Analyze Capabilities Copyright © 2010 Cannady ACOS. All rights reserved
OBJECTIVE n n The objective of this lesson is for each student to analyze capabilities and limitations of current and emerging technologies. Sample(s) of Behavior (SOBs): n n Assess effects of technology on culture, economics, politics, and the environment Compare capabilities of various technologies to address personal, social, lifelong learning, and career needs
TV AND CINEMA 3 D If you have ever been asked to find out a bit more information about a piece of technology or explain how something works, the chances are that after searching the internet you could end up more baffled than when you first started. Our solution is to explain some of the more commonly used technologies in plain, simple English. n. TV and Cinema 3 D n. What is it? It is a three dimensional (3 D) visual technology designed to give you a sense of depth when viewing a program or film. It has become very popular recently, with many cinemas offering '3 D' films and televisions offering built-in 3 D technology
TV AND CINEMA 3 D Continued How does it work? n. All current methods take advantage of the fact that your brain is able to combine the images from your left and right eye to give you a sense of depth. n. Unfortunately, not everyone has 3 d vision - this author has only ever seen out of one eye, so 3 d is a bit of a mystery! n. The way it works is that the projection device or television sends out two images, each slightly displaced from one another. n. Without the right equipment, you just see a blurry pair of moving images. The trick is to make the right eye only see one image and the left eye only see the other image. n. This is done by using an electronic pair of spectacles, but instead of glass lenses they have a pair of electronic shutters.
TV AND CINEMA 3 D Continued n. The shutters are exactly synchronized with the timing of the images - When image 1 is being displayed, the right 'lens' is blocked and so only the left eye sees image 1, then an instant later image 2 is displayed and the left lens is blocked so only the right eye sees this image. n. Now your brain senses two images and combines them into one solid-looking experience. This interplay between the spectacles and the film continues to the end of the film Is it new? n. Not really, even sixty years ago cinemas were trying it out. Back in the day they used a red lens and a green lens to differentiate the two images. But it never caught on because of the inconvenience of having to wear the special specs and the effect was not as dramatic as it is today. Are there issues? n. Yes, because something has to be compromised to create the two images.
TV AND CINEMA 3 D Continued The choices are: 1. Interleave the images in time. At one instant image 1 is present, then the next instant image 2 is displayed. But now each image is only present for half the time. You will sense this as a loss of brightness. 2. Interleave the images on the screen. With this method half the rows of pixels are used by image 1 and the other rows are used by image 2. But now you have effectively halved your resolution. Not so easy to give you a HD experience. 3. Use two projectors, or use a television with twice the resolution. Both of which are very expensive options. Only the most sophisticated cinemas can afford to do this. 4. There are different 3 d technologies in use and they are not compatible.
TV AND CINEMA 3 D Continued And the future? n. The most inconvenient feature of 3 d today is having to wear the specs / visor. Many companies are looking at ways of providing a 3 d experience without the need to wear any special equipment on your part. n. For instance, 3 d holographic displays produce truly 3 d images as you can literally walk around the display to see the back or the front. But these are still laboratory items at the moment.
TV AND CINEMA 3 D Continued n. Lenticular displays have small prism-like shapes on their surface that split the two images. If you look at it from one angle you see image 1, if you look at it from the opposite angle you see image 2. But you need to be within a short, narrow range for this to work well. n. As an interesting aside, this is how it is possible for the passenger in a luxury car to view a DVD film on the dashboard screen whilst the driver can only see the boring Sat-Nav on the same display at the same time. n. Perhaps eventually we will have full-color, wide-angle, user-tech free 3 d technology. But not quite yet.
WHAT IS BLUETOOTH? Bluetooth is a type of radio communication and networking protocol combined. Why was it developed? n. It was developed so devices close to one another could exchange data. n. By close, we mean within about 10 meters of one another even if there is a wall in-between. Advantages of Bluetooth n. One advantage with Bluetooth working within a short range is that it only needs a tiny amount of radio power to work, less than a thousandth' of a Watt. (A torch light uses about 1 Watt to light the bulb) so you can see this is a tiny amount of power. This means it is ideal for battery operated devices such as mobile.
WHAT IS BLUETOOTH? Continued n. Another advantage of Bluetooth is that it is completely automatic - every Bluetooth enabled device will sense the presence of another device within range. They can do this because they share a 'network protocol' that allows them to share data. n. Another clever thing about the protocol is that it can reduce interference from other Bluetooth devices that are also exchanging data nearby. For example if Sam's mobile is exchanging data with Tom's mobile this will not interfere with Sarah's mobile also exchanging data with Mary's mobile nearby. n. Another very common way of sending data over a short distance is to use Infra-Red. This is used widely in TV remote controls. The disadvantage of Infra-Red over Bluetooth is that you must point the control directly at the device.
WHAT IS BLUETOOTH? Continued Examples of how it is used. n. A Bluetooth enabled phone will detect phones nearby and provide you with a list of usernames. You can then send a message, photograph or movie sitting on your phone to any of the usernames. They, of course, have to accept the offer but the rest of it is automatic. n. Another common use of Bluetooth is 'hand-free' operation of mobiles in the car. You wear a Bluetooth headset that senses your mobile nearby. This allows you to talk using the mobile, but most importantly, keeping your hands on the steering wheel! Bluetooth is also used to exchange files between a PDA and a desktop computer - great for keeping your diary and work in synch.
WHAT IS BLUETOOTH? Continued Trivia Facts Fact 1: Harold Blatand "Bluetooth" refers to Harold Blatand, the 10 th-Century Danish king who brought together the Danes and Norwegians. Fact 2: Andretti Green Racing Team The famous Andretti Green Racing team stays connected while racing using Bluetooth devices. Fact 3: Bluetooth in the car It is predicted that by the year 2012 one-third of all new cars will have built-in Bluetooth connections. Fact 4: Bluetooth enabled medical equipment is being employed by an increasing number of hospitals around the world, in an effort to improve patient care.
WHAT IS BLUETOOTH? Continued Fact 5: Digital images sent over Bluetooth technology You can view digital pictures on your television by sending images from laptops or mobile phones over a Bluetooth connection to a media viewer. Fact 6: Printing with Bluetooth technology You can send files from a computer to a printer wirelessly using Bluetooth technology. Fact 7: Multi-point pairing enables you to simultaneously connect two Bluetooth enabled devices (e. g. a phone can be connected to both a PC & a pair of headphones). Source of factoids: Thanks to Motorola.
WHAT IS ENCRYPTION? What is it? n Encryption means to scramble data in such a way that only someone with the secret code / key can read it. Is it new? n Encryption has been around for thousands of years in various forms. For example in Ancient Greece the story goes that a general wanted to send a secret message back to his city, so he had a soldier's head shaven and the message written on his scalp. Soon enough his hair grew back enough to hide the message and was sent off running to the city. When the soldier arrived, the city official knew the secret 'key' i. e. shave his head to reveal the message. Why is it important? n Today, encryption is far more sophisticated, but it serves the same purpose - to pass a secret message from one place to another without anyone else being able to read it. n Encryption is extremely important for e-commerce as it allows confidential information such as your credit card details to be sent safely to the online shop you are visiting.
WHAT IS ENCRYPTION? Continued Web browsers are able to encrypt your purchase details using an encryption method called 'SSL' (Secure Socket Layer). You know this is switched on when a small padlock appears in the bottom right of the browser. SSL gets switched on when you visit a 'secure server' that has an address that starts with HTTPS: // (note the 'S'). How does it work? Encryption works by scrambling the original message with a very large digital number (key). This is done using advanced mathematics. Commercial-level encryption uses 128 bit key that is very, very hard to crack. The computer receiving the message knows the digital key and so is able to work out the original message.
WHAT IS ENCRYPTION? Continued Why don't we use it all the time? n There are three problems. a) It is slower than normal browsing. It takes a while for the browser to do the math required to scramble the message and another delay on the server that has to unscramble the data. b) Online shops have to have a digital certificate that contains part of the key. This is not free and has to be supplied by a “certificate authority. ” c) It can be a complicated business running a secure server, so very often, ordinary online shops will hire a specialist 'Payment Gateway' such as 'World. Pay' or 'Paypal' to handle payments for them. Any more about encryption? Yes, it is going to appear more and more in your home as DRM (Digital Rights Management) is used to encrypt downloaded music or to copy-protect DVD's.
WHAT IS ETHERNET? What is it. Computers often need to be networked so you want the network cables, plugs, network cards and so on, to all work together. The plugs must fit in the sockets; the cable must behave the same way no matter who you buy it from. You should be able to purchase network cards from one supplier and know that they will work with cards from another supplier. For this to happen, manufacturers must use a common standard. And the standard most often used is called “Ethernet. ” So Ethernet is a standard *partly* designed to allow network hardware to work together.
WHAT IS ETHERNET? Continued n The official name for Ethernet is the hard-to-remember IEEE 802. 3 which refers to the American standards body that made it official. n It is one thing for the hardware to physically work together, but then the way data is handled also has to be agreed between the networked computers. And once again Ethernet comes in handy, because it not only defines hardware; it also defines how data is to be handled. n So in a nutshell, Ethernet is a standard that defines network hardware and also how data is to be handled. Speed n Ethernet has been around for a long time, starting in the 1970's with slow networks running at 10 Megabits per second. Then some years later 100 Megabits per second became practical.
WHAT IS ETHERNET? Continued n Higher speed is better because you wait around less for data. But then again higher speed often means higher cost for the hardware, so it is a balance. n An Ethernet standard has defined the kind of cable and network cards you need to work at the higher speeds. Moving on to today 1 Gigabit / sec is becoming common, once again with the right hardware being specified by the Ethernet standard. It is great to be able to shift a 4. 7 GB DVD film across a 1 Gb/sec network in a few seconds, but then the hardware and cables are more expensive than the much slower 0. 1 Gb/s i. e. 100 Mb/s. So which one you go for depends on the kind of data you want to move across the network.
WHAT IS ETHERNET? Continued Sorting out collisions. n Ethernet then goes on to describe how to deal with data “collisions. ” n For example, say computer A and computer B are both trying to send data at *exactly* the same time i. e. within a few millionths of a second of each other. n The Ethernet standard protocol goes like this: n n Collision detected Computer A and B to stop sending immediately Computer A to re-send a small random time later Computer B also to re-send a small random time later n The chance that both Computer A and Computer B pick exactly the same random time is quite low. Collision avoided. n A manufacturer of network cards would read this protocol and build this behavior into his product. Another supplier would do the same, so both products deal with collisions in the same way.
WHAT IS ETHERNET? Continued Addressing n Ethernet standard also specifies how data gets to its correct destination. It does this by defining the make-up an Ethernet data packet. n The packet includes the destination address. Every network card has an unique address (called the MAC address). n The network card on every connected computer examines the data packet and if the destination address inside the packet matches its MAC address, it is allowed to pass into the computer, otherwise the packet is ignored.
WHAT IS ETHERNET? Continued Linking to other standards. n There is a well-accepted information model called the OSI model. n The OSI model describes how data flows from the screen of one user, down through the computer, across the network cable and back up into another person's screen. n The model is split up into a number of abstract layers. Each layer has a name to reflect its purpose. n Ethernet deals with the Physical and Transport layers of this model. The PHYSICAL layer deals with hardware and the TRANSPORT layer of the model deals with the handling of data across a network. And the future? n Ethernet has proven so successful over the years that it will continue to be used in the future. At the moment, people are busy putting together an Ethernet standard that can deal with 100 Gigabits per second. n This will be needed because it will become common for very high speed data such as high-definition television signals to be networked around the home.
FIBER OPTICS COMMUNICATION What is it? It is a communication technology that makes use of light to carry data and information. How does it work? The part that carries the light from one place to another is called a fiber optic cable, sometimes called a 'light-pipe. ’ This describes its function very well as a fiber optic cable is designed to allow light to pass through it with very little loss. What it’s made of? A high quality communication cable is made of glass (or silicon dioxide to be precise). Normally you think of glass as being brittle and easily broken, but when it is made thinner than a human hair, it is very flexible and strong.
FIBER OPTICS COMMUNICATION Continued n Of course it is not just simple glass. The outside of the cable is designed to reflect light inwards whilst the middle core is as transparent as possible. So when a beam of light is “launched” into one end of the cable, it bounces along the cable until it reaches the other end. This type of cable, one that uses reflections to work, is called a “multimode” cable. n There also “single mode” fiber that uses a different effect and work for longer distances - but it is more expensive. n You can also get fiber-optic cable made of plastic. This is a good solution for very short distances (a few meters) so you might see it used in hi-fi systems to carry audio information.
FIBER OPTICS COMMUNICATION Continued Is it just any light? n No, fiber optic is transparent at a very precise wavelength of light i. e. color. Typically it is very transparent at 1550 nm (nano meter is 1 thousand millionth of a meter). We would see it is a reddish color. How is the light created in the first place? n There are two main ways. n 1. A Light Emitting Diode (LED) LEDs are very cheap and do produce reasonably pure light of the right wavelength. So they are used for low power, short distance applications such as local area networks. LEDs are good for a few kilometers and a speed of about 100 Mb/sec Only about a hundredth (1%) of the light it produces is useful for the cable. But even that is good enough for smallish distances. n 2. Laser Beam This is more expensive but has a far higher purity than LED. This means that nearly half the light is useful in the cable, so it is very efficient. Power can be also be much higher, so allowing far greater distances to be covered.
FIBER OPTICS COMMUNICATION Continued How fast can it transmit data? n Transmission speeds can be extremely high. n For example, recently a 160 Km length of cable carried information at 14, 000 Gigabits / sec. This kind of performance is used in oceanic cables that connect continents together. How does it compare to good old copper? n It is very tough - it does not corrode, unlike copper and it is not affected by electrical interference such as lightning or stray radio signals. n But it is more expensive, so copper is still used for most local communications.
FIBER OPTICS COMMUNICATION Continued Where is fiber-optic communication mainly used? n The heart of the UK telephone system runs on fiber optic because it is almost the perfect solution - no interference, massive speed, easily carries voice, television, internet, and telephone calls all down the same cable. But it isn't cheap! n Aircraft use fiber optic cables to transmit data to different systems. They cannot risk any electrical interference interrupting data transmission.
FIBER OPTICS COMMUNICATION Continued What about the future? n The big issue for the UK is how to deal with “the last mile, ” that bit of copper cable that connects your telephone to your local exchange. If a fiber optic cable could replace this bottleneck, then broadband speed could easily be two hundred times quicker. n The problem is who will pay for it? The government is now allowing private companies to take over “the last mile, ” hoping that they will make the investment. n In Korea, for example, it is common to have 100 Mb/sec internet connections because they have invested in fiber optics right to the home.
WHAT IS FLASH MEMORY? What is Flash Memory? Flash memory is a type of non-volatile storage. How is it different to other types of storage? Optical storage devices such as DVD's use light to help store data. The data is burned onto the CD or DVD causing small pits in the surface. Hard disks, floppy disks and magnetic tape make use of magnetism to store data. Flash on the other hand makes use of electrical effects to store data. It is a 'solid state' technology because it is based on a silicon crystal slice and metal layers. There are no moving parts.
WHAT IS FLASH MEMORY? Continued What are the advantages? n 1. Flash is very tough and will not break when dropped or exposed to heat (it is a solidstate device) n 2. It is very reliable as there are no moving parts, the data should be held for decades. n 3. It is very compact and can store gigabytes of data in a small space. n 4. It is very fast. As there are no moving parts needed to get to the data it is much quicker than hard disk or DVD.
WHAT IS FLASH MEMORY? Continued What are the problems? n 1. Data can only be stored in chunks, typically 512 to 2048 Bytes at a time. This means it is fine as a secondary storage method, just like floppy disks, hard disks and DVD's but it is no good as main memory like RAM and ROM. n 2. It does wear out over time. You can write to it roughly a million times before it fails. In practice this is plenty for most applications. What uses Flash technology? n It can be found in many forms n Memory sticks n Jump Drives n Camera memory cards n Solid state hard drives.
WHAT IS FLASH MEMORY? Continued What about the future? n The cost and reliability of Flash memory has improved enough to make it practical to use as part of a hard disk. n Now 'hybrid' hard disks are appearing. These have a few Gigabytes of Flash inside that store the most often used data, whilst the spinning hard disk stores all the rest. This means that the data can be accessed really quickly as Flash is far quicker than the mechanical hard disks. n In the near future you may also see the operating system installed in Flash memory allowing for instant switch on rather than the age it takes to boot up a computer.
WHAT IS GPS? What is it? It stands for Global Positioning System. GPS is a satellite based system that allows you to know your position anywhere on Earth. Why was it developed? It was developed for the USA military to allow soldiers to know exactly where they were regardless of whether it was day or night, deep in a jungle or in a barren desert. It is still owned and controlled by the USA military.
WHAT IS GPS? Continued How does it work? n It makes use of a method called 'triangulation. ' You often see this being used in action films where the villains are being tracked on a map as they move about. n Tracking a villain. . Imagine that you have a machine that can tell you the distance between yourself and the villain. That's all it can tell you - just the distance. So you draw a circle with you as the centre. The villain is somewhere on that circled line. Now a colleague also lets you know how far the villain is away from them. So draw another circle around him. So you know that the villain must be at point A or Point B. But which one? So you need a third colleague to let you know their distance and this pinpoints the villain's location. Hence the word 'triangulation' - three measurements can pinpoint a location.
WHAT IS GPS? Continued So how do satellites help? Well, if you can measure the distance between yourself and at least three satellites (preferably four), then your location on Earth can be worked out. How accurately you can pinpoint your location depends on how accurately you can measure the distances to the satellites. Commercial Sat-Nav systems can measure to within a few meters.
WHAT IS GPS? Continued Where is GPS used? n It now has a vast number of uses. For example n * In cars - satellite navigation systems are becoming common n * Lorry Fleets: Used to track and locate vehicles n * Military - its original purpose, to help soldiers in the field. n * Shipping - to navigate the seas. n * Farming - to track crop growth and fertilizer application. n * Leisure - Mountaineers, hikers, explorers. n * Crime - offenders can now be 'tagged' with a GPS device to make sure they stay where they should. What is the future? GPS has become so widespread in everyday life that some regions want to control their own GPS for their citizens. For example the European Union have been developing a similar system called Galileo.
WHAT IS IP ADDRESSING? Why was it developed? If two machines are networked together, then it is pretty obvious that when you send data from one machine it can only go to the other machine. So no need for complicated addressing. But as soon as more and more machines were added to networks, they needed to be identified by an unique address. What is it? It stands for Internet Protocol address. It is an unique address that identifies a computer on a network such as the Internet. So IP addressing was invented. And it looks something like this 198. 168. 001 There are four sets of numbers because it is a 4 byte scheme - 32 bits. The first three numbers tend to be used to identify the network while the last number tends to pinpoint a particular computer on that network.
WHAT IS IP ADDRESSING? Continued Is that all there is to it? n Things do get a bit more complicated than that though because many companies have thousands of machines connected to their own private network. The network admin will have given these machines their own internal IP address. n But to connect to the internet they have to go through a gateway or firewall. That gateway will 'translate' the private IP addresses into a public address. n So it’s a bit like a funnel controlling the flow in and out of the company network. This is called NAT or Network Address Translation.
WHAT IS IP ADDRESSING? Continued How do IP addresses link with domain names? n As people, we don't use IP addresses on the Internet, they are great for computers but too hard for us to remember or figure out. n So another scheme was developed which allows us to type in a much friendlier address such as www. teach-ict. com (a domain name). When you type in www. teach-ict. com it gets sent to one of a number of computers on the Internet called the 'Domain Name Servers' or DNS for short. n The DNS server then finds the correct IP address to allow you to automatically connect to the teach-ict. com site.
WHAT IS IP ADDRESSING? Continued What about the future? n Well, there is a basic problem - we are running out of IP addresses - 32 bits is not enough. Who would have thought that 4 thousand million unique addresses would not be enough! n But now, not only computers are connecting to the internet but fax machines, printers, mobile phones and even fridges. n So a new scheme has been developed that use 128 bits instead of 32 bits. This will be enough to give every grain of sand on earth an unique address. So it should be big enough for the time being! n The new scheme is called IPv 6.
WHAT IS NANOTECHNOLOGY? n What is it? n The 'Nano' part is referring to the size of the thing being made. n A 'nanometer' is absolutely tiny, being a billionth of a meter. This is hard to imagine, so to give you an idea, the smallest atom in the universe is the hydrogen atom. You can line up ten hydrogen atoms in one nanometer. n So nano-technology is making devices at the atomic scale.
WHAT IS NANOTECHNOLOGY? Continued How did it come about? n It has been around for about 15 years. Maybe one of the most significant starting points was when scientists developed a device that could spell 'IBM' on the surface of a crystal by moving individual atoms around. They won the Nobel Prize for that.
WHAT IS NANOTECHNOLOGY? Continued n Then along came a molecule going by the wonderful name of 'Buckminster-Fullerene'. This is an arrangement of 60 carbon atoms in the shape of a football. It showed that it was possible to make things at the atomic scale. n So thousands of researchers around the world started to look at what could be made. Some looked at new materials with properties never-before seen. Others had ideas to put atoms together in the shape of tubes and rods to see what they could do. n The more over-excited scientists wrote books about tiny machines traveling through your blood, fixing you from the inside-out, or making anything you want from nano-glob, a bit like the star-trek machine that makes coffee from nothing.
WHAT IS NANOTECHNOLOGY? Continued So what has it *really" done for us? n Medicine n Nano-technology has produced better ways of delivering vital drugs to the right place in your body - but not in the shape of a tiny submarine! Nano-cages trap the drug molecules and then carry them to where they are meant to go. Materials Nano-particles are added to steel and plastics to give them improved properties. For example: A new type of carbon fiber, developed at the University of Cambridge, could be woven into super-strong body armor for the military and law enforcement
WHAT IS NANOTECHNOLOGY? Continued Input Sensors n Nano-technology is being used to make very sensitive, tiny sensors for detecting various physical effects. For example there are now sensors used in modern cars that can detect the car being in a potentially lethal situation (i. e. crash), so allowing brakes and safety devices to be used effectively in an emergency. MEMS = "Micro Electro-Mechanical Systems. “ Electronics n This is probably the most significant area for nano-technology. For the past fifty years, engineers have made smaller and smaller devices; today they can make electronics down to about 60 nano meters. n There is a bit of leeway left, but around 35 nm is just about the last stage engineers can go before they have to take a different way. Transistors start to behave in weird, unpredictable ways when they get smaller than this because individual atoms begin have an effect. These are called 'quantum' effects. With nano-technology you will often see the word 'quantum' crop up. n It is early days, but nano-technology is making it possible to build up devices from atoms, so devices will become ever smaller.
WHAT IS NANOTECHNOLOGY? Continued n Recently a scientist/engineer won the 2007 Nobel Prize for discovering a nano-scale effect that allows hard-disk heads to be two thousand times smaller than the width of a human hair. This is why you now see 1 Terabyte hard disks appearing.
WHAT IS NANOTECHNOLOGY? Continued And the future? Renewable Energy n Scientist have recently used nano-wires 200 times thinner than a human hair to create tiny solar power cells. Medicine Nano-technology is being used to create artificial corneas and develop new ways of measuring your health. World Health Millions of people have no clean water to drink. Nano-clay and nano fibers are being used to create cheap, effective water filters for developing countries.
WHAT IS NANOTECHNOLOGY? Continued Smart dust n Engineers have recently made a radio component the size of a virus, so maybe 'smart dust' will become a reality where smart particles are spread over a battle field to report back to base. Or the particles are placed in your body to report back on your health. Computers n Quantum computers, with processing devices at the atomic level, promise to be a million times faster than today's supercomputers. Global warming n Cars are adding to the global warming problem by burning fossil fuels. An alternative to petrol is to use hydrogen. But no-one has figured out a convenient and safe way of storing the hydrogen in the car. Nano-technology is being used to see if the hydrogen can be stored inside a 'Buckminster-Fullerene' type atomic cage. n Nano-technology remains a fascinating field where surprises continue to crop up.
WHAT IS PACKET SWITCHING? This is a method of breaking data files into small packets or chunks in order to send them across a network. What is the idea behind it? n Telephones have been around for over one hundred years. When you want to make a call to someone else then a dedicated connection is set up between you. Whilst that call is taking place you both have sole use of the telephone line - no one else can use it. Once the call is finished the connection is broken and the line becomes available for somebody else to use. n This method has worked fine for many years. However, as said above, the line is tied up for the whole length of the call. This is called 'circuit switching' n Now imagine if this method were used in networks. For every person using the network a dedicated line would be needed. Large companies can employ thousands of staff around the world, all logged into the company network at the same time. Imagine how much that would cost to set up? And what about all that cable? n What about the Internet? Nobody owns the Internet, so who would be responsible for setting up and paying for the lines? And worse still could you imagine just how many lines would be needed for everyone to use the Internet at the same time? Impossible. n So this is where 'packet switching' becomes important.
WHAT IS PACKET SWITCHING? Continued How does packet switching work? n Imagine that you have a data file, perhaps an email or a document which is 2 Megabytes in size. You want to send this file to someone in another country. n When you send the file, it isn’t sent as one document (remember the telephone call), instead it is broken up into lots of small 'data packets'. Our 2 MB file would be broken up into chunks of 512 bytes in size. n Before each packet is sent, it is given a 'header' containing the network IP address that it needs to arrive at and also details of the IP address from which it was sent. The header also gives each packet a number and records how many packets the data was split up into.
WHAT IS PACKET SWITCHING? Continued How do the packets get through the network? n Now comes the clever bit. Try to imagine the Internet as billions of computers all connected together in a huge mesh. There isn’t just one way to get from one computer to another, there are literally millions of different routes which can be taken. n So, the packets leave your computer and are sent through the network, knowing where they need to get to. The packets start to head off in different directions taking the least busy path at that instant. A machine called a 'Router' works out which is the next fastest connection and sends each packet on its way. During the course of its journey, a packet will travel through many routers, possibly in many different countries. This method works extremely well, because if one branch gets too busy or broken, then the packets are automatically routed through another path instead.
WHAT IS PACKET SWITCHING? Continued What happens when the packets arrive? n When the packets arrive at their destination, they are put back together again in the right order. Remember earlier on we told you that each packet was given a number? This makes it possible to correctly reorder them. The header also contained a record of the number of packets into which the file was split. So, if any packets fail to arrive within a certain length of time then a message is sent back to the original computer asking for a replacement packet. What happens to lost packets? n Sometimes packets can get lost and keep bouncing around from router to router, never quite getting to their destination. n A system had to be developed to deal with this because eventually the network would choke with these 'lost' packets. So to solve this problem a ‘hop’ count is also added to the packet header. Each packet is allowed to 'hop' from one router to another a maximum of say 100 times. Each time the packet passes through a router the ‘hop number’ is decreased by one. If the packet hasn’t arrived at its destination within the number of ‘hops’ allowed then it is deleted by the next router.
WHAT IS PACKET SWITCHING? Continued Advantages of Packet Switching n > It makes very efficient use of the network - no tied-up lines. > It can easily get around broken bits of the network. > As customers increase, the network only has to expand slowly compared to circuit switching. Disadvantages of Packet Switching n > The time it takes to put back the data package changes each time, which can be a problem for time-critical information such as an emergency signal. The fancy name is for this is “latency. ” > Not very good for small data packages - for example if the data package itself is only 600 bytes long, then two packets of 512 bytes need to be used, plus the address information.
WHAT IS PACKET SWITCHING? Continued What is the future of Packet Switching? n Packet switching has proven to be so successful; that BT is changing its entire telephone network over to it so that eventually all telephone calls will use this technology. This will take many years and billions of pounds. Questions to think about n Are all packets equally important? Would you pay more, if you could make your packets have priority over someone else's packets? How much would you pay? n These are questions that the big telecom companies are wrestling with. It’s a bit like the old First and Second class post. You pay extra for first class delivery so that your letter will get to its destination faster. n So, would people pay more for their broadband connections if they could guarantee that their data would be sent and retrieved faster than someone else's data? This technology is possible, but it is a sensitive issue because it means the internet could be divided up into 'motorways' or 'slow country lanes', causing another form of “digital divide. ”
WHAT IS PEER-TO-PEER? This is a special kind of network type (Network topology is the fancy description). It describes computers that are networked to each other without a central server being inbetween. Why was it developed? n Peer-to-Peer networks are very popular with people who want to share files directly with one another. The files do not have to be stored on a central server. Software has been developed that can even put together a file from bits of the file stored across several 'peers' on the network. For example Bit Torrent can do this. The advantage is that no single computer needs to be overloaded when a very popular / very large file is requested.
WHAT IS PEER-TO-PEER? Continued Why is it important? n It is an important development because it will affect the way the Internet is used in the future. n Many companies want to provide 'video on demand' services but the problem has been how to provide the vast bandwidth needed when thousands of people are asking for the same video file e. g. the latest episode of 'Lost' or '24' n Peer-to-Peer is an ideal solution to the problem because hundreds of computers can hold parts of the video and so share the load. n Some companies are calling the peer-to-peer connections they are building as 'The Grid' which is a trendier name for the same thing. n What about the future? n In the near future, high definition television programs may be delivered through the internet and so peer-to-peer may be used.
PLASMA DISPLAY What is it? n A type of display technology well suited to making large, flat screen displays. Plasma screens are now very popular in large televisions, having made cathode ray tubes largely obsolete. n The technology was invented in the 1960's but it is only recently that full color screens have become practical.
PLASMA DISPLAY Continued What is Plasma? n 'Plasma' is an electrically charged gas that gives off light (the 'light' might be ultraviolet and so is invisible to humans - but there are ways around that) n Factoid: Sometimes plasma is said to be the fourth state of matter after Solid, Liquid and Gas. n A lightning bolt is a huge example of plasma being created. An electric current flows from the clouds down to the ground as it does so, the air molecules are ripped apart by the sheer amount of energy flowing, so forming plasma. When they come back together again, light is given off, which is why you see a lightning flash. n A plasma display makes use of this effect (although much less dramatically!).
PLASMA DISPLAY Continued How does it work? n One picture element (sub-pixel) of the display is made up of a tiny hollow glass cube/cell filled with a noble gas such as Xenon and Neon. An electric current is made to flow through the gas which creates plasma. The glass on the front of the cube is coated with a special material called a 'phosphor' that gives off a colored light when struck by particles (photons) coming out of the plasma. n The sub-pixels are arranged in a group of Red, Green and Blue very close to one another to form a single 'pixel'. When they each shine with different intensity, your eye combines the Red, Green and Blue light so you sense a different color. With Red Green and Blue you can produce the illusion of any color including white. Black is simply all the element being off.
PLASMA DISPLAY Continued Do they wear out? n Yes eventually, just like a fluorescent tube. It is estimated they last about 60, 000 hours or about 25 years in heavy use. Why large displays rather than small ones? n The gas-filled glass cubes need to be certain size to work well and this lends itself well to large displays, as each pixel can be larger. Trying to make even tinier cubes for small displays is much more expensive and difficult. How does Plasma compare to other technologies? n Compared to a Cathode Ray Tube (CRT) n It is much thinner n It is much lighter for large screens n Easier to make into large screens.
PLASMA DISPLAY Continued Compared to a Liquid Crystal Display n It is not as suitable for small displays n It uses more power n It has a faster response, good for fast moving images n It is brighter n It has higher contrast (difference between black and white) n It has a better 'black', which is good for watching movies. And the future? n It is all down to economics. n Makers of television and display screens have to decide…what is the most economic technology to use for a given sized screen? n At the moment Plasma has the edge over Liquid Crystal for sizes above 36 inches or so. But the developers of LCD technology are fighting back, making their systems lighter, faster and cheaper so perhaps Plasma will be replaced by LCD technology in the future.
WHAT IS RFID? What is it? It is an abbreviation for Radio Frequency Identification. This is a term used to describe a type of wireless technology used to identify objects, animals (or people).
WHAT IS RFID? Continued It is an abbreviation for Radio Frequency Identification. n This is a term used to describe a type of wireless technology used to identify objects, animals (or people). n What does it look like? n There are two parts to the system. n 1. The tag. The simplest version is a tiny microchip that contains a code identifying the thing to which it is attached / glued to. n The microchip is often connected to a flat spiral aerial that allows it to work by radio signals.
WHAT IS RFID? Continued n 2. The Reader. This machine sends a radio signal to the tag asking for its code. The tag senses the request and sends back its unique code. The reader can then connect to a computer or database and uses the code to identify what the object is (or the identity of the person the tag is attached to). n The system works over a foot or so, which is fine when the tags are guaranteed to be close to the reader. n The handy thing about the tag is that it needs no power at all - no battery needed. This is because the reader sends it enough radio power to turn on whilst it is being interrogated.
WHAT IS RFID? Continued Are there other types of RFID? n Yes, the no-battery versions are great for cheap, non-critical tags as might be used in a book-sleeve or shirt package. n But if it is really important to have reliable identification there are more expensive and larger battery-powered versions. These use higher radio power and so they transmit over a much greater distance (100's of meters). n These kind of tags are used for very expensive items such as military stores or toll booth systems where you will be charged for using a road or rail system.
WHAT IS RFID? Continued n Who uses it?
WHAT IS RFID? Continued 1. Businesses that want to keep track of their stock as it move from one place to another. For example, many parcel delivery companies now offer the ability for you to check where your parcel is as it is being delivered. They can do this by attaching an RFID tag on the parcel, and then a reader at each main point of its journey keeps track of its progress. n 2. Security systems that can sense the identity of the person wanting access to a restricted area. The person wears an RFID tag, so when they approach a reader, it can request an identity check without the person having to do anything. n 3. Anti-theft Many shops use RFID to deter shop-lifting. Have you noticed some shops have some tall objects standing either side of the doors? You have to walk between them in order to leave the shop. This is part of an RFID system. Many of the more expensive items in the shop will have hidden RFID tags. If you try and walk out of the shop, the Readers either side will request the tag for its code - that code is checked against a database to see if it has been paid for yet. If not, the alarm sounds. Another reader is located beneath the desk by the till. As you pay, they slide the object over the reader to register it is as having been paid for. n 4. Passports. Many countries, including the UK now use RFID tags inside passports. The tag not only identifies the person, but also stores a digital photograph and a record of their movement in and out of the country. In order to reduce the chance of someone 'skimming' that information, the passport contains a metal film to prevent them being read when closed. n
WHAT IS A SERVER? What is it A server is a computer dedicated to providing some specific service for other computers on the network. What kind of servers are there? You call the server by what task it needs to do. For example: Print server: this is connected to the network printers and acts as the go-between for your computer and the printer when you send a document to print. The print server handles the task for you, leaving you free to get on with something else. If a job seems to be taking a long time, then you can normally click on your printer icon in the task bar to have a look at the 'print queue' to see what is holding it up.
WHAT IS A SERVER? Continued n File server: This handles the sharing and storing of files on the network. You will normally see 'Network Drives' in Windows Explorer as well as your local 'C' drive. These drives are part of the file server. You can have many file servers on a network. n Web Server: This handles the delivery of web pages and files linked to those web pages. A web server can sit on an Intranet so it remains private to those users. Or it can be connected to the Internet, in which case it will be handling one or more domain names. n FTP Server: Sometimes large files need to be moved from one business to another. In theory an email attachment can be used. But if the file is very large, then it is better to provide an FTP server that both companies can connect to. After you login, you use an FTP client (File Transfer Protocol) to upload the file. Then the other person uses an FTP client to download it. n Video Server: This is dedicated to streaming video, such as news, films and so on.
WHAT IS A SERVER? Continued
WHAT IS A SERVER? Continued Are they expensive? n They can be - sometime tens of thousands of pounds. They have to be especially reliable. For example a good file server has several hard disk arranged in parallel (RAID array). Each hard disk has the same data, so if one hard disk fails it can be swapped even with the power still on, this is called 'hot swapping'. Network users are not aware of any problem going on. What is the future? n Up to now, nearly all servers have been in businesses and organizations such as your school. Now servers are beginning to be used in the home as well. For example, you can now buy 'Media servers' for the home that will store and distribute music, television and video around the house on a wireless network.
WHAT IS VIRTUAL REALITY? What is it? n When many people think about the term 'virtual reality', they imagine a scene like the on the right where somebody is wired up to a computer wearing an odd helmet and making weird movements in the air. However, there is a lot more to virtual reality and it has some incredibly practical uses, so read on. n 'Virtual' reality means that the user is fully immersed in a world or artificial environment that the computer has generated. n As you walk around the virtual world your view changes in line with what you would expect in real life. Things get bigger as you walk towards them and smaller as you walk away. Also the direction of sounds move as you move around, once again giving you the impression of a real scene.
WHAT IS VIRTUAL REALITY? Continued How does it work? n There a number of systems but they have some common features that include: -1. A set of goggles that controls what your left and right eyes see. By providing slightly different views into each eye, your brain is fooled into thinking that the scene is 3 D. Virtual chairs look solid and so on. n 2. Other wearable input devices are used such as gloves that detect your finger movements. As you wiggle or tap your fingers on a virtual control then the computer carries out the command, such as turning on a virtual television. n 3. Headphones to control what you hear. n The other part is a powerful computer that can create the graphics and sound in 'real time'. These images may be projected onto the walls and floor of the room. So you can walk around freely.
WHAT IS VIRTUAL REALITY? Continued How good is it now? n It is good enough to physically affect someone in it. For example, when they may be shown a scary situation such as a fire appearing in front of them, their heart will beat faster and breathing speed up. n This shows that the VR is convincing enough to cause an effect. Which is the whole point of VR really? n The graphics are "OK" but not realistic by any means. But the odd thing is that people react strongly even in a low-res scene. It is the situation that matters, not what it looks like.
WHAT IS VIRTUAL REALITY? Continued Is it a game? n Not really, a game is made for entertainment and excitement. But VR is used for more serious purposes (although you could imagine a VR game world). n For example, architects have used basic VR systems for a while to allow clients to 'walk' around their new design. n VR is being used by researchers / therapists to help patients overcome phobias and anxieties. The person is placed in a VR scene where they experience a tame, controlled version of what they are afraid of. For example, someone might be painfully shy, so therapist may put them in a busy virtual place where 'people' come up to them and try and talk (these avatars would be controlled by therapy team as well). Slowly the person becomes used to the situation and can relax.
WHAT IS VIRTUAL REALITY? Continued n Some soldiers have suffered distress on the battlefield and need help to cope and so VR is being used to take them through a carefully controlled version of what gave them a problem. n Some doctors and dentists are using virtual reality with their patients. People with severe burns suffer from incredible pain when their wounds need redressing. Researchers have found that by allowing them to use virtual reality during treatment, their awareness of pain was greatly reduced. n Another important use of VR is training for dangerous situations where it is unethical or impractical to practice the real thing. For example a large fire on an oil rig would never be set up, but in a VR system that is perfectly possible and so workers can practice the emergency in a safe environment. n See the medical burns story http: //arstechnica. com/news. ars/post/20081114 -snowy-game -vr-goggles-take-burn-victims-minds-off-of-pain. html
WHAT IS VIRTUAL REALITY? Continued What are the downsides to VR? n If you have ever been sea-sick or travel-sick then a poor VR set-up might make you feel the same way. This is because you are seeing one thing but your brain is getting a different story from your sense of balance. When what you see and what you feel do not match (like on a ship) then you may feel ill. n Another downside is that VR is very complicated and so needs expensive equipment to set up and run. So proper VR games are a long way away. And the future? n Display technology will continue to improve and so VR will become ever more realistic visually. Sufficient computing power is here already for that. But it is the input and output devices that will have to improve. For example researchers are working on better devices to control the sense of touch and smell.
WHAT IS VIRTUAL REALITY? Continued n In the future it may be practical to use VR to safely fly a remote control aircraft as if the pilot was really in the machine. For example, flying the remote-control aircraft into a hurricane or volcanic eruption to take scientific readings. Sensors on the real aircraft would allow the pilot to see, hear and even feel what is going on in the virtual reality version but without any danger to life and limb. n It could also be applied to remote controlled submarines that explore the sea looking for oil and mineral reserves or perhaps exploring other planets such as Mars and Titan in the far future.
WHAT IS VOIP? Stands for 'Voice Over Internet Protocol'. It is a technology that allows you to make telephone calls over a Broadband internet connection. Why was it developed? In a sentence - to save money. The Internet is designed to send data from one computer to another. It does not care in the slightest what that data actually is - so it could just as easily represent your voice.
WHAT IS VOIP? Continued How does it work? n The technology is fairly straight-forward: n a) You speak into a microphone that is connected to a sound card. b) The sound card has an 'Analogue-to-Digital converter' that translates your speech into a digital stream. c) That data is given a destination address and off it goes like any other data stream. d) The receiving computer has the right VOIP software to convert the incoming data back into speech Advantages n 1. The advantage of VOIP using the internet is that at its most basic the system is essentially free as long as you have an Internet connection. 2. The next step-up is to use a VOIP service company such as Skype. They may offer a free service if you call other subscribers and then charge for other calls.
WHAT IS VOIP? Continued Disadvantages n a) Both ends have to have the right software and hardware to speak to one another n b) There is no guarantee of quality when using the Internet - no one company owns the internet, so if a part of it is broken there is no-one to call to fix it. n c) It uses packet-switching so if packets get dropped along the way then voice quality drops. n d) Even when fully working, it is not as high a quality of voice as a normal telephone line. n e) It does not work if you have a power-cut, unlike your normal telephone. n f) It may not work for emergency service numbers. Sometimes you just can't tell the emergency services where you are, so they use some standard telephone location technology to help locate you. With VOIP this is more difficult.
WHAT IS VOIP? Continued What is the future? n You can now buy VOIP handsets and adaptors that look like a normal phone instead of the microphone sound card method. You can just plug in the phone to an internet connection. There are two things happening: 1) Companies are springing up that offer to connect your VOIP call to any normal telephone number. Of course the service is then no longer free. n 2 The large telecom companies are spending billions, creating their own private IP networks. If you use their VOIP service then the data gets routed through their private system so guaranteeing quality of service. The reason they are doing this is not only to compete with the public Internet companies but using IP and Packet-Switching is more efficient as all calls create packets that share the same network.
WHAT IS WEB 2. 0? This is a bit of an odd one, as there is no 'official' definition of this description. It seemed to appear in the media news when they wanted to describe a new phenomenon that appeared on the internet - namely web sites that were based on what members were placing on the site. For example You. Tube is based almost entirely of material uploaded by members. Flickr became a hugely popular site for storing and sharing your photographs. Then personal spaces such as My. Space, Bebo, Facebook, Piczo and others came on line.
WHAT IS WEB 2. 0? Continued n Alternative open worlds appeared such as Second Life. Unlike the huge multi-player online games, Second Life is not a game defined by its developers but more of an alternative space in which people can meet, have a laugh, make money - in fact everything you can do in real life (well, almost). n Blogs have also become an important part of the Internet experience, with millions of individuals willing to share their thoughts, opinions and links. n Another part of Web 2. 0 is the rise in highly interactive features such as Google Maps. Once again, people can populate the maps with what they deem interesting. n So perhaps a good definition of Web 2 is the point at which the Internet became truly interactive, with users becoming the most important component of many sites. n I wonder what Web 3 will look like?
WHAT IS WEB 2. 0? Continued
WHAT IS WI-FI? It is a communication technology that makes use of radio waves in order to connect to a local area network. It is also widely used to connect to the internet from a laptop or smart phone whilst out and about.
WHAT IS WI-FI? Continued How does it work? n Each Wi-Fi enabled device searches for a Wi-Fi base station located nearby. If it finds a network, you can connect to it by providing the correct password. Some networks are not password protected and your device will connect immediately. The access points are called 'Hot spots'. n The Wi-Fi base station usually takes the form of a network router / ADSL modem. This router is often connected directly to the internet on a standard ADSL telephone line. This is why you are able to connect to the internet using Wi-Fi.
WHAT IS WI-FI? Continued What happens to make a connection? n It works a bit like a television. The radio bandwidth available to the base station is divided into a number of 'channels'. Typically 13 channels. When a device comes along that wants to connect, the base station allocates a spare channel for it to use. More than one device can use the same channel, but it will tend to slow down the connection. n Of course, both the base station and the Wi-Fi device must share the same way of talking to one another. This is called the 'protocol'. A common wireless protocol you will find is the 802. 11 g standard but there are many others as well.
WHAT IS WI-FI? Continued What does Wi-Fi stand for? n The word Wi-Fi is actually a trade name owned by the Wi-Fi alliance. The alliance is a group of about 300 companies from around the world. They work together to make sure that all 'Wi-Fi' enabled devices are compatible with one another. These days most laptops have Wi-Fi built into them. How fast can it transmit data? n The maximum speed of a wireless network using the 802. 11 g standard is 54 Mb/s but in reality the speeds are much lower than this. Compare this to a hard-wired Gigabit network that can transmit 1000 Mb/s. However, even that slower speed is fine for most uses. Speed is mostly influenced by the strength of the radio signal - the weaker it is the slower the speed.
WHAT IS WI-FI? Continued Are there problems with it? n Yes. The main concern is security. After all you are broadcasting your network data over radio waves and these are easily picked up by other devices within range. Originally, Wi -Fi networks were virtually open to anyone. Some people made a hobby of driving around looking for open networks. n Security is now much better, with many wireless networks set up with proper encryption and passwords. There are still plenty of free hotspots around, but they are usually deliberately left open for customers people to use. n Another problem is that it can only connect a limited number of devices as they all have to share a limited number of radio channels. So it is best to use hard-wired cabling for the main company network with some additional Wi-Fi connections available for meeting rooms and so on.
WHAT IS WI-FI? Continued Some cities are now making it an objective to have complete Wi-Fi coverage. For instance London is planning to have city-wide coverage by the time of the Olympics in 2012. This will require hundreds of hot spots to be in place.
Summary n TV AND CINEMA 3 D WHAT IS BLUETOOTH? WHAT IS ENCRYPTION? WHAT IS ETHERNET? FIBER OPTICS COMMUNICATION WHAT IS FLASH MEMORY? WHAT IS GPS? n WHAT IS IP ADDRESSING? n n n
Summary Continued n WHAT IS NANOTECHNOLOGY? n WHAT IS PACKET SWITCHING? n WHAT IS PEER-TO-PEER? n PLASMA DISPLAY n WHAT IS RFID? n WHAT IS A SERVER? n WHAT IS VIRTUAL REALITY? n WHAT IS VOIP? n WHAT IS WEB 2. 0? n WHAT IS WI-FI?
Sources nhttp: //www. teach-ict. com/technology_explained/whatis_home. html n. Copyright © www. teach-ict. com
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