#aroundcity

[teardownit]

Which reflectometer to choose for new fiber-optic lines?

Modernization of 100/400G networks and deployment of 5G networks at the proper quality level require testing of optical fiber communication lines (OFC). Choosing the right methods and additional instruments is critical when conducting bulk testing, as mistakes can be very costly.

If we talk any modern optical networks, fiber and coupling quality are critical. Modernization of existing networks involves checking their condition as well as laying new OFCs—testing the quality of connections. The higher the speed of fiber-optic lines, the more stringent the requirements for the quality of their diagnostics. And here the problem of choosing a testing methodology arises: for example, is "testing to the maximum" using bidirectional tests always the best option?

Bidirectional testing of OFCs with a reflectometer: the answer or new problems?

It is important to understand that fiber-optic communication is related to reflectometry. Without a high-quality optical reflectometer (OTDR), it is impossible to create a reliably operating fiber-optic link. The solution to the problem of testing comes down to the correct initial selection of equipment and determining the most suitable methodology.

There are two main methods of reflectometry: one-way (one compensation coil at one end of the line; launch cable box) or two-way (Bi-dir OTDR, with a compensation coil at the near end and the same at the far end). .

The direction of the emitted light can influence the test results. In any fiber, there is a difference in the return loss coefficients, and in one particular direction, the light loss may be greater.

Single-sided OTDR testing can miss many anomalies. Wire junctions with different return loss values can compensate for the signal loss in one orientation and attenuate it in the other. In addition, there are dead zones in which the OTDR does not record events.

The figure below shows an example of the difference in signal loss depending on the measurement direction. One side of the testing even shows a negative loss of -0.3 dB, which is, of course, impossible. In this case, an amplification effect is observed due to the difference in the backscatter coefficient (BSC) at the junction of the two cables.

Therefore, one-way OTDR testing is better suited for simple tests such as finding and locating fiber breaks and bends, assessing total signal attenuation in fibers, testing connectors, etc. In this case, there is no need to waste time on bidirectional testing. The main advantage of unidirectional fiber-optic testing is that it is enough to inspect and clean the fiber just once for any one line. This is important since contamination of the connectors can lead to failure of the fiber-optic line, which was working properly before testing. Sometimes customers insist on two-way "full testing," but this can be excessive and even harmful as it introduces an unnecessary risk of damage while cleaning the optical connectors.

Bidirectional fiber inspection without running around

One-sided tests are not accurate when laying new lines and monitoring the performance of FOCs. In such cases, industry standards require bidirectional testing with an optical time domain reflectometer (Bi-dir OTDR) measuring the signal at both ends of the line. This is necessary to identify anomalies that are not detected by conventional one-way reflectometry. In addition, there are unique cases where a line uses cables with different fiber diameters, where bidirectional effects can be important. Bi-dir OTDR testing makes it possible to average the measurement parameters and give a clear assessment of the quality of the fiber-optic link. Ultimately, it is possible to unambiguously determine whether the tested line supports high-speed data transfer. This saves time and money that the customer may lose if the cable system fails on launch.

Traditional bidirectional testing of fiber-optic links implies first measuring one side:

And then testing the optical line on the other side:

Then obtain the average parameters. This is an important job that requires manual data processing. It can be accelerated by using two similar instruments with two external cable routes simultaneously (the bidirectional reflectometer technique), but this requires additional equipment expenses.

Another effective technique is testing with an optical reflectometer with a closed circuit (loopback). This method involves using a reflectometer at one end of the line and a reference fiber loop at the other. This way, one can test two optical lines in both directions, alternately swapping cables. This is the most effective method in terms of cost and labor savings since it requires only one reflectometer, loop switching, and two compensation coils.

A major drawback of OTDR-loopback testing is the labor-intensive process of recording and merging test data. Often, manual work with data leads to errors, and repeated tests are needed. This problem has been solved in modern optical reflectometers, such as the VIAVI T-BERD/MTS-4000 V2.

When using such advanced devices, the task of specialists is reduced to the high-quality implementation of procedures for cleaning contamination of optical connectors and one-way checking of launch cables before starting bi-directional testing.

Thus, preference should be given to OTDR modules and platforms that offer the ability to choose any optical cable diagnostic technique with maximum automation. This choice should be made based on practical needs and not on the capabilities of existing equipment. Ultimately, this approach reduces the likelihood of OFC failures.

[talk-with-sebastian]

“let go-“

*he wiggled his tail tip aroundc trying to get him off*

“no sushi- bad Allo-“

@unda-pressure

Can you do it /nf

(Sorry if this makes anybody uncomfortable /gen)

"id let Allo do it... I MEAN WHAT-"

[saporietoys]

#napoli #sundaynight #lifestyle #instagram #followme #love #girls #likeback #women #blogger #aroundcity #friends #wine #beer #cocktails Buona serata. (presso Archivio Storico)

[samarasshoesart-blog]

"Sun-day" (A few hours before with a friend) #athenscity #spring #sun #happypeople #coffetime #sunday #friends #cityview #gr #athina #greece #join #hellas #aroundcity #point #center #myshoes #view #stepside #mylook #today #coffeshop #central #look (στην τοποθεσία Γιασεμί - Yiasemi) https://www.instagram.com/p/BwhzBsSnqCy/?igshid=1pxlsw1n9jfdl

[simo-xoxo]

Ecco come vorrei passare la domenica: a bere chai tea latte passeggiando per le strade di Manhattan 😭 #memories #takemeback #nyc ________________ #manhattan #ny #nycstreet #nystreetstyle #progettocinque #aroundcity #travel #travelblogger #travelphotography #travellist #travellover #lovethis #takemebacktonyc #missthisplace #starbucks #coffeetime #sunday (presso New York, New York) https://www.instagram.com/p/Bt-wzW5Hg7W/?utm_source=ig_tumblr_share&igshid=1dh6ditmjn5d8

[ierogenvy]

if u work in hr and therefore have an office that u are in all day why the hell cant u answer the phone that is in ur office

[lifebigjourney]

Oh yes! I hitchhiked more then 3000 km, slept 2 night in tent at 2 crazy and really cold nights and now I am in Irkutsk city. If you know - Baykal lake it's nearby. Amazing experience! Have a good day my friends!😜✌️ ---------------------------------- Догадайтесь в каком городе я сейчас? Конечно же, это Иркутск - ответ прямо на фото. 3 дня я ехал автостопом, прошёл более 3 тыс км, две жуткие холодные ночи в платки, парочка десятков людей и я в Иркутске. Тёплая, уютная квартира, душик, нормальная еда. И, спасибо Паша за приём! А пока я погуляю пару дней в этом замечательном городе. Он мне уже успел понравиться. Всем отличного дня!😜✌️ ___________________________________ #Lifebigjourney #DenisBashmakov #dharma_travel #бродягидхармы #tpsfotostation #traveler #блоггер #hitchhiking #travel #iamtb #journey #путешественник #чуваш #сыбайскийпарень #gf_streets #Россия #iaminrussia #russia #явроссии #автостопомпороссии #автостоп #иркутск #ялюблюиркутск #irkutsk #baykal #сердце #добро #прогулка #aroundcity (at ТРК "Модный Квартал")

[freckledbastard]

not to be needlessly repetitive or anything, but i was checking over the original japanese chapters for 913 and 914 again (when kiku is first seen and when she introduces herself as a samurai), and you know how people are always like “oh she uses sessha, which is for male samurai”? 1, as we’ve already said it’s a term for any samurai, its just that most samurai were men.

and 2, the first time she uses it she just says せっしゃ (sessha, without the kanji). this is what zoro and luffy are reacting to. kiku, who as far as they know is only the poster girl for the tea house is suddenly using the same pronoun as the samurai they know. once she starts chasing after tama is when she uses sessha again, but this time as 拙者 (sessha, with the kanji), its a confirmation both to zoro and luffy, as well as the audience that she’s a samurai, she’s not just using it wishy washy.

japanese language in one piece can be pretty interesting though. like how perona is all about cuteness, but apart from using ‘watashi’, her use of language is literally as crude as luffy’s, it’s excellent. 

[arflorez]

🍃☁️ #Nature #Fog #Clouds #Green #Cold #Weather #Stones #AroundCity #Trees #Road #Bicycle #Rocks #Flowers #Leaf #Cloudy #Overcast #Nublado #Niebla #Frío #Colombia

[chikkou]

DONT FUCKING PLAY GAMES WITH ME IM NOT FUCKING AROUNDC OYU SON OF A BITCH

[teardownit]

Best budget-friendly optical reflectometer

In recent decades, the rapid development of optical fiber communication (OFC) lines has required simple, reliable instruments for diagnosing optical communications. An optical time domain reflectometer (OTDR) is one of the most common devices for testing fiber optic links and identifying problem areas in fiber optic communication lines. What criteria should be used to choose a reflectometer so that it performs correctly and does not require excessive financial investments?

Reflectometer: luminous intensity

A reflectometer directs a beam of laser light into an optical fiber. Then, it measures the parameters of the reflected light, thus analyzing the characteristics of the optical fiber. This way, one can not only detect but also determine the location of any damage to the fiber optic line: a lousy receptacle or connector, a cable bend, light loss, poor splicing, etc.

This is a very effective technology, but it has two severe limitations. First, the reflectometer's probe pulse is reflected from all connectors, including the first one, which is why "lighting" creates a dead zone in which measuring is impossible. This problem is solved using an additional piece of optical fiber (launch cable) connected to the line under test. The dead zone is on this fiber, and the entire line can be tested. It is necessary to consider the length of the line that is supposed to be tested and select the correct length of the compensation coil; sometimes, the length can reach several miles.

The second limitation is that different types of optical fiber have the highest light reflectance coefficient at different wavelengths. Of course, the best choice seems to be the most versatile device that can operate in a wide range of wavelengths, for example, from 850 nm to 1650 nm. In particular, the VIAVI MTS-8000 universal measuring platform and a set of modules capable of solving almost any problem of fiber-optic communication analysis.

One must keep in mind that expanding the capabilities dramatically increases the cost of the device. However, these capabilities are not always necessary. More straightforward solutions are often sufficient for checking and even last-mile optical line certification, such as an optical reflectometer with the tester function and damage visualizer Greenlee 930XC-20C-UPC-FC.

The situation is similar to the dynamic range—the strength of the reflectometer signal and its ability to detect even slight attenuation of the optical signal. This can result in a severe deterioration in the efficiency of fiber optic lines on long, critical lines. Therefore, more expensive reflectometers with a wide dynamic range are used to check them. Generally, an OTDR with a dynamic range of 6 dB is more excellent than the loss of the longest optical communication line that the OTDR will ever have to service, which is sufficient for reliable testing.

These are the main aspects to consider first when choosing a reflectometer. However, many reflectometer models are on the market, and selecting them is not always easy. Fortunately, there is a simple set of questions, and answering them will give you a "portrait" of the device best suited for a specific set of tasks.

The right questions to ask when choosing an optical reflectometer

First of all, you need to answer questions about using your new reflectometer:

What networks and types of optical fiber will be tested (for example, multi-mode optical fiber or single-mode optical fiber)?

What is the maximum length of the fiber-optic link to be tested?

What measurements are aimed at (certification, troubleshooting, regular maintenance)?

The answer to these questions will significantly narrow the field of suitable reflectometers. For example, 850 nm and 1300 nm wavelengths are used for multi-mode optical fiber, and 1310 nm and 1550 nm are used for single-mode optical fiber. In the case of PON testing, wavelengths of 1490 nm and 1625 nm may be needed in addition to 1310 nm and 1550 nm.

If the reflectometer's main task is to localize damage, then buying an expensive device may be a waste of money.

However, if detailed diagnostics of a fiber-optic link and its certification are needed, professional reflectometers with a large dynamic range, small dead zones, and good software for processing reflectograms and generating a report are necessary.

It is also necessary to consider the aspects related to the device's operation. In particular, the size and weight of the reflectometer are directly related to the team's mobility. Devices with a larger screen (more than 5") are most often chosen for indoor work or as part of a mobile lab. Specialists use portable devices to work on city networks. Such devices must have waterproof housing and withstand a wide range of operating temperatures.

The minimum operating time on one battery charge is preferably at least 8 hours so that field measurements do not extend over two working days. The ability to upload data to the cloud for subsequent analysis and results processing will significantly save time.

Often, several instruments can be combined in one housing: a reflectometer, a tester, a damage visualizer, an optical spectrum analyzer, a dispersion analyzer, etc.

An important feature is the ability to expand the functionality and update the reflectometer software during operation, which means that a more expensive modular solution may be a more profitable purchase in the long term in some cases.

[simo-xoxo]

Buongiorno ragazzi! Finalmente è uscito il video sul mio viaggio a New York. Potete vederlo sul mio canale #youtube , il link lo trovate in bio! Have a nice day! ☀️ #youtubeitalia #newyork #vlog ———- #nyc #ny #video #newvideo #youtubevideos #youtuber #towatch #look #lookat #manhattan #brooklyn #city #view #aroundcity #travelpic #statueofliberty #memories #travelmemories (presso Statue Of Liberty, Liberty Island, New York City) https://www.instagram.com/p/BtN7h_in7Xi/?utm_source=ig_tumblr_share&igshid=ikwm2li63o2i

[thorwinther]

We Just got our wings to see the rest of the world. #worldwidewinther #travel #backpacking #aroundtheworld * * * * * * * * #travelblogger #travelphotography #instagood #artstreet #aroundcity #streetart #streetartglobe #swings #lax #instagramtravelling #instagood #lovetravel #couplesgoals #postoftheday #explorer #plannet #exploretheplanet #blogger (at Melrose Avenue) https://www.instagram.com/p/BpJF25ihcYu/?utm_source=ig_tumblr_share&igshid=rgrzjj1arj20

[saporietoys]

#napoli #maschioangioino #followme #instagram #saturdaynight #love #picoftheday #christmastime #winter #100likes #travelphotography #aroundcity (presso Piazza Bovio 22)

[valentinamancuso81-blog]

#oldcity #calabria #italy🇮🇹 #cosenza #historycenter #lastoria #nothingisordinary #pic #nightime #aroundcity #vscodaily #instagramers #igerscalabria #calabriadaamare #loves_united_italia #oldstreet (presso Cosenza, Italy)

[whole-life-vacation]

Armenian church in Singapore. Amazing place. Beautiful, calm. It's no one there. So quiet... Армянская церковь в Сингапуре. Удивительное место. Красивое, спокойное. И никого нет. Так тихо... #сингапур #красивый_сингапур #церковь #стараяцерковь #старыйгород #архитектура #тишина #красота #singapore #aroundcity #yu_explore #church #oldchurch #arcitecture #silence #beautifulsingapore #oldtown (at Armenian Church, Singapore)