CH8-6
There is a lot of information on the OTDR screen. The slope of the fiber plot shows the fiber attenuation coefficient (loss by length) and is calibrated in dB / km by the OTDR. The fall in the graphical trace of the fiber along the connector allows the loss in dB to be measured. The peak produced by the reflectance of a mechanical connector or joint can also be measured. While some users measure the point-to-point loss of a fiber optic cable network with an OTDR,
Notice the large initial pulse in the OTDR plot shown in the graph above. That is produced by the high power test pulse that is reflected in the OTDR connector and overloads the OTDR receiver. Receiver recovery causes the "dead zone" near the OTDR. In order to avoid problems caused by the dead zone, it is necessary to always use a launch cable of sufficient length when testing the cables.
Connectors and splices are called "events" in OTDR jargon. Both should show a loss, but the connectors and mechanical splices will also show a reflection peak so that you can thus distinguish them from fusion splices. In addition, the height of that peak will indicate the amount of reflection in the event, unless it is so large that it saturates the OTDR receiver. The top of the peak will be flat and will have a tail at the end, which will indicate that the receiver was overloaded. The peak width shows the distance resolution of the OTDR or how close it can detect events.
Fiber optics technician jobs
OTDRs also detect cable problems caused during installation. If a fiber is broken, the fiber end will appear much shorter than the cable or a splice with high loss in the wrong place. If excessive tension is placed on the cable due to folds or a radius of curvature that is too tight, it will resemble a splice in the wrong place. There is no better help in detecting and solving problems with an OTDR than having good documentation, so that you know what the OTDR should be showing at the points along the fiber.
There is a lot of information on the OTDR screen. The slope of the fiber plot shows the fiber attenuation coefficient (loss by length) and is calibrated in dB / km by the OTDR. The fall in the graphical trace of the fiber along the connector allows the loss in dB to be measured. The peak produced by the reflectance of a mechanical connector or joint can also be measured. While some users measure the point-to-point loss of a fiber optic cable network with an OTDR,
Notice the large initial pulse in the OTDR plot shown in the graph above. That is produced by the high power test pulse that is reflected in the OTDR connector and overloads the OTDR receiver. Receiver recovery causes the "dead zone" near the OTDR. In order to avoid problems caused by the dead zone, it is necessary to always use a launch cable of sufficient length when testing the cables.
Connectors and splices are called "events" in OTDR jargon. Both should show a loss, but the connectors and mechanical splices will also show a reflection peak so that you can thus distinguish them from fusion splices. In addition, the height of that peak will indicate the amount of reflection in the event, unless it is so large that it saturates the OTDR receiver. The top of the peak will be flat and will have a tail at the end, which will indicate that the receiver was overloaded. The peak width shows the distance resolution of the OTDR or how close it can detect events.
Fiber optics technician jobs
OTDRs also detect cable problems caused during installation. If a fiber is broken, the fiber end will appear much shorter than the cable or a splice with high loss in the wrong place. If excessive tension is placed on the cable due to folds or a radius of curvature that is too tight, it will resemble a splice in the wrong place. There is no better help in detecting and solving problems with an OTDR than having good documentation, so that you know what the OTDR should be showing at the points along the fiber.
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