Solution: The OBR can find both good and bad splices. Typically, if the splice is bad, you will see a drop in the level of Rayleigh scatter and thus an insertion loss event. In Figure 1 below, there is a bad splice in the network around 1m. You can see at this event, there is an insertion loss of 1.35 dB as measured in the difference of loss between the red and yellow cursors and shown by the change in scatter level, plus you can see a quick change in one of the polarization states of the light (the gray and white lines are the S and P states, with blue being the vector sum).

Bad splice in telecom network

Figure 1. A bad splice in a network as shown on the OBR. This results in a drop in the scatter level and a quick change in the polarization states

If the splice is good, you should not see a drop in the scatter level. However, you can find good splices by looking for an abrupt change in at least one of the polarization states of the light traveling through the fiber. To see this result in the OBR software, change to the Polarization States graph setting. Watch the polarization states as they progess through the fiber, if one of them changes quickly, that typically signifies a splice location, even if there is no change in the scatter level. See Figure 2 below.

Good splice in the OBR

Figure 2. A good splice in a network - demonstrated by an abrupt change in the scatter state, with no change in the level of Rayleigh backscatter.

The OBR provides a easy way to verify splices in a fiber optic network.

Document ID: 0070529001
Last Update: 05/29/2007

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