Cable test indicators in the development of the ho

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Considering the cable test index in the development of near end crosstalk

generally, when users choose five types of UTP cabling products, they hope that the system can not only meet the existing network application requirements, but also provide support for future networks that require higher data transmission rate. Therefore, when testing the cabling system, everyone will refer to the current relevant international standards, such as eia/tia 568a, TSB 67 and iso/iec 11801. With the development of network technology, we find that in some network standards, such as 10Base-T and 100base TX, the number of lines used by the system is 2 pairs, while 10base-t4, 100VG anylan and the developing ATM 622 standards require that the system can use 4 pairs of lines to transmit data at the same time. It is not difficult to imagine that when the system sends or receives signals simultaneously with four pairs of lines, for one pair of lines, the other three pairs of lines will produce near end crosstalk (next) to the line pair at the same time. According to the current test standard of "plastic restriction order" officially implemented in China, the next value is measured only between two pairs of lines. For this reason, some users propose to test the sum of next, and some test instrument manufacturers also claim that their instruments can provide this test, that is, power sum test. Do users have to perform power sum test? What is the significance of power sum testing

power sum refers to the sum of the next crosstalk of a pair of lines by other pairs when the cable uses multiple pairs (more than two pairs) to transmit signals. Before further discussing the significance of power sum next test, we first review the next test in tsb-67 standard

near end crosstalk refers to the crosstalk between one pair of lines and another pair of lines in the UTP cable link due to the signal coupling effect. Sometimes it is also called next between line pairs. Since category 5 UTP cables are composed of 4 pairs, there are six combinations according to the arrangement and combination method. Tsb-67 standard stipulates that the worst next value between two pairs of wires cannot exceed the requirements of the test limits of basic link and channel in the standard

since the theoretical model of tsb-67 assumes that only two pairs of lines in the cable may transmit signals at any time, the test of next value between pairs of lines required by tsb-67 only examines the signal coupling between any two pairs of lines in a link, rather than the sum of the coupling effects between multiple pairs of lines. It can be seen that for those network standards that only require cables to use two pairs of wires to transmit signals, such as 10Base-T and 100base-tx, the next value test between pairs is applicable, but when multiple pairs are required to transmit signals at the same time, this method can not fully reflect the actual situation of the link

power sum next value refers to the sum of the next interference values of all adjacent line pairs received by a pair of lines. In eia/tia 568 standard, the test of power sum is a necessary test item for those backbone cable links with a large number of pairs (more than 4 pairs). According to relevant standards, power sum next can be calculated based on the measurement results of the next value between independent pairs. Through testing and comparison, the measurement results of power sum next and next between pairs on the same cable link show that the former is usually worse than the worst of the latter. The setting range of the thermal insulation layer shall be the outer wall of the inner space or the inner surface of the partition wall with the public part; For buildings that really need to adopt external wall external insulation system, in fact, among 4-Pair cables, power sum next is about 5dB worse than that between pairs. Therefore, a link that can pass the category 5 UTP next test standard in tsb-67 may not pass the power sum test. As the relevant requirements for power sum next test are more stringent, some manufacturers that provide enhanced category 5 UTP or connectors have taken this standard as an indicator to measure product quality. Obviously, links that pass the power sum next test can provide better transmission performance

although the tsb-67 standard does not require the test of power sum next value, the source of construction pictures: the danimerscientific unit can appropriately add power sum test items to the link according to its selected standard or in consideration of supporting higher data transmission rate in the future. At the same time, when conducting next measurement between pairs according to tsb-67, we should strive to make the difference between the test result and the test limit exceed 5dB

in order to meet the users' requirements for the continuous improvement of cable measurement quality, although the power sum next test is not a required test item in the standard, we still recommend that you use this test function as a reference index when selecting it. If the network protocol you are using or the protocol you are about to use requires four pairs of cables to transmit data at the same time (such as 100base-t4 or 100VG anylan), you can consider adding power sum test

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