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Black Box Explains... Plasma vs. LCD Screens

When deciding whether to use plasma or liquid crystal diode (LCD) displays for your applications, you need to consider many factors. Both provide brilliant color, sharp text contrast, and crystal-clear... more/see it nowimages. But the way in which plasma and LCD screens process and display incoming video/computer signals is markedly different.

Compare and contrast.
Both plasma and LCD technology provide stark enough contrasts to make displays sharp and pleasing. But when it comes to contrast output, plasma technology outperforms LCD screens. Some plasma displays have a 3000:1 contrast ratio, which is the measure of the blackest black compared to the whitest white. LCDs use electric charges to untwist liquid crystals, thereby blocking light and emitting darker pixels. Despite this process, LCD displays don’t produce more than a 1000:1 contrast ratio.

Clarity that’s light waves ahead.
Pixels contain enough information to produce every color in the spectrum. Because plasmas use each and every pixel on their screens, color information is reproduced more accurately. Plasma screens display moving images with remarkable clarity, though burn-in can be an issue. For displays with lots of light and dark imagery, plasma panels provide excellent performance with their high-contrast levels, color saturation, and overall brightness.

LCD displays, on the other hand, manipulate light waves and reproduce colors by subtracting colors from white light. Though this makes it more difficult to maintain color accuracy and vibrancy compared to plasma screens, LCDs have an advantage with their higher-than-average number of pixels per square inch. These additional pixels make LCD technology better at displaying static images from computers or VGA sources in full-color detail. Plus, there’s no flicker and very little screen burn-in.

Applications with large amounts of data—such as those found on spreadsheets—display particularly well on LCD monitors.

Brilliant displays that go on and on.
With LCD screens, there are essentially no parts to wear out. LCD screens last as long as their backlights do, with displays lasting, on average, 50,000–75,000 hours. That’s why LCD screens are especially good for long-term applications, such as digital signage or displays that require around-the-clock use.

Plasma screens, however, use a combination of electric currents and noble gases (argon, neon, and xenon) to produce a glow, which in turn yields brilliant color. The half-life of these gases, however, is only around 25,000 hours. The glow they produce grows dimmer over time.

The right angle can make all the difference.
Plasmas light every pixel on the screen, making the brightness on the screen consistent and giving plasmas the edge when it comes to viewing angles. In fact, plasma screens have as much as a 160° viewing angle compared to LCDs. This makes viewing the images on the screen easier to see from a variety of angles. In doing so, however, plasmas consume much more power.

LCDs display at 130–140° angles, but their use of fluorescent backlighting requires much less power to operate than plasmas. This also makes LCDs less prone to burn-in or ghosting of images.
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Black Box Explains...Types of KVM switches.

Black Box has the keyboard/video switches you need to share one CPU between several workstations or to control several CPUs from one monitor and keyboard.

If you do a lot of... more/see it nowswitching, you need premium switches—our top-of-the-line ServSwitch™ KVM switches give you the most reliable connections for the amount of KVM equipment supported. With ServSwitch KVM switches, you can manage as many CPUs as you want from just one workstation, and you can access any server in any computer room from any workstation. Eliminating needless equipment not only saves you money, it also gives you more space and less clutter. Plus, you can switch between PCs, Sun®, and Mac® CPUs. ServSwitch KVM switches can also cut your electricity and cooling costs because by sharing monitors, you use less power and generate less heat.

If your switching demands are very minor, you may not need products as advanced as ServSwitch. Black Box offers switches to fill less demanding needs. Most of these are manual switches or basic electronic switches, which don’t have the sophisticated emulation technology used by the ServSwitch.

For PCs with PS/2® keyboards, try our Keyboard/Video Switches. They send keyboard signals, so your CPUs boot up as though they each have their own keyboard.

With the RS/6000™ KVM Switch, you can run up to six RS/6000 servers from one workstation. Our Keyboard/ Video Switch for Mac enables you to control up to two Mac CPUs from one keyboard and monitor.

With BLACK BOX® KVM Switches, you can share a workstation with two or four CPUs. They’re available in IBM® PC and Sun Workstation® configurations.

You’ll also find that our long-life manual Keyboard/Video Switches are perfect for basic switching applications. collapse


Black Box Explains... Digital Visual Interface (DVI).

The Digital Visual Interface (DVI) video standard is based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to... more/see it nowa low level to create transitions that convey data. To minimize the number of tran-sitions needed to transfer data, TMDS uses a pair of signal wires. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy.

Although there are four types of DVI connectors, only DVI-D and DVI-I are commonly used for monitors. DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. collapse


Black Box Explains... Matrix video switches.

Matrix switches enable computers to mix and match the output of multiple PCs on multiple video monitors.

For instance, if your operation has four PCs and you want to display the... more/see it nowvideo on one monitor to the other three monitors, a matrix video switch is what you need to handle the job. Use matrix switches for:
• Trade shows—Set up a wall of video to wow the senses of attendees.
• Transportation schedules—Provide real-time updates of flights or deliveries on multiple screens.
• Training demonstrations—Control each screen’s video to focus everyone’s attention on what’s important. collapse


Black Box Explains... KVM IP gateways

Just as a gate serves as an entry or exit point to a property, a gateway serves the same purpose in the networking world. It’s the device that acts as... more/see it nowa network entrance or go-between for two or more networks.

There are different types of gateways, depending on the network.

An application gateway converts data or commands from one format to another. A VoIP gateway converts analog voice calls into VoIP packets. An IP gateway is like a media gateway, translating data from one telecommunications device to another.

Gateways often include other features and devices, such as protocol converters, routers, firewalls, encryption, voice compression, etc. Although a gateway is an essential feature of most routers, other devices, such as a PC or server, can also function as a gateway.

A KVMoIP switch contains an IP gateway, which is the pathway the KVM signals use to travel from the IP network to an existing non-IP KVM switch. It converts and directs the KVM signals, giving a user access to and control of an existing non-IP KVM switch over the Internet. collapse


Black Box Explains... Using fiber optics for KVM extension.

If you‘re sending KVM signals between buildings for an extended distance, in areas supplied by different power sources, in an electrically noisy environment, or where data security is a big... more/see it nowconcern, you need to use a fiber optic-based KVM extender.

Optical fiber is an ideal transmission medium not only for backbone and horizontal connection, but also for workstation-to-backracked CPU or server links. It works very well in applications where you need to transfer large, bandwidth-consuming data files over long distances, and where you require immunity from electrical interference or data theft.

The choice for extraordinary reach.
Fiber doesn’t have the 100-meter (328-ft.) distance limitation that UTP copper without a booster does. Fiber distances can range from 300 meters (984.2 ft.) to 70 kilometers (24.8 mi.), depending on the cable, wavelength, and network. With fiber-based KVM extenders, the transmitter converts conventional data signals into a modulated light beam, then transports the beam via the fiber to a receiver, which converts the light back into electrical signals.

Many newer fiber-based KVM extenders support both analog and digital transmission. Often, they work by digitizing video output from a local CPU, then sending it across fiber link to a remote unit, which converts it back to the original analog signal. In many cases, one fiber of the fiber pair transmits monitor video serially and the second fiber sends remote mouse and keyboard information back to the local CPU.

The choice for ensuring signal integrity.
Because fiber is made of glass, which is an insulator, no electric current can flow through. It’s immune to electromagnetic interference and radio-frequency interference (EMI/RFI), crosstalk, impedance problems, and more. This is why fiber-based KVM extenders are beneficial to users in process control, engineering, utility, and factory automation applications. The users need to keep critical information safe and secure off the factory floor but be able to access that data from workstations and control consoles within the harsh environments. Plus, fiber is also less susceptible to temperature fluctuations than copper is, and it can be submerged ?in water.

The choice for greater signal fidelity.
Fiber-based KVM extenders can carry more information with greater fidelity than copper-based ones can. For this reason, they’re ideal for high-data-rate systems in which multimedia workstations are used.

Newer KVM extenders enable you to send both DVI and keyboard and mouse signals over the same fiber cable, transmitting video digitally for zero signal loss. This way, you can get HD-quality resolution even at very long distances from the source. Users in university or government R&D, broadcasting, healthcare—basically anyone who depends on detailed image rendering—can benefit from this technology.

The choice for data security.
Plus, your data is safe when using fiber to connect a workstation with a CPU or server under lock and key. It doesn’t radiate signals and is extremely difficult to tap. If the cable is tapped, it’s very easy to monitor because the cable leaks light, causing the entire system to fail. If an attempt is made to break the physical security of your fiber system, you’ll know it.

Many IT managers in military, government, finance, and healthcare choose fiber-based KVM extenders for this very reason. Plus corporations, aware of rising data privacy concerns over customer billing information and the need to protect intellectual property, use this type of extension technology in their offices, too.

Considerations for fiber-based KVM extension.
Before selecting a fiber-based KVM extender, it’s important to know the limitations of your system. You need to know where couplers, links, interconnect equipment, and other devices are going to be placed. If it’s a longer run, you have to determine whether multimode or single-mode fiber cable is needed.

The most important consideration in planning cabling for fiber-based KVM extension is the power budget specification of device connection. The receiver at the remote end has to receive the light signal at a certain level. This value, called the loss budget, tells you the amount of loss in decibels (dB) that can be present in the link between the two devices before the units fail to perform properly.

Specifically, this value takes the fiber type (multimode or single-mode) and wavelength you intend to use—and the amount of expected in-line attenuation—into consideration. This is the decrease of signal strength as it travels through the fiber cable. In the budget loss calculation, you also have to account for splices, patch panels, and connectors, where additional dBs may lost in the entire end-to-end fiber extension. If the measured loss is less than the number calculated by your loss budget, your installation is good.

Testers are available to determine if the fiber cabling supports your intended application. You can measure how much light is going to the other end of the cable. Generally, these testers give you the results in dB lost, which you then compare to the loss budget to determine your link loss margin.

Also, in some instances, particularly when using single-mode fiber to drive the signal farther, the signal may be too strong between connected devices. This causes the light signal to reflect back down the fiber cable, which can corrupt data, result in a faulty transmission, and even damage equipment. To prevent this, use fiber attenuators. They’re used with ?single-mode fiber optic devices and cable to filter the strength of the fiber optic signal from the transmitter’s LED output so it doesn’t overwhelm the receiver. Depending on the type of attenuator attached to the devices at each end of the link, you can diminish the strength of the light signal a variable amount by a certain number of decibels.

Need help calculating your budget loss? Call our FREE Tech Support. If necessary, they can even recommend a fusion splicing fiber kit, a fiber tester, or a signal attenuator for your specific requirements. collapse


Black Box Explains... Multiplatform cabling environments.

When using a ServSwitch™ with multiple computer platforms, choosing which peripherals to use to control your diverse group of CPUs can be confusing. Because of the wide variation in connector... more/see it nowtypes and compatibilities, there is a hierarchy to follow when choosing your “user station“ keyboard, monitor, and mouse.

1. If you have at least one Sun® computer in your application, you should use a Sun keyboard and mouse to control your CPUs.

2. If you have a mixture of PCs and Mac® computers, use your PC-style keyboard and mouse to control your CPUs. collapse


Black Box Explains...CAT5: When more isn’t always better.

In data communications applications, using products that exceed required capacities is usually not a problem. For example, if a 28.8K modem is required, a 33.6K or 56K model will work... more/see it nowjust fine.

But sometimes, more isn’t better. Take KVM extenders designed to expect CAT5 and only CAT5 cable. You’d expect that Category 3 cable wouldn’t be effective with these products, and you would be right.

But you may also assume that if Category 5 cable works fine, Category 5e, Category 6, and other higher-capacity cables would work even better. Unfortunately, this isn’t the case, and here’s why:

KVM extenders from many manufacturers, including ServSwitch CAT5 KVM Extenders, are designed specifically for the Category 5 specs defined by the TIA/EIA standard. Higher-level cables, such as Category 5e, have different characteristics and specifications. Although differences—specifically twist ratios—might seem small, they can have a negative impact on these extenders, which are expecting a true Category 5 transmission.

So with ServSwitch CAT5 KVM Extenders, you can think big with CAT5—just don’t think bigger. collapse


Black Box Explains...The 13W3 connector.

The 13W3 connector, also called a 13C3 or DB13W3 connector, is an unusual connector that combines a 10-pin D-shell with three analog video conductors. It supports very-high-resolution analog video signals... more/see it nowand has been used by Sun Microsystems®, SGI, NeXt, Intergraph, and other manufacturers. Although 13W3 connectors from different manufacturers look the same, they may be pinned differently.

Pinning for a standard Sun® 13W3 connector:
A1: Red
A2: Green/Gray
A3: Blue
1: Ground*
2: Vertical Sync*
3: Sense 2
4: Sense Ground
5: Composite Sync 
6: Horizontal Sync*
7: Ground*
8: Sense 1
9: Sense 0
10: Composite Ground

* Considered obsolete; may not be connected. collapse


Black Box Explains...Digital Visual Interface (DVI) and other digital display interfaces.

There are three main types of digital video interfaces: P&D, DFP, and DVI. P&D (Plug & Display, also known as EVC), the earliest of these technologies, supports both digital and... more/see it nowanalog RGB connections and is now used primarily on projectors. DFP (Digital Flat-Panel Port) was the first digital-only connector on displays and graphics cards; it’s being phased out.

There are different types of DVI connectors: DVI-D, DVI-I, DVI-A, DFP, and EVC.

DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. Some manufacturers are offering the DVI-I connector type on their products instead of separate analog and digital connectors. DVI-A is used to carry an analog DVI signal to a VGA device, such as a display. DFP, like DVI-D, was an early digital-only connector used on some displays; it’s being phased out. EVC (also known as P&D) is similar to DVI-I only it’s slightly larger in size. It also handles digital and analog connections, and it’s used primarily on projectors.

All these standards are based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to a low level to create transitions that convey data. TMDS uses a pair of signal wires to minimize the number of transitions needed to transfer data. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy. collapse

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