Unprecedented demand for fiber hyperlinks and capability are driving the deployment of high-fiber-count cables with a whole bunch and even 1000’s of fibers. These cables are being deployed by darkish fiber suppliers in addition to in conventional telecommunication networks to offer knowledge heart interconnections, metro connectivity between central places of work, entry community in assist of FTTH, and edge computing for low latency 5G community functions.
There are actual challenges related to testing these cables. The processes that labored effectively for just a few fibers are a lot much less environment friendly when scaled to a whole bunch or 1000’s. Challenge managers are confronted with much more knowledge and experiences to deal with and confirm/audit. Technicians are coping with the sheer quantity of connection/disconnection of the fibers being examined, the handbook post-processing for bi-directional OTDR evaluation, and “on the fly” spreadsheet monitoring of check outcomes. Moreover, reporting of mission standing and progress turns into inefficient and dangers delays in handover of a community or mission.
So, how can we create efficiencies that may permit bi-directional check to scale and what do these efficiencies ship when it comes to reductions to certification occasions?
First let’s take a quick take a look at an Outdated Legacy Technique (OLM) to match the strategy and certification occasions with the very newest options out there.
I’ll define a generic Outdated Legacy Technique (OLM) based mostly on check gear with separate check ports, one for IL and ORL and a second for OTDR (it could possibly be that they’re even separate items of check gear altogether). The OLM additionally doesn’t have the capability for actual time bi-directional OTDR evaluation, which means that for any mission the place bi-directional OTDR certification is required, there may be further work required to submit course of OTDR outcomes, which provides time and value (and I’ll remind you that to be compliant with ITU-T and IEC requirements, bi-directional OTDR check/evaluation is required to certify a fiber hyperlink). Nor does the OLM have the any type of built-in mission administration, which means that monitoring mission progress and go/fail standing is commonly recorded on separate spreadsheets, which requires handbook entry and carries a threat of human error. Plus it interrupts the check circulate, resulting in poor workflow and decrease tech effectivity.
Let’s take a look at a 12-fiber bundle for a comparability and carry out bi-directional IL, ORL and OTDR testing at two wavelengths (1310 & 1550 nm). For this we’ll additionally take a look at a twin ended strategy with two units of check gear and technicians.
Outdated Legacy Technique (OLM)
So, what does the work or check circulate appear to be? First issues first, all 12 fiber connectors or patch panel ports should be inspected and, if needed, cleaned.
Because of the separate check ports with OLM, there should be a primary go to make the IL and ORL measurements; this needs to be synchronized with each devices linked to both finish of the identical fiber on the similar time. This implies the techs need to be in nearly steady communication with a view to coordinate the taking of measurements and transferring to the subsequent fiber. There are small delays, however delays nonetheless, because the check twine is moved and a check manually triggered. Nevertheless, the devices can usually care for auto saving outcomes, thus saving time and one other step having to be manually triggered.
As soon as the IL/ORL go has been made you can begin on the OTDR exams. In an effort to save time and be environment friendly with workflow, some gear distributors suggest an asynchronous strategy the place the tech with the principle unit begins at fiber one whereas the tech on the distant finish begins at fiber 12. They then merely work their means by the 12 fibers and cross over one another on the “center” of the bundle round fiber 6 to 7. The one factor you need to be careful for is testing the identical fiber on the similar time (check collision) which can mess up the outcome. There are different approaches to check fiber in the identical order, parallel 1 to 12, however offset the beginning of the exams by a couple of minutes in order to keep away from check collisions. However for this comparability, I’ll persist with the quickest strategy OLM can provide, which is the asynchronous one and hope that as a consequence of slight variances within the work pace/price of every tech that there can be no check collisions.
This strategy, nevertheless, won’t totally adjust to the TIA and IEC requirements for bi-directional OTDR certification, a subject I explored in an earlier weblog on this collection. In terms of performing the bi-directional OTDR evaluation, you’ll solely have the ability to consider the tip connectors of the hyperlink with a uni-directional OTDR measurement, and as such the certification is non-standard. To conform and totally certify fiber hyperlinks as per the requirements, it’s essential use a obtain cable for the OTDR check, which suggests an additional degree of coordination is required in the course of the OTDR exams. The principle tech testing fiber 1 should ask the distant tech to attach a obtain cable to the identical fiber, the principle tech has to do the identical for the distant tech and join a obtain cable to fiber 12. As soon as the OTDR exams are full the techs should once more coordinate and transfer the obtain cable to the subsequent fiber to allow the testing to proceed, so that they need to be in nearly steady communication. There’s a time related to transferring the obtain cable and once more there are delays that creep as a result of interruption and handbook restarting of the check course of. Once more, auto-save of outcomes will assist take away some delays. For this comparability, we’ve estimated OTDR check time of 30 seconds per fiber and the identical once more for the launch and obtain cable administration, one minute in complete.
Whereas all of this is occurring the techs should manually monitor which fibers they’ve examined utilizing a separate spreadsheet.
As soon as all of the testing is full, the outcomes need to be submitted for submit processing with a view to carry out the bi-directional OTDR evaluation. That is often accomplished by way of USB stick and electronic mail or bulk add to the cloud on the finish of a day’s work. Relying on the quantity of tidy-up work to right file names (or different errors) and the quantity of exams to course of, it might take something from just a few hours to some days to finish. For this comparability we’ve averaged and estimated an add and processing time for a day’s work and damaged that right down to roughly quarter-hour to course of a batch of 12 units of outcomes.
Time spent on every process and check was then grouped and is proven within the time comparability graph beneath. When utilizing this asynchronous approach and submit processing it gave an estimated complete check and certification time of slightly below 40 minutes.
The choice strategy to this was explored in an earlier weblog <INSERT LINK> on this collection, which checked out what strategies could possibly be adopted to cut back the entire check, processing and certification time. Primarily a single check port strategy for IL, ORL, and OTDR testing. The mixing of a multi-fiber swap and fan-out cable, use of extra automation to coordinate the devices and batch check fibers in a single check sequence, together with the automated use of a obtain cable, and eradicating the necessity for outcomes add to the cloud and any bi-directional OTDR submit processing.
FiberComplete PRO methodology
If we assume the identical IL/ORL and OTDR check occasions however take away the time and delays as a consequence of manually transferring, coordinating, and testing by 12 fibers (that is now accomplished by way of an optical swap) and the submit processing effort (that is now accomplished on the instrument by way of the fiber underneath check), the whole check and certification time may be lowered to slightly over 22 minutes, yielding a time financial savings of round 45%.
FiberComplete PRO multi fiber check time examine
Additional time reductions on subsequent batches of 12 fibers will also be achieved by performing duties in parallel. Don’t simply sit and await an automatic sequence of 12 fibers to finish; use the time to examine and clear the subsequent set of 12 fibers so they’re able to go. You may also migrate over every check twine of the fan-out cable because the exams on that fiber are full so that you’re prepared to check the subsequent batch of 12 fibers nearly instantly. This reduces the total certification time to slightly over 14 minutes, yielding a time saving of over 60%.
If you wish to study extra go to our web page on Bi-directional OTDR Testing.
Dou
glas Clague is at present options advertising supervisor for fiber optic subject options at VIAVI. Doug has over 20 years of expertise in check and measurement with a major give attention to fiber optics and cable applied sciences, supporting the telecommunications trade. Previous to VIAVI, Doug held positions as manufacturing engineer, options engineer and enterprise growth supervisor. Doug has participated on quite a few trade panels round fiber and cable know-how developments. He attended Brunel College in London and graduated with an honors diploma in electrical and digital engineering.
