Category: Fiber Transceivers

Optical transceivers, Active Optic Cables, data center switches, and cable management in data centers.

What Is the Difference Between Shielded and Unshielded Network Cables?

by http://www.fiber-mart.com

When installing or updating your network infrastructure, there are a variety of network patch cable types to consider. Among the choices to be made is whether to install shielded twisted pair cables (STP) or unshielded twisted pair cables (UTP). Twisted pair cabling consists of two conductors of a single circuit twisted together to help reduce electromagnetic interference (EMI) or “noise”.
A key factor in this decision is an analysis of how prevalent EMI will be in the installation environment. EMI is commonly caused by nearby motors, generators, air conditioners, and even office mainstays such as fluorescent lights and printers. EMI can cause crosstalk between circuits, resulting in degradation of data, increased errors and slower transmission rates.
While even unshielded UTP cables reduce some EMI, shielded STP cables more effectively block interference. Shielded Cat5 and Cat6 cables are augmented with a thin foil that serves to block EMI. STP cables are ideal for high-speed networks such as data centers where 10GBase-T networks are used because 10G Ethernet is significantly more sensitive to EMI. Properly installed high-quality shielded cables automatically curb EMI and crosstalk, helping to ensure data integrity and high-speed performance.
High-quality shielded cable includes a drain wire to provide grounding that cancels the effects of EMI. However, the cable will only be grounded if jacks and couplers used in the installation are also shielded. Therefore, it’s essential to use shielded jacks and couplers throughout your STP installation to maintain the benefits of STP cabling.
Why not always use STP cables? Shielded cabling is more expensive than unshielded cabling and more difficult to install; it’s stiffer, making it less flexible. The cable also has a larger diameter, taking up more space in conduit. UTP, on the other hand, actually provides faster transmissions in the absence of EMI. It’s less expensive to purchase, easier to install and has been the standard for many years, so it’s already in place in most existing installations.
Regardless of whether you choose UTP or STP, make sure to install high-quality cabling. The better the quality of the cables used, the more years of service you will get out of the installation, reducing long-term replacement and labor costs.

What’s the Difference Between Basic and Smart PDUs?

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A rack power distribution unit (PDU) is a device with multiple outlets designed to distribute power to networking equipment within a rack, including servers, storage devices and other equipment. For example, let’s say you have a 42U rack cabinet loaded with 42 1U servers, that’s 42 cords you have to find outlets for. PDUs solve this problem by taking the power supplied to the rack and distributing it via multiple outlets to the rack’s servers and networking equipment.
A basic PDU is a dependable, space-saving, cost-effective way to deliver power to wiring closets, server rooms and equipment racks from a UPS system, generator or utility wall outlet. It complements the benefits of a UPS system by adding more outlets than are provided by a UPS to essentially convert a single high-amperage UPS outlet to multiple low-amperage PDU outlets. A basic PDU is the easiest way to distribute facility UPS or generator power to multiple rack loads.
Intelligent or “smart” PDUs can be broken down into three categories:
A metered PDU can locally monitor load level and avoid potential overloads with a built-in digital current meter while offering reliable, rack-mount, multi-outlet, single or three-phase, power distribution from any protected UPS, generator or mains input power source.
Monitored PDU
While similar to a metered PDU, a monitored PDU goes one step further with its ability to remotely monitor single- or three-phase voltage, frequency, and load levels in real-time via a built-in network connection. Output current consumption is displayed locally via a visual meter to warn of potential overloads before critical input sources become overloaded.
Connecting additional equipment to a PDU can overload it or the supply circuit, causing breakers to trip or equipment to fail. Both metered and monitored PDUs display load levels in real-time, allowing additional equipment to be connected safely. The primary input plugs into an On-Line UPS system. The secondary input plugs into a wall outlet. If the UPS system is taken offline for maintenance, repair or replacement, the PDU keeps the load powered by automatically switching from the primary input to the secondary input because of its ATS functionality. When the UPS system is restored, the PDU will switch back to the primary input.
Switched PDU
What if you want the ability to remotely monitor, connect or disconnect your data center loads? No problem! A switched PDU provides all of these capabilities. A switched PDU can locally monitor load level and avoid potential overloads with a built-in digital current meter, as well as remotely control individual outlets for the rebooting of locked equipment to avoid costly service calls, custom power-on/power-off sequences and load-shedding of non-essential loads during blackouts to extend battery backup runtime for critical equipment. Unused PDU outlets can be electronically locked off to prevent the connection of unauthorized hardware. Built-in local digital display and remote web/network interface reports detailed voltage, amperage and kilowatt output values per breaker bank / phase with additional reporting options for power unbalance percentage, IP address and optional sensor-based temperature and humidity data. The PDUs network interface connects to an Ethernet jack. Remote users can switch each of the PDUs outlets on or off via SNMP, Web or telnet.
As you can see, intelligent PDUs offer a multitude of advanced features that make it easier to reduce operating costs and increase uptime.

7 Advantages of Fiber Optic Cables Over Copper Cables

by http://www.fiber-mart.com

When you’re planning a new network cable installation or considering upgrades to an existing network, you might want to consider using fiber optic cables.
Network fiber cables have some definite advantages over copper cables.
1. Greater Bandwidth
Copper cables were originally designed for voice transmission and have a limited bandwidth. Fiber optic cables provide more bandwidth for carrying more data than copper cables of the same diameter. Within the fiber cable family, singlemode fiber delivers up to twice the throughput of multimode fiber.
2. Faster Speeds
Fiber optic cables have a core that carries light to transmit data. This allows fiber optic cables to carry signals at speeds that are only about 31 percent slower than the speed of light—faster than Cat5 or Cat6 copper cables. There is also less signal degradation with fiber cables.
3. Longer Distances
Fiber optic cables can carry signals much farther than the typical 328-foot limitation for copper cables. For example, some 10 Gbps singlemode fiber cables can carry signals almost 25 miles. The actual distance depends on the type of cable, the wavelength and the network.
4. Better Reliability
Fiber is immune to temperature changes, severe weather and moisture, all of which can hamper the connectivity of copper cable. Plus, fiber does not carry electric current, so it’s not bothered by electromagnetic interference (EMI) that can interrupt data transmission. It also does not present a fire hazard like old or worn copper cables can.
5. Thinner and Sturdier
Compared to copper cables, fiber optic cables are thinner and lighter in weight. Fiber can withstand more pull pressure than copper and is less prone to damage and breakage.
6. More Flexibility for the Future
Media converters make it possible to incorporate fiber into existing networks. The converters extend UTP Ethernet connections over fiber optic cable. Modular patch panel solutions integrate equipment with 10 Gb, 40 Gb and 100/120 Gb speeds to meet current needs and provide flexibility for future needs. The panels in these solutions accommodate a variety of cassettes for different types of fiber patch cables.
7. Lower Total Cost of Ownership
Although some fiber optic cables may have a higher initial cost than copper, the durability and reliability of fiber can make the total cost of ownership (TCO) lower. And, costs continue to decrease for fiber optic cables and related components as technology advances.

All About Fiber Optic Sights

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In recent years, a number of handgun and also long gun companies have started installing fiber optic sights on their products. A number of companies have also started producing them as aftermarket upgrades for both categories of firearm. Since sights are one of the better upgrades to a gun that one can invest in, a number of people wonder if they’re worth getting or if a gun that has them will be that much more shootable over one with conventional night sights. Short answer is yes, in both cases
What Are Fiber Optics For?
Fiber optic, or more accurately optical fiber, is a flexible and transparent fiber that – in the simplest terms – is able to transmit light along its length. They’re made by drawing plastic or glass through an aperture, which can result in a fiber the same width as a human hair. The properties of fiber optics are optimal for a number of applications. One of the most common of course is in communications, as fiber optic wires are able to transmit information (altered to transmit as light, just like with a television set) with less signal loss or degradation and at higher bandwidth than copper cables. What makes them good is how they interact with light. The typical fiber optic cable is made with an inner core and outer cladding, both of which have a low refractive index (meaning they don’t bend light) but the outer cladding is highly reflective, meaning the light reflects along the whole length of the cable. In telecommunications, this is highly advantageous as you can transmit more signal than with copper cable and also more reliably. In short, once light hits the cable it basically bounces from side to side all the way to the end, sort of like a bowling ball with those bumper guards they put up for kids. These same properties have also made them a fantastic option as handgun sights.
Why Fiber Optic Sights Are Worth Having.
So, why this stuff matters is that those properties also happen to make fiber optic sights very good as handgun sights. In fact, some reckon they’re better than almost any other type of sights, especially when deployed as a front sight, though this may come down to preference. Fiber optics are almost perfectly reflective, which picks up ambient light and transmits it along the length of the cable. If you look at one, the effect is practically amplifying the appearance of the sight. Why is this good? Well, the front sight sticks out like a sore thumb with a fiber optic sight, making it VERY easy to index the front sight. If you happen to practice front sight shooting, a fiber optic happens to make it a lot easier. Hence, there are a whole bunch of handguns out there that come stock with them or an aftermarket fiber optic front sight available for a whole lot of pistols. This is advantageous for handguns, but where you also might notice a lot of fiber optic sights is on shotguns. Thing about scatterguns is darn few of them have a rear sight unlike iron sights for rifles or handgun sights. Granted, there are some out there – for the most part you’ll find them on the slug guns them boys out in Iowa have to use – but not a whole lot. As a result, the front sight is really all you have to use with most shotguns. In the olden days, all you got was a bead on the end of the barrel. However, a fiber optic sight lights up a lot better, making it easier to index onto the target. Doesn’t mean your wingshooting is going to get any better (that’s why you practice hitting clays!) but it does make target acquisition a whole lot easier. Even a small fiber optic sight on a shotgun makes a big difference. That’s why you find them on everything from a Mossberg 500 to a Benelli Super Black Eagle.
Convinced to switch to fiber optic handgun sights? You’re making good choices – keep it up! Here are a few things to look for. First, make sure you pick a sight designed specifically for the handgun you own. This seems like something that goes without saying, but it’s a good idea to make sure you do it…though you might be surprised. Just getting “Glock sights” isn’t good enough; if you have a Glock 26, look for actual Glock 26 sights. Next is color. Fiber optic sights generally come in red or green. Does one of those colors stand out more to you? Then that’s what you should get. The typical green fiber optic is more of a neon green, which is very easily visible. Red or orange fiber optics can also be easily visible, though a brighter shade is preferable. Blaze orange would do very well. That said, so long as it’s easily visible…you’re good to go. Another thing to look at is the circumference of the sight. Length doesn’t matter so much; you’re only going to see the rear of it. Instead, how big around the sight is matters most. For aging eyes, bigger is a bit better…but take care not to get too big of sights. Too large a front sight can occlude the target at longer ranges and impede accuracy.

Learn How Fiber Optic Cables Work

by http://www.fiber-mart.com

But first, let me show you how fiber optic cables work.
I have a bucket that I modified with a window in front and on the other side, I put a stopper in this hole right here. I have a bottle of propylene glycol, with just a little bit of creamer in it. A ring stand and of course a laser pointer. Now, keep your eye on this plug when I turn out the lights.
That’s wonderful. The light follows the liquid flow all the way to the bucket. Amazing. It does this because of total internal reflection. As the light enters the stream, it is reflected as soon as it hits the interface between here and liquid.
You can see here the first reflection and then the second and the third. This occurs because there’s a difference between the index refraction of the guide material, here propylene glycol, and the outside air in this case. Recall that anytime light strikes a surface, it can either be absorbed by the material, reflected from it or passed into and through it, the latter we call “refraction”.
It’s easier to see from a top view. Reflection and refraction could happen at the same time. But if a light ray hits the surface at an angle greater than the critical angle, it will be completely reflected and not refracted.
For this propylene glycol and air system, as long as a beam hits the surface at an angle greater than 44.35 degrees, measured from the normal, it will propagate down the stream via total internal reflection. To create the same effect in an optical fiber, engineers create a core of glass, usually pure silicon dioxide and an outside layer called “cladding,” which they also typically make from silicon dioxide but with bits of boron or germanium to decrease its index of refraction.
A one percent difference is enough to make fiber optic cables work. To make such a long, thin piece of glass, engineers heat a large glass preform. Its center is the pure core glass and the outside the cladding. They then draw or pull a fiber by winding the melt on to a wheel at speeds up to 1600 meters per second. Typically these drawing towers are several stories tall. The height allows the fiber to cool before being wound onto a drum.
One of the greatest engineering achievements was the first ocean spanning fiber optic cable called TAT-8. It extended from Tuckerton, New Jersey, following the ocean floor over 3500 miles until branching out to Widemouth, England and Penmarch, France.
Engineers designed the cable carefully to survive on the ocean floor. At its center lies the core. Less than a tenth of an inch in diameter, it contains six optical fibers wrapped around a central steel wire. They embedded this in an elastomer to cushion the fibers, surround it with steel strands and then sealed it inside a copper cylinder to protect it from water. The final cable was less than an inch in diameter, yet it could handle some 40,000 simultaneous phone calls.
The essence of how they send information through a fiber optic cable is very simple. I could have a pre-arranged signal with someone at the other end. Perhaps we will use Morse code and I just block the laser, so that the person at that end sees flashes that communicate a message.
To transmit an analog signal, like voice from a phone call along the cable, engineers use Pulse Code Modulation. We take an analog signal and cut it up into sections and then approximate the wave’s loudness or amplitude as best we can.
We want to make this a digital signal, which means discrete values of loudness and not just any value. For example, I will use four bits, which means I have 16 possible values for the loudness. So the first four sections of the signal could be approximated by about 10, 12, 14 and 15.
We then take each section and convert its amplitude to a series of ones and zeros. The first bar of value 10, when encoded, becomes one, zero, one, zero. We can do this for each section of the curve.
Now instead of looking at the green wave form or even the blue bars, we can think of the signal as a series of ones and zeros organized by time. It is that sequence that we send through a fiber optic cable of flash for one and nothing for a zero. Now of course, the exact method of encoding is known at the receiving end. So it is a trivial matter to decipher the message.
Now you may be wondering how a laser pulse can travel nearly 4000 miles across the ocean. It doesn’t without some help because the light will escape from the sides of the fibers. Look back at our propylene stream.
Here’s how the light attenuates as it travels. You can see here a narrow beam in the bucket that broadens a bit when it enters the stream and then after the first bounce, the beam leaves even broader than it entered. That’s because the interface with the air is uneven and the rays that make up the beam strike at slightly different angles.
When that beam makes its second reflection, those individual rays diverge even more. Until by the time it reaches the third bounce, many of the rays are no longer at the critical angle and can exit from the sides of the stream. Here it happens in a few inches but in fiber optic cables like TAT-8, the signal travels a stunning 50 kilometers before it needs to be amplified. Absolutely amazing.

Fiber Optic vs. Cable

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If you read our first post on how fiber-optic internet works, you now know that fiber functions by transmitting data as bursts of light through glass fibers that are bundled together inside a protected cable. The data signal is translated into usable information by a photoelectric cell at the receiving end to complete the internet connection.
While this high-tech, futuristic technology may seem exciting, it’s definitely not the only internet option out there. One of fiber internet’s biggest competitors is copper cable internet.
Want to know more about how the two technologies stack up? This second segment in our four-part series looks at the benefits of fiber optic vs. cable internet in terms of speed, reliability, availability, and economy.
How Does Coaxial Cable Internet Work?
Cable internet works similarly to fiber-optic internet, though the method of transmission differs. Copper cable has been in use for decades, delivering television to households across the country. Cable internet uses those same copper wire pathways and a modem to send and receive data as electrical signals.
While cable internet doesn’t have the exact same speed capacity or symmetrical upload speeds and download speeds like fiber often does, its wide availability and affordable pricing make it a popular internet option.
Comparing Fiber Optic vs. Cable Internet
If you’re wondering whether fiber or cable internet are right for you, here’s a quick breakdown of how both services line up across a few main areas of consideration.
Are There Differences in Speed?
At their peak, cable internet download speeds range up to about 300 megabits per second (Mbps), and upload speeds fall much lower than that. However, cable internet shares bandwidth among all customers within the same service area, so users may see a reduction in speed during busy hours.
The laws of physics mean that fiber-optic cable wins hands-down in terms of speed. Download speeds for fiber-optic internet can clock in up to 1,000 Mbps, with upload speeds that far surpass those of cable. Although fiber-optic cables don’t send data at the speed of light, they are only about one-third slower. Comparatively, the electrons in copper wire travel much slower than the light particles in fiber.
In terms of internet bandwidth, single-mode fiber is unlimited while multi-mode optical fiber has a more limited capacity to carry information. But both single-mode or multi-mode optical fiber have a clear advantage over copper cable when it comes to speed and bandwidth.
What does all that mean? Simply that the faster speeds afforded by fiber mean it’s easier and smoother to perform data-heavy tasks like video streaming or file uploading. However, for moderate data use, cable internet is still a solid option.
Which Internet Medium Is More Reliable?
Cable internet is a reliable medium that doesn’t drop out during bad weather like satellite communications. Copper wire is susceptible to electromagnetic interference and variations in temperature, though, which means customers might experience interruptions or outages in their internet.
Since glass doesn’t conduct electricity, optical fiber isn’t susceptible to those issues. Lightning damage or interruptions from high-voltage electrical equipment won’t disrupt internet connections transmitting via fiber-optic cabling.
Furthermore, while coaxial cable internet connection can lose speed and quality over long distances, fiber optic cable still provides speedy, reliable transmission of data even over great lengths.
Are They Equally Available Everywhere?
Copper cable has been a communications standard for decades, and with 89% coverage nationally, it has an edge in terms of internet availability.
Access to fiber-optic internet service, on the other hand, is growing rapidly. As availability and installation of new light-carrying fiber optic cabling expands to more areas, it is worthwhile to check what is available in your area.
What’s the Most Economic Choice?
Because copper cable networks already cover a good portion of the United States, it’s generally easy to set up a reliable internet connection that transmits internet data at an acceptable speed for an affordable monthly price. Plans vary widely, but you can find offerings under $100 in most areas.
Fiber optic internet plans can cost slightly more and possibly additional installation costs to support equipment but you will gain higher reliability and speed.
What’s the Future of Internet Connectivity?
There are multiple players in the marketplace for internet service. The industry is moving in the direction of internet technology that offers high speeds and increased reliability like fiber optics. Cable can provide adequate speed for standard internet usage, but it may be worth upgrading if fiber is available near you.