Do you know how to choose the ideal fiber optic OTDR?

The fiber optic market has shown intensified growth in Brazil and Latin America as a whole in recent years. The increasing expansion of FTTH (fiber to the home) networks brings an increase not only in the acquisition of cables and optical equipment, but also in the tools that guarantee the quality of this transmission.

In this sense, one of the essential instruments to provide efficiency and speed to the maintenance of the fiber optic network is the OTDR – optical time domain reflectometer. 

You OTDRs are able to certify the performance of new fiber links and detect problems in existing links. It is a measurement tool that can be useful to carry out the validation of a network and also to identify a break in the optical cable.

In general, OTDR measurements are used to analyze fiber optic transmission. Therefore, they are essential to map the link loss in relation to distance.
But how does an OTDR work? And how can it help you ensure a more effective and reliable network?

How does OTDR work?

In general terms, the OTDR emits light pulses of short duration and sends them through the fiber core, being able to measure the optical signals that return to it as a function of time. Fundamentally, it uses the Rayleigh scattering principle. That is, the light that is emitted by the OTDR is reflected back to the equipment. By the time the reflection is received, the OTDR calculates the attenuation value of the optical cable.

Without the aid of this device, mapping each fiber segment in search of a fault can be a long process and with a high operational cost for the ISP. As much as network certification can be done in other ways, using the OTDR as the most agile and accurate method to test optical fibers during their installation, maintenance and restoration

And how do you know which type of OTDR is most suitable?

Contrary to what many believe, the network distance that the equipment can reach is not the only criterion for choosing the best OTDR. There are other equally important parameters.

For example, we can find equipment that works with the active fiber, that is, it is not necessary to interrupt the signal to carry out repairs. And there are those that work only with the fiber out or no signal, where it is mandatory that the network is turned off for the technician to carry out the maintenance.

Some important points to consider:

1- CHOOSE FOR ACTIVE FIBER OTDR

For the small provider that is already consolidated and fully operational, it is necessary to opt for an active fiber OTDR. To operate an unlit fiber OTDR, you will need to turn off the PON port related to that leg, and this will affect all users connected to it. Thus, in order not to discontinue services to any user, it is necessary to validate the network while it is in full operation.

2 - AVOID P2P OTDR

Since normally providers that work with fiber opt for FTTx topology, having splitters in their networks, this P2P equipment is not recommended because it measures only from one point to another. Thus, the technician will need to go from box to box, remove the splitter and measure the section in question, which is not the best solution for a PON network. You will need many additional configurations for the complete network metering.

3 - DYNAMIC RANGE

The dynamic range (power) of the OTDR is also important. 

It is recommended that you purchase an OTDR of at least 36 dB, as a less powerful one is not capable of measuring networks with a split of 64 or 128 subscribers per PON port.

4 - VISUALIZATION OF RESULTS

Checking the way the equipment displays the measurement results is also critical. A simplified picture, like the block diagram view, becomes much clearer, and identifying all splitters and events in a didactic way is the best choice. This type of fiber optic OTDR makes life easier for the technician and does not require complex analysis of how and where the network is losing power (or how and where events are occurring).

Advantages of using OTDR on your network​

As far as maintenance is concerned, the benefits of this instrument are significant. The OTDR can perform the exact measurement of where there is an optical cable with a defect or even a break. Furthermore, by certifying the network, the equipment requires a lower level of maintenance and considerably reduces the operating cost for the provider.

OTDRs ensure the quality of fiber optic transmission. And prove to be even more useful. at fault location in long optical links, like us backbones and metropolitan networks, which are tens of kilometers long.

In short, this is an instrument that helps the provider to offer a quality service. By pointing out exactly where the events and defects are, the technician is able to make an assessment and repair very quickly. As far as infrastructure is concerned, acquiring the equipment is undoubtedly a smart management decision.

In order to offer a service of excellence, it is necessary to know its operation in depth, as well as to value planned management and control over the entire network. Only in this way can your company grow more, with quality.

Learn more about the OTDR tool available on OZmap!