Hello, everyone!
Today, I want to continue to explain a new topic – ODN engineering and maintenance. Now, I will continue to explain ODN engineering.
Civil work construction acceptance
Optical cable layout check
Component installation check
Link acceptance test
After installing the system. Testing required. Two methods are used for testing. These are OLTS (LS and OPM) measurements for Insertion Loss and OTDR measurements to check the attenuation and reflection of all events on the optical path.
The OLTS (Optical Loss Test Set) instrument is used to measure IL, which consists of LS (Light Source), OPM (Optical Power Meter) and reference optical cables. There are three methods of measuring IL, namely single-ended, double-ended and the method with three reference optical cables. The single-ended method is used for short links such as patch cords, the double-ended method is used for long cables and the last method is used when the optical cable is with specific optical connectors (e.g. ribbon optical cable with MPO/MTP optical connectors).
The light source is always used with reference optical cables. For SM optical fibers, DFB (Distributed Feedback) and FB (Febbry-Perrot) lasers are used as sources at wavelengths of 1310 nm, 1490 nm, 1550 nm and 1650 nm. For MM optical fibers, LED (Lighted Emitting Diodes), VCSEL (Vertical Cavity Surface Emitting Laser) and FP laser are used as light sources at wavelengths of 650 nm, 850 nm and 1300 nm. Tests at 1310 nm and 1490 nm are used to test the GPON system. If we also have CATV (digital and analog CATV), then 1550 nm is also tested. The double-ended measurement method is used, which means that both TS and OPM use reference optical cables. Reference optical cables are tested optical cables with an attenuation of 0 dB, and are usually 1 to 2 m long. The measurements on the OPM are only on one wavelength at a time. The unit is dBm, and maybe mW, but it is avoided. PON meters are used for parallel measurement of several wavelengths at the same time. The measurement simulates the operation of the PON system and measures the IL and compares it with the project.
This is the end of this article. I will continue to explain this topic in the next article >> ODN Engineering and Maintenance (23).
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