Today, many people in the apartment have a computer, Internet access. Often there is a need to connect a computer to the Internet using a cable or extending the wire when moving a user device to another location. You may also want to create a home network of several computers. All these issues are solved by creating an Internet network from a special cable.
Basic concepts
A special type of cable designed for the manufacture of computer and telecommunication networks is called “twisted pair”. It consists of several pairs of copper cores in insulation, twisted together with a certain number of revolutions per unit length. The most common is 8 twisted-pair wire. All cores are placed in a common polyvinyl chloride (PVC) sheath.
A slight twisting or twisting is done in order to neutralize the interference from electromagnetic radiation generated by the conductors themselves and third-party sources. Because at close proximity of the cores, the electromagnetic radiation created by them is quenched against each other, without creating signal loss. In addition, external noise is caught by two twisted conductors in the same way, so it is easily recognized by the receiving device and cut off. The result is a high-quality digital signal with minimal loss.
Modern computer networks are connected by cable of the fifth category and higher. The most common modification of cables No. 5 and No. 5e to date is capable of operating with a frequency of more than 100 and 125 MHz, passing up to 1000 Mb / s, with a core section of 0.5 mm 2 . The sixth and seventh categories of cables are used for high-speed Internet, have a bandwidth of up to 10 and up to 100 Gb / s, respectively, and with thicker wires.
Types of Twisted Pair
- UTP - twisted pairs are not shielded, there is no external screen. The most common type for apartment computer networks when there are no large interference and distances.
- FTP - twisted pairs are not shielded, but there is an external screen made of foil. It is used in small offices where you need to transfer data over distances of up to 100 m without loss of speed, and where there are pickups.
- STP - each twisted pair is braided with a wire protective screen, there is an external screen. Used in medium-sized offices and establishments where there may be interference. They allow preserving the signal quality during transmission over long distances, but not higher than 100 m.
- SF / UTP - twisted pairs are not shielded, but there is an external copper braid and foil film that make up a double screen. They are used at enterprises to maintain signal quality over long distances and to protect against interference.
- S / FTP - each twisted pair is shielded with foil, there is an external screen in the form of a copper braid. It is used in enterprises with large interference and where it is necessary to maintain the transmission speed of information over a long stretch.
Cable insulation color is gray - the most widely used. Color red or orange - it means the insulation is made of non-combustible material.
Two ways to crimp a twisted pair
The Rj-45 computer cable is connected to the device via the 8P8C connector (abbreviation from English words for 8 positions, 8 contacts). This connector is installed on the cable by crimping twisted pair of 8 cores according to the color scheme, depending on telecommunication standards.
Standard 568-A is outdated and 568-B is most commonly used.
Following the diagram, the cores with the 568-A system are laid as follows:
- White-emerald.
- Emerald.
- White-red.
- Blue.
- Blue and white.
- Ginger.
- White chocolate
- Chocolate
The order of colors when crimping a twisted pair according to the 568-B standard is as follows:
- White-red.
- Ginger.
- White-emerald.
- Blue.
- Blue and white.
- Emerald.
- White and chocolate.
- Chocolate.
There are eight grooves in the connector, where 8 twisted-pair wires are laid according to the color scheme. The pinout is indicated above.
Network cables are needed to connect computers and network devices in various combinations. For example, connect the router to the network, a computer to the router, two computers between each other, a power strip, a splitter, a TV to the router. There are two options for making network cables.
Direct twisted pair connection by color
The first way is direct. The color scheme of the pinout of the twisted pair of 8 wires can be made both according to the standard 568 A (when one and the other ends of the wire are crimped according to the type 568 A), and according to the standard 568 V (when one and the other ends of the wire are crimped according to the type 568 V).
The 568 V method is common in our country, and the 568 A type is most often used in the USA and Europe. The only difference between the two methods is the interchanged cores of white-green with white-orange and green with orange. It is used to connect various user devices (computer, TV, laptop) to network equipment (switch, router, hub, router, patch cords, extension cable), and is also used to connect network devices to each other. The data transfer rate with this scheme is 1 Gb / s.
Direct twisted pair connection 100 Mb / s
In some cases, when high speed Internet is not required and traffic of large volumes is not provided, you can use the connection according to the colors of a twisted pair of 4 wires: white-red, red, white-emerald, emerald. This method saves wire consumption, but keep in mind that the highest information transfer rate drops 10 times and is 100 Mb / s.
Cross connection of twisted pair
The second way is cross or cross. The crimped twisted pair of 8 cores (color scheme) is shown below, used to combine two computers into a home network without any network equipment or two similar client devices (computer, TV, laptop).
To make a cross cable, you need to crimp one end of the wire according to the standard 568 A, and the other according to the standard 568 V. In this case, the cores are interchanged: white-red with white-emerald, red with emerald. In this case, the information transfer rate will be only 100 Mbit / s. The Gigabit Crossover scheme involves the exchange of places of all eight veins: white-red with white-emerald, red with emerald, blue with white-chocolate and white-blue with chocolate. This 8-wire twisted pair pinout color scheme is designed for 1000Base-T and 1000Base-TX high-speed networks, when the data transfer rate is 1 Gb / s.
Summarizing, we can understand that if you need to connect a computer to the Internet, you should crimp both ends of the cable according to type 568 V. If you want to connect two computers to each other, you should use the Gigabit Crossover circuit, where the first end of the wire is crimped according to type 568 A, and another - by interchanging all eight wires.
How to crimp a network cable?
Now that it has become known how to connect the twisted pair in color correctly, you can start crimping. How to do this is described below.
Tools and materials
- Network cable. First you need to calculate the length - it is better with a small margin, so that you do not have to increase it later, the Internet speed drops significantly.
- Connectors A certain amount is a minimum of 2 pieces for each twisted pair (at both ends of the cable), but it is better with a margin, especially for those who crimp the cable for the first time.
- Crimper - a special hand tool, which is a crimping pliers with a socket for the connector 88 (on the case there is an inscription 8). If there is no such tool, then a thin flat screwdriver is suitable.
- Stripper - a special hand tool for stripping insulation from cores. If not, a knife will do.
- Multimeter - to check the quality of crimping.
Sequencing
Using two knives on the crimper, you can cut the cable to the desired length. Then remove 2 cm of external insulation from both ends of the cable with a knife and a notch on the crimper located near the handles of the tool. It can also be done with a stripper or a sharp knife, but only carefully so as not to damage the insulation of the cores.
Twisted pairs are twisted to make 8 separate cores. Spread in a row, according to the color scheme of the pinout of the twisted pair of 8 wires.
It is necessary that the ends of the wires are all on the same line, one not longer than the other. The quality of the crimp depends on this. If some core is longer, it should be cut to the level of others. The connector is turned latch down, then all the cores are inserted into the connector along the grooves until they stop, observing the pinout. The outer insulation of the cable should be in the connector housing, if this did not happen, you need to cut the ends shorter.
Insert the connector with the cable into the crimper jack with the inscription 8P. Squeeze the grips firmly but gently until they click. If you have a tool at hand, this procedure is quite simple, but if there are no ticks, then you can do with a flat screwdriver. To do this, put the tip of a screwdriver on the connector pin and press it until it cuts through the insulation of the core with its teeth. Do this with each of the eight contacts. Then you should also push the central part of the connector housing - a recess on the connector near the cable inlet, for fixing. If the first time did not work, you can cut the failed connector and do it again.
Check the quality of work with a multimeter. To do this, put the “resistance” mode on the device. To test the device, close two probes with each other, should show a resistance of 0 - then there is a contact. Then put one probe on the contact from one end of the cable, and the other probe on the corresponding color contact from the other edge. If it shows 0, therefore, there is a connection, everything is fine. If it shows 1 or so, then the teeth did not break through the insulation, you should either push the contacts again, or cut and re-make.
It is possible in another way to check the quality of the crimped twisted pair of 8 cores. The sequence of wires to ring a special network tester. How to use it is written in the attached instructions. And you can also connect the finished patch cord to the equipment and check if all the packages are arriving.