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Showing posts with label Technology. Show all posts
Showing posts with label Technology. Show all posts

Tuesday, July 3, 2012

USB 2.0 vs USB 3.0

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USB 3.0, the latest version of USB (Universal Serial Bus), provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate.

Comparison chart

USB 2.0


USB 3.0

Released: April 2000 November 2008
Speed: High Speed or HS, 480 Mbps (Megabits per second) 10 times faster than USB 2.0. Super Speed or SS, 4.8 Gbps (Giga bits per second)
Signaling Method: Polling mechanism i.e can either send or receive data Asynchronous mechanism i.e. can send and receive data simultaneously
Price: For a similar product, the USB 2.0 version is generally less expensive than it's USB 3.0 version. For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.
Power Usage: Up to 500 mA Up to 900 mA. Allows better power efficiency with less power for idle states. Can power more devices from one hub.
Number of wires within the cable: 4 8
Standard-A Connectors: Grey in color Blue in color
Standard-B Connectors: Smaller in size Extra space for more wires

What is USB 3.0 and USB 2.0?

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. Now even devices like smartphones, PDAs and video game consoles are connected to the computers with USB ports allowing recharging and communication thereby replacing the requirement of adapters and power chargers.
USB3.0 was released in November 2008, almost eight years after the release of USB 2.0.

USB 3.0 Highlights and Benefits over USB 2.0                

  • Transfer rates - USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps - that's 10 times faster.
  • Addition of another phsyical bus - The amount of wires has been doubled, from 4 to 8. Additional wires require more space in both the cables and connectors, so there are new types of connectors.
  • Power consumption - USB 2.0 provides up to 500 mA whereas USB 3.0 provides up to 900 mA. The USB 3 devices will provide more power when needed and conserve power when the device is connected but idling.
  • More bandwidth - instead of one-way communication, USB 3.0 uses two unidirectional data paths, one to receive data and the other to transmit while USB 2.0 can only handle only one direction of data at any time.
  • Improved bus utilization - a new feature has been added (using packets NRDY and ERDY) to let a device asynchronously notify the host of its readiness.
When data is being transferred through USB 3.0 Devices, cables and connectors transaction is initiated by the host making a request followed by a response from the device. The device either accepts the request or rejects it. If accepted then device sends data or accepts data from the host. If there is lack of buffer space or data, it responds with a Not Ready (NRDY) signal to tell the host that it is not able to process the request. When the device is ready then, it will send an Endpoint Ready (ERDY) to the host which will then reschedule the transaction.

Physical Differences                                                                    

USB 3.0 Connectors are different from USB 2.0 Connectors and the 3.0 connectors are usually colored blue on the inside in order to distinguish them from the 2.0 connectors.
Various types of USB Connectors (click to enlarge). From Left to Right: Micro USB Type AB, Micro USB Type B, USB 2.0 Type A, USB 2.0 Type B, USB 3.0 Type A, USB 3.0 Type B, USB 3.0 Type Micro B, Min USB Type A connector
Various types of USB Connectors (click to enlarge). From Left to Right: Micro USB Type AB, Micro USB Type B, USB 2.0 Type A, USB 2.0 Type B, USB 3.0 Type A, USB 3.0 Type B, USB 3.0 Type Micro B, Min USB Type A connector

Backward Compatible                                                                

USB 3.0 is compatible with USB 2.0. However, the USB 3.0 product will perform at the same level as a USB 2.0 product, so speed and power benefits will not be fully realized.
USB 3.0 receptacles are electrically compatible with USB Standard 2.0 device plugs if they physically match. USB 3.0 type-A plugs and receptacles are completely backward compatible, and USB 3.0 type-B receptacles will accept USB 2.0 and earlier plugs. However, USB 3.0 type-B plugs will not fit into USB 2.0 and earlier receptacles.
This means that USB 3.0 cables cannot be used with USB 2.0 and USB 1.1 peripherals, although USB 2.0 cables can be used with USB 3.0 devices, if at USB 2.0 speeds. 

Price

For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.

3G Vs. 4G

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How much faster is 4G compared to 3G and what applications run better on 4G?
3G and 4G are standards for mobile communication. Standards specify how the airwaves must be used for transmitting information (voice and data). 3G (or 3rd Generation) was launched in Japan in 2001. As recently as mid-2010, the networks for most wireless carriers in the U.S. were 3G. 3G networks were a significant improvement over 2G networks, offering higher speeds for data transfer. The improvement that 4G offers over 3G is often less pronounced. Analysts use the analogy of standard vs Hi-Def TV to describe the difference between 3G and 4G.

Comparison chart:

3G 4G
Data Throughput: Up to 3.1mbps Practically speaking, 3 to 5 mbps but potential estimated at a range of 100 to 300 mbps.
Peak Upload Rate: 50 Mbit/s 500 Mbit/s
Peak Download Rate: 100 Mbit/s 1 Gbit/s
Switching Technique: packet switching packet switching, message switching
Network Architecture: Wide Area Cell Based Integration of wireless LAN and Wide area.
Services And Applications: CDMA 2000, UMTS, EDGE etc Wimax2 and LTE-Advance
Forward error correction (FEC): 3G uses Turbo codes for error correction. Concatenated codes are used for error corrections in 4G.
Frequency Band: 1.8 – 2.5GHz 2 – 8GHz




Comparison Between A-GPS and GPS

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A-GPS and GPS are different navigational aids that both use information from satellites to determine their exact location on Earth.
GPS stands for Global Positioning System. A GPS device communicates with 4 or more satellites to determine its exact location coordinates (latitude and longitude) anywhere on Earth. It works in any weather as long as the device has a clear line of sight to the satellites.
A-GPS stands for Assisted Global Positioning System. While it works on the same principles as a GPS (explained below), the difference here is that it gets the information from the satellites by using network resources e.g. mobile network, also called assistant servers.

Comparison chart

A-GPS GPS
Stands for: Assisted Global Positioning System Global Positioning System
Source of triangulation information: Radio signals from satellites and assistance servers e.g. mobile network cell sites Radio signals from GPS satellites
Speed: A-GPS devices determine location coordinates faster because they have better connectivity with cell sites than directly with satellites. GPS devices may take several minutes to determine their location because it takes longer to establish connectivity with 4 satellites.
Reliability: Location determined via A-GPS are slightly less accurate than GPS GPS devices can determine location coordinates to within 1 meter accuracy
Cost: It costs money to use A-GPS devices on an ongoing basis because they use mobile network resources. GPS devices communicate directly with satellites for free. There is no cost of operation once the device is paid for.
Usage: Mobile phones Cars, planes, ships/boats

Wednesday, April 11, 2012

Difference Between WCDMA and HSPA

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WCDMA vs. HSPA

WCDMA stands for Wideband Code Division Multiple Access, a mobile technology that improves upon the capabilities of current GSM networks that are deployed around the world. People commonly refer to this technology as 3G, or 3rd generation, and it provides newer services like video calling to the traditional call, and text messaging features that are already standard. HSPA (High Speed Packet Access) is what is commonly known as 3.5G, as it offers no substantial upgrade to the feature set of WCDMA, but improves the speed of data transmission to enhance those services.

Prior to the introduction of HSPA, WCDMA networks were only capable of reaching speeds of 384kbps. Although this might be sufficient for most services, people always want faster speeds, especially when browsing the internet or downloading files. HSPA allowed speeds above 384kbps, the most notable of which is 3.6Mbps and 7.2Mbps, which a lot of telecommunications companies often advertise. In truth, HSPA is capable of reaching much higher speeds depending on the type of modulation that is being used. HSPA speeds can even reach a theoretical maximum of 84Mbps.

Aside from increasing the existing data speed provided by WCDMA, HSPA also improved the latency, or the time it takes between the moment the request is placed and the moment the requested data is received. The lower latencies provided by HSPA makes the 3G services more real-time, and conversations are more natural. Lower latencies are also good for people who use their connection to play online games, where high latencies result in lag.

Features in HSPA that make these things possible are Fast Packet Scheduling and AMC (Adaptive Modulation and Coding). Fast Packet Scheduling allows the base station to adjust the amount of data that is being transmitted to a certain device based on the current conditions. AMC also allows the base station to select a better modulation and coding scheme if the signal quality allows it. Initially, users are assigned with QPSK, but can be changed to a lot of other coding schemes that provide better data rates if the signal between the device and the base station is strong enough.

Summary:

1. WCDMA is commonly referred to as 3G, while HSPA is commonly referred to as 3.5G.

2. HSPA provides much higher data rates compared to WCDMA.

3. HSPA has lower latency times compared to WCDMA.

4. HSPA has Fast Packet Scheduling and AMC, features that are absent in WCDMA.

Tuesday, January 3, 2012

Some words on networking

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What is Network?
A network or communication network is a system of interconnected communication devices that can communicate with one another and share information. Therefore computer network can be defined as:
'A system in which more than one computers or large number of computers are interconnected together, communicate freely with one another and share information is called computer network.'
A network can be internal to an organization or span the world by connecting itself to the internet. In computer network, network operating system is used that controls and co-ordinates the activities of computers that are connected to the network. The example of these operating systems are: windows NT, UNIX, and Novell etc.

Types of Network
Networks are of three types. These are:
  • Local Area Network (LAN)
  • Wide Area Network (WAN)
  • Metropolitan Area Network (MAN)
Local Area Network
A local area network is a network system in which computers are interconnected in a limited geographical area, such as network of computers in college computer laboratory or network of computers in office building etc.
Have an efficient networking with data center virtualization solutions to provide seamless operation.
Wide Area Network
A wide area network is a network system that covers a large geographical area such as different cities of country or different countries of the world. In WAN telephone lines, satellites, microwave, fiber optic etc. are used as transmission media.
Metropolitan Area Network
A Metropolitan area Network is a network system that covers area of a single city. Usually, MAN connects more than one LANS in a city or town and covers a smaller geographical area than a WAN. The cable television, telephone companies or local corporations use MAN.

How to Create a VPN Connection for Free

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VPN (Virtual Private Network) is a technology used to create secure connections in a public network like Internet.It often requires a username and password to connect to  a VPN.The data transferred in VPN is encrypted and the connected computers acts as if they are on same secure, local area network.Now you can connect to VPN for free and surf Internet securely.


How to Create a VPN Connection for Free:

  • Download proXPN Wizard (its free). Click here to download.
  • Once the Downloading is complete, open it and click on the Next button.

  • Accept the License agreement to continue with the installation process.
  • Now  installation will start. Be patient while the installation is underway. It may take some time.



  • Once the installation is complete click on Finish button
  • Now the proXPN login window will be open. In this click on Don’t have an Account.



Your default browser will automatically get opened.. Click on the No Thanks, I want a proXPN Basic Account.


  • Give your Email Address and password and then click on Create an Account.
  • A confirmation will be sent to your Email Address. Open your Account and click on that link.
  • Now your proXPN free Account has been created. Just go back to the installed proXPN login window and login with your Email Address and Password.





  • After this click on the Connect button. If everything goes fine then you will see a Green button in your System Tray.
That’s it! Now you are surfing safe and secure on the internet.

Sunday, October 23, 2011

Smartphone OS Comparison

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There was a time when buying a smartphone was easy. You had a couple of platforms and a handful of models to choose from. Things have changed a lot today. You now have over half a dozen platforms out there with hundreds of different models between them, priced very close to each other. It doesn't help matters when several phones are identical to each other but simply running a different brand of operating system.

You can decide what features you want in your phone but what about the operating system? There is no way you can choose between them looking at the spec sheet alone. Being in a position where we get to use all the latest smartphones on all the different platforms, we think we have answers to your operating system related questions.

What follows is a brief comparison of the top four smartphone platforms - iOS, Android, Windows Phone 7 and Symbian ^3 - where we try to find which one is the best, ultimately narrowing down your number of options while buying and helping you choose better.

Aesthetics

iOS is the oldest of the four platforms here. Even though it is four-and-a-half-years old now and has barely undergone any major UI makeover, it still looks great. The UI design has a sense of timelessness to it and no matter how many times you look at it it does not look boring. Apple has also designed it in a manner where it is out of your way most of the time so that you can concentrate on your applications. This means there are no unnecessary animations and transition effects and whatever little is there looks natural and is functional.

Android on the other hand has gone through considerable changes since its first iteration and has only got better with age. Having said that, over the years it has lost some of its simplicity and picked up some UI design elements that seem overdone, such as the 3D image gallery or the live wallpapers, which serve no functional value whatsoever and just consume resources for meaningless eye candy. This behavior is at odds with the usual Google way of designing things, where functionality takes precedents over attractiveness. Still, overall it is an attractive OS and although it lacks the timeless beauty of the iOS or the contemporary look of Windows Phone 7, it manages to look pretty good. Too bad you rarely get to see the real Android below the custom skins.

Symbian ^3 borrows the basic UI design of its predecessor and improves upon it. Despite that the end result is not something that one would call modern. You can see the roots of the operating systems, such as the soft keys at the bottom of the screen that were necessary for devices with buttons and a scroll bar for when there was no kinetic scrolling. It does not look bad per se, but it is not in the same league as others. Luckily, it is skinnable, so you can give a new look to it with a custom skin, although don't expect to make a swan out of a goose.

The latest entrant into the world of smartphones, Windows Phone 7 took the world by surprise when it was first announced, partly because no one expected Microsoft to come up with something that was so fresh and modern. The beauty of the UI design on Windows Phone 7 is unlike anything that you have seen before on other smartphones.

Unlike other operating systems here, especially Android, which borrowed heavily from iOS initially for their UI design, Microsoft came up with something that was completely original and yet incredibly good looking. So good is the UI design that most people would be seduced into buying a Windows Phone 7 device based on the look itself.

Ease of use

Designing a good looking interface is one thing. Designing a good looking interface that is also easy to use is another and no one does this better than Apple. If you don't believe us just search online for videos where kids are given an iPad or an iPhone and within minutes they manage to figure out the basics.

In our experience iOS has turned out to be the easiest mobile operating system, where everything was so clear and obvious that anyone who used it for the first time, regardless of age, could figure it out without having to refer to a manual. The reason for this is that it does not assume that the user knows how to use it and because of that you can go around doing basic things without any help. It is incredibly intuitive and makes you wonder why others haven't figured out a way to make their software work this way. It feels as if it was designed with regular human beings in mind, not robots or geeks. We loved the keyboard especially.

Next in line of intuitiveness is Android. It does not have the same level of simplicity as iOS, were you can detach you brain and still manage to work the interface, but it is still very easy nonetheless. Unfortunately, you would rarely get to use stock Android on every phone you use, which means if you are someone who's not a geek and are used to, say, an HTC Android phone, you will be lost when you pick up a Samsung Android phone.

So even though Google and the OEMs try to make the UI user friendly, the fact that there are so many different types of them is bound to leave a layperson confused.

Using the early versions of Symbian S60 5th Edition was as much fun as amputating your arm with a dull blade. The UI was designed for phones with keypads and Nokia had done little to ensure that it was usable, if not a pleasure. That's not the case with Symbian ^3, however, which feels miles ahead in terms of usability.

Things now work the way they should and there is no longer a doubt in your mind whether clicking something will just highlight it or launch it. We still don't like the way the applications are scattered across the menu and the on-screen keyboard could have been better. But overall the latest version of Symbian is pretty user friendly, and unlike Android, you don't have to worry about different interface layouts on different devices.

Windows Phone 7 may look great but it isn't the best when it comes to user friendliness. There are some things that aren't immediately apparent, such as the way you have to press and hold on certain items to display additional options. Then there is also the quirky behavior of the search button or the tiny call/end keys and the need to unlock the screen before you can receive a call. But more than anything, it's the lack of basic features such as multitasking and copy-paste for text that really makes things difficult for the users. We do love the keyboard though, which is on par with the keyboard on Gingerbread and almost as good as the one on iOS.

Features

Features was never a strong point of iOS, but over the years Apple has added a lot of functionality to the OS, such as the ability to install applications, multitasking, copy-paste, folders, etc. iOS today leaves very little room for complaint. However, there are some things that Apple is yet to take care of such as Bluetooth file transfers, file manager, mass storage, homescreen widgets and FM radio to name a few, but we have a feeling none of these will ever be addressed.

Fortunately, Apple does add additional functionality with every major firmware upgrade but more often than not these are limited to newer devices, whereas the older ones get the short end of the stick.

Android's biggest advantage over iOS has been the features and with the latest release Android has almost every feature that you could want, whether it is multitasking, widgets, tethering, Wi-Fi hotspot or Adobe Flash support. It feels the most complete out of all the four platforms here in terms of features, and if features are all that you are looking for then you would be happiest with Android.

When it comes to features, Symbian ^3 is no slouch either. You will find almost every feature here that you get on Android, along with some that you don't, such as FM radio and USB On-the-Go connectivity. You even get multiple homescreens (three, to be exact) and widgets for them, which are very handy. Features like multi-tasking and copy paste, something others have just discovered and others are yet to, have always been part of Symbian since the first iteration several years ago and have been executed perfectly. Symbian ^3 has most of the features that you would want and there wasn't anything that we felt it should have that it didn't.

This is one aspect where Windows Phone 7 fails miserably. For an operating system launching in 2010, Microsoft has left out some pretty major things. Although they are saying they will eventually incorporate most of them through updates we feel they should have had them from day one. While it was excusable to leave out on those things back in 2007, Microsoft has no such excuse, considering they were in the smartphone business even before Windows Phone 7. It does have some good features, such as the homescreen tiles, Xbox Live support, Zune pass and Office integration, but we don't think that will be enough to compete against the rivals.

Performance

When iOS first came out, it wowed the world with its fluid interface that ran perfectly even on the modest hardware of the first generation iPhone. Over the years the OS has become heavier and the proof of this is the way the iPhone 3G struggles with iOS 4.0. But try the same OS on an iPhone 4 and you will notice a world of difference. The UI is silky smooth throughout with no noticeable sluggishness. Even when switching between multiple applications, the UI maintains its smoothness without faltering.

Something similar has been observed in case of Android. As long as you provide it with fast hardware, it runs fine but tends to choke on slower devices. However, unlike iOS, even when running on faster hardware, Android is never perfectly smooth. At times you will notice unexpected and inexplicable slowdowns while going through the UI, which deters from the overall experience. Google has also added unnecessary eye candy to the UI, which also tends to bog down devices with less than perfect hardware.

Also, Android does not use the GPU to render the on-screen images, which means the CPU is overburdened, causing further slowdowns. Still, with some optimization, Android can be made to work pretty well on slower devices.
One of the greatest strengths of Symbian is that it has always been a very light operating system that could be run even by weaker hardware. This is why all the Symbian phones have hardware that seem less impressive than what we are used to seeing on high-end devices, but that is absolutely fine as even on that hardware the OS runs perfectly well.

Since the OS is so light, it removes the need to unnecessarily jack up the hardware and burn more battery in the process. This is why Symbian phones have the best battery life among smartphones. Nokia has also made good use of the on-board GPU to render all the on-screen images, leaving the CPU free to handle other tasks.
When it comes to UI smoothness, Windows Phone 7 is unbeatable. That's mostly because it is always sitting on powerful hardware, but also because the OS is well optimized for it. This is another good example of the kind of performance you get when you know what the weakest device your software would work on and then optimize it accordingly.

This is also why Android does not work well on low-end devices. The UI of Windows Phone 7 is so smooth, it gives you the illusion of moving physical objects around instead of UI elements, an illusion that Android fails to maintain, thanks to the occasional stutter. Unfortunately, the smoothness is only limited to the default applications as third-party applications could not live up to the same standards that Microsoft has set. We have seen Android developers come up with smoother applications even though they had no idea what phone their application would be running on. We hope things get better in future as these applications are updated.

Applications

This is one area where iOS pulls out a massive lead ahead of all the other platforms here. Being around the longest has certainly benefitted it and there are millions of applications available on the App Store right now waiting to be downloaded. Granted that more than half of them are not worth a second look but there are some really brilliant apps here. In fact, the general quality of applications available is the highest among all the smartphone platforms. Some of these apps have truly revolutionized the way we use our smartphones and in a way that not even Apple would have imagined when they made the iPhone. If apps are all you care about more than the device, then iOS is the platform to be on right now.

Although Android is fast catching up with iOS in terms of number of applications, we have failed to come across truly compelling apps that would sway us in favor of the Droid. Most of the great apps on Android are already available on iOS and the remaining ones are Google's own apps. There are very few great apps or games that are exclusive to Android right now. Sure, things would change down the line and once everyone realizes that Android is the better platform to develop for, considering there are no strict restrictions to follow unlike on the App Store, people would eventually make a move towards Android.

With Android already outselling iPhones in the US soon everyone would want to develop for the OS with the most number of users. Right now though, things aren't that great as such and if it's apps you want you should be looking at iOS, not Android. Also, remember that even if tomorrow Android Market does get all the great applications that does not mean they will stop making them for iOS.

There was a time when people boasted about the number of applications that Symbian has. Although it does have one of the best libraries of applications available in terms of sheer numbers, a lack of application store meant it was difficult to have access to them. Now that Nokia has the Ovi Store, things are looking better. When we reviewed the N8 we remarked about the number of applications available for it.

Even though the platform was quite new, the store had decent number of apps available for it. Even now it is growing at a steady pace. But the thing about the Ovi Store is that it will just take care of the basics and you won't be spoilt for choice as on iOS or Android. Want a Twitter client, there is Gravity. Want an IM app, use Nimbuzz. While this does make it easier to choose, at times you wish you had more apps from the same category to choose from.
Windows Phone 7 has the least impressive library of applications available for it and although one can blame this on the short period of time it has been out we must say the Windows Marketplace didn't flood with great apps the way we expected it to be.

Just like Ovi, it has all the basic applications covered, but there is nothing here that isn't available on the other platforms as of now. Also, the applications and especially games seemed unreasonably expensive on the Marketplace compared to App Store or Android Market. The same app as on these stores would cost two to three times more on the Marketplace for no reason.

Perhaps developers are seeing Windows Phone 7 as a premium platform, considering all the Windows Phone 7 devices are high-end and think they can get away with pricing their apps high (the same reason why Android developers either choose to go the ad-based way or through OEMs because they know Android buyers aren't big spenders).

Verdict

You probably expected Symbian to be at the bottom of the chart when you started reading this article, but as surprising as it may be, it isn't. That (dis)honor goes to Windows Phone 7, which has a long way to go before it can play with the big boys. Sure it has the potential to be great with a killer interface that would seduce people into buying this phone (and flame me in the comments section for writing bad about it). But right now there are few reasons to consider buying a Windows Phone 7 handset. Perhaps by the time you are ready to buy your next smartphone, it would be ready for you.

Symbian has gone through a lot of changes over the past years and it has never been in a better shape before. But we feel it has reached the end of its potential and it's about time it hands over the torch to MeeGo, which will take over as the premium operating system on Nokia's smartphones. While there is nothing bad about it, others just seem a generation ahead and although it still has the one of the best feature list around it's not enough in today's world. The fact the Ovi Store isn't exactly brimming with great quality apps is also another reason why it lags behind.

iOS has had a long and successful journey and it still has a long way to go, but it seems too rigid in today's world. The interface design is still top notch and Apple's attention to detail is exemplary. However, you still miss some of those features, such as widgets for the homescreen or a notification system that does not annoy you. More than anything else, iOS's biggest trump card is the App Store, which is undoubtedly the best in the business. But the fact that you can only enjoy this wonderful OS on two smartphones, both of which are high-end devices, does not bode well for those who don't have 'Ambani' as their last name.

Android today is a completely different animal compared to what it was two years ago. It felt rudimentary, to say the least, and although it showed potential it was difficult to predict back then what it would be today. Google has worked hard on the OS and thanks to a steady stream of updates it has completely transformed into this new OS that can go head-to-head with the best of the business. It's still far from perfect though and certain issues such as fragmentation would never be solved. But people have accepted them and found ways to make things work regardless of presence.

Today's Android offers the best combination of features, performance and support from the developer community in terms of application and the fact that it can run on even a sub Rs. 7,000 handset proves that you don't need big bucks to own a smartphone. And it's because of all these qualities that it manages to narrowly nudge ahead of iOS, which has so far been the undisputed king of the smartphone segment. So our verdict is simple, if you don't have the cash to spend on an iPhone 4, get an Android.












Thursday, September 8, 2011

Wireless window contacts -- no maintenance, no batteries

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Window contacts tell us which of a house’s windows are open or closed. Researchers have now developed a fail-safe system that is particularly easy to use and needs no wiring or batteries. The sensors harvest the energy they need to run from ambient radio signals.

It is 7:30 a.m. and high time she left the house; she mustn’t be late for her 8 o’clock appointment. But the young lady still feels the need to check that she closed all her windows, because the forecast is for thunderstorms that afternoon. Later, in the car, she realizes that she forgot to check one of the rooms when she went round the house. In situations like this, window contacts can make life easier and give peace of mind. These little electronic helpers are fitted onto window handles, and they can tell from the position of the handle whether the window is wide open, tilted open or closed. They transmit this information to a base station, and the house’s occupants can then see at a glance which windows are open.

Research scientists at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg have now developed a version of this sensor arrangement that is particularly reliable and easy to use and which needs no wiring or batteries. “Our wireless window contacts draw all their energy from ambient radio signals,” explains Dr. Gerd vom Bögel, a scientist at the IMS. Until now, wireless models have been reliant on either batteries or solar cells, but both of these approaches have drawbacks. Batteries need to be changed regularly to keep window contacts operational. Solar-powered systems avoid this problem, but they too are liable to fail: all it takes is for the sunlight to be blocked by something casting an unintentional shadow over the solar cell. Solar systems are also aesthetically less pleasing because they cannot be tucked away in a dark corner of the window. Which leaves the classic setup: window contacts with cable connections. Such systems have been on the market for years. The main argument against these is the effort it takes to install them – quite apart from the fact that it is often impossible to retrofit them to existing buildings.

The new system, however, can be fitted with little effort – and they can be positioned very discreetly. Aside from window contacts, each room is equipped with a room controller. This transmitter module not only receives the data from individual window contacts, it also actively provides the sensors with energy via its radio signal. The room controller also has the function of passing the sensor data on to a central base station in the building, from which users can query the status of all windows. Alternatively, the system can be configured to permit remote querying, for instance from a user’s smartphone. The only prerequisite for this is a DSL connection for the base station.

Energy management was the issue which caused the most headaches during development. “Room controllers, too, have to comply with certain limits on the strength of their radio output. This makes it particularly tricky to get enough energy to all the window contacts in bigger rooms,” vom Bögel points out. “But we have made sure all the sensor modules, antennas and components are so finely tuned to each other that the system works reliably even over considerable distances.”

The IMS research scientists have already constructed an initial prototype, and they know which way they want to head next: They are hoping to integrate other types of sensor into the system along the same lines – to regulate room temperature, for example. At the moment, thermostats are generally fitted somewhere just inside the room. If a door is open, the temperature by the door will be lower than in the middle of the room. As a result, the thermostat will then unnecessarily regulate the temperature upwards. The new system would allow a temperature sensor to be placed unobtrusively precisely where a particular temperature is desired – for instance on the display cabinet by the dining room table.

Source: http://www.physorg.com/

(© Fraunhofer IMS)







Friday, September 2, 2011

Direct-To-Home (DTH) Technology

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Overview

Direct to home technology refers to the satellite television broadcasting process which is actually intended for home reception. This technology is originally referred to as direct broadcast satellite (DBS) technology. The technology was developed for competing with the local cable TV distribution services by providing higher quality satellite signals with more number of channels.

In short, DTH refers to the reception of satellite signals on a TV with a personal dish in an individual home. The satellites that are used for this purpose is geostationary satellites. The satellites compress the signals digitally, encrypt them and then are beamed from high powered geostationary satellites. They are received by dishes that are given to the DTH consumers by DTH providers.

Though DBS and DTH present the same services to the consumers, there are some differences in the technical specifications. While DBS is used for transmitting signals from satellites at a particular frequency band [the band differs in each country], DTH is used for transmitting signals over a wide range of frequencies [normal frequencies including the KU and KA band]. The satellites used for the transmission of the DTH signals are not part of any international planned frequency band. DBS has changed its plans over the past few years so as to include new countries and also modify their mode of transmission from analog to digital. But DTH is more famous for its services in both the analog and digital services which includes both audio and video signals. The dishes used for this service is also very small in size. When it comes to commercial use, DBS is known for its service providing a group of free channels that are allowed for its targeted country.

How DTH Works

To know the working of DTH better, take a look at the diagram below.


For a DTH network to be transmitted and received, the following components are needed.

* Broadcasting Centre
* Satellites
* Encoders
* Multiplexers
* Modulators
* DTH receivers

It must be noted the channels that are broadcasted from the broadcasting centre are not created by the DTH providers. The DTH providers pay other companies like HBO, Sony MAX and so on for the right to broadcast their channel to the DTH consumers through satellite. Thus the DTH provider acts as a mediator r broker between the consumers and the programme channels.

The broadcast centre is the main part of the whole system. It is from the broadcast station that the signals are sent to the satellites to be broadcasted. The broadcast station receives the signals from various program channels.

The satellite receives the signal from the broadcast centre and compresses the signals and makes them suitable for re-transmission to the ground.

The DTH providers give dish receivers for the viewers to receive the signal from the satellites. There may be one or multiple satellites that send the signals at the same time. The receiver receives the signal from them and is passed on to the Set Top Box [STB] receiver in the viewer’s house.

The STB receiver changes the signal in a form suitable for our television and then passes it on to our TV.

Advantages of DTH Technology

* The main advantage is that this technology is equally beneficial to everyone. As the process is wireless, this system can be used in all remote or urban areas.
* High quality audio and video which are cost effective due to absence of mediators.
* Almost 4000 channels can be viewed along with 2000 radio channels. Thus the world’s entire information including news and entertainment is available to you at home.
* As there are no mediators, a complaint can be directly expressed to the provider.
* With a single DTH service you will be able to use digital quality audio, video and also high speed broadband.







LED TV Vs LCD TV

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There are some differences that should be noted in the issue of LED TV vs. LCD TV. For starters, a traditional LCD television was created to use florescent lighting or another form of flat lighting while an LED TV will make use of a diode that emits light through an LCD panel. Furthermore, there are a number of different lighting styles within both LED and LCD TVs. For instance, some models contain an LED light panel located behind the LCD panel. In other models, LED lights are found around the outer rim of the screen. While in other models LED lights are tricolored and can be controlled in a way that will allow the picture to have stronger contrasts with blacks and bright colors. This feature is known as local dimming which is ultimately what makes the LED TV so different from traditional LCD television.

Picture Differences between LED TV Vs LCD TV

When a traditional LCD television is in operation, the backlight is always on. LCD televisions create dark areas in contrast by twisting crystals to a closed position to block light. This method provides fewer details in dark areas of the screen by offering a small contrast ratio. The local dimming of LED technology will correct the lower quality dark areas in LCD television. Since the LED diodes that control the lights in this technology are capable of being dimmed rather than blocked, higher details in darker areas of the picture are created. Therefore, LED TV Vs. LCD TV will find a greater advantage in the local dimming possibility of LED technology, simply for the higher contrast providing a detailed picture, and displaying more realistic color.

Life of LED and LCD TV

Another consideration in the LED TV Vs. LCD TV issue is the lifetime of the two television technologies. Many manufacturers will claim that their model will produce roughly 100,000 hours of life. However, since LED is still fairly new there is little data that states the length of the lifecycle of this television. Also model, manufacturer, and type of LED technology can play an important part in determining lifespan. It is true to say that since LED TV technology displays a better picture, there are a larger number of LCD TVs with this technology being produced than traditional LCD television. As this continues it is safe to say that the lifespan of an LED TV will become increasingly longer as it’s popularity continues grows.

Differences in Power Consumption of LED and LCD

In LED TV Vs. LCD TV is important to mention that the LED diodes used in local dimming will consume more power than traditional LCD televisions of the same size. In fact, the local dimming LED technology uses almost as much power as a plasma television. However, although the traditional LCD TV uses less power than the local dimming LED TV technology, it is also true to say that the white edge lit LED technology (LED lights located around the edge of the screen) uses less power than both LCD TV, and local dimming LED TV.




LED Television Technology

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What is LED Backlight TV?
LED (Light Emitting Diode) TVs are basically LCD TVs that use a LED backlight system to illuminate the LCD screen. There are two methods to accomplish this:

1) LED edge lighting (Edge lit): In this method, LED lights are placed around the perimeter (sides) only. This allows for a slimmer TV design.
2) LED Backlight (Array lit): In this method, LED lights are placed in the form of an array (across the whole back of the display). Any of the lights can be turned off to correspond with the scene being displayed, and this is why it can project such an accurate picture.

What makes LED TVs better than traditional LCD TVs?
The advantages include:
Superior picture quality
LED TVs will produce deeper blacks due to “local dimming” technology. In comparison, LCD TVs produce a lower picture quality, especially when projecting dark backgrounds. The Cold Cathode Fluorescent Lamp (CCFL), which is located behind the screen, does not actually remain cool. Instead of using all of its energy to produce light, it wastes energy in the form of heat. Further, since the CCFL current flow must be kept at a high level to preserve its lifespan, LCD screens cannot be easily dimmed. This is one of the reasons why LED TVs can operate more efficiently while providing a more precise image quality.
Slim design
LED TVs have an ultra-thin design because of the LED backlight technology. This design makes it easy to mount your LED television on the wall to save space.

Power efficiency
LED TVs use less power than plasma and traditional LCD TVs. In fact, Samsung states that their TVs use 40% less power than a conventional TV. Switching to a LED TV will save you money on your monthly electrical bill and waste less energy on producing heat.

Eco-friendly
LED TVs are considered to be more environmentally friendly than fluorescent tubes because LED bulbs are mercury and lead free. LED TVs can also operate for longer hours (15 times longer than ordinary bulbs). The overall lifespan is much longer than your average TV.

Given that it is still relatively new and that it is a superior technology, LED TVs are a little more expensive than plasma and LCD TVs. Samsung, a leader in the TV industry, has a wide range of LED TVs that range from $1,600 – $3,200 depending on the size.



Thursday, September 1, 2011

LCD Television Technology

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Introduction to LCD Television

Like the popular flat panel LCD monitors that are now commonly used with computers, LCD Televisions have a slim design and a flat viewing surface, but have been fine tuned for video and television display. Recent advances in flat panel LCD television technology now allow for larger screens, wider viewing angles, and higher-quality video images. LCD Televisions are also competing with plasma television technology. They are several times lighter than comparably sized plasma televisions, and are far more durable.

All LCD Televisions offer progressive scan displays and sleek, slim designs. They also provide users with a bevy of input options, adding to their versatility. Most LDC televisions double as computer displays by allowing standard analog VGA (PC) or even DVI digital input, a great option if you need your LCD Television to pull double duty as a PC monitor. Nearly all LCD Television sets offer the option to mount on a wall, under a cabinet, on on a desktop.

How LCD Televisions Work

An LCD Television is sometimes referred to as a "transmissive" display—light isn't created by the liquid crystals themselves; a light source behind the panel shines light through the LCD Television display. A white diffusion panel behind the LCD redirects and scatters the light evenly to ensure a uniform image.

The LCD television display consists of two polarizing transparent panels and a liquid crystal solution sandwiched in between. The screen's front layer of glass is etched on the inside surface in a grid pattern to form a template for the layer of liquid crystals. Liquid crystals are rod-shaped molecules that bend light in response to an electric current — the crystals align so that light cannot pass through them. Each crystal acts like a shutter, either allowing light to pass through or blocking the light. The pattern of transparent and dark crystals forms the image. It's the same display technology behind your digital watch but way more sophisticated.

LCD Televisions typically use the most advanced type of LCD, known as an "active-matrix" LCD. This design is based on thin film transistors (TFT) — basically, tiny switching transistors and capacitors that are arranged in a matrix on a glass substrate. Their job is to rapidly switch the LCD's pixels on and off. In an LCD Television, each color pixel is created by three sub-pixels with red, green and blue color filters.

One of the biggest challenges for LCD television manufacturers has been speeding up the "pixel response" time (how fast an individual pixel's color can change without blurring) to ensure that fast-moving objects don't exhibit "motion lag" or ghosting. It's especially critical for larger-screen LCD Televisions where much of the viewing will be DVD movies and/or HDTV.

An important difference between plasma and LCD television technology is that an LCD television screen doesn't have a coating of phosphor dots (colors are created through the use of filters). That means you'll never have to worry about image burn-in, which is great news, especially for anyone planning to connect a PC or video game system. LCD televisions are extremely energy-efficient, typically consuming 60% less power than comparably-sized tube-type direct-view TVs.







Wednesday, April 27, 2011

Microturbines

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Introduction and Summary

Microturbines are small electricity generators that burn gaseous and liquid fuels to create highspeed rotation that turns an electrical generator. Today’s microturbine technology is the result of development work in small stationary and automotive gas turbines, auxiliary power equipment, and turbochargers, much of which was pursued by the automotive industry beginning in the 1950s. Microturbines entered field testing around 1997 and began initial commercial service in 2000.

Sunday, November 7, 2010

BARCODE

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    A barcode is an optical machine-readable representation of data, which shows certain data on certain products. Originally, barcodes represented data in the widths (lines) and the spacings of parallel lines, and may be referred to as linear or 1D (1 dimensional) barcodes or symbologies. They also come in patterns of squares, dots, hexagons and other geometric patterns within images termed 2D (2 dimensional) matrix codes or symbologies. Although 2D systems use symbols other than bars, they are generally referred to as barcodes as well. Barcodes can be read by optical scanners called barcode readers, or scanned from an image by special software.


Why use barcodes?
    As far back as the 1960s, barcodes were used in industrial work environments. Some of the early implementations of barcodes included the ability identify rail road cars.
    In the early 1970s, common barcodes started appearing on grocery shelves. To automate the process of identifying grocery items, UPC barcodes were placed on products.
    Today, barcodes are just about everywhere and are used for identification in almost all types of business.
    When barcodes are used in the business process, procedures are automated to increase productivity and reduce human error.
    Whenever there is a need to accurately identify or track something, bar-coding should be used. For example, in a data entry work environment, workers may be required to enter an enormous amount of data into a customer database system.
    Instead of manually typing a customer identification number into a database, if the information is contained in a barcode, a data entry operator may scan it in. This would increase automation and reduce human error.