2017年12月20日星期三

What is DWDM and Why is it Important?

It has been almost 20 years since DWDM came on the scene with Ciena’s introduction of a 16 channel system in March of 1996, and in the last two decades it has revolutionized the transmission of information over long distances.  DWDM is so ubiquitous that we often forget that there was a time when it did not exist and when accessing information from the other side of the globe was expensive and slow.  Now we think nothing of downloading a movie or placing an IP call across oceans and continents.  Current systems typically have 96 channels per optical fiber, each of which can run at 100Gbps, compared to the 2.5Gbps per channel in the initial systems.  All of this got me thinking about how it often takes two innovations coupled together to make a revolution.  Personal computers did not revolutionize office life until they were coupled with laser printers.  Similarly, the benefits of DWDM were enormous because of erbium doped fiber amplifiers (EDFAs).
DWDM stands for Dense Wavelength Division Multiplexing, which is a complex way of saying that, since photons do not interact with one another (at least not much) different signals on different wavelengths of light can be combined onto a single fiber, transmitted to the other end, separated and detected independently, thus increasing the carrying capacity of the fiber by the number of channels present.  In fact non-Dense, plain old WDM, had been in use for some time with 2, 3 or 4 channels in specialized circumstances.  There was nothing particularly difficult about building a basic DWDM system.  The technology initially used to combine and separate the wavelengths was thin film interference filters which had been developed to a high degree in the 19th Century.  (Now a ’days photonic integrated circuits called Arrayed Waveguide Gratings, or AWGs are used to perform this function.)  But until the advent of EDFAs there was not much benefit to be had from DWDM.
Fiber optic data transmission began in the 1970s with the discovery that certain glasses had very low optical loss in the near infrared spectral region, and that these glasses could be formed into fibers which would guide the light from one end to the other, keeping it confined and delivering it intact, although reduced by loss and dispersion.  With much development of fibers, lasers and detectors, systems were built which could transmit optical information for 80km before it was necessary to “regenerate” the signal.  Regeneration involved detecting the light, using an electronic digital circuit to reconstruct the information and then retransmitting it on another laser.  80km was much farther than the current “line of sight” microwave transmission systems could go, and fiber optic transmission was adopted on a wide scale.  Although 80 km was a significant improvement, it still meant a lot of regeneration circuits would be needed between LA and New York.  With one regeneration circuit needed per channel every 80 km, regeneration became the limiting factor in optical transmission and DWDM was not very practicable.  The then expensive filters would have to be used every 80 km to separate the light for each channel before regeneration and to recombine the channels after regeneration.
Since full regeneration was expensive, researchers began to look for other ways to extend the reach of an optical fiber transmission system.  In the late 1980s Erbuim Doped Fiber Amplifers (EDFAs) came on the scene.  EDFAs consisted of optical fiber doped with Erbium atoms which, when pumped with a laser of a different wavelength, created a gain medium which would amplify light in a band near the 1550nm wavelength.  EDFAs allowed amplification of the optical signals in fibers which could counter the effects of optical loss, but could not correct for the effects of dispersion and other impairments.  As a matter of fact, EDFAs generate amplified spontaneous emission (ASE) noise and could cause fiber nonlinearity distortions over a long transmission distance.  So EDFAs did not eliminate the need for regeneration completely, but allowed the signals to go many 80 km hops before regeneration was needed.  Since EDFAs were cheaper than full regeneration, systems were quickly designed which used 1550nm lasers instead of the then prevailing 1300nm.
Then came the “ah ha” moment.  Since EDFAs just replicated the photons coming in and sent out more photons of the same wavelength, two or more channels could be amplified in the same EDFA without crosstalk.  With DWDM one EDFA could amplify all of the channels in a fiber at once, provided they fit within the region of EDFA gain.  DWDM then allowed the multiple use of not only the fiber but also the amplifiers.  Instead of one regeneration circuit for every channel, there was now one EDFA for each fiber.  A single fiber and a chain of one amplifier every 40~100 km could support 96 different data streams. Regenerators are still needed today, every 1,200~3,500km, when the accumulated EDFA ASE noise exceeds a threshold that a digital signal processor and error correction codec can handle.
Of course, since the gain region of the EDFA was limited to about 40 nm of spectra width, great emphasis was placed on fitting the different optical wavelengths as close together as possible.  Current systems place channels 50GHz, or approximately 0.4 nm, apart, and hero experiments have done much more.
In parallel, new technologies have increased the bandwidth per channel to 100 Gbps using coherent techniques that we have discussed in other blog posts.  So a single fiber that in the early 1990s would have carried 2.5Gbps of information, now can carry almost 10 Terabits/sec of information, and we can watch movies from the other side of the globe.

dense wavelength division multiplexing (DWDM)

DEFINITION
dense wavelength division multiplexing (DWDM)
 
Dense wavelength division multiplexing (DWDM) is a technology that puts data from different sources together on an optical fiber, with each signal carried at the same time on its own separate light wavelength. Using DWDM, up to 80 (and theoretically more) separate wavelengths or channels of data can be multiplexed into a lightstream transmitted on a single optical fiber.
 
Each channel carries a wave division multiplexed (WDM) signal. WDM is a method of combining multiple signals on laser beams at various infared (IR)  wavelengths for transmission along fiber optic media. In a system with each channel carrying 2.5 Gbps (billion bits per second), up to 200 billion bits can be delivered a second by the optical fiber.
 
Since each channel is demultiplexed at the end of the transmission back into the original source, different data formats being transmitted at different data rates can be transmitted together. Specifically, Internet (IP) data, Synchronous Optical Network data (SONET), and asynchronous transfer mode (ATM) data can all be travelling at the same time within the optical fiber.
 
DWDM promises to solve the fiber exhaust problem and is expected to be the central technology in the all-optical networks of the future.
 
Coarse wavelength division multiplexing (CWDM) is an alternative method of combining multiple signals on laser beams at various wavelengths for transmission along fiber optic cables, such that the number of channels is fewer than in DWDM but more than in standard WDM.
 

What is fiber to the x (FTTx)?

Fiber to the x (FTTx) is a collective term for various optical fiber delivery topologies that are categorized according to where the fiber terminates.
 
Optical fiber is already used for long-distance parts of the network, but metal cabling has traditionally been used for the stretches from the telecom facilities to the customer. FTTx deployments cover varying amounts of that last distance.
 
In an FTTN (fiber to the node or fiber to the neighbourhood) deployment, the optical fiber terminates in a cabinet which may be as much as a few miles from the customer premises. The cabling from the street cabinet to customer premises is usually copper.
 
 
In an FTTC (fiber to the curb or fiber to the cabinet) deployment, optical cabling usually terminates within 300 yards of the customer premises.
 
 
In an FTTB (fiber to the building or fiber to the basement) deployment, optical cabling terminates at the building, which is typically multi-unit. Delivery of service to individual units from the terminus may be through any of a number of methods.
 
 
In an FTTH (fiber to the home) deployment, optical cabling terminates at the individual home or business.
 
 
FTTP (fiber to the premises) is used to encompass both FTTH and FTTB deployments or is sometimes used to indicate that a particular fiber network includes both homes and businesses.
The FTTH Councils of Europe, North America and Asia-Pacific have agreed upon definitions for FTTH and FTTB. Standard definitions of the other terms have not yet been established.

2017年12月19日星期二

What do Cat5e, Cat6, and Cat6a have in common?

They each utilize 4 twisted pairs in a common jacket. They use the same style RJ-45 jacks and plugs. And, they are each limited to a cable length of 100 meters including the length of the patch cables on either end of the link. The parts are interchangeable, so you can use a Cat5e patch cable with Cat6 house cabling. Your system will just perform at the level of the lowest link, in this case the Cat5e patch cable.
 
So what’s the difference?
 
Better transmission performance. With each upgrade in cable, there is less signal loss, less cross talk, and more bandwidth. And of course, more cost. So the important question is: What exactly am I getting for my money? Rather than talk about near-end-cross-talk requirements or SNR ratios, let’s talk about what each cable delivers in terms of Ethernet performance.
 
Cat5e:   Gigabit Ethernet up to 100 meters   10 Gigabit Ethernet up to 45 meters
 
Cat6:    Gigabit Ethernet up to 100 meters   10 Gigabit Ethernet up to 55 meters
 
Cat6a:   Gigabit Ethernet up to 100 meters 10 Gigabit Ethernet up to 100 meters
 
All three support gigabit, which is enough for most networks. 10 Gigabit, when it is deployed, is typically utilized for aggregation links between switches and not for workstations. Although it is unlikely an enterprise will require 10 gigabit to the workstations, certainly it is reasonable to design a new system with future needs in mind. In this case, the 10 gigabit capacities of Cat5e and Cat6 are problematic. Since data closets are located based on an assumption that workstation lines can be up to 100 meters, the shorter length limitation for Cat5e and Cat6 make them undesirable. That leaves Cat6a as the cabling of choice for future proofing.

How to Inspecting Fiber Optic Cables by Fiber-MART.COM

Visual Inspection Of Connectors With A Microscope
 
Visual inspection of the end surface of connector ferrules with a microscope is used for finding dirt or scratches on fiber optic connectors and inspecting polish-type connectors during the termination process to find possible defects. This requires a microscope which has a fixture to hold the connector in the field of view and a light source to illuminate it properly. Fiber optic inspection microscopes vary in magnification from 30 to 800 power, with 100-200 power being the most widely used range. Some microscopes also can inspect cleaved fibers which are usually viewed from the side, to see breakover and lip.
 
Fiber Optic Inspection Microscopes
Fiber optic microscopes come in many varieties starting with simple inexpensive portable microscopes generally made by modifying simple optical microscopes to hold the connector being inspected.  Special designs for fiber optics will have more sophisticated optics, several illumination options, accessories to hold several types of connectors and probably IR filters to protect the eye from invisible light(see Eye Safety below.) Video microscopes are also popular, offering easier viewing and even saving files of inspections, but at a higher price.
 
Inspecting Connectors with a Microscope
 
Visual inspection of the end surface of a connector is one of the best ways to determine the quality of the termination and diagnose problems like dirt on the connector or scratches. A well made connector will have a smooth, polished, scratch free finish, and the fiber will not show any signs of cracks or pistoning (where the fiber is either protruding from the end of the ferrule or pulling back into it).
 
The proper magnification for viewing connectors is generally accepted to be in the range of 30-400 power, with lower power, usually 100X use for multimode and 200-400 used for more critical singlemode connectors. Lower magnification, typical with a jeweler’s loupe or pocket magnifier, will not provide adequate resolution for judging the finish on the connector. Too high a magnification tends to make small, ignorable faults look worse than they really are. A  better solution is to use medium magnification, but inspect the connector three ways: viewing directly at the end of the polished surface with coaxial or oblique lighting, viewing directly with light transmitted through the core, and viewing at an angle with lighting from the opposite angle or with quite oblique lighting.
 
Viewing directly allows seeing the fiber and the ferrule hole, determining if the  ferrule hole is of the proper size, the fiber is centered in the hole and a proper amount of adhesive has been applied. Only the largest scratches may be visible this way, however. Adding light transmitted through the core will make cracks in the end of the fiber, caused by pressure or heat during the polish process, visible.
 
Viewing the end of the connector at an angle, while lighting it from the opposite side at approximately the same angle or using low-angle lighting and viewing directly will  allow the best inspection for the quality of polish and possible scratches. The shadowing effect of angular viewing or lighting enhances the contrast of scratches against the mirror smooth polished surface of the glass.
 
One needs to be careful in inspecting connectors, however. The tendency is to sometimes be overly critical, especially at high magnification. Only defects over the fiber core are generally considered a problem. Chipping of the glass around the outside of the cladding is not unusual and will have no effect on the ability of the connector to couple light in the core on multimode fibers. Likewise, scratches only on the cladding should not cause any loss problems.
 
More Examples
 
dirty connector
Dirt on a connector. The bright center is light transmitted through the core of the fiber. Note how the cladding is dark, not transmitting any significant light.
 
scratched connector
A scratched singlemode connector. See the small size of the illuminated core?
 
contaminated connector
Ferrule contaminated by liquid.
 
Eye Safety
Microscopes focus the light into the eye, so if optical power is present in the fiber, it will be focused into the eye. Since light in most fiber systems is in the infrared (IR) and invisible to humans, it will not be detected. Most fiber optic systems have power levels too low to be harmful but some might – especially telecom and CATV systems. Always check power levels with a power meter before inspecting connectors with a microscope. If possible, only use microscopes with IR filters to prevent IR light from entering the eye.

Which Fiber Optic Connector should you use?

The network cabling industry’s fiber optic manufacturers over the last few decades have been on a constant mission to develop the better fiber connector. This means lower cost, lower dB losses, easier to terminate out in the field. There have been over 100 connectors developed over the years but a select few have stood the test of time and beat out their competition. Below we will talk about the most common.
 
A fiber optic connector terminates at the end of a fiber optic cable and is used when you need a means to connect and disconnect the fiber cable quickly. A fiber splice would be used in a more permanent application. The connectors provide a mechanical connection for the two fiber cables and align both cores precisely so the light can pass through with little loss. There are many different types of connectors but many share similar characteristics. Many connectors are spring loaded. This will push the fiber ends very close to each other so as to eliminate airspace between them, which would result in higher dB losses.
 
There are generally five main components to a fiber connector: the ferrule, the body, the coupling structure, the boot and the dust cap.
 
Ferrule-the ferrule is the small round cylinder that actually makes contact with the glass and holds it in place. These are commonly made of ceramic today but also are made of metal and plastic.
 
Body-This sub assembly holds the ferrule in place. It then fits into the connector housing.
 
Connector Housing-This holds all sub assembly parts in place and has the coupling that will connect to the customer’s equipment. The securing mechanism is usually bayonet, snap-in or a screw on type.
 
Boot-This will cover the transition from the connector to the fiber optic cable. Provides stress relief.
 
Dust Cap-Just as it implies will protect the connector from accumulating dust.
 
There are many types of connectors on the market. The major differences are the dimensions and the method of connection to equipment. Most companies will settle on one type of connector and keep that as a standard across the board. It makes sense because all equipment has to be ordered with that specific connector type and to have 2 or 3 different connector types can get messy. For typical network cabling projects today LC is fast becoming the shining star of fiber connectors. LC is a small form factor connector which means it requires a much smaller footprint in your IT closet. Thus you can fit many more LC connectors into you fiber panels then say ST or SC connectors.
 
ST Connector
 
 
The ST connector (or Straight Tip) was the first popular connector type to be used as a standard for many organizations in their fiber network applications. It was first developed by AT&T. Often called the “round connector” it has a spring loaded twist bayonet mount with a 2.5mm round ferrule and a round body. The ST connector is fast being replaced with the smaller, denser SFF connectors.
 
SC Connector
 
The SC connector is a push-in/pull-out type connector that also has a 2.5 mm ferrule. It is very popular for its excellent performance record. The SC connector was standardized in TIA-568-A, and has been very popular for the last 15 years or so. It took a while to surpass the ST because of price and the fact that users were comfortable with the ST. Now it’s much more competitive with pricing and it is a very easy install, only requiring a push in and pull out connection. This is very helpful in tight spaces. Simplex and duplex SC connectors are available. The SC was developed by the Japanese and some say stands for Standard Connector.
 
FDDI/ ESCON Connectors
 
You may see FDDI and ESCON(IBM) duplex fiber connectors in older installations. These connectors will mate to their own networks and usually will be seen at the wall outlet locations. These connectors use a squeeze tab coupling mechanism. The closet side of the fiber will usually have a standard ST or SC connector. The FDDI/ESCON connectors can be mated to SC or ST connectors since they both have a 2.5mm ferrule. An adaptor would be required in this case. The FDDI stands for Fiber Distributed Data Interface.
 
LC Connector
 
Image
 
The LC connector was developed by Lucent Technologies, hence the LC. It is a Single Form Factor Connector that has a 1.25mm ferrule. The attaching mechanism is similar to an RJ-45 connector with the retaining clip. It is a smaller square connector, similar to the SC. LC connectors are often held together with a duplex plastic retainer. They are also very common in single mode fiber applications.
 
MT-RJ Connector
 
Image
 
MTRJ stands for Mechanical-Transfer Registered Jack and was developed by Amp/Tyco and Corning. MTRJ is very similar to an RJ type modular plug. The connector is always found in duplex form. The body assembly of the connector is usually made from plastic and clips and locks  into place. There are small pins present that guide the fiber for correct alignment. MTRJ’s  also are available in male or female orientation. They are only used for multi-mode applications. They can also be difficult to test because many testers on the market do not accept a direct connection. You usually need to rig up a patch cord adapter kit to make testing possible.
 
FC Connector
 
The FC connector you may find in older single mode installations. It was a popular choice that has been replaced by mostly ST or SC type connectors. It also has a 2.5mm ferrule. They have a screw on retaining mechanism but you need to be sure the key and slot on the connector are aligned correctly. FC connectors can also be mated to ST & SC’s through the use of an adaptor.
 
Opti-Jack Connector
 
The Opti-Jack is a clean, tough duplex connector cleverly designed around two ST-type ferrules in a package the size of a RJ-45. It has male and female (plug and jack) versions.
 
 
LX-5 is like a LC but with a shutter over the end of the fiber.
 
MU Connector
 
MU looks a miniature SC with a 1.25 mm ferrule. It’s more popular in Japan.
 
MT Connector
 
Image
 
MT is a 12 fiber connector for ribbon cable. It’s main use is for preterminated cable assemblies and cabling systems. Here is a 12 fiber MT broken out into 12 STs.
This connector is sometimes called a MTP or MPO which are commercial names.
 
Hopefully this guide may help you get an idea of what options are out there for your fiber optic connector needs.
 
As always, for all your fiber optic needs go to http://www.fiber-mart.com

2017年12月18日星期一

About the Cummins 4BT engine

About the Cummins 4BT engine 
 

Series B is a series of four-cycle diesel engines with four or six cylinders of "one litter per cylinder" capacity, which Cummins has developed for use in automotive, agriculture, power generation and marine applications. They developed the 4BT engine series as a way to promote the heavy duty work of these engines. 
 
About the 4BT series 
 
4BT is a 4-cylinder version of the first generation B series engine. It is mostly used in light trucks such as BMC Faith 110.08 (110 HG) and in American type large panel cars.
 
These 4BT engines were used a lot in a variety of different ways. The first and most popular vehicles that these engines were used for were light vans. Other similar light commercial vehicles also were fitted with the Cummins 4BT engine as well. This is because the low cost, ease of upkeep and relatively low fuel usage of these engines made them great for smaller cars and other similar lighter vehicles. This use of smaller trucks and vans has actually made many people call the 4BT Cummins Engine the Bakery Truck or Bread Truck engine. This is because the 4BT had 4-cylinder B series engine. And it also had a turbocharger as well. All of these features made it a perfect candidate for use in light vans and trucks. 
 
More about the B-Series:
 
Another thing that made these Cummin 4BT engines really popular was their simplicity. It was really easy to convert a diesel engine to a 3.9L B engine from Cummins. It could be built into basically almost any size of the vehicle. These vehicles included muscle cars, keeps, and even big trucks! This is because the 4BT engine did not need to have any sort of electronic part to it. The only electrical parts of the 4BT engine were the wiring it had for the fuel shut-off. And the wiring for the solenoid as well. This variety of powertrain options for the 4BT could also be switched rather quickly between different bases of horsepower, up to 120 bases. This switch made it possible to go up to 420 pounds of torque force. 
 
The heavy engine market certainly went through a shakeup when Cummins release their 4BT engine. You could say that this particular engine changed the whole history of the heavy-duty engine market. This is because the 4BT engine was a heavy duty one that still had the compactness that made it stand out from the competitor's engines. And the 4BT engine also made Cummins stand out as a fine manufacturer of heavy-duty engines as well. 
 
One of the chief qualities that people love about the Cummins 4BT Engine is its reliability. It still has got a loyal following to the present day, even after production of this sort of engine has already ceased. And enthusiasts of the 4BT engine are still able to purchase replacement parts for it quite cheaply online. And there are numerous third-party and original equipment manufacturers who still continue to produce 4BT parts, even after the production of this engine has ended.

Introduction of 4BT Cummins Parts and Accessories

4BT Cummins Parts and Accessories

One of the coolest engines ever produced is the 4BT Cummins, in all of its variations. You may be wondering why we would be touting a teeny 3.9L, four cylinder engine as one of the coolest engines? Well that’s simple. This little diesel can be swapped into numerous vehicles that simply don’t have the sheer engine bay space for any of the traditional larger engines, let alone the weight. Further, the earlier mechanically controlled engines could be modified to produce impressive horsepower numbers, while still achieving over 40 miles per gallon.

In one of our in-house builds, we took a 2009 Jeep JK four door and slapped a 4BT in it, along with a host of other off road oriented upgrades and made one of the coolest JK’s on the planet (at least we think so). That Jeep took us all over the country on some of the toughest trails you can imagine, and still served as a vehicle that could easily be daily driven, turning heads everywhere it went. It's hard to not look twice when you hear a Cummins rattling under the hood of a Jeep rolling on 40” tires! 


Published by www.hubeijuly.com

  • Engine Name:Cummins B3.9L/4BT
  • Applications:Chevrolet Step Vans, Commercial applications
  • Configuration:Inline 4-cylinder diesel
  • Displacement:3.9L, 239 cubic inches
  • Bore:4.02 inches
  • Stroke:4.72 inches
  • Compression Ratio:17.5:1
  • Aspiration:Turbocharged, non-intercooled
  • Engine Weight:745 - 782 lbs
  • Oil Capacity:10 quarts
  • Horsepower:105 hp @ 2,300 RPM *
  • Torque:265 lb-ft @ 1,600 RPM *

Release new Fusion Splicers - S178A & S153A

The S178A is the successor to the best selling S177A. The S178A has a more rugged, compact and lighter body compared to the previous model with vastly improved splicing & heating time.
 
Using the same rugged metal body of S178A, FEC will also launch another new Fusion Splicer in February 2010.
 
The S153A.
 
The S153A is a new concept machine which uses an 揂ctive clad alignment?function, which achieves lower splicing loss with less user skills required compared to a conventional Fixed V-groove Clad Alignment Fusion Splicer.
 
These two machines are both designed to endure harsh operating conditions by improving shock / impact resistance with rubber pads embedded on 4 corners of the splicer body. Both fusion splicers also achieve water resistance compliant to IPX2 and dust resistance compliant to IP5X.
 
Another key feature of the S178A and the S153A is the significantly reduced operation time. Protection sleeve shrink time is mere 25 seconds, while splicing requires only 7 seconds with S178A. Power saving technology used in these machines allows up to 200 splicing cycles (splicing and heating) with 2 built in rechargeable batteries. By combining improved speed, precision, durability and portability in one body, the S178A and S153A ushers in entirely new possibilities for fusion splicing applications.
 
Currently, Core Alignment fusion splicers are widely used in FTTx, LAN, Long-haul installation, data center and/or OEM applications across the world and traditionally FITEL is well known for its hand-held fusion splicer series. With this even more compact S178A, FEC applied new design ideas to meet our customers requirements for more rugged splicers resulting in increased drop/water/dust resistance. The S178A also enables shorter splicing/heating time by using a redeveloped electronic circuit and design. In using this new design, FEC also achieved 30% less power consumption when the unit is in stand-by mode compared with the previous model (S177A).
 
The S178A is capable of splicing common telecommunication fibers such as SM / MM / DS and EDF/ High-delta fibers which is also widely used for optical components. In addition, the S178A also boasts splice programs for BIF / UBIF (Bend Insensitive Fiber / Ultra Bend Insensitive Fiber) which has been in more common use for FTTH applications.
 
The S153A (Active Clad Alignment Splicer) is developed based on the concept of easy and precise splicing by anybody? The S153A can perform hassle free splicing compared with conventional Clad Alignment Splicers, with an apparent cost benefit compared to Core Alignment Splicers. S153A, users can enjoy almost the same benefit as S178A users, in speed, precision, durability and portability.
 
Features
 
Shock resistant design
4 rubber pads on the corners of the machine boosts the shock resistance significantly compared with the previous models. The S178 is capable of producing precise splicing after 76cm drops from 5 different angles. 
Dust / Water resistant design
New design achieved IPX2 water resistance and IP5X dust resistance.
Compatible with Splice on Connector (SOC)
Both S178A and S153A are SOC compatible with Seikoh Giken and Diamond SA connectors.

PLC Splitter VS. FBT Coupler

We use fiber optic splitter to distribute or combine optical signals in many applications,
we have one question:Shall I use PLC or Fused Coupler ?
 
 
When we do comparison, we need to do comparison for devices of the same split-ratio. 
 
 
Insertion loss and uniformity vs. wavelength 
 
The figure 1 shows the insertion loss plot of a standard 1×8 PLC splitter from 1250 to 1650 nm. You can observe the maximum insertion loss including the water-peak in E band region(1360 to 1460 nm) and also the excellent uniformity out of this plot.
 
Typical value is 9.8dB for insertion loss and 0.5dB for uniformity. 
 
A 1×2 fused coupler insertion loss plot is showed in the figure 2.if you analyze the operating wavelength range from 1250 to 1650 nm as for PLC splitter you will still find an overall good performance level. But that’s a single 1×2 fused coupler, so you are not comparing the same devices. 
 
The 3rd plot represents the insertion loss spectral behavior for 1×8 fused coupler. To fabricate a 1×8 fused coupler device each arm have to be manufactured using 3 cascaded (spliced) 1×2 couplers. it means that the “worst” arm could show 10.8dB insertion loss max and the uniformity will be 3dB. 
 
TDL (Temperature Dependent loss) 
 
Due to the manufacturing process and to the sensitivity of the fused region and of the splices integrated in the device, Fused coupler manufacturers have to specify also the TDL value. for a 1×2 Fused coupler, a typical value is +/10.15dB for a temperature range from -5 to +75 centigrade . At the first sight, it could look good, but we have here again to take into account the cascading effect. To make the comparison with 1×8 PLC splitter we have to multiply 0.15 by 3 (3 1×2 for each arm) to finally obtain 0.45dB.
 
 PLC splitter works from -40 to 85 centigrade with a typical TDL of out +/- 0.25dB (-5 to 75 centigrade:+/-0.15dB)
 
 Please note that this TDL effect is already included in the Max. insertion loss specifications available on data sheets.
 
 PDL (Polarization dependent loss)
 
 An lon-exchange PLC splitter shows a PDL much less than 0.2 dB independently from the split-ratio. A 1×2 fused coupler PDL ranges from 0.1 to 0.15dB.Also in this case, we have to cascade discrete 1*2 Fused coupler to obtain the desired split-ratio, Then also PDL will be increased.
 
 A 1×8 fused coupler will show up to 0.45dB PDL, what is more than the double of a 1×8 PLC splitter.
 
 Reliability
 
 As previously explained, to fabricate a 1×8 fused coupler, you need 7discrete 1×2 couplers and 6 splices. The risk of failure of a device, normally calculated by parameter called FIT(failure in time), is typically low for a single 1×2 fused coupler, but in the case of a 1×8 fuse fused coupler ,it has to be at lease multiplied by 7 and in addition to add the risk associated to the massive presence of splices in the circuits. As everybody knows, a splice is a potential failure point in a system to be minimized a s much as possible.
 
 At the contrary, a PLC splitter knows only 2 critical points: input and output

A Quick Guide To Fiber Optic Power Meter

When you install and terminate fiber optic cables, you always have to test them. A test should be conducted for each fiber optic cable plant for three main areas: continuity, loss, and power. And optical power meters are part of the toolbox essentials to do this. There are general-purpose power meters, semi-automated ones, as well as power meters optimized for certain types of networks, such as FTTx or LAN/WAN architectures. It’s all a matter of choosing the right gear for the need.
Here is a quick guide to fiber optic power meters and how they work.
 
Optical power meters are commonly used to measure absolute light power in dBm. For dBm measurement of light transmission power, proper calibration is essential. A fiber optic power meter is also used with an optical light source for measuring loss or relative power level in dB. To calculate the power loss, optic power meter is first connected directly to an optical transmission device through a fiber optic pigtail, and the signal power is measured. Then the measurements are taken at the remote end of the fiber cable.
 
Fiber optic power meter detects the average power of a continuous beam of light in an optical fiber network, tests the signal power of laser or light emitting diode (LED) sources. Light dispersion can occur at many points in a network due to faults or misalignments; the power meter analyzes the high-powered beams of long-distance single-mode fibers and the low-power multibeams of short-distance multimode fibers.
 
Important specifications for fiber optic power meters include wavelength range, optical power range, power resolution, and power accuracy. Some devices are rack-mounted or hand held. Others are designed for use atop a bench or desktop. Power meters that interface to computers are also available.
 
The fiber optic power meter is a special light meter that measures how much light is coming out of the end of the fiber optic cable. The power meter needs to be able to measure the light at the proper wavelength and over the appropriate power range. Most power meters used in datacom networks are designed to work at 850nm and 1300nn. Power levels are modest, in the range of –15 to –35dBm for multimode links, 0 to –40dBm for single mode links. Power meters generally can be adapted to a variety of connector styles such as SC, ST, FC, SMA, LC, MU, etc.
 
Generally, multimode fiber is tested with LEDs at both 850nm and 1300nm and single mode fiber is tested with lasers at 1310nm and 1550nm. The test source will typically be a LED for multimode fiber unless the fiber is being used for Gigabit Ethernet or other high-speed networks that use laser sources. LEDs can be used to test single mode fibers less than 5000 meters long, while a laser should be used for long single mode fibers.
 
Most fiber optic power meters are calibrated in linear units such as milliwatts or microwatts. They may also provide measurements in decibels referenced to one milliwatt or microwatt of optical power. Typically, fiber optic power meters include a removable adaptor for connections to other devices. By measuring average time instead of peak power, power meters remain sensitive to the duty cycle of digital pulse input streams.
 
Use fiber optic power meter and other useful fiber optic tool kits to ensure that your fiber optic system will operate smoothly.

2017年12月13日星期三

Fiber Optic Patch Cable & Its Production Process

Introduction of Fiber Optic Patch Cable
Fiber optic patch cable, also called fiber optic patch cord or fiber patch cord, is one of the most basic and important parts in optical communication. Fiber optic patch cable is generally used for linking the equipment and components in the fiber optic network, eg. linking between the fiber optic converter and termination box. At the ends of fiber optic patch cable, there are fiber optic connectors. In general, the fiber optic patch cable types are classified by the fiber optic connector types. The commonly used fiber optic patch cable types include SC fiber patch cord, ST fiber optic patch cord, LC fiber optic patch cord, FC fiber optic patch cord etc. In addition, if fiber optic patch cable has the same type of connector on both ends, we call it the same connector type fiber patch cable, otherwise, it is called hybrid fiber optic patch cables. According to its fiber cable mode or fiber cable structure, fiber optic patch cable can be divided into singlemode fiber optic patch cable and multimode fiber optic patch cable or simplex fiber optic patch cable and duplex fiber optic patch cable.
 
 
Production Process of Fiber Optic Patch Cable
The traditional production process of fiber optic patch cable can be divided into three parts: assembly of fiber optic cable andconnectors, end face polishing, inspection & testing. As we know, when the optical signal transmitted through the end face of the fibers, due to back reflection or other reasons, it will have a part of loss. A good polishing end face is very necessary for fiber optic transmission. Thus, among the three parts of fiber optic patch cable production process, the latter two parts are very important for producing a high quality fiber optic patch cable. And this is why many manufactures attach great importance to introduce the advanced equipment and technology to achieve good performance in this operation.
 
In order to achieve best results, a good fiber optic patch cord production includes the following 8 elements:
 
Correct tools and assembly procedures is necessary
Using high quality fiber optic connector parts
Stable polishing machines is very important
>High quality polishing sandpaper
Correct operating procedures
Accurate and reliable test equipment
Responsible and experienced operators
Clean and dust-free working environment
 
Fiber Optic Patch Cable Using Tips
 
When using fiber optic patch cable, we need to pay attention to some details. The following tips will give you some help to more understand the fiber optic patch cables during its application.
 
Choose the right cable with right connectors and lengths according to your requirement.
An unused or spare fiber optic patch cable should be protected with the dust caps. Because contamination, such as dust and grease will damage the fiber optic connectors on the ends of the fiber patch cable.
When you plan to use fiber optic patch cables, be sure what type of cable mode would you need. In general, singlemode fiber optic patch cable is yellow while its connectors and protective cover is blue. singlemode fiber optic patch cable is usually for long distance transmission. Multimode fiber is generally orange or grey, with a cream or black connector that is used for shorter distance transmission.
Don’t excessively bent the fiber optic patch cable when using that will increase the attenuation of optical signal in transmission.
When using with the fiber optic transceiver module, you should ensure that the fiber optic transceiver modules in both ends of the fiber patch cable should be the same wavelength. There is a simple method to judge: ensure the color of the modules must be consistent.
 
Fiber Optic Patch Cable Solution
fiber-mart provides a full set of fiber optic patch cable solution cover from the production processes, product series introduction, description, application and using guide to after-sale maintenance that can satisfy our customers with a full range of services. In addition, fiber-mart can also offer the custom service for your special requirements. We will keep on improving to achieve offering the high quality fiber optic patch cables for your projects.

Fiber Optic Tool Kits From fiber-mart.com

The fiber-mart’s Basic fiber optic tool kits provide you with dozens of basic tools that are essential for fiber optic termination, construction, splicing, polishing and testing. The kit includes strippers, cable slitters and other precision hand tools, consumable products, and much more. All of the contents are packed in a durable case, keeping the items you need within easy reach. For example, the fiber optic termination tool kit provided by fiber-mart.

The traditional Erpoxy and Polish Connector Termination Tool Kit:
This type of kit sometimes is also called universal connectorization epoxy tool kit. They include all the tools necessary for hand-polishing termination of epoxy optic connectors such as FC, SC, ST, LC, etc. The following list shows all essentials tools that should be included.
a. Fiber cable jacket stripper to remove outer jacket from optical cables;
b. Fiber stripper to remove fiber coatings (900um tight buffer or 250um UV coating layer) to expose the bare fiber cladding;
c. Kevlar scissors to cut the yellow strength member inside fiber jacket;
d. Fiber connector crimp tool for FC, SC, ST, LC;
e. Fiber scribe tool to scribe the bare fiber;
f. Epoxy for fixing the fiber inside the connector, empty syringes for epoxy dispensing into the connector;
g. Glass polish plate so you can place rubber polish pad on top of it;
h. Rubber polish pad so you can place the lapping films on top of it;
i. Lapping films (several grits included, typically 12um, 3um, 1um and 0.5um);
j. Connector hand polish pucks for FC, SC, ST, LC;
k. Inspection microscope so you can inspect the quality of your work;
l. Heat cure oven to cure the epoxy (either 220V or 110V);
m. Other misc. items for cleaning such as Kimwipes, Isopropyl alcohol, etc.
Quick Termination Connector Tool Kit
90 percent of quick termination connectors don’t require polishing. They have a factory pre-polished fiber stub inside the connector body, all you need to do is strip your fiber, clean, cleave the fiber and then insert the cleaved fiber into the connector body, with or without assembly tool assistance, then finally crimp the connector with specialized tool.
There is no universal quick termination connector tool kit, since each connector is designed differently by their manufacturers and requires proprietary assembly tool.
The fiber optic tools come in a range of colours, designs and features — from subtle to spunky. For the ones who like to keep it simple, there are designs, such as a portable and practical crimping tool. For someone who like it sophisticated, there are designs, such as the Multi-Function F-Type, RJ-12 and RJ-45 Cable Tester. With affordable pricing, these tools do meet the expectations of as many customers as possible.
Fiber Optic Termination Kits provide field engineers with a low cost and highly portable solution. fiber-mart has provided four different options for the consumer. The basic Fiber Optic Termination Kit includes adhesives and primers, a fiber scraps bin, polishing pads, pre-saturated IPA wipes, lint free wipes, syringes and needles, a cleave tool, and a polishing puck. The other three models contain the tools of the basic kit and options such as light meter and fiber microscope, maximizing the functionality and flexibility of the Kits. And the Fiber Connector Termination Tool Kit contains all of the latest popular fiber optic tools and consumable material necessary for epoxy and polish connector terminations(SC/ST/FC and LC connectors).

Maintaining Fiber Network With Fiber Optic Identifier

During fiber optic network installation, maintenance or restoration, it is also often necessary to identify a specific fiber without disrupting live service. This battery powered instrument looks like a long handheld bar is called fiber optic identifier or live fiber identifier.
 
Optical fiber identifier employs safe and reliable macro bending technology to avoid disruption of network communications that would normally be caused by disconnecting or cutting a fiber optic cable for identification and testing. The fiber optic identifier is intended for engineers and technicians to identify dark or live fiber and excessive losses due to the misalignment of mechanical splices or poor connections.
 
There is a slot on the top of fiber identifier. The fiber under test is inserted into the slot, then the fiber identifier performs a macro-bend on the fiber. The macro-bend makes some light leak out from the fiber and the optical sensor detects it. The detector can detect both the presence of light and the direction of light.
 
A fiber optic identifier can detect “no signal”, “tone” or “traffic” and it also indicates the traffic direction. The optical signal loss induced by this technique is so small, usually at 1dB level, that it doesn’t cause any trouble on the live traffic. Fiber optic identifiers can detect 250um bare fibers, 900um tight buffered fibers, 2.0mm fiber cables, 3.0mm fiber cables, bare fiber ribbons and jacketed fiber ribbons.
 
Most fiber identifiers need to change a head adapter in order to support all these kinds of fibers and cables. While some other models are cleverly designed and they don’t need to change the head adapter at all. Some models only support single mode fibers and others can support both single mode and multimode fibers.
 
Difference Between Fiber Identifier and Visual Fault Locator
Fiber optical identifier and fiber optic visual fault locator all are most important tools for testing in our network. But sometimes we would mistake them. To be honest, they are different test tools.
 
1. Fiber Optical Identifier, it is a very sensitive photodetectors. When you will be a fiber bending, some light rays from the fiber core. The light will be detected by the fiber identification, technical staff according to these light can be a single fiber in the multi-core optical fiber or patch panel identified from the other fiber out. Optical Fiber Identifier can detect the status and direction of the light does not affect the transmission. In order to make this work easier, usually at the sending end to the test signal modulated into 270Hz, 1000Hz or 2000Hz and being injected into a specific fiber. Most of the optical fiber identifier for the operating wavelength of 1310nm or 1550nm single-mode fiber optical fiber, optical fiber identifier can use the macro folding technology to name the direction and power of the transmission fiber and the fiber under test online.
 
fiber optic identifier from Sunmafiber
 
2. VFL (Visual Fault Locator)
This revolutionary product is based on laser diode visible light (red light) source, when the light being injected into the fiber, if fiber fracture, connector failure, folding over, poor weld quality failure by launching the light of the fiber to fiber fault visual images positioning. Visual Fault Locator launched a continuing trend (CW) or pulsed mode. The common frequency of 1Hz or 2Hz, but can also work in the kHz range. Usually the output power of 0dBm (1mW) or less, the working distance of 2 to 5km, and to support all the common connector.
 
You can get fiber optic identifiers from Wilcom, Ideal, 3M, Sunmafiber and other network test equipment manufacturer. We recommend you Wilcom and Sunmafiber products since both manufacturers have very high customer satisfaction rate.

2017年12月12日星期二

Economically Increase Network Capacity With CWDM Mux/DeMux

As the demands for voice, video and data networks are increasing dramatically, more bandwidth and higher transmission speed over long distances are needed. To meet these demands, it means that service providers should depend on more fiber optics which definitely cause more costs for optical devices. But they apply Wavelength Division Multiplexing (WDM) technologies which is a cost-effective way to increase capacity on the existing fiber infrastructure.
 
CWDM Technology
WDM technology multiplexes multiple optical signals onto a single fiber by suing different wavelengths, or colors, of light. WDM can expand the network capacity using existing fiber infrastructure in an economical way. It includes CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing).
 
CWDM is a technology multiplexing 16 channels onto one single fiber between the wavelengths from 1270 nm to 1610 nm. It’s designed for city and access network. Since the channel spacing is 20 nm, CWDM is a more cost-effective method to maximize existing fiber by decreasing the channel spacing between wavelengths. CWDM is a passive technology, therefore, CWDM equipment needs no electrical power.
 
CWDM Mux/DeMux
CWDM technology has been applied into wide areas, such as CWDM optical transceivers, CWDM OADM and CWDM Mux/DeMux. CWDM Mux/DeMux modules are multiplexers and demultiplexers which provide long distance coverage with premium optical technology to enhance fiber optic systems. It multiplexes signals of different wavelengths on one single fiber and demultiplexes wavelengths to individual fibers. CWDM Mux/DeMux can offer low-cost bandwidth and upgrade the existing system without leading spare costs on more fibers. CWDM Mux/DeMux can hold up to 18 channels of different standards (for example, Fibre Channel, Gigabit Ethernet) and data rates over one fiber optic link without interruption. fiber-mart.COM offers a full series of CWDM Mux/DeMux, including 2, 4, 8, 9, 12, 16, 18 channels with or without monitor port and expansion port in 1RU 19” rack chassis or pigtailed ABS module. The following will show you how to use a 18-channel CWDM Mux/DeMux to increase the data rates up to 180 Gbps on a fiber pair.
 
In Figure2, all Cisco compatible 10G CWDM SFP+ 1270-1610 nm 40km DOM transceivers on the switch are connected with the CWDM Mux/DeMux by LC-LC fiber patch cords. This CWDM Mux/DeMux has 18 channels and is designed as 1 RU rack mount size, covering the wavelengths from 1270 nm to 1610 nm and supporting LC UPC port. During the long distance transmission, only one single-mode armored LC fiber patch cord is needed to achieve 180 Gbps by connecting the two 18-channel CWDM Mux/DeMux. Thus, it greatly saves the cost for increasing the bandwidth on the existing fiber infrastructure.
 
 
FMU CWDM Mux/Demux
To increase the capacity, it requires more space and cable management is also a big trouble. So Fiberstore independently researched and developed FMU CWDM Mux/DeMux to solve this problem. We provide FMU 16-ch 1U Rack CWDM MUX/DEMUX specially designed as 2-slot plug and play style, which allows you to add or remove fiber fiber optic cables and plug-in-modules freely according to your applications. There are two separate CWDM plug-in modules. One is high band (1470nm-1610nm) module with an expansion port and the other is low band (1270nm-1450nm, skip 1390nm, 1410nm) module without expansion port. Via this expansion port, channels can be expanded over one pair of fiber without interruption. You can also insert two CWDM Mux/DeMux FMU-plug-in modules without expansion port for two separated 8-channel connections. Besides, you can mix CWDM and DWDM system by adding CWDM Mux/DeMux FMU-plug-in modules and DWDM Mux/DeMux FMU-plug-in modules with matching wavelengths.
 
fiber-mart.COM FMU Plug-in Modules
The table below lists both single fiber and dual fiber FMU plu-in modules for 2-slot CWDM Mux/DeMux. You can choose suitable modules according to you specific requirements. Custom service is available, too.