On February 8, 2008, the TIA/EIA 6A standard (TIA/EIA 568B.2-10) was officially promulgated, which defines a new set of Category 6A cabling system for the 100m transmission distance and 500MHz bandwidth requirements of 10Gbase-T. With the promulgation of this standard, the shielded and unshielded debate over 10 Gigabit copper cables is in front of us again. As more and more 10 Gigabit copper products come out and become more mature, should you choose shielded or unshielded? Next is the transmission performance of 10 Gigabit copper UTP and STP.
UTP vs STP Transmission Performance Showdown – ANEXT
The purpose of the integrated wiring to the 6A system is to ensure the 100m transmission of 10 Gigabit, and to judge the performance of the 6A system, an important parameter is ANEXT, which is a very critical performance parameter after the integrated wiring system reaches 6A. That is, line-to-line crosstalk, also known as alien crosstalk ANEXT. ANEXT is defined as the interference caused by one pair of wires in a cable to an adjacent pair of wires. ANEXT interference is most pronounced between two wires of the same color due to their twist in the pair.
The distance is the same, a further consideration must be based on the combined alien crosstalk, or PSANEXT, because there is also induced noise interference between all adjacent pairs, not just those of the same color. In addition to cables, there is also a strong ANEXT interference effect between the two adjacent ports of the patch panel.
When the 6A system reaches 10 Gigabit transmission
The signal coding has adopted the PAM port coding method as the matrix coding system, and four pairs of cables are transmitted at the same time. The signal-to-noise ratio of each pair of lines must be up to standard.
In order to solve this technical problem, the industry has adopted many technical innovations to make it a reality to transmit 10 Gigabit over a distance of 100m. Specifically, the methods adopted by the industry include many new designs in the structure and connection of cables, 10GBASE-T optical modules, including the use of new materials, new manufacturing techniques, changing the relative positions of the four pairs of cables, Change the printed circuit design of the 10GBASE-T optical module to improve the ANEXT performance and meet the requirements of 10 Gigabit transmission. Of course, due to the different technologies adopted by different manufacturers, their views on recommending 10G shielded and 10G unshielded are also different.
Therefore, shielding and non-shielding are just a means. The purpose of which is to ensure that the interference between lines can be resisted. And the alien crosstalk between each other can be reduced. Therefore, the most critical issue for the 6A system is how to solve the alien crosstalk.
UTP vs STP External Crosstalk Testing – Ease of Detection
First of all, the requirements for passing the 500MHz certification test are the same for a 6A system. Whether it is shielded or unshielded, the current standard only requires sampling “channel” testing. Only after passing the 6A channel certification test is it meaningful to test for line alien crosstalk. Since the absolute “6-in-1” model cannot be found in the field. And the amount of testing to complete all combinations is enormous. It is impossible and unnecessary to carry out alien crosstalk testing in a strict sense in actual engineering. If testing is required, simply test a proportional sample and pay attention to the selection of “victim links” and “interfering links”. Although the test instrument provides the greatest possible automatic and intelligent functions. The actual engineering operation is still laborious and time-consuming.
But for 10G unshielded, the field test of alien crosstalk ANEXT is indispensable. Since alien crosstalk needs to consider the “6-in-1” test environment. It is impractical to require 100% alien crosstalk testing for every unshielded link in actual cabling engineering. In most cases, testing all possible pair combinations for alien crosstalk is not economically feasible or affordable. Even sampling tests require a lot of manpower and time investment. Which makes it difficult for users to obtain sufficient protection.
In addition to the more excellent ANEXT index of the 10G shield
This makes it exempt from on-site testing, the immunity of its shielding layer to noise can provide a better guarantee. For high-speed signal transmission, and is more capable of trouble-free operation in noisy environments. The shielding system can exclude external radiation, thereby improving the security of the signal. But the same problem is that the shielding project itself is qualified to ensure. That the external crosstalk has little effect. But how to judge the shielding project is qualified? Usually this is more difficult. At present, none of the instrument manufacturers can come up with a test instrument with good shielding performance quality.
These instrument manufacturers still rely on the signal between the pairs to analyze the performance parameters, so the test volume cannot be reduced. Secondly, due to the complexity of the alien crosstalk test, the field test still has a long way to go. For example, the test methods are not uniform, the test time is too long. The test cost is high, the instrument accuracy is not high, and the fault diagnosis ability is not enough. Finally, although the shielding system solves the alien crosstalk. It increases the internal crosstalk (interference signals are reflected inside the shielding layer). So the performance margin of the shielding system is not high.
For more questions about 10GBASE-T optical modules and copper cabling, please contact the QSFPTEK technical team.
