisted-pair (STP) and unshielded twisted pair (UTP) two major categories. ---http://bianceng.cn (computer science)

3 according to frequency and signal-to-noise ratio can be divided into: 3 categories, 4, 5 and Super 5 classes. Now many places have used six line or even seven kinds of lines. Used in computer network communication is at least 3 categories. The following types of line description:

One category: Mainly used for transmission of voice (a standard mainly used in the early 80 telephone cable), not for data transmission.

Class II: Transmission frequency of 1MHz, for voice transmission and maximum transmission rate 4[Please use civilized language]ps data transmission, common in the use of 4[please use civilized language]PS standard token Transfer Protocol old token net. I "

Three categories: refers to the current in the ANSI and EIA/TIA568 standards specified in the cable. The transmission frequency of the cable is 16MHz, for voice transmission and the highest transmission rate for 10[please use civilized language]ps data transmission, mainly for 10base-t

Four categories: This type of cable transmission frequency of 20MHz, for voice transmission and maximum transmission rate 16[Please use civilized language]ps data transmission, mainly used in token based LAN and 10BASE-T/100BASE-T.

Five categories: This type of cable increased winding density, jacket a high-quality insulating material, transmission frequency of 100MHz, for voice transmission and the highest transmission rate for 100[please use civilized language]ps data transmission, mainly for 100base-t and 10base-t network, this is the most commonly used Ethernet cable.

4, the performance of the twisted pair of twisted-pair line, the user is most concerned about the performance of several indicators. These indicators include attenuation, near-end crosstalk, impedance characteristics, distributed capacitance, DC resistance and so on.

(1) attenuation. 60

Attenuation (attenuation) is a measure of signal loss along a link. Attenuation is related to the length of the cable, and as the length increases, so does the attenuation of the signal. Attenuation uses "DB" as the unit, indicating the ratio of the signal strength of the source transmitting terminal signal to the receiving end. As attenuation varies with frequency, the attenuation of all frequencies in the application range should be measured.
(2) Near-end crosstalk +:

Crosstalk is near-end crosstalk and remote crosstalk (FEXT), the tester is mainly to measure next, because there is line loss, so the fext of the impact of small amount of value. Near-end crosstalk (NEXT) loss is the measurement of a UTP link from a pair of lines to the other pair of signal coupling. For UTP links, Next is a key performance metric and one of the hardest to measure accurately. With the increase of signal frequency, the measurement difficulty will increase.

Two, super five type unshielded twisted pair wire

What we are using today in the computer communication network is basically "super five type unshielded twisted pair cable". The cable's two head presses in the RJ45 Crystal head separately according to the certain line order, this also is commonly said "the network cable".

1, what is T568A Standard and t568b standard?

This is a series of two international standard lines developed by Super Five twisted pair to achieve performance index and unified wiring specification.

(Can imagine: in the production of RJ45 Crystal Head, if there is no such standard, then when a network of other people made the crystal head at one end of the problem, you have to look at the other end of the line and then back to do the end of the RJ45 Crystal Head, this is a matter of how troublesome. And it is possible that crosstalk is caused by not using the correct alignment. ）

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The line order of T568A is: white green, green, white orange, blue, white blue, orange, white brown, brown

The line order of T568B is: white orange, orange, white green, blue, white blue, green, white brown, brown

2, parallel lines and cross line (reverse wiring)

1 First look at how these two lines are made:

The same wiring standards are used for both ends of parallel lines. In general, the industry uses the T568B standard! Remember!!!

One end of the intersection uses the t568a line sequence, and the other end uses the T568B line sequence.

2 When to use parallel lines, when to use the intersection line?

Parallel lines are used to connect different devices together: Computers to switch crossover lines are used to connect the same devices together: computers to computers, switches to switches.

In order to make the switch and switch can also be connected with parallel lines, many switches have a up-link dedicated port, when you will be a switch to the uplink of another switch to the normal ports, you can use parallel lines but the above argument is only the general situation, Now there are a lot of high-end switch ports are adaptive to the line sequence, and rarely use the crossover line.
3, transmission distance and speed; ~h

The maximum transmission distance of super five twisted pair is 105 meters, and the average transmission speed is 100M (maximum peak 155M). The premise is that the performance of the twisted pair of the specifications of the Super five-type twisted pair of standards.

1 First look at how these two lines are made:

The same wiring standards are used for both ends of parallel lines. In general, the industry uses the T568B standard! Remember!!!

One end of the intersection uses the t568a line sequence, and the other end uses the T568B line sequence.

2 When to use parallel lines, when to use the intersection line?

Parallel lines are used to connect different devices together: Computers to switch crossover lines are used to connect the same devices together: computers to computers, switches to switches.

In order to make the switch and switch can also be connected with parallel lines, many switches have a up-link dedicated port, when you will be a switch to the uplink of another switch to the normal ports, you can use parallel lines but the above argument is only the general situation, Now there are a lot of high-end switch ports are adaptive to the line sequence, and rarely use the crossover line.

Third, the theory advanced

To further understand why you should use the adjusted line sequence, want to know why the same equipment with crossover, heterogeneous devices with parallel and so on this problem must first understand the interface of the electrical network adapter TX

1. Which copper wire is used in the network card interface?

When a network cable to the network card, in fact, the network card does not use all the 4 pairs of pairs (8), it only used 2 pairs of around. That is 1 and 2,3 and 64 lines. Some people ask: why not use 1 and 2,3 and 4 or 1 and 2,5 and 6?

White orange, orange, white blue, blue, white green, green, white brown, brown

First of all, in order to remember, we will line by: White Orange, orange, white blue, blue, white green, green, white Brown, Brown in order. From the diagram above, you can know that the network card only uses the 1th, 2, 3, 6 line sequence. In order for 3 and 6 to be in the same windings of the network cable (why to use the same around the front has been mentioned), so we only have the crystal head of the line 3 and Line 5 lines, so in fact, the inside of the network wire to use 5 and 6 around the pair.
2, why do you use the crossover line?

The problem is to go back to the electrical definition of the NIC interface, namely:

tx+--rx+

tx---rx-

rx+--tx+

rx---tx-

tx+-for sending, rx+-for receiving

If you haven't figured it out yet, let's take a look at the two international standard lines that we talked about earlier-

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The line order of T568A is: white green, green, white orange, blue, white blue, orange, white brown, Brown wc=z

The line order of T568B is: white orange, orange, white green, blue, white blue, green, white brown, Brown 4>j5.

Look at the relationship between T568A and t568b is not just the 1, Line 3 line, 2, Line 6 line swap?

This is one of the reasons why the two standards for T568A and T568B are defined

3, how to switch between the various port connections how to select the line?

In fact, the Up-link port of the switch is the manufacturer in the production of the switch when the special design of a bypass method has been a dedicated port, and make this dedicated port can be connected with parallel lines and other switches of the ordinary port. In addition, generally speaking, the bandwidth of the Up-link port on the switch is larger than that of ordinary ports.

What are the crossover lines to use when connecting all the devices below? or parallel line ~? (If the intersection and parallel lines can be connected to the situation, do not accidentally, now many high-end switches can be automatically converted line order)

Device Line Style

Computer--Computer crossover line

Computer--Parallel switches

Computer--up-link intersection Line

Switch-switch crossover line

Switch--up-link Port Parallel

Up-link Mouth--up-link intersection line