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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How To Amplify Wireless Signals without an FCC Operators License

May 1, 2013 at 10:00 AM

 

Example of a Wireless Amplifier Setup for a Laptop

Do you need a wireless amplifier but can't get one?

 

That's because the Federal Communications Commission (FCC) Part 15 regulations dictate the use of RF power amplifiers in the United States. Individual RF power amplifiers are not offered for general sale within the United States and must be part of a wireless system previously certified by the FCC.

 

Customers in the US that are inquiring about purchasing individual amplifiers must first be prequalified to see if they meet certain requirements. Those who qualify are typically Federal Government agencies, Department of Defense (DOD) and FCC licensed operators. This is obviously not ideal for the typical home or commercial business user.

 

So how can you get one?

 

L-com carries FCC-certified amplifier kits. These kits are complete 2.4 GHz wireless systems that feature a wireless USB adapter, rubber duck antenna and amplifier. Since FCC ID numbers have been granted to these kits, prequalification is not required in order for them to be sold.

 

L-com carries three types of FCC-certified WiFi boosters: standard, economy grade, and PoE compliant. Available with amplifiers ranging from 100 mW to 1 Watt, they provide exactly the boost your signal needs.

 

Click here for a helpful video on how to setup a laptop WiFi booster kit:

 

Wireless Amplifier Video

 

Using Latching USB Cables for Vibration-Proof Connections

April 24, 2013 at 10:00 AM


Latching USB Cables

One of the most successful connectivity technologies is Universal Serial Bus or USB 2.0. Why? You can find it everywhere, from laptops and desktop computers to peripheral devices like printers, mice and keyboards, to consumer electronics like cell phones and camcorders. 

 

(Click here for a tutorial on USB technology.)

 

Surprisingly though, there are some fundamental problems with USB 2.0, one of which is its sensitivity to vibration.

Latching USB Drawing

 

USB 2.0 uses what's called a "friction fit" to remain connected, which means the friction between the connector and the jack is all that holds the connection together. As you'd find with vehicles and in military/aerospace applications, vibration can cause connectors to unexpectedly separate.

 

L-com has countered this problem by offering "latching" USB 2.0 cables.  The latches, which are on the sides of the connector, fit into any standard USB 2.0 female jacks.  Currently latches are only available on USB 2.0 Type A male connectors and they come standard on micro-B male connectors. L-com offers:

 

 
 
Quick note: Latching connectors are also available for SATA cables.
 
Additionally, L-com now offers USB 3.0 cables with locking thumbscrews. These cables can be used in machine vision applications or with any application where vibration is an issue.
 
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