Using an OTDR: How to keep it simple

by Fiber-MART.COM

Communications networks never go slower, never get simpler, and never stay the same. Likewise, certification testing for fiber-optic cabling has also changed.

 

New test equipment and enhanced testing regiments help ensure that cabling can support the new demands placed on networks. Born from legacy test equipment for telecommunications networks, some of these fiber testers were difficult to use. But a new generation of fiber test equipment is designed to make it easy to certify fiber to the latest standards.

 

Not long ago, the state-of-the-art for fiber-optic cabling was the 100Base-FX standard from the Institute of Electrical and Electronics Engineers , which supported a bit rate of 100 Mbits/sec over a channel with an attenuation of 11 decibels (dB). Today, for IEEE 10GBase-S to support a transmission rate 100x higher than 100Base-FX, the transmission channel must attenuate the light by no more than 2.6 dB. It is this tightening of requirements for the physical media that represents a challenge for all components used to build and test a transmission path.

 

A standards-compliant connector can contribute up to 0.75 dB (0.5 dB typical) to the total loss. This would mean that if you patch two fiber segments together, there would be a total of four connectors, which could-even though each individual segment is compliant-result in worst-case loss of 3 dB (4 x 0.75). This exceeds the loss budget left for the entire link, and with a negative allowance left for the fiber itself.

 

More than a loss measurement

It is here where new test methods are required. Installers who work with optical fiber are, no doubt, familiar with the optical loss test set (OLTS). Performing a loss-length test with an OLTS is an essential part of fiber installation. Every link needs to be tested to ensure it is within the loss limits. But an OLTS will only show if a link has passed or failed. If it fails, the OLTS will not show you why it failed, or where.

 

For these answers, an optical time-domain reflectometer (OTDR) comes into play. Using an OTDR need not be complicated or confusing. Understanding a few basic concepts will make OTDR use as straightforward as using a copper certification tool.

 

Testing fiber links as defined by national and international standards, such as the TIA/EIA-568-A and ISO-11801 specifications, includes the use of an OLTS. Recently updated standards that focus on test methods for installed fiber links, such as ISO-14763-3 and TIA TSB-140, now recommend the complementary use of an OTDR. These new standards add the use of an OTDR to verify not just that the link has passed, but to ensure the quality of each installed component on the link.

 

Two levels of testing are defined in these updated standards: Basic (or Tier 1) testing uses an OLTS. Extended (or Tier 2) testing involves the use of an OTDR and an OLTS.

 

The following example helps demonstrate how an extended test regime can help to ensure consistent quality during installation. Assume that the first connector in a 2-connector, 100-meter fiber link performs extremely well, while the second connector is poorly installed or contaminated. In such a circumstance, the measurement with an OLTS may show that the link passed by a slim margin of 0.02 dB, but does not identify the second connector as a bottleneck (noted in bold).

 

Identifying bottlenecks is the strength of an OTDR, which sends a pulse of light into fiber and measures the light reflected back at each component as the light lost at that component. The same is true for backscattered light along the length of the fiber itself.

 

Little setup required

An OTDR can produce accurate, highly detailed measurements, if the correct setup and necessary accessories are employed. Recent versions of standards like ISO-14763-3 make an attempt to specify all necessary elements for a correct measurement with an OTDR, eliminating common sources of measurement error, including:

 

Specifications for launch and receive fibers;

Correct use of launch and receive fibers;

Instructions detailing how to position the cursor for the correct reading of link, component, and segment attenuation;

List of conditions under which it is vital to measure each fiber in both directions.

You may view these setup requirements as overly complex, which may explain why many consider the OTDR to be a tool for experts only. This is also why installers and contractors may choose not to bid on projects that require an OTDR, or subcontract this work to a company specializing in fiber. Such thinkingis in contrast to the certification of twisted-pair copper cabling systems, where after setting the correct standard, a single press of the autotest button does everything.

 

Fortunately, the actual use of the OTDR is not as challenging as it appears. Making sure that test leads, launch fibers, andreceive fibers are in a crisp condition, and are clean and correctly connected, will always be your responsibility. But the remainder of the setup steps can be taken care of by the instrument. Newer OTDRs will create an image of the proper setup configuration. You merely need to make connections and have the instrument “learn” the launch and receive fibers.

 

After this step, the tester will be ready to certify links and all included components for their compliance. Often, a project-specific standard, which is derived from the manufacturer’s data sheet or reference implementation, will be used to set these limits.

 

Pass, fail, or squeak by

When the tester is properly configured, the tests are as simple as copper certification. The most common situation should be that the link passes, and a “pass” indication on the summary screen will indicate the tester evaluated all elements of the link. Results are stored for later reporting. The instrument also automatically subtracts the contribution of the launch and receive fibers from the total link, showing only the total overall loss.

 

While this example is sufficient information for a passing link, you will need to dig deeper and get more-detailed information if the link (or parts of it) failed the specified limits.

 

You can see, for example, that the loss may be 1.07 dB and within the limits, but a single bottleneck contributes 0.92 dB to the overall loss.

What Makes Optical Fibre Immune To EMI?

by Fiber-MART.COM

Optical Fibre Is Immune To EMI

Fibre optic cables are non-metallic... they transmit signals using pulses of light in glass threads! As a result, they are immune to Electro-Magnetic Interference and Radio Frequency Interference. In other terms, the integrity of signals is not affected by electrical noise in the environment.

 

In copper cables, the integrity of signals can be affected by electrical noise. This can also reduce speed of transmission as larger numbers of lost and/or corrupted data packets can lead to excessive levels of retransmission.

 

Attenuation loss can be as low as 0.2 dB/km in optical fibre cables, allowing transmission over long distances without the need for repeaters (than you will have with copper systems to ensure satisfactory performance over long distances with higher data rate).

 

Fibre connections isolate data from dangerous increases in ground potential, ground loops, and electrical EMI/RFI (radio-frequency interference). It also removes a potential security vulnerability, as data cannot be read from the magnetic field around the cable. 

 

Fibre Optic Eliminates The Spark Hazard

As they don’t carry current, fibre cables can’t generate even the smallest spark. This is a considerable advantage in explosive environments such as chemical plant or oil refineries as it increases the safety of your installation. We will recommend this specific Fanless Intel Mini PC as it integrates 2 fibre optic GbE LAN ports, which will enable you to get a direct connexion to a fibre backbone.

 

At TinyGreenPC, we help customers with their project, from the evaluation to the deployment. 

Five Kinds Best Quality Material Fiber Optic Patch Cable

multimode fiber optic Patch cables

 

SOPTO supplies a complete line of multimode fiber optic patch cords with SC, FC, ST, LC, MU, MT-RJ, DIN, D4 and MPO terminations available in 62.5/125 (Standard) or 50/125 (Custom) multimode fiber types, Simplex and Duplex, used for short distance data transmission, we usually use MMF for multimode fiber optic patch cable.

 

The multimode fiber optic Patch cords are made of best quality materials with 1.8mm, 2.0mm,3mm outer diameter, normally orange jacket and jacket type like riser , LSZH or Plenum rated, Corning optical Fiber cable are available .

single mode fiber optic patch cables

 

Single mode fiber optic patch cables supplied by SOPTO are used in fiber optic communications filed; they are with typical 9/125 single mode fiber, with Riser, Plenum and RoHS standards optional. Our duplex single mode fiber patch cables are fully compatible to use with equipment from other suppliers, these products are reliable quality and good prices with prompt delivery.

 

Gigabit OM3 Fiber Optic Patch Cables

 

We are the manufacturer and supplier of 10Gig fiber optic patch cord,OM3,10G fiber optic patch cable,SC,LC,FC,ST,MU,MTRJ,E2000,Multimode,50/125,aqua,10gb fiber cable.

 

Typically this fiber optic patch cable is  with 50/125 multimode fiber, with aqua jacket, they can be terminated with various kinds of connectors like LC,SC,FC,ST,MU,MTRJ,E2000 etc ,they support bandwidth up to 10GB.

 

With the development of multimedia, there is requirement for more and more broad bandwidth for audio and video applications. Nowadays many people need the multimode fiber optic cable that can transmit 10G signal. SOPTO10 Gig fiber optic patch cord are designed to meet this requirement ,these 10g fiber optic patch cords are with aqua OM3 50/125 fiber glass and they are typically used in 10 Gigabit Ethernet, our 10 gigabit fiber optic patch cord the bandwidth supported is as specified IEEE802.3z which is for Gigabit Ethernet.SOPTO10 gig fiber optic patch cords are manufactured according to TIA-492AAAC-A standard for OM3 cable ,and the typical cable color is as per aqua standard which was developed by Lucent technologies.

 

here are OM4 fiber optic patch cables and MPO MTP fiber patch cords as well.

 

Typical Outdoor Fiber Optic Cables

Fiber optic cable provides protection for the fibers from the environment encountered in an installation. Outdoor Fiber Cable is designed strong to protect the fibers to operate safely in complicated outdoor environment, it can be buried directly, pulled in conduit, strung aerially or even placed underwater. While indoor cables don’t have to be that strong.

 

Outdoor fiber optic cable is composed of many fibers enclosed in protective coverings and strength members. Common features for fiber optic cable include polarization maintaining, graded index, and metalization. Most outdoor fiber cables are loose buffer design, with the strengthen member in the middle of the whole cable, the loose tubes surround the central strength member. Inside the loose tube there is waterproof gel filled, whole cable materials used and gels inside cable between the different components will help make the whole cable resist of water.

Typical outdoor fiber optic cable types are used for aerial, direct buried and duct applications.

 

Loose Tube Cables

 

Loose Tube cables are the most widely used cables for outside plant trunks, as it can be made with the loose tubes filled with gel or water absorbent powder to prevent harm to the fibers from water. Loose Tube Fiber Optic cables are composed of several fibers together inside a small plastic tube, which are in turn wound around a central strength member and jacketed, providing a small, high fiber count cable. They can be installed in ducts, direct buried and aerial/lashed installations for trunk and fiber to the premise applications. Loose tube cables with singlemode fibers are generally terminated by spicing pigtails onto the fibers and protecting them in a splice closure. Multimode loose tube cables can be terminated directly by installing a breakout kit, also called a furcation or fan-out kit, which sleeves each fiber for protection.

 

Ribbon Cable

 

Ribbon cable is preferred where high fiber counts and small diameter cables are needed. This cable has the highest packing density, since all the fibers are laid out in rows in ribbons, typically of 12 fibers, and the ribbons are laid on top of each other. Not only is this the smallest cable for the most number of fibers, it’s usually the lowest cost. Typically 144 fibers in ribbons only has a cross section of about 1/4 inch or 6 mm and the jacket is only 13 mm or 1/2 inch diameter! Some cable designs use a “slotted core” with up to 6 of these 144 fiber ribbon assemblies for 864 fibers in one cable! Since it’s outside plant cable, it’s gel-filled for water blocking or dry water-blocked. These cables are common in LAN backbones and data centers.

 

Armored Fiber Optic Cable

 

Armored cable is used in direct buried outside plant applications where a rugged cable is needed and/or for rodent resistance. Armored cable withstands crush loads well, for example in rocky soil, often necessary for direct burial applications. Cable installed by direct burial in areas where rodents are a problem usually have metal armoring between two jackets to prevent rodent penetration. Another application for armored fiber optic cable is in data centers, where cables are installed under the floor and one worries about the fiber cable being crushed. This means the cable is conductive, so it must be grounded properly.

 

Aerial Fiber Optic Cable

 

Aerial cables are for outside installation on poles. They can be lashed to a messenger or another cable (common in CATV) or have metal or aramid strength members to make them self supporting. A widely used Aerial Cable is optical power ground wire (OPGW) which is a high voltage distribution cable with fiber in the center. The fiber is not affected by the electrical fields and the utility installing it gets fibers for grid management and communications. This cable is usually installed on the top of high voltage towers but brought to ground level for splicing or termination.

 

Indoor/Outdoor Cables

 

Fiber Optic Indoor/Outdoor Cables are designed to meet both the stringent environmental requirements typical of outside plant cable AND the flammability requirements of premise applications. Ideal for applications that span indoor and outdoor environments. By eliminating the need for outside to inside cross-connection, the entire system reliability is improved and with lower overall installation costs.

 

Underwater and Submarine Cables

 

It is often necessary to install fibers under water, such as crossing a river or lake where a bridge other above water location is not possible. For simple applications a rugged direct burial cable may be adequate. For true undersea applications, cables are extremely rugged, with fibers in the middle of the cable inside stainless steel tubes and the outside coated with many layers of steel strength members and conductors for powering repeaters. Submarine cables are completed on shore, then loaded on ships and laid from the ship, often while operational to ensure proper operation.

 

fiber-mart.com offers a comprehensive range of multimode fiber cable and single-mode fiber optic cables. Indoor, outdoor, armoured, tight buffered or loose tube structures, which cover all possible applications.

How to Deploy 10G, 40G, 100G in the Same Network

In 2010, 10G SFP+ became the primary equipment interface in data center applications. However, jump to 2017, as demand for greater bandwidth shows no signs of slowing, 40G and 100G transceiver shipments saw a whopping increase. While shipments of 40G and 100G modules are on the rise, the large majority of data center networks don’t undergo a whole replacement of 10G device with 40G or 100G device. Instead, many typically deploy necessary equipment to achieve the coexistence of 10G, 40G, and 100G in the same network. Read this post, and you will get detailed solution.

QSFP+ 40G to 10G

In the following scenario, an upgraded 40G switch is networked to existing 10G servers with a 1×24-fiber to 3×8-fiber MTP conversion cable. At the switch, a cassette combines three 40G ports (QSFP 8-fiber) on the 24-fiber trunk. In the server cabinet, each 40G port is segregated into 10G LC connections to support server connectivity.

 

Note: in this architecture, if you have existing 12-fiber MTP trunks, you can use a cassette with two 12-fiber MTP inputs that breakout into 3×8-fiber MTP strands, instead of deploying a new 24-fiber MTP trunk cable. However, if you have to move to denser and more complicated applications, the 24-fiber MTP solution makes for easier migration.

 

CFP2 100G Port (10×10)

Like the previous example, the following figure 2 also shows a similar scenario in existing 10G servers, but it uses 100Gbase-SR10 ports on the switch, which requires a 24-fiber connector to drive the 10×10 transceiver port. Instead of breaking into 8-fiber connections, it uses 24-fiber MTP patch cord from the switch to the patch panel in the top of the rack. A 24-fiber MTP trunk connects the switch and server cabinet. The MTP cassette at the top of the server cabinet converts the 100G port into ten individual 10G port with LC connectors.

 

 

Note: As in the figure 1, in this scenario, if you already have two 12-fiber MTP trunks, you can use 12-fiber MTP adapter panel, then a 2×12-fiber to 1×24-fiber MTP harness cable could be used at the switch to build the same channel.

 

New Installation for 40G/100G Deployment

Figure 3 shows an example of a completely new installation, using 40G/100G right out of the box without any 10G switches in the channel. This method has 40G or 100G port on the core switches, and 40G uplinks at the ToR switches. The patch panels at the top of each rack use MTP bulkhead, with all 8-fiber cords from one QSFP port to the next.

 

40G100G Deployment - 

In this architecture, we can either use 24-fiber trunks that break into 40G ports, or create trunks with 8-fiber strands on every leg, with 8 fibers per 40G or 100G port, as shown in the diagram above. However, we have to pay attention that with 8-fiber legs, the density will become a challenge. In addition, 12-fiber MTP trunks are avoided in this scenario, since integrating existing 12-fiber trunks with 8-fiber connectivity on the patch cord creates fibers unused.

 

Deploying 10G, 40G, 100G in the same network can effectively avoid costly upgrades that require ripping out cabling and starting over with a new network architecture. This post have provided three solutions. All the devices in these three scenarios can be purchased in FIBER-MART.COM. If you are interested, kindly visit FIBER-MART.COM.