How to find and deal with the obstacles of communication cable

AddTime£º25-07-2016   Author£ºadmin

¡¡When our system is formed, in the use of the process will inevitably have this or that problem, and some problems even lead to paralysis of the entire system, it is difficult to carry out normal. At this time, we need to deal with the broken system in time. How to find and deal with the problem? (recommended reading: how to transform the optical cable terminal box photoelectric signal)

¡¡OTDR (optical time domain reflector) is the main tool for the maintenance of the test cable obstacles, used to test the location of the cable breakpoint, so that the timely arrival of personnel to repair personnel to the scene to carry out repairs. According to the working principle of the Rayleigh scattering, the situation of each point is analyzed by collecting the signal curve. Below, the author of the optical cable line of different obstacles to find and deal with the detailed analysis.

Partial system blocking

¡¡¡¡If the obstacle is a certain system obstacle, in the premise of the exclusion of equipment failure, accurately adjust the refractive index, pulse width and wavelength of OTDR instrument, so that it can reduce the test error as much as possible with the parameters of the core. Then the distance information and maintenance information will be measured to check whether the obstacles at the joint point.

If the OTDR curve observed obstacles have obvious Fresnel reflection peak (Fresnel reflection is a special example of the Rayleigh scattering, it is special phenomenon appears in the fiber of the sudden change of the refractive index), and verify the information and a joint distance closer, preliminary judgment for box fiber disorder (fault in fiber boxes for mirror fracture, large Fresnel reflection peak). Repair personnel to the scene, you can first and room personnel to further judge, and then processing.

¡¡¡¡If the distance between the obstacle and the joint is larger, it is the obstacle in the cable. This kind of obstacle of strong concealment, if positioning, blind search may cause unnecessary human and material waste, such as the excavation buried cable large quantities of earthwork, aerial optical cable pick a hook hanging, etc., will extend the barriers which lasted. This type of obstacle can be used to accurately determine the obstacle points.

OTDR instrument for accurate test obstacles to the adjacent joint relative distance (SLIM), will test the slender converted into cable length (skin), and then made the long cable sheath conversion, the growing size of the barriers, can pinpoint barrier point position. The specific algorithm is as follows: (1) long converted into long leather La= (S1-S2) / (1+P). La length of cable sheath; S1 to test the relative distance; S2 for optical cable connector box of unilateral disc to stay the length of, generally taken from 0.6 to 1.0; P for the cable twist shrinkage, varies with different cable structure, available to the same type of backup cable tested, manufacturers to provide the indicators. P= (Sa-Sb) /Sb, Sa for testing long single disk cable; Sb single disk cable labeled skin long size length. (2) the calculation of the length of the length of the optical fiber cable barrier is Ly=Lb + La. Type of Ly in the length of the size of the skin length of the barrier value; Lb for the adjacent junction point of the box root length of the cable length measurement, +, - symbol selection can be determined according to the cable layout. Determine the value of Ly, you can determine the specific location of the obstacle point according to the data. This method can be used to reduce the test error caused by the inaccurate engineering data, the deviation of the refractive index of the instrument and the optical fiber, so that the length of the cable is avoided and the test result is more accurate. Practice has proved that this method is simple and effective.

Optical fiber cable barrier

¡¡¡¡For optical cable line is blocked, find more easily, general is caused by external influence, using OTDR detect obstacles and bureau (station) between the distance, combined with maintenance data, determine the location of obstacles, command patrol line along the cable route check whether construction, aerial optical cable is obvious strain, etc., to find the fault point. If you can't find the way to use the above described method to accurately calculate, determine the obstacles.

Optical fiber attenuation caused by excessive obstacles

Disorders of the OTDR test system core, to find if the obstacle is the attenuation of air caused by, determine the basic obstacles in a joint is caused due to the bending loss. The remaining fiber disk remain inside the box or improper heat shrinkable tube off to form a small circle, the radius of curvature of the remaining fiber is too small. In addition, the water inlet of the joint box may also cause the joint disorder. After opening the box connector can be further judgment, normal core around in the fingers, the small radius of curvature, then OTDR test (1550 nm) the premises will have a high attenuation, if the attenuation and obstacle of optical fiber attenuation consistent position, obstacle point is the point. And then carefully check the obstacle fiber damage or disk small circle, if there is a small circle of the amplification can, or reconnection process.

¡¡¡¡Terminal obstacle of computer room

¡¡¡¡If the obstacle occurs in the terminal room, in the end of the test, due to the OT-DR instrument can not clean out the regular curve, the test can be found in the end of the test curve of the normal test curve. For precise positioning and need to add a section to avoid blind instrument pigtail, length is generally not less than 500m to accurately detect the tail length, and barriers to access fiber test.

¡¡¡¡Through the above analysis, it can be seen that the causes of the optical cable barriers are many, in addition to external impact, the joints are more obstacles. ¡¡¡¡Therefore, it is necessary to strictly control the quality of construction, so as to conform to the operating rules, strengthen the maintenance, the establishment of a set of integrity, complete and accurate maintenance information, and in practice constantly sum up experience, to quickly find and deal with all kinds of obstacles.