Cabling for LAN and Premise Architecture

July 31, 2013 at 10:00 AM

 

Diagram of Wiring Closet Rack

It's hard to fathom just how quickly Ethernet technology has grown. Today no modern office building would be functional without premise wiring, or the cabling run throughout the building to connect computers to the LAN.

 

We may be on the verge of a wireless revolution with new technologies like DAS and MESH, but for now you should at least understand the basic architecture of LAN cabling.

 

LAN wiring is often broken into three types: backbone, horizontal runs, and patch cabling, each with its own purpose and requirements. In an especially large building or in a campus of buildings, the backbone is the wiring that connects server locations together and to the Internet through an ISP. Since a large amount of data may be carried back and forth by these cables, they are typically designed for bandwidth, like T1 lines or fiber optic cables (usually multi-fiber lines like breakout or distribution style, or even ribbon fibers).

 

Close Up View of Solid Conductor Category-rated Cable

The horizontal runs are the individual cables coming from the servers to the Work Areas. Work Areas are the points where the cable is terminated in a wall plate or jack so a user can plug their computer or other device into it.

 

It is often deceptive to assume that a single horizontal run will connect to a single computer. More likely than not, it is connected into a local Ethernet switch or wireless access point, and many computers may be connected to that. For this reason, the actual data carried on a single horizontal cable could vary greatly, and if you are planning your LAN architecture, this is the trickiest thing to get right. It can also be the most expensive piece to change if you get it wrong as you may need to fish the cable back out of a wall or conduit to re-arrange it.

 

Horizontal runs are currently most often solid-conductor Category rated copper cable. This is slowly changing over to fiber optic cabling as the price gap between the two narrows and fiber optic technology improves. Note that the horizontal cable may also require special jacket types to comply with building fire codes.

 

Right Angle Ethernet Cable Assembly

The patch cabling in a LAN is often overlooked, but is also very important. In general it is used to connect two devices together in a rack in a server room, or to connect a device to a wall jack where a horizontal cable is terminated. Being exposed (not behind a wall or on a rack ladder) and possibly being moved frequently, a patch cable needs to be robust and flexible.

 

While patch cables are easily available and can be bought relatively cheap, you might want to consider that cheap cables may introduce problems to your LAN. Cheap cables often use substitute materials such as copper clad aluminum or feature low quality plugs not rated for the application. Cheap cables seldom pass the testing required for the network and will degrade your network performance.

 

With more devices requiring power (POE), the cheaper cables often cannot carry the added burden due to undersized conductors and low grade copper. For a single user's computer, the impact of this may be limited, but in a server room low quality cables can have a disastrous effect on the entire LAN. If the cable manufacturer you purchase from has a robust QC process, it will help.

 

Other features to consider are molded right angle connectors to ensure the connector isn't bent to fit into limited space, cable boots to make depressing the connector latch easier, and high-flex construction and oil resistant jackets for demanding environments.

 

L-com stocks components for every facet of your LAN, from Ethernet cables, plugs and jacks, to bulk copper or fiber cable, to active media converters. We also go beyond that, to reliable racks, panels and cable management accessories, lightning and surge protectors, Power-over-Ethernet components and everything for wireless deployment.

 

How to Install Grid Antennas

July 24, 2013 at 10:00 AM


Grid Antenna Mounted on a Mast or Pole with Downward Angle

To make installation for your application easier, here’s a rundown of what to look for. First though, let’s decipher this: why use a Grid Antenna?

 

For point-to-point communications, a grid antenna has a lot of advantages that may make it the best choice for your application. First- since they are directional, they can provide better gain by focusing the beam in a particular direction. Second, though they are typically larger than other antenna types, they usually break down easily to fit in a box for easy transport to the installation site, or for storage while not being used.

 

Once assembled, the grid provides better wind loading than dish antennas. They are very also very easy to mount in either vertical or horizontal polarization and easy to tilt for precise aiming.

 

 

Assembly

 

We suggest double-checking the quality of the antenna before you purchase, especially if the installation is outdoors. The grid should have a UV protective coating and all of the hardware should be stainless steel.

 

When you order a grid antenna, it usually comes disassembled. Different manufacturers make grid antennas with slightly different installation instructions. When putting the grid antenna together, take all normal safety precautions to avoid coming into contact with dangerous electrical lines, etc., then go over the parts list. All grid antennas need the grid itself (often broken into two halves to reduce shipping costs), mounting "L" bracket, mast clamps, hardware such as screws, nuts and washers, and the feed horn. The feed horn is the long, protruding piece in the center of the grid that sends the actual signal. The below video (or this tutorial) demonstrates step by step assembly of the grid antenna. 

 

 

Where can you find a reliable antenna? L-com's HyperLink® line of grid antennas features tons of options for 2.4 GHz and 5.8 GHz bands, along with specialty versions for the 900 MHz, 1.9 GHz, 3.5 GHz and 4.9 GHz. Many options are available in convenient 5-packs that save you time and money. There are also hardware packages for replacing or maintaining components of a grid antenna.
 

Choose the Right Cable Jacket Material

July 17, 2013 at 10:00 AM


Plenum, LSZH and More

 

L-com's Plenum rated multiconductor cable

 

For buyers and technicians using signal-grade cabling, much attention is usually given to the connector type, termination process and bulk cable construction. Another aspect not to be forgotten that can be critical to many applications is the cable jacket material.

 

 

What does the jacket do?

 

More than just a color coding cable management technique, the jacket has several important functions. It allows the separate conductors to be organized into a single data line for ease of organizing, or it can even contain several conductors or wires to be broken out at a drop point.

 

The cable jacket also aids tremendously in the cable's flexibility and durability. In covering any shielding within the cable, it can prevent noise that collects on the shield from degrading the signals of other cables nearby, or from draining at inappropriate spots. Finally, the outer jacket is often the last line of defense between the data-carrying conductors and the environment in which the cable is used.

 

 

Fire Code Considerations

 

Comparison of cable jackets burning

Perhaps the most important aspect of a cable's jacket is how that jacket burns in a fire. PVC, the flexible plastic material that makes up most general purpose or residential grade cables is cheap and convenient, but it burns quickly and releases poisonous gas while burning.

 

If cables are run behind the walls of a building or in a vehicle and a fire breaks out, that fire can "leap" from room to room or floor to floor by burning along the cables behind the walls. And if the location where the cables are run is difficult to exit, as in a submarine, ship, airplane or even crowded warehouse, the poisonous smoke would compound the difficulty in dealing with the fire.

 

Because of this, many cables are given flammability compliance codes to help technicians from buying or using inappropriate cables. But, differences in measurement techniques and designations can make the process very confusing. In general, though, there are two "types" or classes of jacket materials other than PVC.

 

 

Plenum for Fire Retardation and Self-Extinguishing

 

In many large buildings, the duct work between rooms and floors is also the raceway for much of the building's data cabling. This space is often called the building's "plenum", and so the types of cables run in these environments are often called Plenum rated cables or just Plenum cables.

 

Plenum materials must be self-extinguishing, meaning that after they start burning and then the external fire or heat source is removed, the material must stop burning. This prevents the cables from "carrying" the fire to another location in the building and re-igniting unexpectedly. Sometimes Plenum cables are referred to as CL2P, OFNP, or CMP. Plenum cables are known to be more expensive than PVC, but in cases where a fire code requires plenum the cost must be factored into the overall installation job.

 

 

Low Smoke, Zero Halogen (LSZH) for Sealed or Mobile Locations

 

Jacket materials that have been designed to release very little smoke and no poisonous gas when burned are often called LSZH. These are typically reserved for special applications where the occupants near the cables may not be able to escape or ventilate the room in the instance of a fire. Again, this occurs frequently in military and aerospace applications.

 

 

Special Jacket Considerations

 

In addition to the above designations for particular fire codes, jackets may have other features useful in niche applications. UV resistance is important in applications where the cable may be exposed to strong sunlight for long periods. UV light can weaken and eventually destroy many PVC compounds over time. Or, oil resistance may be needed in many factory automation apllications as the petroleum-based compound could dissolve if immersed in oil. High-flex or hi-flex cables often use a special jacket that will not crack and split when the cables are flexed over and over again.

 

If you're looking for industry's largest selection of off-the-shelf Plenum, LSZH and other special-jacketed cable and cable assemblies, stop in at L-com's online configurator or contact customer service to get a quote started. We can custom manufacture cables with the jacket type you need.

 

How to Install Wireless Amplifiers

July 10, 2013 at 10:00 AM

 Setting up a WiFi Booster for an Indoor Wireless System

 

An Assortment of WiFi Amplifiers

If you do not work with wireless components every day, the prospect of adding a new component to boost the power of your signal may seem daunting. While we always recommend you have a professional install communications equipment to ensure it is done correctly, this brief tutorial will give you the basic steps to set up a simple WiFi booster. If it helps, you can also take a look at the video in this post or visit our complete tutorial here.

 

 

 

If you have a WLAN setup that requires a stronger signal, a simple WiFi booster may do the trick. Due to FCC regulations, if you are doing this installation in the United States, you need FCC approval to buy the amplifier. If you don't need an amplifier with power over 1 Watt, you can purchase an FCC certified amplifier kit which requires no special operator's license. Either way, most setups follow this simple procedure.

 

Diagram of an RF amplifier setup

On the amplifier, you will typically see two coaxial cable jacks, one labeled "Antenna" and the other labeled "Radio". There should also be a power jack (usually a DC jack requiring an external power adapter), which is where the amplifier gets the power to repeat the signal.

 

Using low-loss coaxial cable, simply connect the antenna to the antenna jack on the amplifier, and the radio (or access point or router, etc) to the radio jack. Then, after the two sides are hooked up, attach the power adapter and plug it in. Most amplifiers have LED lights to indicate activity, which helps you to see if it is working.

 

It's that easy!

 

Quick note: L-com has a huge selection of top-quality wireless RF amplifiers for the 2.4 GHz WiFi band and 5.8 GHz WiFi band, as well as 900 MHz, 3.5 GHz, and 4.9 GHz frequencies. These ampifiers feature HyperLink's® Active Power Control (APC), which automatically maintains a constant output power regardless of the length of the attached cables. Aside from the indoor wireless amplifiers, L-com also carries HyperLink® brand outdoor wireless amplifiers for all-weather operation.
 

Tutorial on Coaxial Cabling

July 3, 2013 at 10:00 AM

 

 

 

Coax is one of the most venerable cabling standards having been developed for the US military over 50 years ago. Unlike some standards that were popular for a while and eventually became legacy, coaxial cabling is still very relevant and used in a lot of common applications. It is a robust and reliable cable type with no sign of going away any time soon.

 

 

 Types of Coax Cabling

 

As you can imagine, over the years that coax has been around, many variations have been designed for specific applications. We will talk about the Radio Guide (RG) styles and the low-loss styles that were made popular by Times Microwave's LMR® standard. Though there are many other coax options like mini coax, twinaxial and tri-axial, the applications for those have dwindled in recent years.

 

 

RG-style Coaxial Cable

 

The original Radio Guide standard called for a number followed by codes to determine specific aspects of the cable (such as jacket type, center conductor material, etc.). However, today many of the standards have become "soft" meaning that RG58B/U, for instance, may have very different characteristics from manufacturer to manufacturer.

 

Exposed view of a coaxial cable

Most RG numbers refer to cables made with specific diameters (as thicker diameters typically have lower attenuation over long lengths), shielding, jacket type, and dielectric type. The dielectric is important as it can control the "characteristic impedance" of the cable. In general, cables with a characteristic impedance of 50 Ohms are used in data and wireless network applications, and cables with a characteristic impedance of 75 Ohms are used in higher bandwidth audio/video applications.

 

The bottom line about RG-style coax cable: if you need to get a specific type for your application, you should include the characteristics of the cable with your request. The actual standard may have some variations that would make the off-the-shelf product unsuitable for some circumstances.

 

 

Low-loss Coaxial Cable

 

Low-loss cable is almost exclusively used in wireless applications. It is ideal for any antenna-to-radio setup, and is often used extensively in wireless system installations. Low loss cable is often referred to by its series number, such as 200-Series cable, which is usually a rough approximation of the diameter of the cable. The higher the number (ie, 400, 800, etc), the thicker and heavier the cable, and the less attenuation over the length. Because of this, higher series numbers are typically used in cases where the antenna is permanently installed at some distance from the radio. Lower series numbers are used in cases where the antenna is closer, especially in portable setups where the weight of the cable is important.

 

 

Connectors

 

There are a large variety of coaxial connectors, usually designated by a letter or combination of letters. Most coaxial connectors are round or hex shaped, and can come in screw-on, push-on, or twist-lock designs. Be extra careful if you need a connector that is called "reverse polarized" or preceded with the letters "RP". These connectors are similar to the regular polarity versions except that the gender of the connector is reversed, making it unable to mate unless it is with another RP style connector. For a complete list of coaxial connectors with large images, try this coaxial connector chart.

 
If you are in need of coax: L-com has carried RG style coax cable and assemblies for decades, and together with our vast collection of low-loss coax cables it is one of the most comprehensive in the industry.
 
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