Uniuyo students (Communication Arts)

This research work will benefit Uniuyo Students, Communication Arts Department. Contribution by E. Ephraim Jerry

ASSIGNMENT (a) Explain the roles of five persons that you consider were instrumental to the Radio that we have today. (b) Explain the roles of five persons that you consider were instrumental to the Television that we have today.

Table of Contents

1.    Introduction

2.    Persons who contributed and their responsibility to Radio Development

3.    Persons who contributed and their responsibility to Television Development

4.    Major Merits of Radio and Television to Broadcasting

5.    Conclusion/Summary

6.    References

(1)  Introduction:  Within the history of radio, many people were involved in the invention of radio technology that continues to evolve in modern wireless communication systems today. Radio development began as "wireless telegraphy", first invented by David Edward Hughes. Later, during the early commercial development of wireless technology that followed the first Hughes demonstrations, highly publicized disputes arose over the issue of who could claim credit for the invention of radio. The enormous publicity and commercial importance of these disputes overshadowed the much earlier theoretical, experimental, and applied work of James Clerk Maxwell, David Edward Hughes, Heinrich Hertz, Jagadish Chandra Bose, and others.

Various scientists proposed that electricity and magnetism were linked. In 1802 Gian Domenico Romagnosi suggested the relationship between electric current and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted performed a simple and today widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass needle. ^[6] Ørsted's work influenced André-Marie Ampère to produce a theory of electromagnetism.

Several different electrical, magnetic or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires.

The various methods for wireless signal transmissions include:

• Electrical conduction through the ground, or through water.
• Magnetic induction
• Capacitive coupling
• Electromagnetic waves

All these physical phenomena, as well as various other ideas such as conduction through air, were tested for the purpose of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell's treatise and its verification by Hertz and others.

Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used today for long-distance wireless communications involves the use of modulated electromagnetic waves, which is radio.

Radio antennas radiate electromagnetic waves that can reach the receiver either by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting). The ground wave component is the portion of the radiated electromagnetic wave that propagates close to the Earth's surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the Earth's surface. A portion of the ground wave energy radiated by the antenna may also be guided by the Earth's surface as a ground-hugging surface wave.

In 1879, David Edward Hughes working in London discovered that a bad contact in a Bell telephone he was using in his experiments seemed to be sparking when he worked on a nearby induction balance (an early form of  metal detector). He developed an improved detector to pick up this unknown "extra current" based on his new microphone design (similar to later detectors known as coherers or crystals detectors) and developed a way to interrupt his induction balance to produce a series of sparks. The sparks would generate a radio signal that could be detected by listening to a telephone receiver connected to his new microphone design.

He developed his spark-gap transmitter and receiver into a working communication system using trial and error experiments, until he eventually found he could pick up these "aerial waves" and he could demonstrate the ability to send and receive Morse code signals with his telephone device down the street out to a range limited to 500 yards (460 m). Prominent attendees of the demonstrations were Sir William Crookes Sir William Henry Preece, William Grylls Adams, and James Dewar.

On February 20, 1880 he demonstrated his technology to representatives of the Royal Society, including  Thomas Henry Huxley, Sir George Gabriel Stokes, and William Spottiswoode, then president of the Society. Stoke was convinced the phenomenon Hughes was demonstrating was merely electromagnetic induction, and was it was incorrectly dismissed as not a type of conduction through the air Hughes was not a physicist and seems to have accepted Stokes observations and did not pursue the experiments any further.

1888:Heinrich Rudolf Hertz 1857-1894 produced, detected and measured radio waves for first time with a simple oscilator design. Between 1886 and 1888 Heinrich Rudolf Hertz studied Maxwell’s Theory and conducted experiments that validated it through more rigorous scientific techniques than Hughes had used. He engineered a method of detecting spark-gap radio waves by observing that another unpowered spark-gap, acting as an antenna, would absorb the radio energy and convert it back into an electric spark. Hertz published his results in a series of papers between 1887 and 1890, and again in complete book form in 1893.

The first of the papers published, "On Very Rapid Electric Oscillations", gives an account of the chronological course of his investigation, as far as it was carried out up to the end of the year 1886 and the beginning of 1887.

For the first time in the decade since the work of David E. Hughes, electromagnetic radio waves ("Hertzian waves") were intentionally and unequivocally proven to have been transmitted through free space by a Hughes spark-gap device, and detected over a short distance.

Hertz was able to have some control over the frequencies of his radiated waves by altering the inductance and capacitance of his transmitting and receiving antennas. He focused the electromagnetic waves using a corner reflector and a parabolic reflector, to demonstrate that radio behaved the same as light, as Maxwell's electromagnetic theory had predicted more than 20 years earlier. He demonstrated that radio had all the properties of waves, and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation.

1890: Édouard Branly (1844-1940) invented a device, known as "coherer," that becomes conducting in the presence of natural electric disturbances, such as lightning. (Powdered metal particles that attract one another as a field induces minute currents in them).

In 1890, Édouard Branly demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube, and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to bring the filings more closely together, that is, to cohere, and thus their electrical resistance decreases, from which cause this piece of apparatus was termed by Sir Oliver Lodge a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered they retained their low resistance until shaken apart, for instance, by tapping on the tube. The coherer, however, was not sensitive enough to be used reliably as radio developed.

1892: William Preece (1834-1913) detected current interruptions in one with the other using loops of wire several hundred feet long. He signaled between two points by a system which employed both induction and conduction. This resulted in the appointment of a royal commission to investigate the practicability of the use of his system for communication between lightships and shore. (England).

1892: William Crookes (1832-1919) published an article in the Fortnightly Review in which he definitely suggested the use of Herzian waves for wireless telegraphy and pointed out that the method of achieving that result was to be found in the use and improvement of then known means of generating electrical waves of any desired wave length, to be transmitted through the ether to a receiver, both sending and receiving instruments being attuned to a definite wave length. In a speech before the Royal Academy in England, Sir William Crookes commented upon electromagnetic waves: "Here is unfolded to us a new and astonishing world, one which is hard to conceive should contain no possibilities of transmitting and receiving intelligence."

                                                      Television

(2)              Persons who contributed and their responsibility to Television Development:

Brief Introduction  about Television:Television wasn't invented by a single person. The efforts of many people working over the years, together and separately, contributed to the evolution of the technology.

At the dawn of television history, two competing experimental approaches led to the breakthroughs that eventually made the technology possible. Early inventors attempted to build either a mechanical television based on Paul Nipkow's rotating disks or an electronic television using a cathode ray tube  developed independently in 1907 by English inventor A.A. Campbell-Swinton and Russian scientist Boris Rosing. 

Because electronic television systems worked better, they eventually replaced mechanical systems. Here is an overview of the major names and milestones behind one of the most important inventions of the 20th century. 

Mechanical Television Pioneers

German inventor Paul Gottlieb Nipkow developed a rotating disc technology in 1884 called the Nipkow disk to transmit pictures over wires. Nipkow is credited with discovering television's scanning principle, in which the light intensities of small portions of an image are successively analyzed and transmitted.

In the 1920s, John Logie Baird patented the idea of using arrays of transparent rods to transmit images for television. Baird's 30-line images were the first demonstrations of television by reflected light rather than back-lit silhouettes. Baird based his technology on Nipkow's scanning disc idea and other developments in electronics.

Charles Francis Jenkins invented a mechanical television system called Radiovision and claimed to have transmitted the earliest moving silhouette images on June 14, 1923. His company also opened the first television broadcasting station in the U.S., named W3XK.

Electronic Television Pioneers

German scientist Karl Ferdinand Braun entered history books by inventing the cathode ray tube (CRT) in 1897. This "picture tube," which for years was the only device that could create the images viewers saw, was the basis for the advent of electronic television.

In 1927, American Philo Taylor Farnsworth became the first inventor to transmit a television image—a dollar sign—comprising 60 horizontal lines. Farnsworth also developed the dissector tube, the basis of all current electronic televisions.

Russian inventor Vladimir Kosma Zworykin invented an improved cathode ray tube called the kinescope in 1929. Zworykin was one of the first to demonstrate a system with all the features that would come to make up televisions.

Additional Television Components

In 1947 Louis W. Parker invented the Intercarrier Sound System to synchronize television sound. His invention is used in all television receivers in the world.

In June 1956 the TV remote controller first entered the American home. The first TV remote control, called "Lazy Bones," was developed in 1950 by Zenith Electronics Corp., then known as Zenith Radio Corp.

Marvin Middlemark invented "rabbit ears," the once-ubiquitous V-shaped TV antennae, in 1953. His other inventions included a water-powered potato peeler and a rejuvenating tennis ball machine.

Plasma TV display panels use small cells containing electrically charged ionized gases to generate high-quality imagery. The first prototype for a plasma display monitor was invented in 1964 by Donald Bitzer, Gene Slottow, and Robert Willson.

Other Television Advances

In 1925, Russian TV pioneer Zworykin filed a patent disclosure for an all-electronic color television system. Following authorization by the FCC, a color television system began commercial broadcasting on Dec. 17, 1953, based on a system invented by RCA.

TV closed captions are hidden in the television video signal, invisible without a decoder. They were first demonstrated in 1972 and debuted the following year on the Public Broadcasting Service. 

Television content for the World Wide Web was rolled out in 1995. History's first TV series made available on the Internet was the public access program "Rox."

(3)  Major Merits of Radio and Television to Advertising

Merits of Radio Advertising

1. Of the various media of advertising, radio has the widest coverage. It can reach any household.

2. Radio advertisement can reach even illiterate people.

3. The advertisement appears in the midst of an interesting programme. Therefore, those who listen to the programme also listen to the advertisement.

4. As the advertisement matter can be presented as a song or as a short story or in some other interesting form, it enhances the
memory value.

5. The advertisement can be broadcast at the regional, national or international levels.

Merits of Television Advertising

1. Like radio, television also provides a wider coverage. These days television is a common household item.

2. Television advertising can reach every one including the illiterate people.

3. Both audio as well as visual effects can be created through television. Therefore, the advertiser can create the best impact on the viewers.

4. The advertiser can select the programme in which he wants to advertise. He can also select the channel and advertise so as to create the best possible impact on the people. Goods meant for children can be better advertised in the ‘Cartoon network Channel.

5. It is also possible for the advertiser to sponsor a popular programme. As a result, his product will come to be identified with
the programme. This, indeed, is beneficial for the advertiser. For example, ‘Airtel – Super Singer’, has come to be a very popular programme on ‘Vijay TV’.

(4)              Conclusion and Summary:

With the development of radio communication—whether wireless or wired—the condenser discharge through an inductive circuit has assumed a great additional importance since, with the exception of a few of the highest power transoceanic stations, which use power-driven high-frequency alternators, the source of power in the radio communication up to 1922 was the condenser discharge through the inductive circuit, whether as a damped wave or as an undamped wave. In undamped wave radio communication, the condenser discharge circuit is coupled with a source of electric power—a battery—in such a manner, that, without interfering with the character of the oscillation, sufficient energy is fed into the circuit to maintain the oscillation, similarly as in the clock, the pendulum is coupled with a source of mechanical power—weight or spring— so as to maintain its oscillation undamped. The usual method of producing a condenser discharge through an inductive circuit is gradually to charge a condenser from a source of electric power, until the condenser voltage has risen sufficiently high to jump a spark gap (the rotary gap, or quenched gap of the damped wave wireless for instance) and thereby discharge through the inductive circuit.