by Greg | Jun 6, 2012 | Testing
Fiber optic testing with an OTDR is a fairly straight forward process. When you’re talking single-mode fiber most customers require, at a minimum, testing each fiber at 1310nm and 1550nm windows to insure that splice specifications are maintained. When testing outside plant this involves an OTDR , a pulse suppression box (launch) , knowledge of the network and the know-how to use the test equipment. There are many, many man hours involved in testing and proofing fiber networks. Thus, it is important that time is well utilized and the data is collected properly. Although most OTDR’s manufactured today are very easy to use they don’t do the job for you. They are a tool to aid you in doing your job. We were recently sent a pack of traces for review for one of our customers. There was an anomaly in the 1550nm window data that they could not explain and the contractor that did the work didn’t have any answer for them either. The contractor actually said the fiber was bad. The anomaly (shown in the photo to the left) was caused due to the fact the OTDR being setup wrong by the technician. This particular OTDR has a macro event setting. It was turned on and for some strange reason the trace data had a false event imposed into the data. In all actuality there are no events at these points and the fiber cable was not damaged. Tips when using an OTDR: First, always use a launch cable. An OTDR pulses must traverse a minimum distance before the OTDR can take meaningful measurements. Always start with the OTDR set...
by Greg | Dec 26, 2010 | Testing
OTDR trace data They say a picture is worth a thousand words, and the OTDR picture, or “trace” as they are called, takes a lot of words to describe all the information in it. The image to the left illustrates a common distance measurement data of a fiber optic strand. Click on the image to get a bigger version. The screen shot shows the OTDR setup parameters including things like pulse width, range, wavelength and average points of data acquired. Likewise, data such as the length of fiber optics and 2 point loss (db) is also shown. Equipment used to acquire trace : CMA 4000 GN Nettest Networks infoBit – If the fiber looks nonlinear at either end, especially near a reflective event like a connector, avoid that section when measuring fiber...
