Crosstalk and integrated wiring

With the development of science and technology, the price of computer is getting lower, the performance is getting better, the transmission speed of LAN is more and more fast, and the transmission medium of LAN has shifted from coaxial cable to twisted pair and optical fiber, twisted-pair line from the initial CAT1, CAT3, CAT5 to the present CAT5e, CAT6 CAT7.

Although the performance of twisted pair has been continuously improved, but there is a parameter like the ghost has been accompanied by twisted pair, and with the development of twisted pair, this parameter is more and more important. This parameter is-------crosstalk (Crosstalk).

Crosstalk may be one of the most important factors in high-speed data transmission. It is an unwelcome energy value generated by the coupling of a signal to another signal. According to Maxwell's law, as long as there is a current, there will be a magnetic field, the interference between the magnetic field is the source of crosstalk. This inductive signal may result in loss of data transmission and transmission errors. So crosstalk for the integrated wiring, is undoubtedly the most powerful natural enemy.

CAT1, CAT3, CAT5, CAT5e, CAT6, CAT6A, CAT7 the difference between them is the diameter of copper wire more and more coarse, more and more small torque, 2 cable twist more and more tight, line pairs between more and more (cross skeleton, aluminum foil, Mylar, row streamline, copper wire weaving nets), Frequency from 16MHz to 100MHz, 250MHz, 500MHz, 600MHz, etc. but Crosstalk also follows changes from line to line pairs between the next, Psnext, Fext, Elfext, Psnext development to the anext between cables, Psanext , these are the extensions of crosstalk, crosstalk expression.

In crosstalk testing, high test values (DB) are better than low test values. Because the number of crosstalk is the ratio between the useful signal and the noise signal. High test value means that the useful signal is far greater than the noise, low test value means that there is little difference between the useful signal and the noise, and the receiver can not receive the signal correctly, resulting in the loss of the packet. Crosstalk is associated with frequency, when the frequency increases, the crosstalk value becomes lower, which needs to increase the diameter of the copper wire, increase the torque of the cable, increase the cross skeleton to separate the cables, increase the thickness of the outer sheath or increase the shielding layer and so on a variety of production technology to solve the more and more thorny crosstalk problem.

Near-end Crosstalk (NEXT), which is caused by the coupling of signals transmitted by the device at the sender end to the adjacent receiving end of the other pair of wires. This is the most important crosstalk for transmission rate less than 100Mbps. However, with the increasing rate of data transmission, all line pairs of twisted pair need to transmit data, which is the method of parallel transmission mode. LAN systems are also affected by other crosstalk-remote crosstalk (fext) and equivalent remote crosstalk (elfext). The remote crosstalk (fext) is a signal caused by the cable link near the end of the other line pair, and is induced to the distal line alignment. Elfext is subtracted from attenuation and fext. is more practical than fext,elfext, because as the length increases fext certain changes will occur, which means that the same cable at different lengths, the measured fext for different values, which can not measure the quality of the cable, but Elfext because of the introduction of attenuation this parameter, Makes the online cable test more practical, so the test report will often appear elfext rather than fext this parameter.

With the increase in transmission rate, such as the current hot 802.3an standard 10G base-t, 500MHz of high-frequency rate so that the previously overlooked cable and cable interference between, is also beginning to consider in which, this is the external crosstalk anext (alien crosstalk), If this parameter is not qualified, the 10Gbps rate will be greatly reduced, even can not run. CAT7 straightforward to give up the unshielded structure, using a single pair of shielding and copper wire woven shielding method to solve the internal interference between the cables and cables outside the interference, it must be said that Crosstalk makes the cable structure more and more complex.

Addison as a global supplier of wiring products, product line is more complete, covering the CAT3, CAT5e, CAT6, CAT6A, CAT7, UTP, FTP, STP, SFTP and so on various categories of various types of cable structure, can meet the needs of a variety of users, welcome inquiries.