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Black Box Explains...MT-RJ fiber optic connectors.

Bringing fiber to the desktop is a great way to provide your users with increased bandwidth. The first step in achieving this goal is to provide an inexpensive fiber optic... more/see it nowsystem that is intuitive to the end user, easy to terminate in the field, and widely supported by equipment manufacturers. MT-RJ could be the answer to all these requirements.

A collaborative effort by leading fiber optic manufacturers, MT-RJ has an intuitive RJ latch that users recognize from copper Category 5 patch cords and traditional telephone cords, and it operates in the same way. The plug and jack are also similar in size to traditional RJ-type connectors.

Field installation, a common concern, is easier because of MT-RJ’s no-polish, no-epoxy, quick-termination design. MT-RJ is available in single- or multimode configurations and is backwards compatible for integration into existing networks. Since MT-RJ has duplex polarity, you don’t have to worry about the polarity reversal that happens with traditional ST type connectors. The TIA/EIA recently voted to accept MT-RJ, indicating wide acceptance of the new design and possible future inclusion in the TIA/EIA 568A standard.

Black Box, the name you trust to keep you up with the latest industry developments, supports this new technology. collapse


Black Box Explains...UARTs and PCI buses.

Universal Asynchronous Receiver/Transmitters UARTs are designed to convert sync data from a PC bus to an async format that external I/O devices such as printers or modems use. UARTs insert... more/see it nowor remove start bits, stop bits, and parity bits in the data stream as needed by the attached PC or peripheral. They can provide maximum throughput to your high-performance peripherals without slowing down your CPU.

In the early years of PCs and single-application operating systems, UARTs interfaced directly between the CPU bus and external RS-232 I/O devices. Early UARTs did not contain any type of buffer because PCs only performed one task at a time and both PCs and peripherals were slow.

With the advent of faster PCs, higher-speed modems, and multitasking operating systems, buffering (RAM or memory) was added so that UARTs could handle more data. The first buffered UART was the 16550 UART, which incorporates a 16-byte FIFO (First In First Out) buffer and can support sustained data-transfer rates up to 115.2 kbps.

The 16650 UART features a 32-byte FIFO and can handle sustained baud rates of 460.8 kbps. Burst data rates of up to 921.6 kbps have even been achieved in laboratory tests.

The 16750 UART has a 64-byte FIFO. It also features sustained baud rates of 460.8 kbps but delivers better performance because of its larger buffer.

Used in newer PCI cards, the 16850 UART has a 128-byte FIFO buffer for each port. It features sustained baud rates of 460.8 kbps.

The Peripheral Component Interconnect (PCI®) Bus enhances both speed and throughput. PCI Local Bus is a high-performance bus that provides a processor-independent data path between the CPU and high-speed peripherals. PCI is a robust interconnect interface designed specifically to accommodate multiple high-performance peripherals for graphics, full-motion video, SCSI, and LANs.

A Universal PCI (uPCI) card has connectors that work with both a newer 3.3-V power supply and motherboard and with older 5.5-V versions. collapse


Black Box Explains...IRQs, COM Ports, and Windows

Windows® 95 normally requires each serial port to have its own unique Interrupt Request Line (IRQ). However, if you use a third-party communications driver that supports IRQ sharing, you can... more/see it nowshare interrupts. Unfortunately, data throughput will not be as high as with single interrupt port configurations.

With Windows NT®, you can share interrupts across multiple ports as long as the serial ports have an Interrupt Status Port (ISP) built into the card.

The Interrupt Service Routine, a software routine that services interrupts and requests processor time, reads the ISP and is immmediately directed to the port that has an interrupt pending. Compared to the polling method used if the serial ports don’t have an ISP, this feature can determine which port generated the interrupt up to four times more efficiently—and it almost eliminates the risk of lost data. Windows NT supports the ISP by enabling the user to configure the registry to match the card’s settings. Black Box models IC102C-R3, IC058C, and IC112C-R3 all have ISPs and come with a Windows NT setup utility to simplify installation and configuration.

If your serial port doesn’t have an ISP, the Interrupt Service Routine has to poll each port separately to determine which port generated the interrupt. collapse


Black Box Explains...Media converters.



Media converters interconnect different cable types such as twisted pair, fiber, and coax within an existing network. They are often used to connect newer Ethernet equipment to legacy cabling.... more/see it nowThey can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).


Traditional media converters are purely Layer 1 devices that only convert electrical signals and physical media. They don’t do anything to the data coming through the link so they’re totally transparent to data. These converters have two ports—one port for each media type. Layer 1 media converters only operate at one speed and cannot, for instance, support both 10-Mbps and 100-Mbps Ethernet.


Some media converters are more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services—in other words, they’re really switches. This kind of media converter often has more than two ports, enabling you to, for instance, extend two or more copper links across a single fiber link. They also often feature autosensing ports on the copper side, making them useful for linking segments operating at different speeds.


Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.




Rent an apartment

Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available. With the development of Gigabit Ethernet (1000 Mbps), media converters have been created to make the transition to high-speed networks easier.




...or buy a house.

Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, and Gigabit modules may also be mixed.

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Black Box Explains...Modem eliminators.

Understanding the process of elimination.
If your office environment has sync equipment, and if that equipment is also used for local data communications, you should consider replacing those modems with cost-effective... more/see it nowand versatile modem eliminators.

What does a modem eliminator do?
One modem eliminator can connect a local terminal and computer port in lieu of the pair of modems that they would normally connect to. Plus, a modem eliminator enables DCE-to-DTE data and control-signal connections that are not easily achieved by standard cables or connectors in a sync environment.

Basically, a modem eliminator simulates a sync data link. It does this two ways. First, it provides clocking, which is mandatory for sync devices to communicate. Second, it provides the handshaking that DCEs do.

Why should you use a modem eliminator?
One—if you have two sync DTEs in the same room or close to each other, you will need a modem eliminator.

Two—if you have a network with routers, you just found the perfect equipment tester.

A modem eliminator can enable in-house bench testing of routers or existing equipment. There’s no need to place routers all over your network only to find out they don’t work once you test the LAN. A modem eliminator tells you what equipment passes your tests before you install.

Three—a modem eliminator makes good economic sense. One does the job of two modems—and it does the job better. You get a high return on your investment. collapse


Black Box Explains...Straight-pinned and crossover cable.

Straight-pinned cable has the most common type of pinning. The send and receive pairs are wired straight-through on either end of the cable.

Crossover cable is generally used for peer-to-peer connections.... more/see it nowThe send and receive pairs are crossed between Connector A to Connector B on either end of the cable. collapse


Black Box Explains...USB.

What is USB?
Universal Serial Bus (USB) is a royalty-free bus specification developed in the 1990s by leading manufacturers in the PC and telephony industries to support plug-and-play peripheral connections. USB... more/see it nowhas standardized how peripherals, such as keyboards, disk drivers, cameras, printers, and hubs) are connected to computers.

USB offers increased bandwidth, isochronous and asynchronous data transfer, and lower cost than older input/output ports. Designed to consolidate the cable clutter associated with multiple peripherals and ports, USB supports all types of computer- and telephone-related devices.

Universal Serial Bus (USB) USB detects and configures the new devices instantly.
Before USB, adding peripherals required skill. You had to open your computer to install a card, set DIP switches, and make IRQ settings. Now you can connect digital printers, recorders, backup drives, and other devices in seconds. USB detects and configures the new devices instantly.

Benefits of USB.
• USB is “universal.” Almost every device today has a USB port of some type.
• Convenient plug-and-play connections. No powering down. No rebooting.
• Power. USB supplies power so you don’t have to worry about adding power. The A socket supplies the power.
• Speed. USB is fast and getting faster. The original USB 1.0 had a data rate of 1.5 Mbps. USB 3.0 has a data rate of 4.8 Gbps.

USB Standards

USB 1.1
USB 1.1, introduced in 1995, is the original USB standard. It has two data rates: 12 Mbps (Full-Speed) for devices such as disk drives that need high-speed throughput and 1.5 Mbps (Low-Speed) for devices such as joysticks that need much lower bandwidth.

USB 2.0
In 2002, USB 2.0, (High-Speed) was introduced. This version is backward-compatible with USB 1.1. It increases the speed of the peripheral to PC connection from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1.

This increase in bandwidth enhances the use of external peripherals that require high throughput, such as printers, cameras, video equipment, and more. USB 2.0 supports demanding applications, such as Web publishing, in which multiple high-speed devices run simultaneously.

USB 3.0
USB 3.0 (SuperSpeed) (2008) provides vast improvements over USB 2.0. USB 3.0 has speeds up to 5 Gbps, nearly ten times that of USB 2.0. USB 3.0 adds a physical bus running in parallel with the existing 2.0 bus.

USB 3.0 is designed to be backward compatible with USB 2.0.

USB 3.0 Connector
USB 3.0 has a flat USB Type A plug, but inside there is an extra set of connectors and the edge of the plug is blue instead of white. The Type B plug looks different with an extra set of connectors. Type A plugs from USB 3.0 and 2.0 are designed to interoperate. USB 3.0 Type B plugs are larger than USB 2.0 plugs. USB 2.0 Type B plugs can be inserted into USB 3.0 receptacles, but the opposite is not possible.

USB 3.0 Cable
The USB 3.0 cable contains nine wires—four wire pairs plus a ground. It has two more data pairs than USB 2.0, which has one pair for data and one pair for power. The extra pairs enable USB 3.0 to support bidirectional asynchronous, full-duplex data transfer instead of USB 2.0’s half-duplex polling method.

USB 3.0 Power
USB 3.0 provides 50% more power than USB 2.0 (150 mA vs 100 mA) to unconfigured devices and up to 80% more power (900 mA vs 500 mA) to configured devices. It also conserves power too compared to USB 2.0, which uses power when the cable isn’t being used.

USB 3.1
Released in 2013, is called SuperSpeed USB 10 Gbps. There are three main differentiators to USB 3.1. It doubles the data rate from 5 Gbps to 10 Gbps. It will use the new, under-development Type C connector, which is far smaller and designed for use with everything from laptops to mobile phones. The Type C connector is being touted as a single-cable solution for audio, video, data, and power. It will also have a reversible plug orientation. Lastly, will have bidirectional power delivery of up to 100 watts and power auto-negotiation. It is backward compatible with USB 3.0 and 2.0, but an adapter is needed for the physical connection.

Transmission Rates
USB 3.0: 4.8 Gbps
USB 2.0: 480 Mbps
USB 1.1: 12 Mbps

Cable Length/Node
5 meters (3 meters for 3.0 devices requiring higher speeds).
Devices/bus: 127
Tier/bus: 5
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Black Box Explains...Solid vs. stranded cable.

Solid-conductor cable is designed for backbone and horizontal cable runs. Use it for runs between two wiring closets or from the wiring closet to a wallplate. Solid cable shouldn’t be... more/see it nowbent, flexed, or twisted repeatedly. Its attenuation is lower than that of stranded-conductor cable.

Stranded cable is for use in shorter runs between network interface cards (NICs) and wallplates or between concentrators and patch panels, hubs, and other rackmounted equipment. Stranded-conductor cable is much more flexible than solid-core cable. However, attenuation is higher in stranded-conductor cable, so the total length of stranded cable in your system should be kept to a minimum to reduce signal degradation. collapse


Black Box Explains... Advantages of the MicroRACK system.

• Midplane architecture—Separate front and rear cards make changing interfaces easy.
• Multiple functions—Supports line drivers, interface converters, fiber modems, CSU/DSUs, and synchronous modem eliminators.
• Hot swappable—MicroRACK Cards can be replaced... more/see it nowwithout powering down, so you cut your network’s downtime.
• Two-, four-, and eight-port MicroRACKs—available for smaller or desktop installations. They’re just right for tight spaces that can’t accommodate a full-sized (16-port) rack.
• Optional dual cards—Some Mini Driver Cards have two drivers in one card. One MicroRACK chassis can hold up to 32 Mini Drivers!
• All standard connections available—DB25, RJ-11, RJ-45, fiber, V.35.
• Choose you own power supply—120–240 VAC, 12 VDC, 24 VDC, or 48 VDC. collapse


Black Box Explains...Choosing a wireless antenna.


Ride the wave.

One of the most critical components to operating a successful wireless network is having the right antennas. Antennas come in many different shapes and sizes,... more/see it noweach designed for a specific function. Selecting the right antennas for your network is crucial to achieving optimum network performance. In addition, using the right antennas can decrease your networking costs since you’ll need fewer antennas and access points.


Basically, a wireless network consists of data, voice, and video information packets being transmitted over low-frequency radio waves instead of electrically over copper cable or via light over fiber lines. The antenna acts as a radiator and transmits waves through the air, just like radio and TV stations. Antennas also receive the waves from the air and transport them to the receiver, which is a radio, TV, or in the case of wireless networking, a router or an access point.


Type cast.

The type of antennas you use depends on what type of network you’re setting up and the coverage you need. How large is your network? Is it for a home, single office, campus, or larger? Is it point-to-point or multipoint?


The physical design-walls, floors, etc.- of the building(s) you’re working in also affects the type and number of antennas you need. In addition, physical terrain affects your antenna choices. Obviously, a clear line of sight works best, but you need to consider obstructions such as trees, buildings, hills, and water. (Radio waves travel faster over land than water.) You even need to consider traffic noise in urban settings.


The ideal shape.

Let’s take a look at the different types of antennas.


Isotropic Antenna. First, think of the introduction to the old RKO movies. A huge tower sits on top of the world and emanates circular waves in all directions. If you could actually see the waves, they would form a perfect sphere around the tower. This type of antenna is called an isotropic antenna, and does not exist in the real world. It is theoretical and is used as a base point for measuring actual antennas.


Go in the right direction.

Now let’s turn to real-world antennas. There are many types of antennas that emit radio waves in different directions, shapes, and on different planes. Think of the spherical isotropic antenna. If squeezed from the sides, it will become shaped like a wheel and will concentrate waves on a vertical plane. If squeezed from the top, it will flatten out like a pancake and radiate waves on a horizontal plane. Thus, there are two basic types of antennas: directional and omnidirectional.


Directional antennas.

Directional antennas, primarily used in point-to-point networks, concentrate the waves in one direction much like a flashlight concentrates light in a narrow beam. Directional antennas include backfire, Yagi, dish, panel, and sector.


Backfire. This small directional antenna looks like a cake pan with a tin can in the middle. It’s designed to be compact, often under 11" in diameter, making it unobtrusive and practical for outdoor use. These antennas also offer excellent gain, and can be used in both point-to-point or point-to-multipoint systems.


Yagi. The Yagi-Uda (or Yagi) antenna is named for its Japanese inventors. The antenna was originally intended for radio use and is now frequently used in 802.11 wireless systems.


A Yagi antenna is highly directional. It looks like a long fishbone with a central spine and perpendicular rods or discs at specified intervals. Yagi antennas offer superior gain and highly vertical directionality. The longer the Yagi, the more focused its radiation is. Many outdoor Yagi antennas are covered in PVC so you can’t see the inner structure.


Yagi antennas are good for making point-to-point links in long narrow areas (for instance, connecting to a distant point in a valley) or for point-to-point links between buildings. They can also be used to extend the range of a point-to-multipoint network.


Parabolic or Dish. These antennas look like a circular or rectangular concave bowl or "dish". The backboard can be solid or a grid design. Parabolic grid designs are excellent for outdoor use since the wind blows right through them. The concave nature of this dish design focuses energy into a narrow beam that can travel long distances, even up to several miles. This makes parabolic antennas ideal for point-to-point network connections. Since they generate a narrow beam in both the horizontal and vertical planes, offer excellent gain, and minimize interference, they’re ideal for long-distance point-to-point networks.


Panel or Patch. These antennas are often square or rectangular, and they’re frequently hung on walls. They’re designed to radiate horizontally forward and to the side, but not behind them. Sometimes they’re called "picture-frame" antennas.


Panel antennas are ideal in applications where the access point is at one end of a building. They’re good for penetrating a single floor of a building, and for small and medium-size homes and offices. Since they might not have much vertical radiation, they might not be a good choice for multifloor applications.


Because panel antennas can be easily concealed, they’re a good choice when aesthetics are important.


Sector. A sector antenna can be any type of antenna that directs the radio waves in a specific area. They are often large, outdoor flat-panel or dish-type antennas mounted up high and tilted downward toward the ground. These antennas are often used in sprawling campus settings to cover large areas.


Omnidirectional antennas.

Omnidirectional antennas provide the widest coverage possible and are generally used in point-to-multipoint networks. Their range can be extended by overlapping circles of coverage from multiple access points. Most omnidirectional antennas emanate waves in a fan-shaped pattern on a horizontal plane. Overall, omnidirectional antennas have lower gain than directional antennas. Examples of omnidirectional antennas include: integrated, blade, and ceiling.


Integrated. Integrated antennas are antennas that are built into wireless networking devices. They may be embedded in PC card client adapters or in the covers or body of laptops or other devices, such as access points. Integrated antennas often do not offer the same reception as external antennas and might not pick up weak signals. Access points with integral antennas must often be moved or tilted to get the best reception.


Blade. These small, omnidirectional antennas are often housed in long, thin envelopes of plastic. They are most often used to pick up a signal in a low-signal or no-signal spot. You usually will see them on the walls of cubicles, mounted on desktops, or even hung above cubicles to catch signals. They’re basically an inexpensive signal booster.


Ceiling Dome. These are sometimes also called ceiling blister antennas. They look somewhat like a smoke detector and are designed for unobtrusive use in ceilings, particularly drop ceilings. Ceiling dome antennas often have a pigtail for easy connection to access points. They’re excellent for use in corporate environments where wide coverage over a cube farm is needed.


Wave basics.

To better understand wireless antennas and networking, there are some basic measurements and terms that need to be discussed.


Gain. One of the primary measurements of antennas is gain. Gain is measured as dBi, which is how much the antenna increases the transmitter’s power compared to the theoretical isotropic antenna, which has a gain of 0 dBi. dBi is the true gain the antenna provides to the transmitter’s output. Gain is also reciprocal-it’s the same transmitting and receiving. Higher gain means stronger sent and received signals. An easy way to remember gain basics is that every 3 dB of gain added doubles the effective power output of an antenna. The more an antenna concentrates a signal, the higher the gain it will have.


You can actually calculate the gains and losses of a system by adding up the gains and losses of its parts in decibels.


Frequency and Wavelength. Electromagnetic waves are comprised of two components: frequency and wavelength.


Frequency is how many waves occur each second. Wavelength is the distance between one peak of a wave and the next peak. Lower frequencies have longer wavelengths; higher frequencies have shorter wavelengths. For example, the frequency of AM radio is 1 MHz with a wavelength of about 1000 feet. FM radios operate at a much higher frequency of 100 MHz and have a wavelength of about 100 feet.


The two most common frequencies for wireless networking are 2.4-GHz and 5-GHz. Both are very high frequencies with very short wavelengths in the microwave band. The 2.4-GHz frequency has a wavelength of about 5 inches.


Beamwidth. Consider an antenna to be like a flashlight or spotlight. It reflects and directs the light (or radio waves) in a particular direction. Beamwidth actually measures how energy is focused or concentrated.


Polarization. This is the direction in which the antenna radiates wavelengths, either vertically, horizontally, or circularly. Vertical antennas have vertical polarization and are the most common. For optimum performance, it is important that the sending and receiving antennas have the same polarization.


VSWR and Return Loss. Voltage Standing Wave Ratio (VSWR) measures how well the antenna is matched to the network at the operating frequency being used. It indicates how much of the received signal won’t reach either the transceiver or receiver. Return loss measures how well matched an antenna is to the network. Typical VSWR numbers are 1:1.2 or 1:1.5. A typical return loss number is 20.

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