How to deal with the cable problem in the wiring system
The selection of cables should be comprehensively considered according to system requirements, technical performance, and investment estimates. In the wiring system, the type of cable used and the wiring structure (shielded cable, non-shielded cable, optical cable, or they are used together) should be determined first.
Cables usually consist of 2 to 1800 pairs. Large-pair cables are usually used in trunk cabling systems and are suitable for use in voice and low-rate data applications. They are the largest in trunk and horizontal (hub-to-desktop) cabling systems. The length is specified in the international standard ISO/IEC IS11801. It should be noted that these maximum length restrictions apply to all media, but do not take into account the performance aspects due to the different cable types and protocol types used in the network. the impact of differences. In practice, the maximum cable length will depend on the application of the system, the type of network and the quality of the cable.
In addition, the selection of cable types should be considered in combination with the application requirements of the wiring system. The Cat5e system can support the operation of Gigabit Ethernet, and the Cat5e systems of different manufacturers can be interoperable;
The price of Category 6 is more expensive than that of Category 5, but its bandwidth is expanded by 25%, and the transmission rate has increased significantly. Category 6 systems are dedicated, and components of each manufacturer have their own unique design and performance indicators. Components of different manufacturers The possibility of interoperability is very small, and the index of the components is still under study; the use of Category 6 cables should select the same level and the plug-in device produced by the manufacturer, because Category 6 is a special component, and the products of various manufacturers cannot yet be interoperable.
The selection of shielded and unshielded cables depends on the external electromagnetic interference. When the interference field strength is lower than 3 V/m, protective measures are generally not considered. When the interference signal exceeds the standard amount, shielded cables can be selected. The price of shielded cables is 1.2 to 1.6 times that of unshielded cables. Therefore, shielded cables are suitable for areas with severe electromagnetic interference and places with high confidentiality requirements.
At the same time, the wiring system should not only take into account the current needs, but also take into account the future development, and can not ignore external factors, just like the foundation of the building, the basic role of the wiring system in the intelligent system determines that once it is built It is impossible to change in the short term, so the cabling system has a long life cycle - ie 15 to 25 years.
In today's rapid development of technology, if the development is not considered, it is very likely that when the wiring system is completed, its products and performance have fallen behind the needs of users. Is it right to choose an advanced product? Not necessarily. Going too far not only increases investment, but also may be out of touch with demand and waste resources.
In addition, external factors such as the performance of network products, bandwidth of access lines, office equipment, etc., also affect and restrict the performance of products to a large extent. Without comprehensive consideration of environmental conditions and one-sided pursuit of product advancement, it will also Fall into the misunderstanding of product purchase. According to the previous analysis of user needs and selection principles, there are roughly the following three options for current users and their selection of wiring products:
First, high-end users have high requirements on the processing and transmission speed of various types of information, attach great importance to the stability and security of products and systems, and have abundant funds, represented by media, stadiums, transportation and hospitals. Most of its wiring systems use Category 6 or higher systems, and optical fibers are also considered for special needs. For example, audio/video transmission in media buildings has high requirements on the frequency and field strength of information flow, and there are many sources of radio interference. In order to avoid interference between transmission line signals and electronic equipment, shielding and fiber optic wiring are often used. system. Another example is the competition venue wiring system to pay attention to three aspects:
Considering the large surface area of the stadium, multiple telecommunications rooms should be set up, and it is best to use optical cables for intercommunication between the telecommunications rooms;
·Pay attention to the deterioration of technical parameters and performance indicators due to the aging of the device caused by the outdoor environment. Therefore, from a safety point of view, shielding and fiber optic wiring systems are often used. The traffic building is characterized by a large building area. If it involves the connection between buildings in different places, it reflects the form of decreasing cables along the pipeline, which is an extended star network. The main part of the cable routing is very long, it is advisable to use the optical fiber cabling system.
For problems involving electromagnetic interference of electromechanical equipment, the shielding of cables should also be considered. The most important thing in the hospital is to consider the cable's demand for transmission bandwidth and the electromagnetic interference of medical equipment. Because the hospital occupies a large area, has many buildings, and has complex functional requirements, it should be considered as a multi-functional building group. , It is designed according to the cable layout requirements between buildings. In order to meet the needs of many conditions, it is more appropriate to use a shielded wire + fiber optic wiring system.
The second is intermediate users, mainly dealing with comprehensive data, voice or multimedia information, with a certain scale, but not high requirements for information transmission speed, represented by mid-range office buildings, factories, schools and smart communities. Such buildings generally use optical fibers as the backbone for wiring, and use Category 5 copper cables (or Category 6) for horizontal wiring. Most of the voice lines use Category 3 large logarithmic copper cables. For example, the integrated wiring in a school building is the overall wiring of a building complex, and more consideration should be given to the construction of the backbone optical fiber of the network. In addition, the school has many functions, including teaching buildings, experimental bases, public lecture halls, libraries, science museums, and student dormitories, etc., but the overall demand for the network is relatively low, so most of the level systems will choose super five class cable. Of course, it is not ruled out that some individual places will also take into account their needs and use Category 6 cables horizontally, such as science museums.
The third is ordinary users, mainly based on the ability to realize information transmission as the basic demand, such as ordinary houses. The integrated wiring of residential buildings has two characteristics:
Use household integrated wiring box to complete the wiring function, but does not process the information (such as exchange, storage, processing, transmission);
Combining wiring management and information processing together, it should actually be called "family information wiring equipment", which not only has wiring functions, but also exchanges and transmits information on telephones and networks. Conversion and transmission of home intelligent control information such as CC, emergency call, etc. Generally, pure copper cable is used for wiring, which is of high quality and low price.
In the integrated cabling product line, there is a one-line-to-home solution, which mainly adopts pin-shaped modules and adopts a special design of one-line-to-home mode, which can simultaneously transmit one data and two data on a Category 5e UTP cable. Door phone, save a lot of money for investors, with excellent cost performance.
Every active electronic and electrical device can generate electromagnetic interference that can disrupt network communications. This problem has also become more prominent with the increase in the use of electronic devices. How to prevent electromagnetic interference to protect communication is also a very critical issue in the selection of cables and cable routing considerations.
All network components, including the selected connectors and patch panels, must have measures against EMI. When using shielded cables, it is very important that the cable and the connector are properly terminated and that the cable jacket is properly grounded. Any incomplete shielding will reduce the protective effect of the shield and thus reduce the effectiveness against electromagnetic interference (EMI). The cables should be routed according to the method recommended by the manufacturer, and potential signal source interference should be avoided as much as possible.
Here, the indicators stipulated by the rapidly developing international standards related to cable routing should be fully considered. Fluorescent lights, elevator motors, automatic doors, and air conditioning units are all potential sources of electromagnetic interference. The older the equipment, the more electromagnetic interference it generates. For those sources of EMI that cannot be avoided and overcome, the use of enclosed metal conduits can provide additional protection for the wiring system. In certain EMI or sensitive environments, the use of fiber optics may be the only option.