Why we need to use launch cable? After reading this article, we can learn about what the fiber launch cable is, and why we need to use it when measure the fiber optics with OTDR.
What is a fiber launch cable
Optical Time Domain Reflectometers (OTDR) are an important tool for fiber testing. However, when testing optical fibers with an OTDR, it is difficult to accurately measure the first few tens of meters of the fiber. The undesirable phenomenon is known as the “dead zone” of the OTDR. This dead zone limitation can be avoided by using a fiber launch cable. Fiber launch cables are designed to be used with an OTDR to measure the complete link loss of fiber optics.
A fiber launch cable is a device used to connect an OTDR with the optic fiber during testing . It typically serves as the initial length of fiber that is connected to a device for measurement, troubleshooting, or performance testing of fiber optic networks.
Why we need launch cable?
Ensure fiber test accuracy:
The OTDR works by analyzing the backscattered signal that returns from different points along the fiber. Allowing it to construct a profile of the fiber’s characteristics.
However, the initial pulse launched into the fiber often experiences instability due to factors like the transition the OTDR’s testing equipment. This instability can cause inaccuracies in the measurements, particularly in the first few meters of the fiber, which can be difficult to measure precisely. This initial section is known as the “dead zone,” where the OTDR is unable to provide reliable data because the pulse has not fully stabilized and the reflected signal from this region can be weak.
To address this issue, it is used as a buffer between the OTDR and the fiber under test. The launch cable acts as an extension of the fiber and allows the initial pulse to stabilize before it enters the fiber section that is actually being tested. Essentially, the launch cable ensures that the pulse is launched into the fiber with consistent power. By providing this “smooth start,” the launch cable eliminates the inaccuracies caused by the unstable initial pulse, allowing the OTDR to gather more accurate data about the fiber’s true characteristics.
Protest the devices and reduce signal loss:
Fiber launch cables help protect both the fiber under test and the testing equipment. They prevent damage by buffering the fiber from excessive stress or bends and reduce the risk of harmful reflections that could damage the OTDR’s receiver. Additionally, they help ensure that the signal tested is clean and free of losses, especially in cases where the fiber may be subject to bends or connector issues at the start of the network.
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