Wireless LOS Terminology

November 28, 2013 at 10:00 AM

Why Line of Sight (LOS) is so important

 

Sample of LOS and Fresnel Zone Diagram

When designing an outdoor wireless network, ask yourself this: what is between point A (antenna 1) and point B (antenna 2)? This path between two antennas is referred to as the Line of Sight (LOS).

 

There are three main categories of Line of Sight. Full Line of Sight (LOS) is where no obstacles reside between the two antennas. Near Line of Sight (nLOS) includes partial obstructions such as tree tops between the two antennas. Lastly, Non Line of Sight (NLOS) is where full obstructions exist between the two antennas.

 

By determining the specific Line of Sight conditions in the WiFi network area you can then determine the correct type of wireless system to install.

 

Another common term to be aware of is The Fresnel Zone, referenced in the diagram above. It is is an electromagnetic phenomenon where light waves or radio signals get diffracted or bent from solid objects near their path. The radio waves reflecting off the objects may arrive out of phase with the signals that traveled directly to the receiving antenna, thus reducing the power of the received signal.

 

Line of Site (LOS) Overview Diagram

Print and post the above diagram.

 

For indoor wireless network installations it is important to consider obstacles such as walls, ceilings, and furniture that will affect Line of Sight since these all play a role in wireless signal reception. In wireless transmissions, reflections (when wireless signals "bounce" off objects) and multipath (when wireless signals travel in multiple paths arriving at the receiver at different times) are as important as signal strength in determining the success of an installation. A signal will also exhibit peaks and nulls in its amplitude and alteration of its polarization (vertical or horizontal) when propagating through walls, ceilings and reflecting off metallic objects. 

 

Path Loss is another area of concern when dealing with Line of Sight. For instance, although 2.4 GHz signals pass rather well through walls, passing through trees and leaves is a challenge. This is due to the difference of water content in each. Radio waves in the 2.4 GHz band absorb into water very easily, so the high level of moisture in trees or leaves would trap the waves. When faced with nLOS or NLOS conditions due to trees, 900 MHz is your best choice as it is not absorbed like 2.4 GHz.

 

 

Click here to shop L-com’s Hyperlink brand wireless products.

  

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.
 

A Tutorial on USB

May 22, 2013 at 10:00 AM

 

What exactly is USB?

USB Cable

 

USB stands for Universal Serial Bus and is a connectivity standard that transfers large amounts of data between devices. While it is far from the first standard designed for this purpose, the need for an effective method to transfer data between devices has become enormous due to the increase in portable and mobile devices.

 

The USB standard does just this, providing a universal method across different products and manufacturers. Other, "proprietary" standards exist, but they are often derivatives of USB with slight changes to the wiring or physical connector type.

 

 

Types of USB Cabling and Connectors

 

In the years since USB was first implemented, there have been three dominant versions, each providing faster data throughput than the last. USB 1.1, sometimes called "full-speed", can transfer data at about 12 Mbps. USB 2.0, which is currently the most common, operates at 480 Mbps. The latest standard, USB 3.0, operates at over 4.8 Gbps (about 10 times that of USB 2.0).

 

The most common USB connector types, Type A and Type B, are the same throughout the different versions. Though, other connector types such as the Mini B4, Mini B5, and Micro B are gaining popularity for their small size, which is preferred in smaller portable electronics such as mobile phones and tablets.

 

However, even if the connectors are similar, the cable itself must be constructed to the standard. For example, a USB 2.0 compliant cable could not pass 4.8 Gbps of data even if it were plugged into a USB 3.0 compliant device.

 

 

Why is USB so popular?

 

USB has several advantages over other standards that are used for the same purpose. First, it is a "hot connection", or has the ability to plug and unplug into a computer without causing it to freeze or causing programs to crash. USB is also uniquely designed to carry some low-voltage power which makes it capable of powering or charging devices that it is plugged into.

 

Also, though most applications only need standard USB cables, another advantage of USB is that it has the capability of specialization. Today we are seeing a rapid expansion of USB applications which require more specialized cabling- outdoor, wet or dusty environments, high-vibration situations, and places where special flame ratings, armor, or angled connectors are required. 

 

Check out our detailed USB tutorial here. Or, if you find yourself in this kind of special situation, try browsing L-com's USB product center for innovative solutions.

 

© L-com, Inc. All Rights Reserved. L-com, Inc., 50 High Street, West Mill, Third Floor, Suite 30, North Andover, MA 01845