General Cabling System Testing FAQ

Generally, the integrated cabling system is updated every few years. From three to five types of integrated cabling system only five years, five types of systems to replace five systems, only three years, and now six types of systems have been mature and increasingly widely used. As the implementation of Gigabit Ethernet on six types of integrated cabling system has become possible, the standard of seven types of integrated cabling systems is being developed in response to network and video speed demands.


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since 2002 TIA and ISO6 standards have been promulgated, for the comprehensive cabling Project acceptance of the comprehensive cabling system testing more and more attention, with our GB 6 of installation design and test acceptance standards to speed up the pace of development, the whole market will set off a certification of integrated wiring system testing boom. The more you practice, the more problems you will find, in order to allow the vast number of technical personnel to better understand the certification of integrated wiring system testing, protect their investment, we will often ask questions listed, hoping to play the role of the doubts, in order to promote the correct, impartial, scientific acceptance methods to make a contribution.





One, why the new tester DTX Series IV Precision Certification has not been received?





now because of the need to support the test of 10G Ethernet, each standard is to the accuracy of the instrument needs to discuss, basically only to achieve IV accuracy of the instrument to support the 10G Ethernet test. However, neither the Tia,iso nor the IEEE have yet finalized the criteria for IV accuracy, so we can only make our instrument exceed the IV precision defined in the draft, but we cannot apply for or affirm any certification.





but now the market needs to test the system are 6 categories and super Five categories, 10G applications in China there is no commercial case. According to the standard stipulation, 6 kind of comprehensive cabling system tester needs to satisfy is the third level precision. For instrument accuracy certification of international agencies currently have UL and ETL two compare name, Fluke Cable certification integrated Cabling System tester at the same time to obtain the accuracy of these two institutions certification, the investment for customers, is a good protection.





Two, why should fluke use that "expensive" adapter





Some manufacturers have introduced the Integrated Cabling System test scheme without adapters, and the principle is to set reference values in reference to the optical fiber integrated wiring system test method. Theoretically, it does have its own uniqueness.





But if we look at it from the actual situation, we will find the problem. If you look at the manufacturer's instructions, they will ask you to use a good jumper to set the reference value. So what's a good jumper? Is it based on ansi/tia/eia-568-b.2-1 and iec61935-2forpatchcordtesting, or do you think it's a good jumper? and their salespeople are demonstrating in the field, The use of damaged jumpers does not affect the effectiveness of the final cabling system test. Is it really so?





first of all, what's the jump jumper? You go to buy jumper, no matter who the supplier is, who the manufacturer is, they will tell you that their jumper is good, but the fact is ansi/tia/eia-568-a-4 five class jumper standard is after numerous changes, the field attestation only then formally finalized, Because the performance of the jumper is very large, different manufacturers, different batches of the production of jumpers in the electrical performance of a great difference, only through the certification Test jumper can be considered "good" jumper. And no adapter cabling System test Scheme in the reference settings, only one jumper, the formal integrated wiring system test needs two jumpers. Then the performance of the second jumper on the entire test results of the impact, how to authenticate, how to guarantee it? You will find that in the live demo, the factory chamber for the first set of reference to the jumper, and ignore the second is not made reference to the jumper set. This invisible jumper is a loophole. When doing the instrument demonstration, the environment is simpler than the formal cabling system test environment, the technical personnel also likes to use the quality good link, guarantees two times the comprehensive wiring system test is the result which passes through. Such testers, testers and bystanders are all happy. But the scene is often more complex, and many links do not have a large margin to offset the impact of bad jumper. If the test results are not passed because of the invisible jumper, who should pay the bill?





simply give a parameter for example: characteristic impedance. The jumper allows the characteristic impedance deviation to be less than 5%, while the link allowable characteristic impedance deviation is within 15%. Suppose the characteristic impedance of the jumper is 95 ohms, the characteristic impedance of the link is 115 ohms, both of them are in the standard allowable deviation range, but the impedance deviation between the two is 20 ohms, the deviation reaches 20%, so the signal reflection can make the test result ideal? Because the jumper and link between the characteristic impedance mismatch caused by the integrated wiring system test does not pass, who should pay the bill?





In addition, if a special adapter is used, then there is only one RJ45 connection connected to the link, if the use of an adapter-free cabling System test scenario, there will be more than one additional RJ45 connection in the link. As we all know, the RJ45 connection for the cable structure is to play a destructive role, RJ45 Crystal Head performance is particularly unstable, due to the more stringent requirements of the 6 categories, the market basically can not buy the user to make their own jumper of the crystal head. If you are using a no-adapter test scenario, what if you treat the effect of repeated superposition of interference signals, such as next,rl,fext, between two crystal heads? This is not a simple setup reference can solve the problem. The coupling between the jumper Crystal Head and the instrument interface and the link modules formally to be integrated into the cabling system test can be completely different. This cabling system test, if not through, who should pay for it?





sounds simple and inexpensive solutions that are not as beautiful in the real world as they seem to be. The use of completely uncertain performance jumper, the overall wiring system test site situation is completely unable to authenticate the test plan, in the current owner of the project quality of more and more attention to the situation, it is like Mashi, Night pro deep pool, is very dangerous.





use a dedicated adapter, first of all, its integrated cabling system test jumper is sstp, characteristic impedance of 100 ohms ±1 ohm, can be calibrated in the field, on the RL, NEXT, fext on the guarantee that it will not adversely affect the test results, secondly, it uses the test module, the internal no cable, is completely integrated circuit connection, avoids the RJ45 crystal head next influence, this test result is correct, just, scientific.





Three, days when the heat of the integrated wiring system test, why attenuation is always unqualified?





The cable attenuation is affected by the link length, temperature, humidity and other factors. For 6 types of cable, the standard has clearly stated that the operating temperature of the cable is 20oC, in the 20oC to 40oC range, the temperature of each increase 1oC, attenuation increased by 0.4%, between 40oC to 60oC, the temperature of each increase 1oC, attenuation increased by 0.6%. In fact, the cable will decay at 40oC 8% higher than 20oC. So when the weather is hot, long links, such as links over 80 meters, attenuation tests usually occur fail. Many engineers would like to have some method of temperature compensation during the integrated cabling system test, which will reduce the attenuation of the degradation caused by high temperature and increase the pass rate. Before the formal promulgation of the ansi/tia/eia-568-b, in the field of integrated wiring system testing at the time of the test instrument to enter the field temperature, through the calculation of the method of compensation.





but in practical applications, attenuation is a key parameter, it is related to the final application can ensure that the receiver received sufficient strength signal, so temperature compensation is not desirable. After the formal promulgation of ansi/tia/eia-568-b.2-1 and iso/iec11801:2002, the on-site temperature compensation is no longer an acceptable solution. In order to ensure the attenuation performance of the final channel, the only way is to shorten the permanent link length according to the field situation. You can refer to the table below to calculate how long the permanent link length should be adjusted according to the field temperature. The length of the whole channel assumes a maximum of 90 m horizontal link plus 10 m user jumper at 20oC.





if because the project site must be longer than 80 meters of the link, you need to coordinate with the owner, to explain the attenuation and length, temperature relationship, to obtain the understanding of the owners, to accept these attenuation did not pass the integrated wiring system test information points. However, since the decay of unqualified links is very unstable in the transmission of data, owners should be persuaded to use these links as low speed data transmission or telephone applications.