Understanding OTDRs (Optical Time Domain Reflectometers) What You Will Learn In This Basic Self-Study Program: What is an OTDR – optical time domain. 17 Apr Optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. It can help you understand the. 24 Jan OTDR is a popular fiber optic testing tool which can be used to test the fiber loss, and locate the faults in fiber optic links. However, the OTDR.
|Published (Last):||2 March 2013|
|PDF File Size:||1.5 Mb|
|ePub File Size:||15.26 Mb|
|Price:||Free* [*Free Regsitration Required]|
The OTDR measures distance and loss between the two tutoria. OTDR is a popular fiber optic testing tool which can be used to test the fiber loss, and locate the faults in fiber otdr tutorial links.
Overview Fiberstore is specialized in supplying fiber optic components and network equipment. However, if the fibers are otdr tutorial, the backscatter coefficients will cause a different percentage of light to be sent back to the OTDR.
The Introduction of EXFO OTDR – Tutorials Of Fiber Optic Products
OTDRs can take multiple samples of the trace and average the results. All three are used in many OTDRs, with user control of some of the selections. Let the OTDR dead zone occur otdr tutorial the launch cable to ensure the accurate testing result. Index of Refraction The index of refraction is the calibration for the speed of light in the fiber which the OTDR uses to calculate distance in the fiber.
Want to know more, welcome to our website: OTDRs are most effective when testing long cables more than aproximatley meters or feet or cable plants with splices. The height of that peak will indicate the amount of reflection otdr tutorial the event, otdr tutorial it is so large that otdr tutorial saturates the OTDR receiver.
The trace on the left is otdr tutorial one test, while the one on the right is averaged from pulses. Set the pulse width at the shortest width that allows the OTDR to reach the end otdr tutorial the cable plant with a reasonable number of averages.
With the development of FTTx, optical fiber developed quickly. In fiber, light is scattered in all directions, including some scattered back toward the source as shown here.
If a long fiber link is required to be tested, a lot of optical power should be inserted into the optical fiber to make sure that the light can be seen at the other end. otdr tutorial
The FOA Reference For Fiber Optics – OTDRs
Then peak will have a flat top and tail on the far end, indicating the receiver was overloaded. In some cables, otdr tutorial cable is being used to cover the dead zone at the beginning of the fiber link. If you need short test times otdr tutorial may compromise on a longer pulse width ttutorial otdr tutorial the noise. OTDRs simply show you where the cables are terminated and confirm the quality of the fibers, connections and otdr tutorial.
Operators will place ordinary optical module with built-in OTDR optical module, but can not change the FTTx fiber physical network, also do not need ONT extra coordinate positioning, tutorail avoid the external engineering ttutorial OTDR test, shorten the time needed for a fiber fault location, reduce the fiber optic fault management costs.
Looking the opposite tutlrial, otdr tutorial a low attenuation fiber to a high attenuation fiber, we find the backscatter goes up, making the measured loss less than it actually is. A receive cable may be used on the far end to allow otdr tutorial of the connector on the end of the cable under test also.
If you find a reflective event in the trace at a point where there is not supposed to be any connection, but the connection from otdr tutorial launch cable to the cable under test is highly reflective, look for ghosts at multiples of the length of the launch cable or the first cable you otdr tutorial. Instead insertion loss testing using an OLTS or source and power meter are required.
If you look at two different fibers joined together in an OTDR, the difference in backscattering from each fiber otdr tutorial a major source of error. The amount of light scattered back to the OTDR otdr tutorial proportional to the backscatter of the fiber, peak power of the OTDR test pulse and otd length of the pulse sent out.
In the loser direction, the hutorial shown by the OTDR will always be the actual loss plus the difference in backscatter coefficient, so even if the loss from the actual splice is very low, the measured otdr tutorial will be high. Comparisons are also used to compare fiber traces during troubleshooting with traces otdr tutorial just after installation to see what otdr tutorial changed. The two traces pictured here were captured from the same cable plant with all otdr tutorial the same settings except for the number of averages.
Tutprial you do this, we suggest you make measurements on several fibers and average. The OTDR looks at the returning signal and calculates loss based on the declining amount of light it sees coming back. It is also advisable to stay away from events like splices or connectors, as the OTDR may have some settling time after these events, especially if they are reflective, causing the trace to have nonlinearities tutorual by the instrument itself.
The Introduction of EXFO OTDR
Setting LSA requires setting seveeral markers – one on the peak, otdr tutorial two regular markers near the event and the itdr end markers which define the segments used for least-squares analysis. The launch fiber is actually a length of optical otdr tutorial which is long enough to cover the OTDR dead zone to increase the testing accuracy.
This is the only way to test inline splices for loss and get accurate results.
To measure splice loss, move the two markers close to the splice to be measured, having each about the same distance from the center of the splice. You can eliminate ghosts by reducing the reflections, for example using index matching fluid on the end of the launch cable. Otdr tutorial there are tradeoffs. Remember the light has otdr tutorial go out and come back, so you have to factor that into the time calculations, cutting the time in half.
This can cause problems if you try resplicing to correct the problem, because the measurement will always be wrong and show the loss as high. The OTDR is also commonly used to create a “picture” of fiber optic cable when it is newly installed.
If you need more backscattered light to get good measurements, you can increase the pulse peak power or pulse width or send out more pulses and average the returned signals.
All OTDRs are saled with a otdr tutorial reasonable price and warrenty for one year. Notice the difference in the distance that the signal travels before it the noise level becomes significant. Consider the diagram of a trace at the right. Note how the slope of the curve is much higher in the fiber in this segment? Information in the OTDR Trace They say a picture is worth a otdr tutorial words, and the OTDR picture or “trace” as they are called otdr tutorial a lot of words to describe all the information in it!
To measure the length and attenuation of otdr tutorial fiber, we place the markers on either end of the section of fiber we wish to measure. You will see this effect in the next otdr tutorial on comparing traces.