connects the OTDR to the link-under-test FTTh transparent invisible installation bare fiber optic cable

Optical fibers are measured using an optical time domain reflectometer (OTDR), sometimes with short fiber links. Large attenuation values (xxdB/km) are often obtained when measuring short fiber links. Attenuation indicators can not get a better evaluation and evaluation. Why is this? What method can I use to get a better test result?

Due to the short fiber link (generally less than 1km), the OTDR measures the curve with certain volatility, and these small fluctuations affect the final numerical calculation. Among the technical parameters describing the OTDR, there is an indicator about the linearity. The general OTDR is 0.05dB/dB (E6000C: 0.05dB/dB; N3900A: 0.03dB/dB). In fact, this indicator describes the OTDR. The range of fluctuations of the curve. So for short fibers, the accuracy of OTDR measurements is challenging. This issue is also a common problem faced by OTDRs. So what methods are used to reduce this impact?

1. Add 2km test fake fiber.

Due to the addition of 2km test fibrils, the fiber length is increased and this effect is reduced. A satisfactory result should be obtained. However, due to the increase in length and the introduction of test errors, this method still has the error caused by certain test methods. However, as a test data to verify the quality of the project, it has considerable reference value.

2. Measure the link loss with a light source and an optical power meter, and measure the length with an OTDR.

Since the link loss is measured close to the standard loss measurement method using a light source and an optical power meter, the accuracy of the loss measurement is improved. Of course, for short fibers, an optical power meter with a higher resolution accuracy level is used as much as possible to reduce the error. Length measurements are obtained using an OTDR. The unit length attenuation value is obtained by dividing the loss value by the length value.

3. The OTDR measurement curve is for reference only, and the OTDR measurement focuses on eliminating link barriers.

In short fiber optic measurements, the OTDR measurement curve is best used as a reference only as a basis for characterization and not as a basis for quantification. More tasks of the OTDR are used to deal with obstacles in the link, such as the quality of the connector connection, the quality of the fusion splice, and the micro-bend of the fiber.