Leather cable attenuation

Household optical cables usually use butterfly optical cables (commonly known as "skin cables"). Why is there a large attenuation?

1. Fault phenomenon

What is the difference between the bending performance of commonly used G.657 and G.652 optical fibers? ", we analyzed the use of the G.652 pigtail at the end of the FTTH cable at the fiber distribution box and the fiber cat, which is the main reason for the excessive attenuation of the FTTH cable. However, about 25% of the link loss is too large, This is caused by the bending of the pigtail itself.

The sheathed optical cable mainly adopts G.657A2 type optical fiber with good bending resistance system performance. Generally, when the bending radius of the sheathed optical cable does not exceed 7.5mm, the basic information of the macrobend loss can be ignored. However, the faults and phenomena found in the on-site investigation are indeed related to the bending of the leather cable.

Loosen those bends and the fault goes away; if not macrobend loss, what caused it?

2. Failure cause analysis

Considering the stress of the leather cable under certain conditions, we tested the additional loss of the leather cable under bending stress, and found that bending did not significantly increase the additional loss.

Could it be related to the knotting of the fiber optic cable? Because from the point of view of the fault phenomenon, the leather wire and optical cable at the fault point are often knotted. After testing, it was found that knotting did not significantly increase additional loss. Even if the cable is knotted and subjected to external forces, the additional loss will not increase significantly.

A careful study of field failure photos reveals that the cable is twisted in most cases, so the excess loss is measured after the cable is twisted. The additional losses of stranded cables increase significantly. When the leather cable is twisted, the additional loss increases more significantly. In the case where the leather cable is twisted and knotted, an external force is applied for testing: the additional loss is as high as 3.24 decibels. The twisting of the fiber optic cable is the main cause of the extra loss. consistent with the situation on site.

3. Conclusions and recommendations

Due to the use of G.657A2 optical cable, as long as the bending radius is not less than 7.5mm, even if there is bending and knotting, the external force will not significantly increase the additional loss.