8.2.3: Information Technologies(fiber optics, wi-fi, information technology)

In what ways do you use information technologies? Do you send emails? If so, did you know that about 200 million emails are sent around the world each day? Do you tweet? Did you know that over 500 million tweets are sent each day. Do you send texts? Each day, there are over 10 billion texts sent. In fact, in 2014 there was a total of about 5 zettabytes (5 trillion gigabytes) of digital information created on Earth (this includes documents, pictures, emails, movies, tweets, etc.). This is the equivalent of a trillion high-definition movies (at about 5 gigabytes per movie). All of this information is part of the rapidly growing field of information technology.

[Graphic: table showing that 1 zettabyte equals a thousand exabytes, a million petabytes, a billion terabytes, a trillion gigabytes, quadrillion megabytes, quintillion kilobytes, and a sextillion bytes; graph of increase in data]

What is Information Technology?Information technology is the application of computers and telecommunications equipment to store, transmit, receive, and manipulate data. There are two parts to information technology: hardware and software. Hardware is the equipment involved, which includes the circuits, cables, and transmission towers used to send information as well as the phones and computers that people use. Software is the set of all the programs that code, decode, and interpret information, including Internet browsers and the operating systems of phones and computers.

The development of information technologies really goes back thousands of years. As soon as the Sumerians in ancient Mesopotamia developed writing about 5000 years ago, people began developing ways to store, transmit, and receive information using methods such as stone and clay carvings or papyrus writings. Over time, mechanical devices were developed to store information and carry out calculations. For example, in 1642 the French inventor Blaise Pascal created the first mechanical calculator. However, modern electronic information technologies began in the early

1940’s with the creation of the first electronic computers, and this marks the start of the period of what is usually referred to as information technology.

Information technology is one of the fastest growing parts of global industry and technology. It is also the newest. The world’s first text message was sent in 1994; the first tweet was in 2006. At the start of the 21st century, there were only 50 exabytes of digital data in the world; this is just 1/100 of the amount today. In order for this growth to occur, and continue, many different technologies are being developed: old technologies are being used in new ways, and whole new areas of technology are springing up.

Infrastructure The physical hardware that carries the wave packets of information from one location to another is called infrastructure. This involves the telephone lines, cable television lines, fiber optic cables, satellites, and antennas used to transmit signals. This also includes equipment called routers that transfer the information signals from one transmission mechanism to another. If you use computers in your home or classroom, there is a router that passes digital signals (email, web pages, videos, etc.) between your local computers and the Internet.

Data Storage Many methods are used to store information. A century ago nearly all information was stored as typed writing, such as in books, journals, and newspapers. Now, almost all information is stored digitally on computer hard disks, optical CD-ROMs and DVDs, or digital magnetic tape. The global amount of stored digital data is now more than an exabyte, and doubles roughly every three years. An important part of the information technology for data storage involves the development of databases, which are programs that organize and structure large amounts of data so that they can be easily stored and retrieved as needed.

Data Transmission The transmission of data really has three separate parts: transmission, propagation, and reception. Data transmission occurs over the infrastructure of wires, cables, satellites, and receivers. The signals propagate electronically or electromagnetically and can be modulated or altered in many different ways, and are often compressed to reduce the volume of the transmitted signals. When the signals are received, they are often uncompressed and converted into more usable formats. When data transmission occurs in only one direction, such as with radio and television signals, it is called broadcasting. When the communication goes in both directions, both upstream and downstream, it is called telecommunications.

Data manipulation – A wide variety of software applications have developed to use digital data. These programs manipulate the signals in order to support the applications that we like to use. This includes broadcasting our favorite radio or television programs as well as supporting the many different telecommunication applications such as Twitter, Snap-chat, Vine, Instagram, and all of the other “apps” that are available on smart phones. These functions are carried out by the

integrated circuit, or microchip, that is at the heart of all digital electronics. The actual computations are carried out by microprocessors using binary digital signals.

Importantly, information technology is one of the fastest growing areas of new jobs. In order to keep up with the growth of information, there is a great demand for electrical engineers, computer engineers, and computer programmers. However, all large businesses now have information technology (called “IT”) departments, whose responsibility is to make sure that the right information technologies are used in the most efficient ways in order to best serve the company. Many people are needed to fill these jobs. Some IT people design Internet web pages for their company. Some work on networking together the company’s computers. Others work on efficient ways to carry out communications within the company and with other organizations.

[Photo Idea: communications satellite; smart phone with apps; microchip; IT jobs]

What Technologies Are Used for Communication?In the last section you learned about the different ways that signals are used to carry information. They can be analog or digital; and they can be electronic or electromagnetic. They can carry written information, sounds, images, 3-D structure, and video. For this information to be sent, however, new technologies have had to provide the physical means of transmitting signals from one location to another, to store that information, and to retrieve and manipulate it. Pre-industrial cultures used many ways to send information – smoke signals, drum beats, carrier pigeons, etc. Nowadays, there are three main means of signal transmission: electronic transmission through wires, electromagnetic transmissions through space, and

electromagnetic transmissions through optical fibers (called fiber optics). These can be used in different ways for sending information for different purposes.

Telephone Person-to-person communication is one of the oldest forms of information technology and still one of the fastest growing. It has grown from just analog voice communication through phone wires to sending digital voice, text, and video electromagnetically to and from mobile phones. In all of them, the basic idea is the same: information energy at one end is changed into a form that can be transmitted using one transducer, and converted back into the original signal at the receiving end using another transducer. A transducer is a device that converts a signal from one form of energy to another form of energy.

An example is shown in Figure XX for two people talking on cell phones. One person speaks into their phone. In this case, the transducer is a microphone that converts the sounds into an electronic analog signal. That electronic signal is transmitted along a wire by a varying voltage and then converted into a binary signal by an electronic processor. That signal is then converted into microwaves and broadcast from the phone to a receiver such as a cell phone tower. The signal can be carried through a series of other stages that could involve cables and even satellites until ultimately arriving by microwaves at the receiving phone. There, it is converted into an electronic analog signal and sent to a speaker (another form of transducer), where the vibrations of the speaker recreate the sound waves of the original words spoken into the first phone. When the receiving person answers the phone, the process runs in reverse, with the signal running from the second person back to the first.

Radio and Television Music and video signals are a large part of telecommunications. Radio and Television can be broadcast from powerful antennas or sent over copper wire cables. They can be sent as analog or digital signals. For analog broadcast transmissions, both radio and television use radio waves. Different frequencies are used for different stations. Signals can be sent either by modulating (changing) the amplitude of the signals (AM = Amplitude Modulation) or modulating the frequency of the signals (FM = Frequency Modulation) (See Figure XX). This is the difference between AM and FM radio. Analog broadcast television actually uses both: the picture is sent by amplitude modulation and the sound is sent by frequency modulation. There has been a graduate transition away from analog broadcast television toward digital broadcast television. Because more information can be sent in digital form, this has allowed for a higher-resolution television format called HDTV (High Definition Television).

Television has the additional challenge of trying to represent a two-dimensional image with only a continuous signal. This is done by dividing the screen up into a large number of horizontal lines with the signal written across the screen the way you would type out a letter on a word processor: starting in the top left, going left to right on each line, and going top to bottom with successive lines. When the bottom right corner is reached, the process starts over again. For analog television, there

are typically 525 lines (though the viewer can only see 480 of them) and the whole screen gets refreshed 30 times per second. That is fast enough that your eye cannot see the changes happening. For digital television, the horizontal lines are broken up into individual pixels. Standard definition digital television (SDTV) typically has 480 horizontal lines with 640 pixels in each line; high-definition digital television (HDTV) can have 1080 lines with 1920 pixels in each line. There are, however, many variations in the details of how the image is displayed for both analog and digital television. For example, some television systems use an interlaced scanning system, which alternates between writing out all of the odd-numbered lines and writing out the even-numbered lines. This creates a more smoothly changing image.

Satellite Communication Wires and cables work well for regional communications, but for large distances, such as between continents, more than 1000 satellites in space are used to relay telephone, radio, television, and Internet signals. Signals are broadcast from the ground, received by the satellite, and then rebroadcast to other areas of Earth’s surface. Most of the satellites orbit Earth in one of two ways: geostationary orbits and low-Earth orbits. A geostationary-orbit satellite will sit above one location at the equator, about 36,000 km above the Earth’s surface. If you watch it with a telescope, it will always be seen in about the same location in the sky. The advantage is that it is far enough from the surface so that it is in view from a large portion of Earth’s surface. The disadvantage is that it is so far away that it has to use a lot of power to rebroadcast signals. Satellites in low-Earth orbits are only about 200 km above Earth’s surface, so they can receive and rebroadcast signals using much less energy. However, they orbit the Earth quickly, once every 90 minutes, and each satellite can only be seen by a small area of Earth’s surface at any given time, so a large network of satellites is needed. Signals are sometimes relayed multiple times between many satellites before reaching their final destination. For example, imagine if you are in America and you call someone in Australia! Many satellite relays might be needed to connect the two of you!

Fiber Optics The fastest and most efficient way to send information is through fiber-optic cables. As the amount of global information rapidly increases, fiber-optic communication is rapidly replacing both copper wire and satellite communications. Fiber optics works by sending electromagnetic waves through a narrow cable made of glass or plastic. Though the speed of light in glass or plastic is slower than in a vacuum, it is still very fast: about 180,000 – 200,000 km/s. At this speed, a fiber optic signal could go to the other side of the earth and back again in 2/10 of a second. Fiber optic cables also carry a much greater signal bandwidth than copper wire cables, by about thousand times, which means a single fiber optic strand can carry about a thousand times the information of a single copper wire. Fiber-optic cables also use less energy, can carry information greater distances, don’t interfere with electrical devices, are more secure from hacking, and are safer concerning risks of fire (because no electricity is involved). Because of all these reasons, large numbers of fiber-optic cables are being installed for all uses, from short distances within buildings to long distances across ocean sea floors between continents.

Internet and WiFi Today’s computers are connected to each other in a complex set of interconnected networks known as the Internet. A schematic diagram of this network is shown in Figure XX. The Internet uses all of the technologies we have already talked about – electronic, electromagnetic, satellite, and fiber optics. The internet carries emails, files of many different formats (such as text, audio, and video), and also supports the World Wide Web, commonly known as “the web.” The web is a set of interlinked documents called web pages that can contain imbedded links to other documents or web pages. You use a program called a web browser to navigate across the Internet to other linked web pages and documents. Individual computers were initially linked to the Internet using connected wires and cables. However, there is a growing trend toward using microwaves to connect devices wirelessly to the Internet. One common example of this is WiFi, which uses microwave communication to connect your computer to a wireless network access point, which is commonly referred to as a hotspot. This is what allows people to take laptop computers and use them in any room of a house, as well as in classrooms, cafes, or anywhere that there is a wifi hotspot.

[Graphics : some kind of diagram of different IT components; sequence of signal transmission; diagram of AM and FM; fiber optic cables; Internet web]

What are the Advantages of Digital Signals?The new information technologies that are emerging are almost entirely using digital signals instead of analog signals. This is because there are so many advantages of using digital signals. There are still instances where analog signals are used. For example, if you listen to local FM radio station using a traditional radio, the signals are sent and received as analog signals. However, there are even growing numbers of digital radio stations. Digital signals are becoming the standard in almost every application of information technology. Here are some of the advantages of digital signals over analog signals.

Used by Computers Modern electronic computers are designed to work with binary signals, as described in the previous section. This means that transmitted digital signals do not need to be converted before being used by a computer. The digital signals can be directly interpreted and manipulated by a computer. Once inside the computer, many different kinds of manipulations such as filtering can be applied to the digital signals.

Noise Transmitted digital signals are much less susceptible to noise than analog signals. As a result, digital signals are able to retain their original information without losing resolution and getting noisy. Both transmitted digital and analog signals get weaker as they travel. As a result, the signals often get boosted by amplifiers that are installed along the transmission routes. As an analog signal travels, other random signals, called noise, can get incorporated into the signal. You hear this in a radio station as hiss and crackling, especially as you get farther from the transmitting radio tower. If you amplify this signal, you amplify the noise as well. After some time, there is more noise present than there is signal. However, a digital signal is just broadcasting two values, the 1’s and 0’s of binary code, usually in the form of two different voltages. The digital signals get noisy with distance as well, but because there are only two possible signals, the exact information is still retained. If the digital signal is amplified, the noise is removed and the original binary signal is retrieved and resent. An example of this is shown in Figure XX. This means that digital signals can be sent greater distances than analog signals.

Security Digital signals are more secure than analog signals. If a spy listens in on an analog signal, they can directly record the original signal. Digital signals are recorded as numbers, which are stored as digital bytes. They are already encoded as numbers, and it is very easy to further encrypt those numbers. An increasing amount of digital information is now sent in an encrypted form so that it cannot be interpreted by computer hackers.

Bandwidth The amount of information that can be transmitted, measured in bits per second, is called the bandwidth. Digital signals can store more information in less space than analog signals, so they have greater bandwidth. This means that cables can carry more information if it is in digital form, which is important because of the steady increase in the amount of information transmitted each year. One way that digital signals can take up less room is through a process called compression. The numbers making up the digital signal can be compressed so that they are stored in a more efficient manner for transmission. The numbers are uncompressed when the full signal is needed again at the receiving end.

Multidimensional Signals Analog signals work well when the signal is one-dimensional, such as with simple functions of time. Examples are the recorded voices of a telephone call or the music of a radio station. However, what do you do if what you want to send is a two-dimensional photograph or a three-dimensional object? Digital technology can still work in two or three dimensions. For example, look at the photograph of the cat in Figure XX. The left side looks very smooth and realistic. However, if you zoom in on the cat (right side), you will see that the photograph is actually broken up into the small little squares of pixels. Each of these pixels can be described in digital binary code. These numbers can be sent to another location, such as a computer screen or a printer, where they are reconstructed into the original photograph. As before, because there is very little noise introduced into the digital signal so the original photograph can be exactly reconstructed. However, if you do want to alter the photograph, in a process called photo “retouching,” computer programs can easily change the number values of the individual pixels, so as to change colors, smooth rough areas, or even remove objects from the photograph.

In a few cases, analog signals may be better than digital. Remember that a digital signal measures and records a physical signal only at certain intervals. All information in between those samples is lost. In modern information technology the sampling rate is usually small enough that you don’t notice the intervals and the signal appears smooth. However, if you were to greatly expand the digital signal (such as enlarging the photo of the cat’s eye), you would notice its choppiness. In certain circumstances, analog signals could be more secure than digital ones. A strong magnetic field could erase the digital information from a computer’s hard drive, but if the same information were stored on a vinyl record, the magnetic field would have no effect. However, in almost all other cases, digital signals are safer, more secure, more efficient, and more reliable than analog signals.

[Graphics: 1) demonstration of digital vs. analog noise = http://www.bbc.co.uk/schools/gcsebitesize/science/21c/radiation_life/waves_communicationrev2.shtml; 2) pixelated cat]

Assessment1. a. Evaluate Suppose you wanted to establish telecommunications between

California and Hawaii. What are the advantages and disadvantages of using satellites or fiber-optic cables? Which would you choose?b. Communicate Suppose someone asked you why digital signals are more secure than analog signals. What would you tell them?c. CCC (Structure and Function) Telephone speakers and microphones are both examples of transducers. In terms of signal transmission, what functions do they serve?

2. a. Integrate If you just had access to one telecommunications satellite, which would you chose—one in a geosynchronous orbit or one in a low-Earth orbit?b. CCC (Connections to Engineering and Technology) Explain how email has changed the rate at which business operates from how things were 50 years ago.

Study Guide2.3 Information TechnologiesWhat is Information Technology? Information technology is the application of computers and telecommunications equipment to store, transmit, receive, and manipulate data.What technologies are Used for Communication? Information signals are sent as electronic transmission through wires, electromagnetic transmissions through space, and electromagnetic transmissions through fiber-optic cables in order to provide communication through telephone, radio, television, and the Internet.What are the Advantages of Digital Signals? Compared to analog signals, digital signals are faster, more efficient, less noisy, more secure, and more reliable.