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.

 

What is an Omni directional antenna for 2.4 GHz?

May 15, 2013 at 10:00 AM

 

Omnidirectional antenna

As wireless technology continues to grow and develop, several antenna shapes and designs have arisen to provide different types of coverage. An Omni directional antenna is so called because it provides a wireless signal in a 360° radius, or in "all directions". These types of antennas are very common, and typically look like a very straight, stick-like shape.

 

Since the energy of the signal is not directional or pointed in a specific way, Omni directional antennas tend to be of lower gain than directional antennas such as parabolic dish, Yagi, and panel style antennas. However, higher gain isn't usually required for small installations such as Wi-Fi "hotspots" in stores and cafes. For those kinds of applications, a single Omni directional antenna installed near the center of the location often does the trick.

 

The 2.4 GHz band is typically designated for Wi-Fi use, and is the most common band for things like laptop and tablet wireless access. Therefore, if you are setting up a network for customers or visitors to access the Internet wirelessly, you'll often be installing a 2.4 GHz antenna. However, check the specifications of the access point that is being hooked up to the antenna to make sure the frequencies match. 

 

Quick note: L-com has a huge selection of 2.4 GHz antennas, from parabolic dish antennas, to Omni directional and everything in between.
 

How To Differentiate VGA, SVGA and UXGA

May 8, 2013 at 4:38 PM

 

VGA Cable

While knowing these specific terms is helpful in buying some analog display equipment (such as computer monitors), each refers to the same type of video format. These acronyms relate to the resolution a monitor supports, thus the same type of cabling and connectors are used.

 

Another common denominator with VGA, SVGA, and UXGA is that they are all mostly now legacy. No new products are being built using VGA analog video interfaces. 

 

However, if you have irreplaceable or expensive equipment that requires using VGA analog video, you'll find it useful to know its functionality. 

 

Typical VGA cables have a high-density fifteen-pin (HD15) connector on each end, using a combination of mini-coaxial cables and straight or twisted pair conductors to carry a video signal. VGA does not include audio support like HDMI® and DisplayPort cables do.

 

What do these terms mean? VGA stands for Video Graphics Array. As video display equipment that used the VGA standard became more sophisticated, manufacturers began adjusting the name of the standard to reflect the maximum resolution of the display device. For example, SVGA stands for Super Video Graphics Aray which supports a resolution of 800 x 600. As the list grew, it became easier to just list the maximum resolution rather than the letters that corresponded to it.

 

Today, there are over 20 different letter combinations referring to all sorts of different resolutions, a list of which can be found here. Most of these terms are rarely used to refer to analog video equipment anymore. And as mentioned previously, the standard itself is rapidly becoming legacy in the face of digital video standards such as HDMI®, DVI, and DisplayPort.

 

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Identifying Array Antennas

April 17, 2013 at 10:00 AM

What are they?


An antenna array is a group of two or more directional (usually panel style) antennas that are grouped together to form an Omni directional signal. Many times an RF splitter is used to connect the multiple antennas to a single access point or WiFi amplifier.

 

The benefit of using an antenna array over a single Omni directional antenna is that the antenna array provides radiation patterns that a single Omni antenna would not. Many times antenna arrays provide greater coverage than a single Omni antenna could.

 

 

Antenna array mounted on a pole RF splitter connected to an antenna array
Antenna array mounted on a pole RF splitter connected to an antenna array

Down tilt mounting feature
Down tilt mounting feature 

 



Where Would You Use Them?


Antenna arrays are used in outdoor point-to-multipoint applications. L-com's antenna arrays are available in 90° (4 panels), 120° ( 3 panels), and 180° (2 panels) configurations and include appropriate splitter and cables. Additionally, these antenna arrays feature zero to 20° down tilt capability to compensate for the geography of the installation location. This helps ensure maximum wireless signal coverage in the service area.

 

 

Antenna Array Configurations Available

 

 

Antenna Arrays with four 90° sectorial antennas Antenna Arrays with four 90° sectorial antennas
Antenna Arrays with three 120° sectorial antennas Antenna Arrays with three 120° sectorial antennas
Antenna Arrays with two 180° sectorial antennas Antenna Arrays with two 180° sectorial antennas
 

All sectorized omni array configurations are designed to all-weather operation. They feature both heavy-duty polymer antenna radomes and stainless steel mounting systems. 

 
  
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