Distributed temperature sensing (DTS).

OptixSoft Company’s Blog has started new trend from now - "Invited Blogger". We will invite engineers and specialists in related fields from outside (fiber optics, software development, etc.) to post at our Blog. It may help us to hear and share different opinions and ideas.

Here is the first such post written by our friend and fiber optic specialist Andrew Luzgin (currently working for FOD Ltd).

Distributed temperature sensing – is a great technology on OTDR base.

A few words about theory. Well known, that original OTDR measures a backscattered Rayleigh light in the optical fiber. Except Rayleigh effect, there are another scattering effects in the oprical fiber (not in fibers only, of course). It is so called Brillouin and Raman scattering. The intensity of the Raman scattered light is very sensitive to optical fiber temperature. So, it is available to measure distributed temperature along optical fiber. It can be original singlemode (SM) or multimode (MM) fibers. Both fiber types application has merits and demerits.

Simplified schematic of DTS system is below.

At first glance, it looks like an original OTDR, but DTS includes optical filter (OF) and optical commutator (OC). These parts are necessary to choose Raman light from total backscattered signal. And then — a usual OTDR. In a simple case, it can be an OTDR interface with some special processing on the software level.
Nowadays, DTS system becomes a powerful attribute for environment research, fire alarm, piping control etc. Of course, most useful application is a long time temperature monitoring. This allows storing information about control object, producing necessary analysis and predictions.

Many thanks to Invited Blogger - Andrew Luzgin.

Optical network monitoring in practice – what do you need to know.

We decided to write a series of publications (articles) about the practical use of optical network monitoring systems (RFTS). Thus, together with the IIT company, we wrote the first article, which is titled "Methods of Optical Fiber Parameters Analysis under Automatic Monitoring" (this article was published in the Russian edition of Lightwave magazine).

As is usual, in the process of creating an article, our work has born a lot of material that goes beyond the originally planned topic. Based upon this material a number of useful articles on the following issues will soon appear:


- Network monitoring system architecture
Here we are going to talk about various ways to set up a monitoring system. We will try to give an answer to such question as: Should OTDR operate continuously or should it start measuring once it has received an alarm signal from a permanently active OPM (optical power meter). This issue is important if it is necessary to save the resources of expensive OTDR devices. Also we will explain the frequent problem of separating zones of responsibility during the monitoring of large networks, covering, for example, several administrative units (subnational entities) within their organizations.

- "Vectorial" method of fiber parameters analysis during automatic monitoring (RFTS)
Since this method has been applied to the monitoring system software, which we develop at OptixSoft, we will describe it in detail. We will give practical advices for users on how to markup the trace properly, how to choose parameters to measure a reference trace, how to optimize the reference trace template to increase the system reaction rate and so on. Such interesting issue like Faults Prediction will be described too.

- Economic effects of the use of monitoring systems (RFTS)
We will try to evaluate once again the qualitative and quantitative effect of using network monitoring system in practice. We will deal with the subject of Reducing Mean Time to Repair has usually been taken to restore communications after the accident. We will describe Faults Prediction usability in case of fiber degradation and other benefits like unification of tools and documents.