Cabling test methods and Optical Fiber Transmission Channel Test -- wire and cable Application

Introduction to computer network structured Integrated Wiring System

StructuredCablingSystem (SCS) is a module system based on star topology developed by Bell laboratory experts for many years. It is also the preferred system for LAN construction. The system has the advantages of practicality, flexibility, economy, modularization and scalability. It can connect data communication equipment with other information management systems and connect these devices to external communication networks.

SCS are the most basic and important component of the network. It is the link connecting each server and workstation. As the medium for transmitting high-speed data, SCS have strict requirements on cables. Once a cable fails, the entire network system may be paralyzed in severe cases. Therefore, after the cabling project is completed, the entire cabling system must be thoroughly tested. Generally, a testing working group is composed of technical personnel of the cabling company and the company to conduct on-going tests on all information points. For example, five types of tests are spot-checked according to 20% of all information points. After acceptance, technical personnel are responsible for routine maintenance and management of the network.

Testing Instruments and testing standards

Before testing, we need to select appropriate testing instruments and testing standards. Generally, we use internationally recognized testers for testing. For example, when testing copper cables, we use a cable test table for basic connectivity (on) testing. When testing Category 5 lines, we used the Microsoft Pentascanner5 class Tester for Category 5 line tests. In progressOptical FiberIn terms of wear and tear, we use Microsoft's optical cable Tester for testing. At the same time, we choose EIA/TIA568ATSB-76 standards as the basis for testing.

Test Methods

Currently, there are three main types of cables used for network construction, namely, quotation, parameters, pictures, group music and coaxial cables for optical fiber cables, unshielded twisted pair wires, and shielded twisted pair wires. Optical fiber has high transmission rate, good anti-interference performance, and long-distance transmission. It is mainly used for main trunk lines. Unshielded twisted pair wires are widely used communication media in recent years. They provide good transmission performance and can be transferred through switches or hubs. They are often used for close-range transmission. Coaxial cable is a widely used transmission medium in early years. Due to its drawbacks, it is rarely used.

1. unshielded twisted pair wires

From the engineering point of view, the unshielded twisted pair wires of Structured Cabling can be divided into two types: On-going testing and certification testing.

In order to ensure that the cable installation meets the performance and quality requirements, during the construction process, the construction personnel can perform construction and testing. This method is a conducting test, it can ensure that every connection completed is correct. The on-going test focuses on the connection performance of structured cabling and does not care about the electrical characteristics of structured cabling.

Certification testing refers to testing the structured cabling system in accordance with the standards to determine whether all structured cabling meets the design requirements. Generally, the channel performance of Structured Cabling depends not only on the construction process of cabling, but also on the quality of the cables used and related connection hardware. Therefore, you must perform authentication tests on structured cabling, also known as 5-class test certification. Through tests, we can confirm whether the installed cables, related connection hardware and their processes meet the design requirements, including connection performance testing and electrical performance testing.

(1) link verification test

Cable installation is mainly based on the installation process. Since no one can work correctly, we must conduct link testing to ensure that the installation of cables meets the performance and quality requirements. If no test tool is available, connection errors may occur. Common connection errors include cable label errors, open connections, and short circuits.

① In the construction of open and short circuits, problems such as lack of tools, wiring skills or wall Threading Technology will lead to open or short circuit faults.

② Reverse the pin position at both ends of the same pair. For example, one end is 1-2, and the other end is 2-1.

③ An incorrect pair is connected to another line at the other end. For example, one end is 1-2, and the other end is connected to 4-5.

④ String winding refers to splitting the original two pairs and then forming a new line pair. As the connectivity of the end-to-end is not affected when such a fault occurs, the common multimeter cannot be used to check the cause of the fault. Only a dedicated cable tester can be used to check the cause.

(2) cable transmission channel certification test

The certification test does not improve the channel performance of the integrated wiring, but only confirms whether the installed cables, related connection hardware and their processes meet the design requirements. The result is valid only when a testing instrument that meets specific requirements is used and tested according to the corresponding testing method.

For example, the Microsoft Pentascanner5 class tester is used to perform five types of tests. The method is to first connect the two ends of the Jumper with the tester, then perform tests according to AutoTEST, then display the test results according to F1, and finally print the test results.

The certification test includes nine technical metrics, including Length, Next (Nearendcrosstalk), Attenuation, Acr (Attenuationtocrosstalk), WireMap, Impedance, Capacitance, LoopResistance, and Noise. When all test results are "PASS" (1), it indicates that the cabling system meets the transmission technical requirements of Category5Cable.

If some problems occur during the test, we can analyze them from the following aspects and then troubleshoot them one by one.

① The cause of the failure of the close-end crosstalk may be the problem of the close-end connection point, or because of the performance problems of the series, external interference, remote connection point short-circuit, link cable and connection hardware, not the same type of products and cable, and so on.

② The failure of the wiring diagram may be caused by an open circuit, short circuit, cross or broken connection at both ends, or a cross-connection error.

③ Failure of attenuation may be caused by excessive cable length, temperature, connection points, performance problems of link cables and connection hardware, or not the same type of product, there may also be problems with the quality of the end-to-end cables.

④ Failure of the length may be caused by excessive cable length, open circuit or short circuit, or the total length of the device connection and cross-wiring.

⑤ The fault of the tester may be caused by the tester not being started (The problem can be solved by replacing the battery or charging) tester cannot work or remote calibration, tester is set to incorrect cable type, tester is set to incorrect link structure, tester cannot store automatic test results and tester cannot print Storage automatic Test results.

2. Test the Optical Fiber Transmission Channel

Although there are many types of optical fibers, the basic testing methods of optical fibers and their transmission systems are basically the same, and the testing instruments used are also basically the same.

Optical fiber properties tests must be performed on the worn optical fiber or optical fiber transmission system to conform to the optical fiber transmission channel test standards. The basic test content includes continuity and attenuation/loss, optical fiber input power and output power, analysis of optical fiber attenuation/loss, and determination of Optical Fiber continuity and optical loss. The actual test also includes the optical cable length and latency. The main measure of optical fiber testing is attenuation. If the attenuation is "PASS" within the standard range, the opposite is "FALL ". If some problems occur during the testing of the optical fiber, we need to check whether the optical fiber grinding is correct and whether the optical fiber heads correspond one by one.

Wiring is for future investment. Therefore, you must have a sense of advancement when wiring, especially the quality of wiring, because the quality of wiring directly affects the normal operation of the network. Wiring testing is an indispensable "threshold" for ensuring the normal operation of the network. Only through rigorous testing can the network system be put into operation.