Computer Fundamentals & Programming

1. 
   INTRODUCTION
   

2. 
   Radio and TV
   

A radio is a receiver, which contains an input circuit for tuning into the frequencies of different transmitters to be received, a demodulation circuits for separating audio frequencies from the high-frequency carrier waves, a low frequency amplifier stage, and a loud speaker. A radio contains a device to receive long waves 9150-285KHz), Medium waves (up to 1605 KHz), short waves (6-21.4MHz), and ultra-short waves (up to 100 MHz). Long, medium and short wave reception function with a channel spacing of 9 KHz and with amplitude modulation (AM). The channel spacing in the ultra-short wave range is 300 KHz, and in this range frequency modulation (FM) is employed. All the four waves are elector magnetite waves.

The propagation conditions of the four radio wave ranges determine their possibilities of application and the purposes for which they are used.

Television

Television is a system of sending and receiving pictures and sound by means of electronic signals transmitted through wires and optical fibers or by electromagnetic radiation. These signals are usually broadcast from a central television station to reception devices in television sets in homes. The most common use of television is as a source of information and entertainment. Security personal use television to monitor buildings and facilities as also a cc TV. Doctors can check the interior of the human body with a microscopic television camera. Thus television is the world's most power form of communication.

The TV receives electrical signals, either through air, from broadcast stations or over cable or from CR. These signals are pulses of electrical energy that arrive in the wave. These waves can have many different shapes, and each shape can tell the TV something about what it is suppose to do A TV uses two kinds of waves AM (for Amplitude modulation i.e. for AM picture information) and FM (for frequency modulation i.e. for FM radio signals). FM signals can carry multiple audio channels- in this case two for stereo sound. AM waves, which are the same kind as the one use to carry radio signals, carry two picture information. AM can carry 30 pictures per second.

The TV draws pictures by synchronizing the electron guns (which shoot the beams that light the screen) with the yoke, a circle of magnets that deflects the electron beam left and right, and up and down, across the screen. Together guns and yoke can draw pictures, by knowing what to draw and where to draw it. Another AM signal carries the color information. It tells the TV where to put the color. This signal actually consists of two signals on the same wave, separated by time.

(ii) Transmission of Television Signals

Cable television was first developed in the late 1940s to serve people. Viewers in most areas can now subscribe to cable television services. Network television stations use microwave relay stations to broad case to affiant's communication satellites also receive television signals from a ground station and relay them back to specific area. Satellite transmissions are used to efficiently distribute television and radio programs from one geographic location to another. In addition, direct-broadcast satellites deliver television programming directly to individual receivers through small home dishes.

3. 
   Microwave System
   

Communication satellites in space, orbiting in the Clarke orbit are also used as microwave relay stations because they rotate at the preside point and speed above the equator, that makes them appear stationary to the microwave transmitters on the ground. Microwave systems have the capacity to carry large quantities of data, both digital and analog at high rates of speed. They are used for the transmission of television and telephones signals.

4. 
   Communication Satellites
   

One of the most important events in the history of satellite communication took place when COMSAT or communications satellite corporation, lunched four satellites within 6 years that is between 1965 to 1970. The first of these series was the "Early Bird", which was launched in 1965. This was the first communications station to handle worldwide commercial telephone traffic from a fixed position in space. The next series, INTELSAT was a group of satellites that served 150 stations on 80 countries.

The communication satellites are placed in orbits called EQVATORIAL GEOSYNCHRONOUS orbit. The satellite place in this orbit will appear stationary over a selected location on the earth's surface. So communication satellites are placed in an orbit that is directly over the equator, moving in a west-to-east direction at an altitude of 22,282 mile above sea level and with a forward velocity of 6874 mph to couplet one orbit in 24 hours. This orbit is called the CLARKE ORBIT.

Up-link system includes all the ground equipments along with the transmission path and receiving antenna are the satellite. The down-link is described in terms of satellite transmitter output power, down-link antenna gain and beam width and ground area that the transmitted signal will cover the FOOT PRINT.

At the altitude if the CLARKE ORBIT, one satellite could command a footprint area of 42.2% of the earth's surface. The beam width from the satellite for such coverage is 17.2 degree. Since such a satellite is not sufficient for global coverage, we need more than one (to be specific, 3) satellite.

These 3 satellites are placed 120 degrees apart in CLARKE ORBIT and would cover the earth's entire surface except for the polar caps. Due to such arrangement of the 3 satellites, one can communicate form one part of the glob to the opposite side of it. As described below in the figure, the distance between two satellites is 45,458 miles. From this picture, it is clear that to travel one information from one part of the earth to its opposite part, it travels 90,014 miles (i.e earth-satellites A- satellite B- opposite of the earth).



Fig: Cross-link connections for global coverage.
INTELSAT was the first to set up such a communication link. With satellites spaced over the Indian, Atlantic and Pacific oceans above the equator.
(iv) Component of a satellite:

There are five major components in the satellite. They are as follows:

1. 
   The transponder.
   
2. 
   The antenna system.
   
3. 
   The power package.
   
4. 
   The control and information system.
   
5. 
   The rocket thruster system.
   

The control and information system and the rocket thruster system are called the station keeping system. The function of the station keeping system is to keep the satellite in the correct orbit with the antennas pointed in the exact direction desired.

5. 
   Radar and Fiber Optical
   

The “RADAR” means the Radio Detecting and Ranging device. It devotes the method of scanning the surrounding space by means of high frequency radio waves, which are sent out from a powerful transmitter and are reflected by any object, which they encounter. The reflected beam is picked up by a receiver and its strength and direction gives information on the size, distance, altitude, etc of the object.

For example, an observer in an aircraft wishes to survey by radar the terrain over, which he is flying. The observer is strikes out the radar beam from the aircraft on the ground. The radar beam scans a circular area in the form of a sector, which sweeps round and round. Depending on the nature of the reflecting objects the intensity of the reflected beam will very as shown in the following picture.

The transmission and reception of the high frequency of radio waves are effected in the radar apparatus. The radar waves are generated in the transmitter, which is equipped with radio tube of special design. The transmitting antenna usually also functions as the receiving antenna. This process is called “periodic changeover”. The receiver picks up the beam in a cathode Ray Tube (CRT). The beam is so deflected that it scans the luminescent screen from the center to the edge. Fiber Optic Cable

Fiber optic cable and laser technology allows huge amounts of data to be routinely transmitted at the speed of light through tiny threads of glass or plastic. Fiber optic cable, the size of a human hair can transmit 2 billion bits per sec. This is about ten times greater than co-axial cables and 200 times better than twisted-pair wired. It is a tiny glass pipe.

The 'core' of a fiber optic cable is a very thin strand of highly refined cylindrical glass. The glass core of the cable may have a diameter as small as 4.5µm (2/10,000in) or as large as 400 µm. A second layer of glass called the 'clad' surrounds the core.

Protective

Outer sheath

Glass

covering

14. 
    Fig: Fiber optical cable
    

(i) The main ingredient in glass is sand, which is very cheap and available everywhere compare to copper and aluminum.

(ii) Photon of light, rather than an electrical current move through the optic fiber. Therefore, there is no chance of spark flash. Hence the system is safer.

(iii) Since the fiber optical system carries no electrical current; the energy transmitted through the fiber cannot radiate radio frequency interference, nor can it be contaminated by any external noise or radio frequency fields.

(iv)Because of absence of current flow through fiber, intrusion, into the system is also prevented. Confidential information cannot be routed to unwanted receivers, nor can false information be fed into the data stream.

(v) The transmission losses of fiber optic cables are much lower than that of the twisted-pair wires and co-axial cables.

(vi)Fiber optic cables provide substantial size and weight reduction as well as increased speed and grater carrying capacity. A half inch diameter fiber optic cable can carry up to 50,000 channels, compared to about 5,500 channels for a standard co-axial cable.

(vii) Glass is immune to corrosive and oxide degradation and will stand up well in hostile environment.

(viii) The size of the core and clad of a single fiber conductor is much smaller than the diameter of the common copper wire. Since fiber optic cables are not affected by and do not generate electromagnetic radiation. Therefore, multiple fibers can be placed in the same cable.

(b) Disadvantages of the fiber optic systems are:

(i) Use of fiber optical cable is limited. That is, they can be used only on point-to-point on the ground level.

(ii) It cannot be used to the very low powered devices.

(iii) The ways in which the light source can be modulated are limited.

ISDN is a high speed, fully digital telephone service. ISDN upgrades to day’s analog telephone network to a digital system. ISDN can operate at speed up to 128 kilo bits/sec, which is 5 or more times faster than today’s analog modem. ISDN can dramatically speed up transfer of information over the Internet or over a remote LAN connection, especially rich media like graphics, audio or video or applications that normally run at LAN speeds.

There are several types of ISDN service, but the most appropriate type for individual computer users, and the type that this site focuses on is the ISDN Basic Rate Interface (BRI).

Most of the world’s existing telephone networks are already digital. The only part that typically is not digital is the section that runs from the local exchange to your house or office. ISDN makes that final by of the network digital.

The original version of ISDN employs base band transmission. Another version, called B-ISDN, uses broad band transmission and is able to support transmission rates of 1.5 Mbps. B-ISDN requires fiber optic cables and is not widely available.

(a) Why is ISDN so Important?

More than just a means for fast, accurate, data transmission, ISDN truly represents the next generation of the world’s telephone service for all forms of telecommunication including voice.

ISDN brings the digital network to the individual users. Thus, the same twisted-pair wire telephone line that could traditionally carry only voice or one computer or one fax “conversation” can now carry as many as three separate “conversation” at the same time through the same line. ISDN the “magic” that makes this happen. Thus at the same line and through same cable three separate “Conversions” like (i) a voice call (ii) a computer transmission, (iii) an e-mail massage or a credit card authorization for example, could also takes place through the same connection.

10. 
    Internet and World Wide Web (Www).
    

1. 
   Introduction
   

2. 
   History of Internet
   

Later, a concept of network had been developed in which many devices were connected so they had shared resources. But here nothing was centralized, that is why it was quite a new concept. To fulfill this concept, a project called ARPA net was started in the USA. Later ARPA net changed into Defense Advanced Research Project Agency net (DARPA net) during 1970 to 1980 AD. Later other networks like BITNET, NSFNET, USENET and UUCP were connected with DARPANET. Then US government had facilitated its development by providing funding and some guidance. Then the name of this group of this Network was given as Information Super Highway. Then after 1996 the name of information super Highway also changed into Internet. Again at the beginning of 2000 AD, Intranet and Extranet also came into the world market as a special part of the Internet.

There are three obvious reasons. Internet is the cheapest and fastest means to:

At present people are using Internet (i.e. world wide web- www) to get information about people, products text, organization, research data, electronic version of the printed media, etc.

People can use Internet to provide information about their Institutes, organizations, companies, products, facilities, rule and regulations, graphical pictures, photo’s, etc. They can advertise globally for a long time in a cheap price and providing more spaces, using website (Internet). People are using Internet for the distance learning and assistance for students.

You can conduct a survey collecting opinion of the people within or outside your country for example using SMS in TV or radio etc. The web provides you ideal platform and opportunity.

3. 
   Internet Access
   

i) Dialing into an internet service Provider (ISP) and

ii) With a direct connection to internet service provider. The difference is mainly in the speed and cost, in most cases you connect to your ISP using a telephone line and modem. This type of connection is called dial up connection. Some times you go in for a direct connection.



Fig: Computer of a dial up connection
In the dial up connection you use modem, but in the direct connection to ISP you do not use modem. In the direct connection you will use Integrated Services Digital Network (ISDN). ISDN can handle more than 56,600 bps. ISDN provides you voice mail, e-mail, chatting and computer processing facilities,

4. 
   Internet Basic,
   

i) A set of computer

ii) A modem

iii) Access to the Internet host

iv) A communication software (Internet Explorer & Netscape Navigator, etc.)

v) A dedicate telephone line.

vi) Registration to one of the local Internet Service Providers

1. 
   Internet Protocol
   

i) Transmission control protocol/ Internet protocol (TCP/IP)

ii) File transfer protocol (FTP)

iii) Hyper text transfer protocol (HTTP)

iv) Telnet.

v) Gopher

vi) Wide area information service (WAIS)

5. 
   Internet Addressing
   

An IP (Internet Protocol) address is an Identifier for a particular machine on a particular network. It is a part of a scheme to identify computers on the Internet. IP addresses are also referred to as IP numbers and Internet addresses. An IP address consists of four sections separated by periods. Each section contains a number ranging 0 to 255. Example 202.54.1.6. These four sections represent both the machine itself or host and network that the host is on. The network portion of the IP address allocated to internet services providers (ISPs) by the Inter NIC, under authority of the Internet Assigned Numbers Authority (IANA). ISPs then assign the host portion of the IP address to the machines on the networks that they operate. The IP addresses have the following characteristics in common:

i) IP addresses are unique.

ii) No two machines can have the same IP number.

iii) IP addresses are also global and standardized.

iv) All machines connected to the internet agree to use the same scheme for establishing an address.

6. 
   DOMAIN NAME:
   

Examples:. Microsoft.com, Tel.net, Nide.org, Min.edu etc. www. Microsoft.com. etc.

7. 
   Activities Available In the Internet
   

1. 
   Visit web sites.
   
2. 
   Send and receive electronic mail.
   
3. 
   Read and post articles in news groups.
   
4. 
   Down load files on your PC.
   
5. 
   Chat with other user on line.
   
6. 
   Play games with others on line.
   
7. 
   Access on- line multimedia including radio and video broadcasts.
   
8. 
   Search the internet for information.
   
9. 
   Subscribe to electronic newspaper, newsletters, e-mail, etc.
   
10. 
    Join contests.
    
11. 
    Contribute articles and other materials.
    
12. 
    Do on line shopping.
    
13. 
    Post your resumes on the internet.
    
14. 
    Create your own web sites.
    
15. 
    Create an e-mail ID and account for you.
    
16. 
    Use the e-mail remainder service.
    
17. 
    Find a person’s details.
    
18. 
    Send flowers or gifts to other.
    

The above list is by no means a computer and comprehensive one. There are a lot of other things that you can do on the Internet.

8. 
   WebPages, Html, Web Browsers, Searching the Web, Internet Chat.
   

11. 
    WORLD WIDE WEB (WWW):
    

At present, any user can use Internet explorer, or Netscape Navigator to view the websites or web page. In general, these programs are called web browser. It is a kind of interactive application program. Using this, you can search, find, copy, print the information found in the websites. Similarly, you also can send the information and create the websites for the global users at any time.

12. 
    Electronic Mail:
    

1. 
   
   Directory: 2013
   2013 -> Annual InStructional unit plan
   2013 -> The Ministry of Education and Science of Ukraine
   2013 -> #1 a lifesafer of virginia inc
   2013 -> Name(s): your name here team or Group #(if applicable): Professor’s name
   2013 -> Alcott Local School Council (lcs) Meeting Minutes
   2013 -> Table Of Contents introduction 2
   2013 -> Supplemental demographic information
   2013 -> 【Education&Working Experience】
   
   
   
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