The blind zone length of an OTDR can have the following effects on test results:
1. Failure to detect faults or events: The blind zone length indicates that reflection or scattering events in the fiber cannot be accurately detected within that distance. This means that connection problems, broken fibers, bends, or other faults that occur within the blind zone may not be accurately identified and localized.
2. Misdiagnosed or missed events: If events or faults exist on the fiber but are located in the blind zone, the OTDR may not be able to display or correctly identify them in the test results, resulting in missed or misdiagnosed test results.
3. Inaccurate measurements: Events within the blind zone cannot be measured correctly, which can lead to inaccuracies in parameters such as attenuation and reflection in the test results. Events behind the blind zone may also be affected by the blind zone and their measurements may be inaccurate.
4. Inability to assess connection quality: The connection point is often an important location in a fiber optic network, but if the connection point is located in a blind zone, the OTDR may not be able to provide an accurate assessment of the quality of the connection. This can result in performance issues at the connection point being overlooked or not detected in a timely manner.
To minimize the impact of blind zones on test results, the following measures can be taken:
Use shorter pulse widths: Reducing the pulse width reduces the length of the blind zone, thereby improving the detection of events in the fiber.
Increase the power of the light source: Increasing the output power of the light source enhances the strength of the return signal and reduces the effect of the blind spot.
Use a high sensitivity detector: Selecting an optical detector with high sensitivity can improve the detection of weak signals and reduce the impact of the reception blind spot.
Although these measures can be taken to reduce the impact of blind zones, they are still a factor to be aware of and consider in actual testing, especially when locating and evaluating fiber optic faults.
