How Bar code Scanners Work(BCR - Bar-code Reader)

How do Bar code Scanners work? To understand how a barcode scanner works, we have to explore the different parts of the device. Basically, there are 3 functional parts to the bar code scanner itself, the illumination system, the sensor / converter, and the decoder. The simple explanation... Barcode scanners begin by illuminating the code with red light. The sensor of the barcode scanner detects the reflected light from the illumination system and generates an analog signal with varying voltage that represent the intensity (or lack of intensity) of the reflection. Theconverter changes the analog signal to a digital signal which is fed to the decoder. Thedecoder interprets the digital signal, does that math required to confirm and validate that the barcode is decipherable, converts it into ASCII text, formats the text and sends it to the computer the scanner is attached to. Let's look at each functional part of a barcode scanner in more detail: Illumination Systems - The illumination system is the method by which the bars and spaces on the barcode are illuminated. There are a variety of illumination systems commonly used in barcode scanners: Single Point LED - This technology is exclusive to the barcode wand reader and the barcode slot reader. The illumination of the barcode comes from either a single or pair of LED's and is focused through a single ball-type opening.  This technology requires the ball to physically touch the barcode being scanned.                 Since the illumination is on a single point, the operator has to provide motion to the barcode past the light source. In the case of a barcode wand, the operator drags the illumination ball across the barcode. For swipe or slot readers, the barcode is typically printed on a credit-card like media. The operator pulls the card through a fixed slot, past the illuminating head.  Slot and wand readers are inexpensive, and can accommodate any length of barcode. There are several disadvantages of the single point illumination method. Slot and wand readers require the operator to control the speed at which the barcode passes in front of the illumination head. Because barcodes must be in contact with the illumination head to read, the barcode can easily be damaged by abrasion of the head on the media that hosts the printed barcode. Although the illumination head is hardened, it will wear out and must be replaced regularly. Linear Multiple LED - Expanding on the single-point illumination system, placing multiple LED's in a line give the ability to light the entire width of the barcode. This type of illumination is used in CCD scanners and Linear Imagers. When used in CCD scanners, the LED's are paired with a line of photocells to detect the reflected light from the barcode  Since the LED's are relatively low in power, and the photocells are low in sensitivity, the range of CCD barcode scanners is generally limited from being in contact with the barcode to 1" away. Laser - This type of illumination method uses a single point red laser diode similar to a laser pointer. The point of light is expanded into a line by oscillating the laser into a stationary mirror, or projecting the point into an oscillating mirror.  This illumination method is very popular because of the working distances typically achieved are superior to the point illumination or linear LED illumination methods. Typical working distances are from 1" to 18". By increasing the power of the laser and decreasing the angle of oscillation, ranges of over 20 feet can be obtained. LED Imager - The linear and full imager is very similar to the CCD device, with some important changes. In linear imagers, the amount of illumination is increased by using high light LED's, and the sensing photocells are more sensitive. Linear imaging technology mimics both the range and focus of laser scanners. In full imagers, high-intensity LED's illuminate a square scanning "target". The light sensors in full imagers are very similar to the light sensors in monochrome cameras. The sensors search the scanning square target for a valid barcode. By pairing the target square with sensors that search the target square for a valid barcode, LED full imagers are omni directional - you don't have to line up the barcode in any way in order for it to be decoded. The target / snapshot method give LED imagers the ability to read 2-dimensional barcodes as well. Regardless of the method used to illuminate the barcode, the illumination method is causes reflected light to return to the scanner head and be seen by the sensor. Pen Type Readers and Laser Scanners Pen type readers consist of a light source and a photo diode that are placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars in a steady even motion. The photo diode measures the intensity of the light reflected back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the bar code. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is an exact duplicate of the bar and space pattern in the bar code. This waveform is decoded by the scanner in a manner similar to the way Morse code dots and dashes are decoded. Laser scanners work the same way as pen type readers except that they use a laser beam as the light source and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. Just the same as with the pen type reader, a photo diode is used to measure the intensity of the light reflected back from the bar code. In both pen readers and laser scanners, the light emitted by the reader is tuned to a specific frequency and the photo diode is designed to detect only this same frequency light. Pen type readers and laser scanners can be purchased with different resolutions to enable them to read bar codes of different sizes. The scanner resolution is measured by the size of the dot of light emitted by the reader. The dot of light should be equal to or slightly smaller than the narrowest element width ("X" dimension). If the dot is wider than the width of the narrowest bar or space, then the dot will overlap two or more bars at a time thereby causing the scanner to not be able to distinguish clear transitions between bars and spaces. If the dot is too small, then any spots or voids in the bars can be misinterpreted as light areas also making a bar code unreadable. The most commonly used X dimension is 13 mils (roughly 4 printer dots on a 300 DPI printer). Because this X dimension is so small, it is extremely important that the bar code is created with a program that creates high resolution graphics (like B-Coder).

Pranav Mistriy`s SixthSense

integrating information with the real world

          

         

'SixthSense' is a wearable gestural interface that augments the physical world around us with digital information and lets us use natural hand gestures to interact with that information.

We've evolved over millions of years to sense the world around us. When we encounter something, someone or some place, we use our five natural senses to perceive information about it; that information helps us make decisions and chose the right actions to take. But arguably the most useful information that can help us make the right decision is not naturally perceivable with our five senses, namely the data, information and knowledge that mankind has accumulated about everything and which is increasingly all available online. Although the miniaturization of computing devices allows us to carry computers in our pockets, keeping us continually connected to the digital world, there is no link between our digital devices and our interactions with the physical world. Information is confined traditionally on paper or digitally on a screen. SixthSense bridges this gap, bringing intangible, digital information out into the tangible world, and allowing us to interact with this information via natural hand gestures. ‘SixthSense’ frees information from its confines by seamlessly integrating it with reality, and thus making the entire world your computer.

 

          

The SixthSense prototype is comprised of a pocket projector, a mirror and a camera. The hardware components are coupled in a pendant like mobile wearable device. Both the projector and the camera are connected to the mobile computing device in the user’s pocket. The projector projects visual information enabling surfaces, walls and physical objects around us to be used as interfaces; while the camera recognizes and tracks user's hand gestures and physical objects using computer-vision based techniques. The software program processes the video stream data captured by the camera and tracks the locations of the colored markers (visual tracking fiducials) at the tip of the user’s fingers using simple computer-vision techniques. The movements and arrangements of these fiducials are interpreted into gestures that act as interaction instructions for the projected application interfaces. The maximum number of tracked fingers is only constrained by the number of unique fiducials, thus SixthSense also supports multi-touch and multi-user interaction




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The SixthSense prototype implements several applications that demonstrate the usefulness, viability and flexibility of the system. The map application lets the user navigate a map displayed on a nearby surface using hand gestures, similar to gestures supported by Multi-Touch based systems, letting the user zoom in, zoom out or pan using intuitive hand movements. The drawing application lets the user draw on any surface by tracking the fingertip movements of the user’s index finger. SixthSense also recognizes user’s freehand gestures (postures). For example, the SixthSense system implements a gestural camera that takes photos of the scene the user is looking at by detecting the ‘framing’ gesture. The user can stop by any surface or wall and flick through the photos he/she has taken. SixthSense also lets the user draw icons or symbols in the air using the movement of the index finger and recognizes those symbols as interaction instructions. For example, drawing a magnifying glass symbol takes the user to the map application or drawing an ‘@’ symbol lets the user check his mail. The SixthSense system also augments physical objects the user is interacting with by projecting more information about these objects projected on them. For example, a newspaper can show live video news or dynamic information can be provided on a regular piece of paper. The gesture of drawing a circle on the user’s wrist projects an analog watch.




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 Android Architecture

The following diagram shows the major components of the Android operating system. Each section is described in more detail below.

On November 5th, 2007 leading technology and wireless companies came together to announce the future development of a truly open platform for all kinds of mobile devices – Android. Leading this development are Google Inc, T-Mobile, Intel, HTC, Qualcomm, Motorola along with many other companies under the umbrella of the Open Handset Alliance – a global alliance between technology and mobile industry leaders.

 

The Open Handset Alliance’s common goal is to foster and develop a new breed of innovation for mobile devices allowing a far better user experience than today’s current mobile platforms. 

The OHA will provide a far greater degree of openess that will enable developers to work and collaborate in ways never before seen, Android will greatly improve and speed up the process in which new and innovative mobile services are development and made available to the end user.

 

Through the development of Android, developers, manufacturers and operators will be far better positioned to ship out new and innovative products far quicker and far cheaper than todays standards.

The Android platform will consist of an operating system, middleware, a user-friendly interface and powerful applications. 

This fully integrated bundle of software will sgnificantly lower the current costs of developing mobile devices and services.

The Android platform is licensed under one of the most progressive open-source licenses available giving operators and manufacturers unprecedented freedom to design, build and distribute their own products.

All Apple Products Launch From Starting History
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How Touch Screen Technology Works

This is for every person who ever wondered how in the world the iPhones touch screen works!! Ill add more to how the GUI works and about the iPhone for all the noobs like me who had no idea how it works. until now...

The basic idea is pretty simple -- when you place your finger or a stylus on the screen, it changes the state that the device is monitoring. In screens that rely on sound or light waves, your finger physically blocks or reflects some of the waves. Capacitive touch-screens use a layer of capacitive material to hold an electrical charge; touching the screen changes the amount of charge at a specific point of contact. In resistive screens, the pressure from your finger causes conductive and resistive layers of circuitry to touch each other, changing the circuits' resistance.


Most of the time, these systems are good at detecting the location of exactly one touch. If you try to touch the screen in several places at once, the results can be erratic. Some screens simply disregard all touches after the first one. Others can detect simultaneous touches, but their software can't calculate the location of each one accurately. There are several reasons for this, including:

Many systems detect changes along an axis or in a specific direction instead of at each point on the screen.
Some screens rely on system-wide averages to determine touch locations.
Some systems take measurements by first establishing a baseline. When you touch the screen, you create a new baseline. Adding another touch causes the system to take a measurement using the wrong baseline as a starting point.


Multi-touch Systems
To allow people to use touch commands that require multiple fingers, the iPhone uses a new arrangement of existing technology. Its touch-sensitive screen includes a layer of capacitive material, just like many other touch-screens. However, the iPhone's capacitors are arranged according to a coordinate system. Its circuitry can sense changes at each point along the grid. In other words, every point on the grid generates its own signal when touched and relays that signal to the iPhone's processor. This allows the phone to determine the location and movement of simultaneous touches in multiple locations. Because of its reliance on this capacitive material, the iPhone works only if you touch it with your fingertip -- it won't work if you use a stylus or wear non-conductive gloves.

Interpreting Touch-location Data

The iPhone's processor and software are central to correctly interpreting input from the touch-screen. The capacitive material sends raw touch-location data to the iPhone's processor. The processor uses software located in the iPhone's memory to interpret the raw data as commands and gestures. Here's what happens:

Signals travel from the touch screen to the processor as electrical impulses.

The processor uses software to analyze the data and determine the features of each touch. This includes size, shape and location of the affected area on the screen. If necessary, the processor arranges touches with similar features into groups. If you move your finger, the processor calculates the difference between the starting point and ending point of your touch.

The processor uses its gesture-interpretation software to determine which gesture you made. It combines your physical movement with information about which application you were using and what the application was doing when you touched the screen.
The processor relays your instructions to the program in use. If necessary, it also sends commands to the iPhone's screen and other hardware. If the raw data doesn't match any applicable gestures or commands, the iPhone disregards it as an extraneous touch.

All these steps happen in an instant -- you see changes in the screen based on your input almost instantly. This process allows you to access and use all of the iPhone's applications with your fingers. We'll look at these programs and the iPhone's other features in more detail in the next section, as well as how the iPhone's cost measures up to its abilities.

What is a mouse?

The mouse is a pointing device which helps us to operate the computer. Unlike the complicated hardwares such as Mother board,RAM, Hardisk, Processor of the computer, the mouse is designed with a simple circuit to process. Now a days, we get varieties of mouse with different technologies in the market.

The developing applications in the computer field has not completely excluded the mouse yet. Although, we have switched to Touchpads in Laptops, "the function of mouse is easy and user-friendly when compared with touch pads for a new user", says the users. Mostly all the applications are operated with mouse for easy working. In recent days, the optical mouse had overcome the old ball mouse, because of its 'easy to use' function.

Disadvantages of Ball mouse

With the previous ball-rolled mouses, the movement of the pointer in the computer  is decided by the ball inside the mouse. So, if the ball gets damaged, or if dust gets clustered, the operation of the mouse becomes problem. When dust gathers, it takes some time to clear it too.With these disadvantages, the ball mouse was slowly moved away form the computer technology leaving the optical mouse to fill its space.

Working of Optical mouse

Now, almost everyone tries to switch from ball/roller mouse to Optical mouse. As the cost of the mouse is also being decreasing, the replacement is quiet quicker.To connect this optical mouse, the necessity is PS/2 or USB plug, and windows, macintosh or LINUX operating system installed in the computer.

The main components of the optical mouse are:

• Inbuilt optical sensor
• High speed camera which can take 1000 pictures at a time
• LED

These optical mouses do have an inbulit optical sensor. The optical sensor reads the movements of the optical mouse (moved by the user) with the help of the light rays which comes out from the bottom. ( The area in which a light glows). When the user moves the optical mouse, the LED (Light Emitting Diode) present inside the mouse emits the light according the minute movements. These movements are send to the camera as light rays. The camera captures the difference in light rays as images. When the camera captures the images, each and every pictures and compared to one another with the digital technology. With the comparison, the speed of the mouse and the direction of the movement of the mouse are rapidly calculated. According to the calculation, the pointer moves on the screen.

  

Comparison between a roller/ball  mouse and optical mouse

• The optical mouse does not have any movable parts as of the ball mouse. So, the life of the optical mouse is long compared to the ordinary mouse.
• Since the mouse works with the sensor recognition, the movements are clearly captured and so the moves gives out a same function in all moves.
• Since the ball is absent in the optical mouse, the weight of the optical mouse is less than that of the ball mouse.
• The dust clustering problem is abolished in the optical mouse as its parts are all static.
• The optical mouse can also function good without a mouse pad, which is impossible with ordinary mouses.Any way, optical mouses cannot be used above reflecting glasses or any glass materials.

What is a Network?

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

The two basic types of networks include:

• Local Area Network (LAN)
• Wide Area Network (WAN)

You may also see references to a Metropolitan Area Networks (MAN), a Wireless LAN (WLAN), or a Wireless WAN (WWAN).

Local Area Network

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Rarely are LAN computers more than a mile apart.

In a typical LAN configuration, one computer is designated as the file server. It stores all of the software that controls the network, as well as the software that can be shared by the computers attached to the network. Computers connected to the file server are called workstations. The workstations can be less powerful than the file server, and they may have additional software on their hard drives. On many LANs, cables are used to connect the network interface cards in each computer; other LANs may be wireless. See the Topology, Cabling, and Hardware sections of this tutorial for more information on the configuration of a LAN.

Wide Area Network

Wide Area Networks (WANs) connect larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of network.

Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of minutes, without paying enormous phone bills. A WAN is complicated. It uses multiplexers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN.

Advantages of Installing a School Network

• Speed. Networks provide a very rapid method for sharing and transferring files. Without a network, files are shared by copying them to memory cards or discs, then carrying or sending the discs from one computer to another. This method of transferring files (referred to as sneaker-net) can be very time-consuming.
• Cost. Networkable versions of many popular software programs are available at considerable savings when compared to buying individually licensed copies.
• Security. Files and programs on a network can be designated as "copy inhibit," so that you do not have to worry about illegal copying of programs. Also, passwords can be established for specific directories to restrict access to authorized users.
• Centralized Software Management. One of the greatest benefits of installing a network at a school is the fact that all of the software can be loaded on one computer (the file server). This eliminates that need to spend time and energy installing updates and tracking files on independent computers throughout the building.
• Resource Sharing. Sharing resources is another advantage of school networks. Most schools cannot afford enough laser printers, fax machines, modems, scanners, and CD players for each computer. However, if these or similar peripherals are added to a network, they can be shared by many users.
• Electronic Mail. The presence of a network provides the hardware necessary to install an e-mail system. E-mail aids in personal and professional communication for all school personnel, and it facilitates the dissemination of general information to the entire school staff. Electronic mail on a LAN can enable students to communicate with teachers and peers at their own school. If the LAN is connected to the Internet, students can communicate with others throughout the world.
• Flexible Access. School networks allow students to access their files from computers throughout the school. Students can begin an assignment in their classroom, save part of it on a public access area of the network, then go to the media center after school to finish their work. Students can also work cooperatively through the network.
• Workgroup Computing. Collaborative software allows many users to work on a document or project concurrently. For example, educators located at various schools within a county could simultaneously contribute their ideas about new curriculum standards to the same document, spreadsheets, or website.

Disadvantages of Installing a School Network

• Expensive to Install. Although a network will generally save money over time, the initial costs of installation can be prohibitive. Cables, network cards, routers, and software are expensive, and the installation may require the services of a technician.
• Requires Administrative Time. Proper maintenance of a network requires considerable time and expertise. Many schools have installed a network, only to find that they did not budget for the necessary administrative support.
• File Server May Fail. Although a file server is no more susceptible to failure than any other computer, when the files server "goes down," the entire network may come to a halt. When this happens, the entire school may lose access to necessary programs and files.
• Cables May Break. The Topology chapter presents information about the various configurations of cables. Some of the configurations are designed to minimize the inconvenience of a broken cable; with other configurations, one broken cable can stop the entire network.
• Must Monitor Security Issues. Wireless networks are becoming increasingly common; however, security can be an issue with wireless networks.

How computer RAM works?

Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. The capacitor holds the bit of information -- a 0 or a 1. The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.

RAM stands for Random Access Memory. This means Information can be retrieve and store by the computer at any order. RAM gives your computer a temporary place to process electronic data. This means that, RAM chips continue to store information only as long as computer has electrical power. In other words, when you shut off your computer, all the data stored in RAM are lost.
All actual computing starts with the the CPU (Central Processing Unit).

The chipset supports the CPU and contains several controllers that control how information travels between the CPU and other components in the PC.

The memory controller is part of the chipset and establishes the information flow between memory and the CPU.

A bus is a data path that consists of parallel wires and connects the CPU, memory and other devices. The bus architecture determines how much and how fast data can move around the motherboard.

The memory bus goes from the memory controller to the computer's memory sockets. Newer systems have a frontside bus (FSB) from the CPU to main memory and a backside bus (BSB) from the memory controller to L2 cache.

For the PC to get information...

The CPU sends a request to the memory controller to memory and gets a report back of when the information will be available. This cycle can vary in length according to memory speed as well as other factors, such as bus speed.

Residing on the motherboard, the system clock sends a signal to all components, just like a metronome ticking. Each click of the clock represents a clock cycle. A clock running at 100Mhz represents 100 million clock cycles per second. Every action is timed by the clock where different actions require a different number of clock cycles.

Many people assume that the speed of the processor is the speed of the computer. Most of the time, the system bus and other components run at different speeds. Because all information processed by the CPU is written or read from memory, the performance of a system is dramatically affected by how fast information can travel between the CPU and memory. Therefore, faster memory technology contributes greatly to the overall system performance.

Cache memory is a relatively small amount (normally less than 1 MB) of high speed memory and resides very close to the CPU. It is designed to supply the CPU with the most frequently requested data. It takes a fraction of the time, compared to normal memory, to access cache memory.

The concept is that 20% of the time, what is needed is in cache. The cache memory tracks instructions, putting the most frequent used instruction at the top of the list. Once the cache is full, the lowest need is dropped.

Today, most cache memory is incorporated in the CPU. It can also be located just outside of the CPU. Cache that is closest to the CPU is labeled Level 1, the next closest Lever 2, etc.

Interleaving is a process in which the CPU alternates between two or more memory banks. Every time the CPU addresses a memory bank, the bank needs about one clock cycle to reset. The CPU can save processing time by addressing a second bank while the first bank is resetting.

Check this site for  information about DDR SDRAM memory and DDR Memory recommendations.