Testing problems of the most popular category 5 an

Recently, many generic cabling suppliers have successively launched some new cable systems, such as the category 5 cable system of American amp, the Gigabit cable system of American lucent, and similar cable systems later launched by other companies. Faced with these new cable systems, those users who have just installed five types of systems feel as if they are out of date, and users who are preparing to install cable systems are hesitant about which cable system to choose. This paper does not want to discuss the relevant detailed test parameters and technology, the rapid development of thin-walled technology of automotive parts, but just want to introduce the overview of current cable test standards for your reference according to the currently available information. I hope it will be helpful for users to choose what kind of cable system to install

first of all, there is a concept to be clear, which is bandwidth (expressed in MHz) and data transmission rate (expressed in Mbps). If this concept is unclear, it is difficult to make a correct choice. For the definitions and specific meanings of the two, please refer to relevant technical articles. The basic conclusion is that there is a relationship between the two, which is related to the coding method. But it is not necessarily a one-to-one relationship: for example, atm155, 155 refers to the data transmission rate, that is, 155mbps. The actual band is only 80MHz. Another example: 1000Mbps, due to the 4-Pair full duplex working mode, its transmission bandwidth is only 100MHz. In the computer network industry, data transmission rate is widely used. In the cable industry, bandwidth is used, so don't confuse the two

first, the current new cable system

1. Enhanced Cat 5 cable system (enhanced Cat 5)

it can improve the performance of the current five types of unshielded twisted pair, and the performance of many parameters, such as near end crosstalk (next), attenuated series to interference ratio (ACR), has been improved, but its bandwidth is still determined to be 100MHz

2. Category VI cable system (Cat 6)

it is a new level of cable. In addition to the great improvement of various performance parameters, its bandwidth will be expanded to more than 200MHz

whether it is a category 5 or category 6 cable system, its connection structure is still compatible with the plug-in module (RJ45) widely used now

3 and 7 cable systems

7 cable system is a cable standard proposed by Europe. Its planned bandwidth is 600MHz, but its connection structure is completely incompatible with the current RJ45 form. It is a shielded cable system

the current progress of field test standards for these three types of cable systems is: at the end of 1998 or the beginning of 1999, the current five types of field test standards will be updated; The on-site test standards for category 5 cable systems are expected to be formulated by the end of this year or the beginning of next year; The test standards for the six categories are planned to be formulated before the end of 2000; The seven categories of standards are under study and discussion in Europe and are not on the agenda of the Standards Committee in the United States

what is the significance of these standards? Because the cable system has the problem of secondary construction. After purchasing fully qualified products from the cable system supplier, the construction personnel need to assemble them to form the cable system. As the construction process and quality seriously affect the final quality of the cable system, the installed cable system may not be able to meet its specified indicators. So after installing a certain cable system, you (usually the end-user of the network) want to know whether the installed cable system meets the indicators it should meet, and whether the cost you pay is consistent with the actual quality. This is the significance of field testing standards. When the installed cable system passes the test of corresponding standards, the construction quality can be guaranteed, so as to ensure the return on investment

second, the current network technology's demand for transmission media

the cable system is installed to meet the needs of network applications, so what are the current network speed requirements? At present, the main computer networks include 4m and 16m token rings, 10M Ethernet, 100M Ethernet (including 100Base-T and 100base-t4), atm155 (based on twisted pair). These networks can operate on the current five types of twisted pair

the only undetermined thing that can be seen at present is 1000Mbps Ethernet. That is, what kind of copper medium Gigabit Ethernet needs to run on. At present, the final standard of Gigabit Ethernet has not been completed, but some basic indicators have been determined. For example, its requirement for unshielded twisted pair is to use all four pairs of wires (only two pairs for 100Base-T), operate in full duplex, and the transmission bandwidth is within 100MHz

according to the above basic requirements, users will naturally be concerned that since the bandwidth of Gigabit Ethernet is still within 100MHz, can it run on the current five types of twisted pair? Judging from the current draft standard, Gigabit Ethernet will operate on four pairs of lines in full pairs. Although the bandwidth is still 100MHz, it has new and more stringent requirements for some other performance of twisted pair cable system. For example, transmission delay (propagation

delay), delay skew, far end crosstalk (FEXT), etc. For these indicators and other technical details, please refer to the technical articles of fluke or other companies. The most important of these new parameters is equivalent far end crosstalk (elfext). Because of the problem of Gigabit Ethernet. As long as the five twisted pair system can meet the new standards formulated at the end of the year, including the most important elfext index, it can operate Gigabit Ethernet

what is the draft of the current standard and its content? The first is to revise the current category 5 twisted pair standard (tsb67) and add some new parameters. For example, transmission delay, delay difference, far end polypropylene (PPR) crosstalk, etc. Second, CAT5e, the super five standard, does not add new parameters, and the bandwidth is still limited to 100MHz. However, the indicators of many parameters are more stringent than those of the five types of systems. The third is the standard of six types of cable system, which is planned to be completed by the end of 2000. At present, the software design of the lower computer is still under discussion considering the real-time and accuracy of control. But one thing is very important and certain, that is, its bandwidth must be expanded to 200MHz or higher. (see Table 1)

Table 1 overview of test standards