Measurement of splicing loss using optical time domain reflectometer ( Optical Time Domain Reflectometer, OTDR ), the instrument uses the backscattering method to measure fiber loss of fusion joint value. Welding machine is also significantly
Showing the splicing loss value, but because it is the optical fiber core shaft direct method for the local monitoring measured, only in ideal
State to reflect the actual loss of fusion, it is commonly used for reference only. Because the refractive index of the optical fiber, core diameter, mode field
The diameter and the Rayleigh scattering coefficient is different, so from the fiber optic connectors are respectively measured by splicing loss in a two direction
The splice loss measured values are different and the difference, the GB / T15972 1995 fiber optic technology standard " appendix "
A " optical backscattering power curve analysis " provisions, the splicing loss measurements should be separately from the ends of optical fiber connector
Measurement, i.e. the bidirectional measurement, two directions measured value algebra and as the average of the joint splice loss value;
Due to the subsequent two optical scattering performance differences, OTDR measured optical fiber connector splice loss value may be positive
May also be negative, on splice loss of optical fiber connectors can be considered as negative welding qualified, do not generally to weld; weld
Then each joint splice loss of OTDR measurements in general should be less than the splicing loss required index value 1 / 2
2 / 3, such as the requirement of less than 0.1dB, the check measurement value should be less than 0.050.06dB.
Measuring splice loss method generally has a distal end monitoring method, is arranged in the room with OTDR through the connector tail
Fiber optical cable is connected with the measured optical fiber connection point, keep moving, and OTDR is always in the engine room to continue to matter
Monitoring and measurement of the splice loss, the utility model has the advantages of small measurement error, the drawback is only one-way measurement, suitable for mode field straight
Size consistent optical fiber. Proximal monitoring method OTDR always continue to point in the front margin of a long cable tray,
Disadvantage is that OTDR needs to constantly move forward, affect the use of the apparatus, advantage is that the OTDR measuring range does not require too much.
The two kind of method for the measurement of the splice loss value are one-way measurement values, in a fiber optic splice all weld is completed and then from the light
The other end of the fiber line are measured in various optical fiber splice splice loss value, then each joint in a two direction.
Measuring the value of the sum of average as the joint splice loss. Remote loop bidirectional monitoring method is the light inside the light
Fiber temporary loop to form a loop, thereby to fiber optic connectors for bidirectional measurement, avoids unidirectional measurement can not be timely
Obtain splice loss value shortcomings, this measurement method requires OTDR of apparatus for measuring distances to, but because the measurement

Methods are too complex and therefore only applicable to below 12 core cable.

On optical fiber CATV engineering general can adopt a remote monitoring.

In the method, the premise is the two optical fiber mode field diameter must be consistent
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