Term Paper on Radio by Pradip & Partha_ICT_3rd Batch_1st Semester_2011

7/31/2019 Term Paper on Radio by Pradip & Partha_ICT_3rd Batch_1st Semester_2011

http://slidepdf.com/reader/full/term-paper-on-radio-by-pradip-parthaict3rd-batch1st-semester2011 1/24

TERM PAPER ON RADIO

SUBMITTED TO:KHONDOKAR FIDA HASANEMAIL: [email protected]

LECTURERDEPT. OF INFORMATION &COMMUNICATIONTECHNOLOGY (ICT)COMILLA UNIVERSITY (COU),COMILLA-3503BANGLADESH

SUBMITTED BY:NAME ID NO EMAILPRADIPCHANDRAKARMAKER

1109021

[email protected]

PARTHACHAKRABAR

TY

1109025

[email protected]

DATE OF SUBMISSION: 29-04-2012

1

mailto:[email protected]

mailto:[email protected]



TABLE OF CONTENTS

NAME PAGE

NO

1 INTRODUCTION 3

2 LITERATURE REVIEW 4

3 METHODOLOGY 64 DISCUSSION 12

5 CONCLUSION 21

6 BIBLIOGRAPHY 22

7 APPENDIX 23

2



INTRODUCTION

What is Radio?

Radio is part of the Electromagnetic Spectrum (EM) along with Light.

The Electromagnetic Spectrum

Whenever an electric charge changes speed or direction it gives off an electromagnetic (EM) wave.

Wireless communication products, such as cell phones and satellite radio, have

become a much a part of today’s everyday life as the microwave did two decades ago. During

the next few years, this technology will spread from consumer products on to the shop floor.

Automation and process engineers and managers need to understand wireless—or radio

frequency (RF)—technology to properly assess and deploy the many wireless automation

products that soon will become available to

them. Working with wireless products, which use the air as the medium of communication,

offers challenges different from their more familiar wired product counterparts. Early

incarnations of wireless automation products often left the buyer feeling mystified and

shortchanged. They offered spotty performance and were difficult to install, configure and

maintain. Fortunately, the new generation of wireless products is easier to use. In addition to

consuming much less power, these new products are easy to configure and install, offer built-in tools for monitoring the reliability of the wireless connection and can easily be integrated

with existing wired infrastructure.

.

Motivation

This article takes I into the past into the history of radio invention. In this section, I

will like to discuss the motivation for choosing this topic.

1. The choice of this topic is apparently linked with the irritation of a student of

electronics and communication engineering that the fact that Marconi’s wireless was actually invented by Sir J C

Bose is not well-known among engineering students, academicians and professionals.

The classic text on antenna theory, which is widely referred across the globe is

“Antennas”, by J D Kraus [2]. The author dedicates the book is to Hertz and Marconi

and has a scarce mention of Bose. While discussing the historical perspective of radio

invention

2.

3



In the present article, I have tried to systematically explain the actual experiment conducted by Marconi and thereby

explaining the relevance of all equipment used. This would clearly give an

idea as to what exactly was Marconi’s contribution and what Bose did.

3. History always opens channels for new thinking. It would be interesting and exciting to note how communication

was done for the first time without any amplitude modulation techniques, no understanding of

bending of electromagnetic waves ,existence of any of the active (non-linear) devices (e.g.,

diode, vacuum tubes, etc.). It

gives a definite peep into how science progressed and came to the current stage anhow it would progress further.

LITERATURE REVIEW

If success has many fathers, then radio is one of the world’s greatest successes. Perhaps one simple way to sort out

this multiple parentage is to place those who have been given credit for “fathering” radio into groups.

The Scientists:•

Henrique Hertz—

This German physicist, who died of blood poisoning at age 37, was the first to prove

that you could transmit and receive electric waves wirelessly.

Although Hertz originally thought his work had no practical use, today it is

recognized as the fundamental building block of radio and every frequency

measurement is named after him (the Hertz).

• Nicola Tesla —

He was a Serbian- American inventor who discovered the basis for most alternating-

current machinery.

In 1884, a year after coming to the United States he sold the patent rights for his

system of alternating current dynamos, transformers, and motors to George

Westinghouse.

He then established his own lab where he invented, among other things, the Tesla

coil, an induction coil widely used in radio.

• Alexanderson —

Born in Sweden, this remarkable inventor developed the first alternator to make

transmission of speech (as opposed to the dots and dashes of telegraphs) possible.

It is said that this holder of 344 patents “virtually invented everything General

Electric did in the field of AM, FM, and TV.”

4



• Fessenden —

This Canadian spent much of his working life in the U.S. where he developed a way

to combine sound and radio carrier waves.

His first effort to transmit this mixed signal— to a receiver where the carrier wave

would be removed and the listener could hear the original sound— failed.

However, in 1906, using Alexanderson’s Alternator, Fessenden made the first long

range transmission of voice from Brant Rock, MA.

• ED Armstrong —

This WWI Army officer, Columbia University engineering professor, and creator of

FM radio invented the regenerative circuit, the first amplifying receiver and reliable

continuous-wave transmitter; and the Super heterodyne circuit, a means of receiving,

converting and amplifying weak, high-frequency electromagnetic waves.

His inventions are considered by many to provide the foundation for cellular

phones.

• Marconi —

This Italian creator spent most of his working life in England where he introduced

many of the first uses of wireless telegraphy to European navies.

His radio apparatus is widely considered to be the reason that over 700 people

survived the Titanic disaster in 1912— instead of dying as they likely would have if

ships at sea were still using carrier pigeons to communicate over great distances.

• Lee De Forest—

Credited with being the “father of American radio.”

De Forest was a direct competitor to Marconi at the turn of the century (1899), when

he was the chief scientist at the U.S.’s first radio firm—American Wireless

Telephone and Telegraph—until Marconi took over the company’s assets in 1912

after a series of financial scandals.

Although he held 300 patents, De Forest’s greatest technological contribution is

considered to be his 1906 “Audient” vacuum tube.

David Sarnoff -

Began as telegraph operator for Marconi.

Originated idea of “broadcasting.”

Became president of the corporation of America.

5





Fig. 2: Poled Transmitter, 1901

The (assumedly) actual transmitter used by Marconi is shown in Fig2The two-stage spark circuit (somehow caused)a multiplication of voltage, such that the second capacitor (C2) discharged at a much higher voltage. Several periods

of the supply generator were required to charge the first capacitor, while the second loop had a spark rate of just two

to three sparks per second . Finally the current was sent to the antenna 4 through the coupling. It is interesting to

note that the power of the generating plant was

around 25 KW and capacitor sizes went to several times human height!

The antenna used by Marconi is believed to be a cone antenna as shown in Fig. 3(70 metes in height It was

essentially based on the concept of Hertz Ian Monopole, but was extended by Fleming to this form. It is also believed that Marconi was using an end loaded antenna (by connecting a horizontal wire) at the top of the monopole,

which improved the performance of the antenna. An interesting study of what probably Marconi was using is given

in .

Fig. 3: Marconi’s Podium’s transmitter

c. Details of experiment:

All scientists at the time of Marconi thought that he would never be able to transmitinformation across the trans-Atlantic, since EM waves behave like light and they couldn’t bend due to earth’s

7



curvature. However, Marconi had a queer faith that he would be able to transmit informationacross few hundred

miles using EM waves.

To test his hypothesis, Marconi had established a huge transmitting antenna at Podium in

Cornwall, UK and aimed at receiving the signal at Newfoundland, St. Johns, which was a distance of around 2000miles.

On December 12, 1901, Marconi set to receive the letter ‘S’ (three dots) at Newfoundland as they were transmittedfrom Oldham. He had the antenna (150m long wire [26]) put on a kite, from which a wire came to a pole and finally

to the receiver. The receiver consisted of some kind of a ‘coherer’ and a telephone receiver to hear the signal using

an earphone. Marconi claimed to hear the three dots of the signal ‘S’. This is the famous transatlantic experiment of

Marconi, where signal was transmitted wirelessly for the first time.

Interestingly, the exact wavelength of the EM wave used by Marconi is unknown and is considered around 366

metes (820 KHz). An article by H. M. Bradford [9] argues the claim of Marconi whether he received the firsttransatlantic wave.

d. The receiving equipment:

As mentioned before, Marconi used a coherer to detect the EM waves. Consider that we have EM waves

coming at the RF frequency, which the antenna would sense and supply a current at the same frequency. It was

required to detect this current on a galvanometer or paper tape recorder. The only way which seems plausible to

detect such a current is to convert it into (or trigger) a direct current that could be measured or used to drive a

secondary action. This is analogous to what we do to detect AM signals using a diode detector. However, no diodeswere available at that time and ‘coherer’ was the device, which replaced the diode detector. The technical details of

the coherer are given in Section 5.The coherer used by Marconi to receive the first trans-Atlantic signal was invented by Sir J. C. Bose [1]. Marconi

got it patented in his name since he didn’t want to share the credit of his accomplishment with any other scientist

[11]. The next section brings to light the whole scandal.

RADIO WAVES COVER THE EARTH-

In this topic we will learn how radio waves spread themselves over the face of the earth,

carrying messages and music from one country to another country.

THE RADIO WAVE-

When it leaves a vertical antenna, the radio wave resembles a huge doughnut lying on

the ground, with the antenna in the hole at the center. Part of the wave moves outward in contactwith the ground to form the GROUND WAVE, and the rest of the wave moves upward and

outward to form the SKY WAVE. This is illustrated in figure 148.

Figure .4:-Formation of the ground wave and sky wave.

8



The GROUND and SKY portions of the radio wave a. responsible for two different METHODS of

carrying the messages from transmitter to receiver.

The GROUND WAVE is used for SHORT-RANGE COMMUNICATION at high frequencieswith low power, and for LONG-RANGE COMMUNICATION at low frequencies and very high

power. Day-time reception from most commercial stations is carried by the ground wave.

The SKY WAVE is used for long-range, high-frequency daylight communication. At night, the

sky wave provides a means for long-range contacts at LOWER FREQUENCIES.

THE GROUND WAVE

The ground wave is made up of four parts-DIRECT, GROUND-REFLECTED, TROPOSPHERIC,

and SURFACE waves. The relative importance and use made of each part is dependent on several

factors. The chief factors are-frequency, distance between the transmitting and receiving antennas,

height of the antenna, the nature of the ground over which the wave travels, and the condition of

the atmosphere at the lower levels.

The DIRECT WAVE travels directly from the transmitting antenna to the receiving antenna. For

example-two airplanes are several thousand feet in the air and only a few miles apart. This directwave is not influenced by the ground, but may be affected by the atmospheric conditions through

which the wave travels.

The GROUND-REFLECTED WAVE permits two airplanes several miles distant and at low

altitudes to communicate with each other. The wave arrives at the receiving antenna after beingreflected from the earth's surface. When the airplanes are close enough and at the correct altitude to

receive BOTH direct waves and ground-reflected waves, the signals may be either reinforced or

weakened, depending upon the relative phases of the two waves.

The TROPOSPHERIC WAVE is the part of the wave that is subject to the influences of theatmosphere at the low altitudes. The effects of the atmosphere on this type of wave propagation are

most pronounced at frequencies above the high end of the H-F band. Communication by the use of

the troposphere wave is gaining in importance, both from the standpoint of its usefulness, and itsfrequent unpredictable ranges. This type of communication is discussed in more detail later in this

chapter.

The SURFACE WAVE brings most of the low and medium frequency broadcasts to your receiver.

These frequencies are low enough to permit this wave to follow the surface of the earth. The

intensity of the surface wave decreases as it moves outward from the antenna. ThisATTENUATION-rate of decrease-is influenced chiefly by the conductivity of the ground or water

and the frequency of the wave.

As it passes over the ground, the surface wave induces a voltage in the earth, setting up eddycurrents. The ENERGY to create these currents is PIRATED or taken away from the surface wave.

In this way, the surface wave is weakened as it moves away from the antenna. increasing the

9



frequency rapidly increases the rate of attenuation. Hence surface wave communication is limited

to the lower frequency.

69019V-46-15

THE SKY WAVE

In behavior, the SKY WAVE is quite different from the ground wave. The part of the expanding

lobe that moves toward the sky "bumps" into an IONIZED layer of atmosphere, called the

IONOSPHERE, and is bounced or bent back toward the earth. If your receiver is located in the

area where the returning wave strikes, you will receive the program clearly even though you areseveral hundred miles beyond the range of the ground wave.

The ionosphere is found in the rarified atmosphere, approximately 30-350 miles above the

earth. It differs from the other atmosphere in that it contains a higher percentage of positive and

negative ions.

The ionosphere has three effects on the sky wave. It acts as a CONDUCTOR, it absorbs energyfrom the wave, and it REFRACTS or bends the sky wave back to the earth as illustrated in figure

150

Figure .5:-Refraction of the sky wave by the ionosphere.

When the wave from an antenna strikes the ionosphere, the wave begins to bend. If the frequency

is correct, and the ionosphere sufficiently dense, the wave will eventually emerge from the

ionosphere and return to the earth. If your receiver is located at either of the points B, in figure 150,you will receive the transmission from point A.

Don't think that the antenna reaches as near the ionosphere as is indicated in figure 5 Remember

the tallest antenna is only about 1,000 feet high.

The ability of the ionosphere to return a radio wave to the earth depends upon the ANGLE at

which the sky wave strikes the ionosphere and upon the FREQUENCY of the transmission.

10



For discussion, the sky wave in figure 6 is assumed to be composed of four rays. The angle at

which ray 1. strikes the ionosphere is too nearly vertical for the ray to be returned to the earth. The

ray is bent out of line, but it passes through the ionosphere and is lost.

The angle made by ray 2 is called the CRITICAL ANGLE for that frequency. Any ray that leaves

the antenna at in angle GREATER than theta (θ) will penetrate the ionosphere Ray 3 strikes theionosphere at the SMALLEST ANGLE that will be refracted and still return to the earth. Any

smaller angle, like ray 4, will be refracted toward the earth, but will miss it completely.

As the FREQUENCY INCREASES, the size of the CRITICAL ANGLE DECREASES. Low

frequency fields can be projected straight upward and will be returned to the earth. The HIGHEST

FREQUENCY that can be sent directly upward and still be returned to the earth is called theCRITICAL Frequency. At sufficiently high frequencies, the wave will not be returned to the earth,

regardless of the angle at which the ray strikes the ionosphere.

The critical frequency is not constant. It varies from one locality to another, with differences in

time of day, with the season of the year, and according to sunspot cycle.

This variation in the critical frequency is the reason why you should use issued predictions-FREQUENCY

Figure.6:-Effect of angle of refraction on sky wave

Radio is consist of just a few parts -

An outside wire antenna, which captures the various radio signals

coming our way.

An antenna coil and variable capacitor, which do two jobs. The antenna

coil is wired as a transformer ,coupling the antenna signal to the radio.

The secondary of the coil ,along with the variable capacitor also form

11



a turned circuit which select the station we want , while rejecting we

do not want. A diode rectified the AM signal.

A .001F capacitor which filters, out the high frequency carrier and

sidebands ,and keeps only the envelop the audio signal.

A pair of headphones which convert the audio signal to sound.

DISCUSSIONRadio waves" transmit music, conversations, pictures and data invisibly through the air, often over

millions of miles -- it happens every day in thousands of different ways! Even though radio waves

are invisible and completely undetectable to humans, they have totally changed society. Whether we are talking about a cell phone, a baby monitor, a cordless phone or any one of the thousands of

other wireless technologies, all of them use radio waves to communicate. How Was Radio

Astronomy Discovered?

Karl Junky joined the staff of the Bell Telephone Laboratories in Holmdel, NJ, in 1928. Junky had the job of

investigating the sources of static that might interfere with radio voice transmissions at “short wavelengths”

(wavelengths of about 10-20 meters). These wavelengths were being considered for transatlantic radio telephones.After recording signals from all directions for several months, Junky identified three types of static: nearby thunderstorms distant thunderstorms, and

a faint steady hiss of unknown origin.

Junky spent over a year investigating the third type of static. It rose and fell once a day, leading Junky to think at

first that he was seeing radiation from the Sun. The signal repeated not every 24 hours, but every 23 hours and 56

minutes (sidereal time – the motion of the stars). This is characteristic of the fixed stars, and other objects far from

our solar system. He eventually figured out that the radiation was coming from the Milky Way and was strongest in

the direction of the center of our Milky Way galaxy, in the constellation of Sagittarius. The discovery was widely

publicized, appearing in the New York Times of May 5, 1933. Junky wanted to follow-up on this discovery but BellLabs did not.

Although fascinated by the discovery – no one investigated it for several years. Grote Rebel – 1911-2002Grote Rebel learned about Karl Junky’s discovery (1932) of radio waves from the Milky Way Galaxy and wanted to

follow up this discovery and learn more about cosmic radio waves. Rebel built a parabolic dish reflector in his

backyard in Wheaton, IL in 1937 because this shape focuses waves to the same focus for all wavelengths. Rebel

spent long hours every night scanning the skies with his radio telescope. He had to do the work at night because

there was too much interference from the sparks in automobile engines during the daytime. After two failed attempts

he finally succeeded with a receiver at 160 MHz (1.9 meters wavelength) to detect radio emissions from the Milky

Way. In the years from 1938 to 1943, Rebel made the first surveys of radio waves from the sky and published his

results both in engineering and astronomy journals, ensuring radio astronomy’s future.

The list goes on and on... Even things like radar and microwave ovens depend on radio waves.

Things like communication and navigation satellites would be impossible without radio waves, as

would modern aviation -- an airplane depends on a dozen different radio systems. The currenttrend toward wireless Internet access uses radio as well, and that means a lot more convenience in

the future!

The funny thing is that, at its core, radio is an incredibly simple technology. With just a couple of electronic components that cost at most a dollar or two, you can build simple radio transmitters and

12



receivers. The story of how something so simple has become a bedrock technology of the modern

world is fascinating!

In this article, we will explore the technology of radio so that you can completely understand howinvisible radio waves make so many things possible!

The Basics of Radio Frequency SystemsAll RF systems consist of two major elements: a transmitter and a receiver . As the namesimply, a transmitter transmits a signal to a receiver, which listens for the signal. The systemincludes a set of rules that define how the transmitter and receiver communicate. A rule setcan simply specify that the transmitter must communicate with the receiver at a specificfrequency. More complicated rule sets define not only the frequency, but the time when thetransmitter and receiver communicate, how “loud” they can talk, the “language” they speak,and what to do if they can’t “hear” one another. Government regulatory agencies such as theFederal Communications Commission (FCC) set these rules, as do national and internationalstandards groups such as the Institute of Electrical and Electronics Engineers (IEEE).

Problems with Early Designs-In early RF systems, a transmitter was connected to a sensor thattransmitted information to a simple receiver. Early systems had a limited bandwidth—therange of frequencies they broadcast across and the amount of data transmitted in that band.Usually the data traveled on a single frequency, a system called narrowband. Because of limitations in early integrated circuit (IC) technology, the transmitter could only transmit andthe receiver could only receive. Without two-way communication,it was impossible to know if the receiver was receiving all the information thetransmitter was sending.Additionally, sometimes the receiver would not receive the signal, because signals candegrade, or attenuate, as they reflect off or pass through objects such as walls or filingcabinets. The RF system was unaware that the transmitted signal was lost, because thereceiver was unable to acknowledge, or ACK , reception. Because reliability was poor, those

who tried these systems were generallydisappointed and developed a jaded view of RF systems.

Improvements in RF System DesignAs technology evolved, radio design saw major improvements in three key areas:

• IC technology. Both the transmitter and receiver were incorporated into a singlecomponent, called a transceiver . The transceiver makes it economical to implementbidirectional communications, dramatically improving reliability and maintainability.

• Higher frequency RF components. Because higher-frequency components generallyoperate across a wider RF band, they transmit more data than their low frequencycounterparts. A drawback is that higher frequencies degrade—that is, they are

absorbed—more readily as they pass through objects, which decreases range. Tocounter this effect, designers add amplifiers to the transmitter and design moresensitive receivers, increasing cost.

• Spread spectrum modulation. Modulation is the way data is impressed onto a radiowave. Today, many radio systems use a technique called spread spectrum to modulatedata across the bandwidth of the radio. Spread spectrum allows multiple users to sharethe same frequency channel at the same time.

Two different spread spectrum technologies are commonly used today:

13



1) Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping SpreadSpectrum (FHSS). Some hybrid schemes use both DSSS and FHSS.

2) Another modulation scheme commonly used in ISM bands—those used forindustry, science and medicine—is Orthogonal Frequency-Division Multiplexing(OFDM).

Two newer spectrum-sharing modulation techniques are ultra wide band (UWB) and chirp

modulation, both of which are gaining popularity.For a description of the history of spread spectrum and the various types of spread spectrum,see the ISA’s tutorial “The Physics of RADIO.”

Every so often it occurs to me that radio reception is pure magic. When you turn on the radio you

hear music, voice or other audio entertainment that is broadcast from hundreds or thousands of

miles away. It's really not magic. Radio is actually easy to understand and this article will help de-mystify how radio waves are created and broadcast.

Both AM and FM radio programs are transmitted over the air via radio waves, which are part of

a broad range of electromagnetic waves that include visible light, X-rays, gamma rays and others.

Electromagnetic waves are all around us in different frequencies. Radio waves are similar to lightwaves but are at a frequency our eyes are not sensitive to.

Electromagnetic waves are generated by alternating current (AC), the electrical power used to run

every appliance in our homes from washing machines to televisions. Alternating current in the US

is 120 volts at 60Hz, which means that the current alternates or changes direction in the wire 60times per second. Other countries use 50Hz as the standard. Both 50 and 60Hz are relatively low

frequencies, but even 60Hz alternating current generates some level of electromagnetic radiation,

meaning that some of the electricity escapes the wire and is transmitted into air. The higher thefrequency of the electricity, the more electricity escapes the wire and into space. Thus,

electromagnetic radiation can be described as 'electricity in the air'.

AM Radio Broadcasts

AM radio uses amplitude modulation and is the simplest form of radio broadcast. To understand

amplitude modulation, consider a steady signal broadcasting at 1000 kHz on the AM band. Theamplitude or height of the constant signal is unchanged or un-modulated, thus no useful

information. The steady signal produces only noise until it is modulated with a voice or music as

shown in figures 1 & 2. Notice how the amplitude or loudness of the signal increases or decreasesto produce useful sound or information.

AM radio in the Americas operates in a range of frequencies from 520kHz to 1710kHz. Other

countries and regions have a different frequency range. The specific frequency is called the carrier

frequency, the vehicle by which the signal is carried from the broadcast antenna to the receivingtuner.

AM radio has the advantage of transmitting over greater differences because AM signals bounce

off the upper atmosphere but suffers from more noise and interference than FM, especially during

thunderstorms. The electricity generated by lightning produces noise spikes picked up by an AMtuner. AM radio also has a very limited audio range, from 200Hz to 5kHz, which limits its

usefulness to talk radio and less for music.

14



FM Radio Broadcasts

FM radio uses frequency modulation, which changes or modulates the frequency of the

unmotivated signal while keeping the amplitude of the signal constant. When the frequency is

modulated, music or talk is transmitted via the carrier frequency (see figures 3 & 4).

FM radio operates in the range of 87.5MHz to 108.0MHz, a much higher range of frequencies thanAM radio.

The distance range for FM transmissions are more limited than AM, usually less than 100 miles,

but are better suited for music because the frequency range of FM is from 30Hz to 15kHz. FM

broadcasts are also commonly in stereo, although a few AM stations also broadcast stereo signals.

Although FM signals can be subject to noise from lightning like AM signals, FM broadcasters use

a limiter function that clip-off the noise spikes to produce a relatively noise-free signal.

Software Defined RadioWith the exponential growth in the ways and means by which people need to communicate -data communications, voice communications, video communications, broadcast messaging,command and control communications, emergency response communications, etc. – modifyingradio devices easily and cost-effectively has become business critical. Software defined radio(SDR) technology brings the flexibility, cost efficiency and power to drive communications

forward, with wide-reaching benefits realized by service providers and product developers through

to end users.

Free Space Waves-

15



•

Fig.7:-Free Space Wave

» Free-space wave is a signal that propagates from Point A to

Point B without encountering or coming near an obstruction.

SOME GORGEOUS WORK OF RADIO

The Sudan Radio Service (SRS).Serving adults at all levels throughout Sudan, this program provides instruction concerning civic

education, current events (news), health, general education, agriculture and animal husbandry, andculture, among other content areas. Programming is conducted primarily in Arabic, however it includesEnglish and local languages such as Nuer and Dinka. Starting with 2 hours of daily programming in

2003, the current schedule includes 6 hours of daily programming, 3 hours in the morning and 3 in theevening (personal communication, Jeremy Groce, Nov. 7, 2007).

Southern Sudan Interactive Radio Instruction (SSIRI)This project anticipates reaching over 100,000 children in grades 1 to 4 through daily half-hour radio programs per grade. The lessons teach math, local language literacy, English, peace building, and life

skills.The broadcasts are in English, with instructions for the local instructor to translate directions into the

local language as may be necessary depending on the grade level and the subject matter.In addition, SSIRI is developing an English language series for youth and adults consisting of 240 half-

hour programs ranging from beginning to advanced levels. In addition to teaching English, the

programs provide information on civic education, health, and numeracy.

Finally, SSIRI has developed the first of several planned modules of radio programs to support teacher training (personal communication, Thomas D. Tilson, Nov. 6, 2007).

Zambia Quality Education Services Through Technology (QUESTT) Project This project “aims toimprove the quality of basic education delivery systems” (International Education Systems, 2007e).

Serving rural, hard-to-reach students from grades 1 through 7, this program teaches math, science,

Free-Space Waves

16





piloted the use of iPods and cell phones in instructional settings (personal communication, RichardTrewby, Nov. 6, 2007).

Somali Interactive Radio Instruction Program (SIRIP)Designed to reach students both in and out of the formal education system, this program uses radio toreach students in grades 1 to 5 to teach Reading, Math and Life skills (health, conflict prevention and

mediation, democracy-building). Instruction is conducted in Somali, and has already reached nearly120,000 students, and has a goal of reaching 400,000 students (personal communication, Said Yasin,

Nov. 6, 2007).

Somalia Distance Education Literacy Programme (Somdel)As part of the BBC World Services Trust, this project used radio instruction to teach more than 10,000

Somalis basic literacy, numeracy, and life skills. Using teachers who were nominated by the

community, this project allowed for substantial community involvement in determining when and

where classes would be held. “Of the 10,908 people on Somdel, 9,000 passed their final exam. Of those, 70% were women” (BBC News, 2003).

Technology Tools for Teaching and Training in India (T4 Phases I & II)

With the potential to reach 15 million students in 200,000 schools throughout the Chhattisgarh,Jharkhand, Karnataka, Madhya Pradesh regions of India, this project proposed to use radio to teachEnglish as a Second Language (ESL), Mathematics, Science, Social Studies, Kannada and Hindi to

students in grades 1 through 5. Instruction occurred in English, Kannada and Hindi. Phase II was toreach students in grades 1 through 8 with an expanded offering of educational programs. Due to

funding difficulties, many project elements were modified or cancelled (personal communication,

Victor Paul, Nov. 9, 2007).

Distance Education Inside and Beyond the Classroom (Haiti)Utilizing solar and wind-up powered radios, this project teaches both in-school and out-of-school youth

in Haiti. Utilizing Creole as the language of instruction, this project has reached more than 42,000

students in traditional school settings while preparing materials for the out-of-school youth programs.The in-school program covers the grades 2 through 4 content, while the out-school program is an

accelerated program which seeks to teach 6 years of primary school in 3 years. Level 1 programs(grades 1

18



and 2) have been developed and are currently being tested, while level 2 programs (grades 3 and 4) areunder development.

The Ministry of Education has only recently completed the draft accelerated curriculum for level 3(grades 5 and 6) so it is expected that level 3 learning objectives will be adapted to radio under the next

USAID project slated to start in 2008 (personal communication, Gaëlle Simon, Nov. 6, 2007).

Interactive Radio Instruction-Based Pre-School Program in HondurasCovering the Comayagua, Francisco Morazan, and La Paz regions of Honduras, this project delivered

Spanish-language instruction in all pre-school subjects. An unanticipated outcome of this project saw

the parents of participating students become more active and purposeful in their participation.

Guyana Interactive Radio Instruction ProgramThe EDC helped the Government of Guyana develop Interactive Radio Instruction programs, which are

now the official national curriculum for Guyana grades 1 and 2 math. The government is continuing to

work on Grade 3. A nationwide assessment of grade one students showed very positive results after using only a third of the programs; however, there are no further assessment results yet as grade 2 went

nationwide only this year and Guyana discontinued the grade 1 assessment.Guyana's national assessment unit administered tests in mathematics to first graders throughout the

country in two recent school years, with the first group having received no Interactive RadioInstruction and the second group having received

19



approximately one third of a year's lessons during a pilot phase of the program. The post-testdemonstrated learning gains in all eight mathematical domains tested, with six of the changes proving

statistically significant.The Interactive Radio Instruction programs are now the official national curriculum for Guyana grades

1 and 2 math and government is continuing to work on Grade 3 (personal communication, Daniel Pier,

Nov. 26, 2007).

Malawi Interactive Radio Instruction (Tikwere!)Using national radio broadcasts, covering all 5,200 primary schools in Malawi as well as all out-of-

school students (although this is not the primary audience), this project will teach language skills,

literacy, English, math, and life skills to children in grades 1 through 3. This project will develop 150interactive radio episodes per grade. Each of these radio episodes is thirty minutes long and is delivered

in the chiChewa local language with the English lessons taught in English (personal communication,Jennifer Kennedy, Nov. 7, 2007).

The Zambia Interactive Radio Instruction Program for Out-of-School Children:Focused primarily on reaching out-of-school youth, this project taught English language, math, science,

social studies, life skills and health (predominantly concerning HIV/AIDS) to students in grades 1

through 5. As an unintended consequence, the popularity and quality of this program led to a demand

for it to be integrated into the governmental schools (personal communication, R. Zimmerman, Nov. 1,2007).

20



In addition, the use of radio to educate adult learners has also been demonstrated through several projects. Among these are:

SintonizadosThis program brings teachers in Columbia together to “microcenters” in the cities of Guapi and Quibdofor the purpose of learning new instructional methodologies. The radio instruction that occurs at the

microcenters is formatted into 45-minute programs and was designed to “reflect the Afro-Columbiancultures, something previously missing from the region’s teaching materials” (International Education

Systems, 2007d).

The Mali Teacher Training via RadioAlso focused on the instructional needs of teachers, this program is intended to strengthen the capacity

of the Malian Ministry of Education “at central and decentralized levels to create quality teacher

training focused on student-centered and gender-sensitive pedagogy” (International Education Systems,

2007c). This program also intends to establish a series of four “virtual teacher training centers” in order to facilitate the use of ICT in teacher training programs.

HEAR SUDANThis program intends to build the “capacity of local stakeholders to plan, implement and monitor health

and education services” (International Education System, 2007b). Interactive radio education is used tosupport improvement in instructional methods as well as provide health curricula to both teachers andhealth workers.

21



Population Services International (PSI)Population Services International (PSI) uses radio services (among other media) to deliver both straight

information as well as serialized programming related to health awareness issues in countries as diverse

as Benin, Angola, Botswana, Cambodia, Malawi, Nigeria, Rwanda, and Cameroon among others(Population Services International, 2007). According to PSI, this type of programming offers "creative

interventions appropriate to the specific health needs and cultural setting of each country."== == Advantages of radio-

* A universal medium. Can be enjoyed at home, at work, and while driving. Most people listen to

the radio at one time or another during the day.* Permits you to target your advertising dollars to the market most likely to respond to your offer.

* Permits you to create a personality for your business using only sounds and voices.

* Free creative help is usually available.

* Rates can generally be negotiated.* Least inflated medium. During the past ten years, radio rates have gone up less than other media.

== == == Disadvantages ==

* Because radio listeners are spread over many stations, to totally saturate your market youhave to advertise simultaneously on many stations.

* Listeners cannot refer back to your ads to go over important points.

* Ads are an interruption to the entertainment. Because of this, radio ads must be repeated

to break through the listener's "tune out" factor.

* Radio is a background medium. Most listeners are doing something else while listening,

which means your ad has to work hard to be listened to and understood.

* Advertising costs are based on ratings which are approximations based on diaries kept in a

relatively small fraction of a region's homes.

* Not as fast as using a phone; could take a little bit

* The line could get fuzzy, or not clear

CONCLUSION

Since its inception, the science of astronomy had been limited to the observationof objects in the visible light spectrum. The detection of radio emission hasadded a new dimension to our perception. From Rebar’s modest backyardantenna built in 1937, to the innovative James Clerk Maxwell Telescope with itsstate-of-the-art multi-feed receiver system, single-dish radio telescopes havemade important contributions to the field of radio astronomy and will continue todo so. The single-dish telescope has not been rendered obsolete by

interferometers; rather, they work together as a complementary couple, withsingle-dishes giving an overview of the large-scale structure of the cosmos, andinterferometers revealing the fine details. The astronomical research programscarried out by single-dish radio telescopes have expanded our view of the skyand enhanced our understanding of the nature of the universe.

22



BIBLIOGRAPHY

WWW.GOOGLE.COM.Early Radio History:-http://earlyradiohistory.us.Electromagnetic spectrum:-http://imagine.gsfc.nasa.gov/docs/science/know_11/emspectrum.html

.Radio History Society:- http:// www.radiohistory.org/.Marconi Calling:- http: //www.marconicalling.com/front.htm

.Edwin Armstrong:- http: //users.erols.com/oldradio/index.html

23

http://imagine.gsfc.nasa.gov/docs/science/know_11/emspectrum.html


http://www.radiohistory.org/

http://www.marconicalling.com/front.htm

http://users.erols.com/oldradio/index.html




http://www.radiohistory.org/

http://www.marconicalling.com/front.htm




APPENDIX

EM- Electromagnetic Spectrum.

RF- Radio Frequency.

IEEE- Electrical and Electronics Engineers.

AM- Amplitude Modulation.

FM- Frequency Modulation.

DSSS- Direct Sequence Spread spectrum.

FHSS- Frequency Hopping Spread spectrum.

OFDM- Orthogonal Frequency-Division Multiplexing.

UWB-Ultra Wide Band.

Documents

Term Paper on Radio by Pradip & Partha_ICT_3rd Batch_1st Semester_2011