Fluke: A New Method for testing indoor Optical Cable Link Loss

Strict methods are required to obtain accurate and effective results on the optical cable link in the test room. The ANSI/TIA/EIA-526-14A Standard specifies the loss test for Multimode Optical Cable chains. This Standard specifies two testing methods. Method A and method B. This article introduces method A and method B and explains why Method B is A better way to test the indoor optical cable link.

This article also proposes a new method for improving method B to overcome some shortcomings of method B. This new method is the preferred test method, because the test results are consistent with method B, and more flexibility is provided to the user, so that the test can be performed by a variety of different, A cable link consisting of a cable connector, including an SFF (micro head. This article also describes in detail the advantages of the improved method B, such as the simplicity of the test method and the reduction of possible errors.

Method

Method A is used to test the optical fiber link. All the attenuation is mainly caused by the optical fiber cable, excluding the loss of the connector. This is usually the network of the Telecommunications Department. Method A uses two user-connected optical cables and A connection adapter to connect to the tested Optical Cable Link (SEE ). Two connection cables and one connection adapter are excluded from the test as reference values. The test results include the loss of the tested optical fiber link and the loss of a connector (the blue part in attention ).

 

Two-way Tester for the simultaneous test of the Two Optical Fiber Links reference settings

Figure 2 test settings of Bidirectional Optical Cable Tester

This method has always been an effective method for the telecommunications department to test the long-distance optical fiber link, but its accuracy is insufficient for the indoor optical fiber link test. The reason is that the network actually works with a lost optical cable and a connector at both ends. Method A discounted the optical power loss test because it only contains one connector. This is not a problem for Long-Distance Optical Fiber Links, because the main contribution of loss is the optical fiber itself rather than the connector. However, for indoor applications, the optical cable length is very short, and its own loss is very small. The main problem of loss is the connector at both ends of the optical cable link. The Loss Test of Optical Fiber Links is increasingly strict with application requirements. For example, Gigabit Ethernet must be used to test the loss of the entire Link. This is why the re-method B.

Method B

Method B is used to test the optical cable link. The loss of its connector is an important part of the overall loss. This is an example of indoor optical cable. Method B. Refer to the setting procedure to test each optical cable link using a connection Optical Cable (SEE ). (Note: This figure shows a two-way tester testing two optical cables at the same time ).

 

Figure 3. Reference settings of Method B

 

Figure 4 test settings of Method B

Because there is only one optical fiber connection (each link) as a reference, the test results include the loss of the tested optical fiber and the connectors at both ends (see the blue section ). From a technical point of view, it also includes additional optical fiber loss, but its length is very short and the loss can be ignored. For indoor optical cable networks, This method provides accurate optical cable link testing because it includes the optical cable itself and connectors at both ends of the cable.

However, when using Method B, you need to know its shortcomings:

1. When switching from the reference settings to the test settings, You need to disconnect the optical cable at one end of the tester. It is very important not to disconnect the output or light source end. If you disconnect the connection, the original reference value is lost. If you do not repeat the settings, the test results will be seriously affected. Unfortunately, it is often easy to break the Open Source (output) end rather than the test (input) end.

2. Although the connection cable must be disconnected from the tester test (input) End, be very careful to avoid contamination of the connector or damage to the detector.

3. In order to test the SFF connector sent and received in the same connector, you must disconnect from the source (output) End, which violates the correct reference and test steps.

4. Method B requires that your tester connector be the same as the connector of the tested optical cable.

Next we will introduce a new test method, which is an improvement of model B, but it not only provides the same results but also ensures the consistency with the test standard, overcome the shortcomings listed above.

Method B

The simple improvement of Method B allows us to maintain the original precision (each measurement includes optical cables and connectors at both ends) but avoids major defects. The reference steps for this improvement method are to use two connected optical cables and a connection adapter for each of the tested optical cables (SEE ). However, the test steps are new. For more information, see the description.

The test procedure includes an additional short test jumper with a connector, so that the test results are different from those obtained by method B. Like Method B, the results include cable damage and connectors at both ends (note the blue part ). The two optical cables and the connectors of each link are excluded from the reference settings.

Maintain test consistency

The improved method B provides several key advantages over the original method B and maintains its consistency:

1. The damage measurement result obtained by Improved Method B is caused by Method B in ANSI/TIA/EIA-526-14A. According to Method B, the link damage can be correctly measured. The test path must have two additional adapters than when setting the reference path. The test steps described in this article are just in line with this requirement. The damage measured in this way will be the loss of optical cables in the link and the loss of connectors at both ends of the link. This loss value is exactly the value encountered in actual network hardware applications.

Figure 5. Improvement Method B's reference settings

Figure 6. Improvement Method B test settings

2. Method B is improved so that different types of connection optical cables can be used to connect the tester and the tested optical cable link. This allows you to perform consistent tests on the optical fiber links that contain different types of connectors, including those that use micro connectors (SFF.

The improved method B removes the need to disconnect the optical cable from the test instrument end, reducing possible contamination errors caused by re-insertion or damaging the optical interface of the test instrument.

Solved the complexity of testing the SFF connector.

A single light source and optical power meter can effectively test the optical cable link containing a single optical cable, while a single cable tester can be used to test the dual optical cable link, which is clumsy and error-prone. The dual-Optical Cable tester is the best way to test dual connectors, so it is recommended to test SFF.

As demand for optical cable link testing continues to grow, new testers are required for newly installed indoor optical cables. Method B is the preferred method and is defined in ANSI/TIA/EIA-568-A standards. The improvement method for using additional test jumpers is also preferred because it provides the same test results as Method B, while providing greater flexibility to test the optical cable links of different connectors.

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