Optical fiber Construction Quality Detection Method

Based on years of experience in design and construction, the author summarizes a set of practical detection methods and shares them with colleagues.

Check and install

After the optical cable is connected and the connector is installed, the continuity check of the optical fiber must be carried out, and all the optical fiber cables must be tested. Therefore, the personnel responsible for testing should have some testing equipment capable of testing the installation quality. Two measurements are required: A Comprehensive Test of attenuation of the optical fiber and connectors; Reflection measurement of the loss curve of the optical fiber connection line. This measurement also tells people the length of the connection line and the error point.

Attenuation Measurement

Attenuation Measurement, also known as the first-level measurement, is carried out using a high-power calibration Generator for transmitting signals and an optical fiber radiation measuring instrument for measuring reception. Measure the attenuation of a line and determine whether the line or a line is in the specified tolerances. This is the first level measurement. All connectors should be cleaned before each measurement. To avoid measurement errors, two instruments (generator and receiver) should use the same measurement cable (such as 3 meters long ). These cables should have the same characteristics as the optical fiber core.

The test can be carried out in two ways: one tester performs the test, the two instruments are placed in the same place, but can form a loop with the other; the two testers, there is a tester in each of the two places. All testing procedures start with the calibration receiver. To this end, the generator and receiver must be directly connected with a 3-meter long cable, and then transmit high power to the receiver, and then calibrate the receiver to the LCD display 0 dB; the maximum attenuation obtained in the test is equal to the attenuation of the optical fiber (dB/Km) at the wavelength of nm. The attenuation produced by various connections (connectors and connectors) is increased ). We believe that the attenuation of the connection device 90% is 0.db when it does not exceed nm.

This document describes how to test by a tester. A tester requires that different optical cables on the final distribution frame form a loop through some optical fiber jumpers with a length of 10 meters, and then a pair of one pair of Optical Fiber cores can be detected for each pair. The transmitter and receiver are placed in the same location; A 3-meter optical fiber cable is used to connect the transmitter to the first optical fiber on the optical fiber head or fiber trunk; connect the receiver to the second optical fiber with the second 3-meter fiber cable.

Measure the loop first, and then the tester connects the receiver to the third optical fiber for the same test, and tests the fourth, fifth, and sixth optical fiber in the same way.

The test procedure is to calibrate the receiver, install the jumper cable, measure the line, and store the test results into the computer. Use a 3-meter long cable to form a loop between the transmitter and receiver on time. High-power transmission should be carried out to the receiver and the receiver should be calibrated to 0dB for LCD display. If the tested value exceeds the maximum expected value, the fault location should be determined by the optical fiber reflector.

Measured with a reflection measuring instrument

Measured using a reflection measuring instrument, also known as the second-level measurement, aims to test the physical status of the optical fiber core. The loss distribution can be displayed on the display screen.

The measurement principle is: the reflection measuring instrument emits a high-power calibration beam and then observes whether there is a visually visible reflection power signal on the display screen. This reflection is caused by the incompleteness of the silicon that forms the optical fiber, which is consistent with the linear attenuation. The rest of the reflected signal is equal to the reflection of the possibly faulty part of the connected part. At the same time, these losses can be located and the exact length of the optical cable can be detected.

These tests can detect whether the optical fiber is in an abnormal situation (bending radius, excessive pulling or extrusion), or detect whether there is a broken line or whether the broken line is improperly operated. At the same time, you can also know whether the ST connector is correctly connected.

Related Articles]

• Optical Cable Construction Site and acceptance testing methods and standards