After a long silence from this blog, today I bring you a new picture of my sand Angkor replica. I led a team of a few people [they are all my nieces and nephews] to build this for a few hours in the evening of April 15, 2012. This building attracted many people who walked on the beach and by-standers. At least they stopped for a few minutes before continuing their walk. However, there were still a few people who messed with it. I love this after all.

The Sand Angkor

My sand Angkor replica

Rest in Peace my Beloved Steve Jobs

Apple Inc co-founder and former CEO Steve Jobs, one of the greatest American CEOs, died on Wednesday at the age of 56. He had been suffering cancer and other health issues.

Although he is just one year older than Bill Gates of Microsoft, Steve was never lucky enough. He had been battling cancer and health issues until his death.

Following is Steve’s biography in brief from wikipedia:

Jobs was born in San Francisco and was adopted by Paul and Clara Jobs (née Hagopian) of Mountain View, California, who named him Steven Paul. Paul and Clara later adopted a daughter, whom they named Patti. Jobs’ biological parents – Abdulfattah John Jandali, a Syrian Muslim graduate student from Homs who later became a political science professor and Joanne Simpson (née Schieble), an American graduate student who went on to become a speech language pathologist – eventually married. Together, they gave birth to and raised Jobs’ biological sister, novelist Mona Simpson.

Jobs attended Cupertino Junior High and Homestead High School in Cupertino, California. He frequented after-school lectures at the Hewlett-Packard Company in Palo Alto, California and was later hired there, working with Steve Wozniak as a summer employee. Following high school graduation in 1972, Jobs enrolled at Reed College in Portland, Oregon. Although he dropped out after only one semester, he continued auditing classes at Reed, while sleeping on the floor in friends’ rooms, returning Coke bottles for food money, and getting weekly free meals at the local Hare Krishna temple. Jobs later said, “If I had never dropped in on that single calligraphy course in college, the Mac would have never had multiple typefaces or proportionally spaced fonts.”

In autumn 1974, Jobs returned to California and began attending meetings of the Homebrew Computer Club with Wozniak. He took a job as a technician at Atari, a manufacturer of popular video games, with the primary intent of saving money for a spiritual retreat to India.

Jobs then traveled to India to visit the Neem Karoli Baba at his Kainchi Ashram with a Reed College friend (and, later, the first Apple employee), Daniel Kottke, in search of spiritual enlightenment. He came back a Buddhist with his head shaved and wearing traditional Indian clothing. During this time, Jobs experimented with psychedelics, calling his LSD experiences “one of the two or three most important things [he had] done in [his] life”. He has said that people around him who did not share his countercultural roots could not fully relate to his thinking.

Jobs returned to his previous job at Atari and was given the task of creating a circuit board for the game Breakout. According to Atari founder Nolan Bushnell, Atari had offered $100 for each chip that was eliminated in the machine. Jobs had little interest or knowledge in circuit board design and made a deal with Wozniak to split the bonus evenly between them if Wozniak could minimize the number of chips. Much to the amazement of Atari, Wozniak reduced the number of chips by 50, a design so tight that it was impossible to reproduce on an assembly line. At the time, Jobs told Wozniak that Atari had only given them $700 (instead of the actual $5,000) and that Wozniak’s share was thus $350.

Read full article about Steve Jobs on Wikipedia

After having been busy which makes me away from my blog for a long time, today, I felt I wanted to make a collection of my beloved geeks who have changed the way I (and all of us) live. Some geeks may appear first or last in my collection, but it doesn’t necessarily mean they are ranked first nor last. I love them all.

Geeks who have changed the way we live.

As in my disclaimer, it is to be noticed that these individuals who appear here in my list are not necessarily the single founders of their respective firms/products. They may be co-founders. The reason why I listed only these people and not their co-founders was because these are at least representatives of those in their team. Also, it was because they are commonly known by the public; there is no big deal. There still lovely geeks who are not listed here, but they are all in my heart.

It is also to be noticed that they are not just founders of the firms/products I mentioned in the list. In fact they founded a lot more than just what I mentioned. I just listed their most known firms/product they founded.

Note: Some founders here might have left the firms/products.

Enjoy loving them and have a nice weekend.


Who invented the radio is a very debatable topic. A number of researchers have contributed to it. The history of radio can be considered from 1895. Who invented the radio?

The credit of inventing the radio goes to a number of researchers. The names of Guglielmo Marconi, Nikola Tesla, Alexander Popov, Sir Oliver Lodge, Reginald Fessenden, Heinrich Hertz, Amos Dolbear, Mahlon Loomis, Nathan Stubblefield and James Clerk Maxwell can be included.

Guglielmo Marconi

He was an Italian inventor who demonstrated the practicability of radio communication. His first radio signal was sent and received in 1895. In 1899, the first wireless signal was sent across the English Channel. In 1902, the letter ‘S’ was telegraphed from England to Newfoundland. This was the first triumphant transatlantic radiotelegraph.

Nikola Tesla

In 1892, he designed the fundamental design for radio. Later, in 1898, a radio controlled robot-boat was patented. This boat was controlled by radio waves and shown in the Electrical Exhibition in Madison Square Garden. This boat had an antenna that transmitted the radio waves arriving from the command post. A radio sensitive device called coherer received these radio waves. This device transmitted these waves to mechanical movements of the propellers on the boat.

Alexander Popov

He constructed his first radio receiver containing a ‘coherer’ in 1894. This was then modified as a lightning detector and demonstrated before the Russian Physical and Chemical Society on May 7, 1895. This day is remembered by the Russian Federation as “Radio Day”. It was in March 1896, that transmission of radio waves was done across disparate campus buildings in St. Petersburg. A radio station was built on Hogland island to facilitate two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. This was done as per Popov’s guidance in 1900.

Sir Oliver Lodge

He designed a device called a ‘coherer’ upto perfection. This was a radio-wave detector and the basis of the early radiotelegraph receiver. He was showered with international recognition as he became the first human to transmit a radio signal.

Reginald Fessenden

He was a Canadian inventor reputed for his achievements in early radio. The first audio transmission by radio in 1900, the first two-way transatlantic radio transmission in 1906 and the first radio broadcast of entertainment and music in 1906 were his three significant milestones. Fessenden concluded that he could devise a better system than the spark-gap transmitter and coherer-receiver combination that had been put forth by Lodge and Marconi.

Heinrich Hertz

He was a German physicist and mechanician. In 1888, he became the first person to prove the presence of electromagnetic waves by constructing a system to create and detect UHF radio waves. His name was used for radio frequencies. The hertz designation was an official part of the international metric system in 1933.

Amos Dolbear

He was a professor at Tufts University and received a U.S. patent for a wireless telegraph in March, 1882.

Mahlon Loomis

He is called as the “First Wireless Telegrapher”. In 1868, he demonstrated a wireless communication system between two sites 14 to 18 miles apart.

Nathan Stubblefield

It is thought that Stubblefield invented the radio before Tesla or Marconi. However, his devices appear to have worked by audio frequency induction or audio frequency earth conduction rather than radio frequency radiation for radio transmission telecommunication. It is claimed that he is the inventor of wireless telephony or wireless transmission of the human voice.

James Clerk Maxwell

He predicted the existence of radio waves. It was on this basis that radio waves were discovered and Einstein’s theory of relativity took off.

History of the radio

The lightning-recording antenna was invented by Aleksandr Popov in 1895. The first experimental transmission of wireless signals were carried out by Guglielmo Marconi in the same year. A patent of wireless communication was filed by Marconi in 1896. In 1899, a 42 km link was laid between two cruisers containing Ducretet-Popov devices in France. In the same year, a wireless transmission was laid through the English Channel from Wimereux to Dover by Marconi. In 1901, Marconi demonstrated the first transatlantic wireless transmission between Poldhu and St. John’s by using Morse code. In 1903, Valdemar Poulsen began arc transmission to create high-frequency alternators to send radio waves. The New York Times and the London Times knew about the Russo-Japanese war due to radio in 1903. In the next year, a commercial maritime radio network was established under the control of the Ministry of Posts and Telegraphs in France. Then, John Fleming invented the thermionic two-electrode valve so that sound transmission was feasible. In 1905, lead sulphide could be used to detect radio-electric signals. In 1906, Reginald Fessenden designed a high-frequency alternator and transmitted human voice over the radio. In 1906, Lee de Forest made the detection, transmission and amplification of sound possible. In 1910, a broadcast from the Metropolitan Opera House in New York city could be heard on a ship that was 20 km away. 1911 to 1930 was the period of the growth of the radio. The Radio Corporation of America was founded. This was done by combining General Electic, Western Electric, AT&T and Westinghouse. It was in this era that radio broadcasting began in Australia. Battery-powered receivers having headphones and valves were seen in France. A radio telephone concert was broadcast across the Atlantic Ocean to several receivers. In this era, radio broadcasting started in Shanghai and Cuba. The first regular broadcasts took place in Belgium, Norway, Germany, Finland and Switzerland. Soon radio became prevalent throughout the globe.

By Abhay Burande
Published: 11/1/2007


From Wikipedia, the free encyclopedia

Radio is the transmission of signals, by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing (modulating) some property of the radiated waves, such as amplitude, frequency, or phase. When radio waves pass an electrical conductor, the oscillating fields induce an alternating current in the conductor. This can be detected and transformed into sound or other signals that carry information.


Originally, radio or radiotelegraphy was called “wireless telegraphy”, which was shortened to “wireless”. The prefix radio- in the sense of wireless transmission, was first recorded in the word radioconductor, coined by the French physicist Edouard Branly in 1897 and based on the verb to radiate (in Latin “radius” means “spoke of a wheel, beam of light, ray”). “Radio” as a noun is said to have been coined by advertising expert Waldo Warren (White 1944). The word appears in a 1907 article by Lee de Forest, was adopted by the United States Navy in 1912 and became common by the time of the first commercial broadcasts in the United States in the 1920s. (The noun “broadcasting” itself came from an agricultural term, meaning “scattering seeds”.) The term was then adopted by other languages in Europe and Asia, although British Commonwealth countries continued to use the term “wireless” until the mid-20th century.

In recent years the term “wireless” has gained renewed popularity through the rapid growth of short-range computer networking, e.g., Wireless Local Area Network (WLAN), WiFi and Bluetooth, as well as mobile telephony, e.g., GSM and UMTS. Today, the term “radio” often refers to the actual transceiver device or chip, whereas “wireless” refers to the system and/or method used for radio communication, hence one talks about radio transceivers and Radio Frequency Identification (RFID), but about wireless devices and wireless sensor networks.


Radio systems used for communications will have the following elements. With more than 100 years of development, each process is implemented by a wide range of methods, specialized for different communications purposes.

Each system contains a transmitter. This consists of a source of electrical energy, producing alternating current of a desired frequency of oscillation. The transmitter contains a system to modulate (change) some property of the energy produced to impress a signal on it. This modulation might be a simple as turning the energy on and off, or altering more subtle properties such as amplitude, frequency, phase, or combinations of these properties. The transmitter sends the modulated electrical energy to an antenna; this structure converts the rapidly-changing alternating current into an electromagnetic wave that can move through free space.

Electromagnetic waves travel through space either directly, or have their path altered by reflection, refraction or diffraction. The intensity of the waves diminishes due to geometric dispersion (the inverse-square law); some energy may also be absorbed by the intervening medium in some cases. Noise will generally alter the desired signal; this electromagnetic interference comes from natural sources, as well as from artifical sources such as other transmitters and accidental radiators. Noise is also produced at every step due to the inherent properties of the devices used. If the magnitude of the noise is large enough, the desired signal will no longer be discernable; this is the fundamental limit to the range of radio communications.

The electromagnetic wave is intercepted by a receiving antenna; this structure captures some of the energy of the wave and returns it to the form of oscillating electrical currents. At the receiver, these currents are demodulated, which is conversion to a usable signal form by a detector sub-system. The receiver is “tuned” to respond preferentially to the desired signals, and reject undesired signals.

Early radio systems relied entirely on the energy collected by an antenna to produce signals for the operator. Radio became more useful after the invention of electronic devices such as the vacuum tube and later the transistor, which made it possible to amplify weak signals. Today radio systems are used for applications from walkie-talkie children’s toys to the control of space vehicles, as well as for broadcasting, and many other applications.



The meaning and usage of the word “radio” has developed in parallel with developments within the field and can be seen to have three distinct phases: electromagnetic waves and experimentation; wireless communication and technical development; and radio broadcasting and commercialization. Many individuals — inventors, engineers, developers, businessmen — contributed to produce the modern idea of radio and thus the origins and ‘invention’ are multiple and controversial.

Development from a laboratory demonstration to commercial utility spanned several decades and required the efforts of many practitioners.

Tesla demonstrating wireless transmissions during his high frequency and potential lecture of 1891. After continued research, Tesla presented the fundamentals of radio in 1893.

In 1893, in St. Louis, Missouri, Nikola Tesla made devices for his experiments with electricity. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of his wireless work.[1] The descriptions contained all the elements that were later incorporated into radio systems before the development of the vacuum tube. He initially experimented with magnetic receivers, unlike the coherers (detecting devices consisting of tubes filled with iron filings which had been invented by Temistocle Calzecchi-Onesti at Fermo in Italy in 1884) used by Guglielmo Marconi and other early experimenters.[2]

The first radio couldn’t transmit sound or speech and was called the “wireless telegraph.” The first public demonstration of wireless telegraphy took place in the lecture theater of the Oxford University Museum of Natural History on August 14, 1894, carried out by Professor Oliver Lodge and Alexander Muirhead. During the demonstration a radio signal was sent from the neighboring Clarendon laboratory building, and received by apparatus in the lecture theater.

In 1895 Alexander Stepanovich Popov built his first radio receiver, which contained a coherer. Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895. A depiction of Popov’s lightning detector was printed in the Journal of the Russian Physical and Chemical Society the same year. Popov’s receiver was created on the improved basis of Lodge’s receiver, and originally intended for reproduction of its experiments.


Telephone Herald in Budapest, Hungary (1901).

In 1896, Marconi was awarded the British patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for, for radio. In 1897 he established the world’s first radio station on the Isle of Wight, England. Marconi opened the world’s first “wireless” factory in Hall Street, Chelmsford, England in 1898, employing around 50 people.

The next great invention was the vacuum tube detector, invented by Westinghouse engineers. On Christmas Eve, 1906, Reginald Fessenden used a synchronous rotary-spark transmitter for the first radio program broadcast, from Ocean Bluff-Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. The first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan. The first college radio station began broadcasting on October 14, 1920, from Union College, Schenectady, New York under the personal call letters of Wendell King, an African-American student at the school.[3] That month 2ADD, later renamed WRUC in 1940, aired what is believed to be the first public entertainment broadcast in the United States, a series of Thursday night concerts initially heard within a 100-mile (160 km) radius and later for a 1,000-mile (1,600 km) radius. In November 1920, it aired the first broadcast of a sporting event.[4][5] At 9 pm on August 27, 1920, Sociedad Radio Argentina aired a live performance of Richard Wagner’s Parsifal opera from the Coliseo Theater in downtown Buenos Aires, only about twenty homes in the city had a receiver to tune in. Meanwhile, regular entertainment broadcasts commenced in 1922 from the Marconi Research Centre at Writtle, England.

American girl listens to radio during Great Depression.

One of the first developments in the early 20th century (1900-1959) was that aircraft used commercial AM radio stations for navigation. This continued until the early 1960s when VOR systems finally became widespread (though AM stations are still marked on U.S. aviation charts). In the early 1930s, single sideband and frequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes. Radio was used to transmit pictures visible as television as early as the 1920s. Commercial television transmissions started in North America and Europe in the 1940s. In 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a “standard 22.5 V Battery”.

In 1960, Sony introduced its first transistorized radio, small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next 20 years, transistors replaced tubes almost completely except for very high-power uses. By 1963 color television was being regularly transmitted commercially, and the first (radio) communication satellite, TELSTAR, was launched. In the late 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing digital radios for many of its links. In the 1970s, LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation, culminating in the invention and launch of the GPS constellation in 1987. In the early 1990s, amateur radio experimenters began to use personal computers with audio cards to process radio signals. In 1994, the U.S. Army and DARPA launched an aggressive, successful project to construct a software defined radio that can be programmed to be virtually any radio by changing its software program. Digital transmissions began to be applied to broadcasting in the late 1990s.

Uses of radio

Early uses were maritime, for sending telegraphic messages using Morse code between ships and land. The earliest users included the Japanese Navy scouting the Russian fleet during the Battle of Tsushima in 1905. One of the most memorable uses of marine telegraphy was during the sinking of the RMS Titanic in 1912, including communications between operators on the sinking ship and nearby vessels, and communications to shore stations listing the survivors.

Radio was used to pass on orders and communications between armies and navies on both sides in World War I; Germany used radio communications for diplomatic messages once it discovered that its submarine cables had been tapped by the British. The United States passed on President Woodrow Wilson’s Fourteen Points to Germany via radio during the war. Broadcasting began from San Jose in 1909[6], and became feasible in the 1920s, with the widespread introduction of radio receivers, particularly in Europe and the United States. Besides broadcasting, point-to-point broadcasting, including telephone messages and relays of radio programs, became widespread in the 1920s and 1930s. Another use of radio in the pre-war years was the development of detection and locating of aircraft and ships by the use of radar (RAdio Detection And Ranging).

Today, radio takes many forms, including wireless networks and mobile communications of all types, as well as radio broadcasting. Before the advent of television, commercial radio broadcasts included not only news and music, but dramas, comedies, variety shows, and many other forms of entertainment. Radio was unique among methods of dramatic presentation in that it used only sound. For more, see radio programming.


A Fisher 500 AM/FM hi-fi receiver from 1959.

AM broadcast radio sends music and voice in the Medium Frequency (MF-0.300 MHz to 3 MHz) radio spectrum. AM radio uses amplitude modulation, in which the amplitude of the transmitted signal is made proportional to the sound amplitude captured (transduced) by the microphone while the transmitted frequency remains unchanged. Transmissions are affected by static and interference because lightning and other sources of radio that are transmitting at the same frequency add their amplitudes to the original transmitted amplitude. The most wattage an AM radio station in the United States and Canada is allowed to use is 50,000 watts and the majority of stations that emit signals this powerful were grandfathered in; these include WGN (AM), WJR, KGA and CKLW. In 1986 KTNN received the last granted 50,000 watt license.

FM broadcast radio sends music and voice with higher fidelity than AM radio. In frequency modulation, amplitude variation at the microphone causes the transmitter frequency to fluctuate. Because the audio signal modulates the frequency and not the amplitude, an FM signal is not subject to static and interference in the same way as AM signals. Due to its need for a wider bandwidth, FM is transmitted in the Very High Frequency (VHF-30 MHz to 300 MHz) radio spectrum. VHF radio waves act more like light, traveling in straight lines, hence the reception range is generally limited to about 50-100 miles. During unusual upper atmospheric conditions, FM signals are occasionally reflected back towards the Earth by the ionosphere, resulting in Long distance FM reception. FM receivers are subject to the capture effect, which causes the radio to only receive the strongest signal when multiple signals appear on the same frequency. FM receivers are relatively immune to lightning and spark interference.

High power is useful in penetrating buildings, diffracting around hills, and refracting for some distance beyond the horizon. Consequently, 100,000 watt FM stations can regularly be heard up to 100 miles (160 km) away, and farther (e.g., 150 miles, 240 km) if there are no competing signals. A few old, “grandfathered” stations do not conform to these power rules. WBCT-FM (93.7) in Grand Rapids, Michigan, USA, runs 320,000 watts ERP, and can increase to 500,000 watts ERP by the terms of its original license. Such a huge power level does not usually help to increase range as much as one might expect, because VHF frequencies travel in nearly straight lines over the horizon and off into space. Nevertheless, when there were fewer FM stations competing, this station could be heard near Bloomington, Illinois, USA, almost 300 miles (500 km) away.[citation needed]

FM subcarrier services are secondary signals transmitted in a “piggyback” fashion along with the main program. Special receivers are required to utilize these services. Analog channels may contain alternative programming, such as reading services for the blind, background music or stereo sound signals. In some extremely crowded metropolitan areas, the sub-channel program might be an alternate foreign language radio program for various ethnic groups. Sub-carriers can also transmit digital data, such as station identification, the current song’s name, web addresses, or stock quotes. In some countries, FM radios automatically re-tune themselves to the same channel in a different district by using sub-bands.

Aviation voice radios use VHF AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM’s capture effect). Aircraft fly high enough that their transmitters can be received hundreds of miles (or kilometres) away, even though they are using VHF.

Marine voice radios can use single sideband voice (SSB) in the shortwave High Frequency (HF-3 MHz to 30 MHz) radio spectrum for very long ranges or narrowband FM in the VHF spectrum for much shorter ranges. Narrowband FM sacrifices fidelity to make more channels available within the radio spectrum, by using a smaller range of radio frequencies, usually with five kHz of deviation, versus the 75 kHz used by commercial FM broadcasts, and 25 kHz used for TV sound.

Government, police, fire and commercial voice services also use narrowband FM on special frequencies. Early police radios used AM receivers to receive one-way dispatches.

Civil and military HF (high frequency) voice services use shortwave radio to contact ships at sea, aircraft and isolated settlements. Most use single sideband voice (SSB), which uses less bandwidth than AM. On an AM radio SSB sounds like ducks quacking. Viewed as a graph of frequency versus power, an AM signal shows power where the frequencies of the voice add and subtract with the main radio frequency. SSB cuts the bandwidth in half by suppressing the carrier and (usually) lower sideband. This also makes the transmitter about three times more powerful, because it doesn’t need to transmit the unused carrier and sideband.

TETRA, Terrestrial Trunked Radio is a digital cell phone system for military, police and ambulances. Commercial services such as XM, WorldSpace and Sirius offer encrypted digital Satellite radio.


Mobile phones transmit to a local cell site (transmitter/receiver) that ultimately connects to the public switched telephone network (PSTN) through an optic fiber or microwave radio and other network elements. When the mobile phone nears the edge of the cell site’s radio coverage area, the central computer switches the phone to a new cell. Cell phones originally used FM, but now most use various digital modulation schemes. Recent developments in Sweden (such as DROPme) allow for the instant downloading of digital material from a radio broadcast (such as a song) to a mobile phone.

Satellite phones use satellites rather than cell towers to communicate. They come in two types: INMARSAT and Iridium. Both types provide world-wide coverage. INMARSAT uses geosynchronous satellites, with aimed high-gain antennas on the vehicles. Iridium uses 66 Low Earth Orbit satellites as the cells.


Television sends the picture as AM and the sound as FM, with the sound carrier a fixed frequency (4.5 MHz in the NTSC system) away from the video carrier. Analog television also uses a vestigial sideband on the video carrier to reduce the bandwidth required.

Digital television uses 8VSB modulation in North America (under the ATSC digital television standard), and COFDM modulation elsewhere in the world (using the DVB-T standard). A Reed-Solomon error correction code adds redundant correction codes and allows reliable reception during moderate data loss. Although many current and future codecs can be sent in the MPEG-2 transport stream container format, as of 2006 most systems use a standard-definition format almost identical to DVD: MPEG-2 video in Anamorphic widescreen and MPEG layer 2 (MP2) audio. High-definition television is possible simply by using a higher-resolution picture, but H.264/AVC is being considered as a replacement video codec in some regions for its improved compression. With the compression and improved modulation involved, a single “channel” can contain a high-definition program and several standard-definition programs.


All satellite navigation systems use satellites with precision clocks. The satellite transmits its position, and the time of the transmission. The receiver listens to four satellites, and can figure its position as being on a line that is tangent to a spherical shell around each satellite, determined by the time-of-flight of the radio signals from the satellite. A computer in the receiver does the math.

Radio direction-finding is the oldest form of radio navigation. Before 1960 navigators used movable loop antennas to locate commercial AM stations near cities. In some cases they used marine radiolocation beacons, which share a range of frequencies just above AM radio with amateur radio operators. Loran systems also used time-of-flight radio signals, but from radio stations on the ground. VOR (Very High Frequency Omnidirectional Range), systems (used by aircraft), have an antenna array that transmits two signals simultaneously. A directional signal rotates like a lighthouse at a fixed rate. When the directional signal is facing north, an omnidirectional signal pulses. By measuring the difference in phase of these two signals, an aircraft can determine its bearing or radial from the station, thus establishing a line of position. An aircraft can get readings from two VORs and locate its position at the intersection of the two radials, known as a “fix.” When the VOR station is collocated with DME (Distance Measuring Equipment), the aircraft can determine its bearing and range from the station, thus providing a fix from only one ground station. Such stations are called VOR/DMEs. The military operates a similar system of navaids, called TACANs, which are often built into VOR stations. Such stations are called VORTACs. Because TACANs include distance measuring equipment, VOR/DME and VORTAC stations are identical in navigation potential to civil aircraft.


Radar (Radio Detection And Ranging) detects objects at a distance by bouncing radio waves off them. The delay caused by the echo measures the distance. The direction of the beam determines the direction of the reflection. The polarization and frequency of the return can sense the type of surface. Navigational radars scan a wide area two to four times per minute. They use very short waves that reflect from earth and stone. They are common on commercial ships and long-distance commercial aircraft.

General purpose radars generally use navigational radar frequencies, but modulate and polarize the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of heavy storms, as well as land and vehicles. Some can superimpose sonar data and map data from GPS position.

Search radars scan a wide area with pulses of short radio waves. They usually scan the area two to four times a minute. Sometimes search radars use the Doppler Effect to separate moving vehicles from clutter. Targeting radars use the same principle as search radar but scan a much smaller area far more often, usually several times a second or more. Weather radars resemble search radars, but use radio waves with circular polarization and a wavelength to reflect from water droplets. Some weather radar use the Doppler Effect to measure wind speeds.

Data (digital radio)

Most new radio systems are digital, see also: Digital TV, Satellite Radio, Digital Audio Broadcasting. The oldest form of digital broadcast was spark gap telegraphy, used by pioneers such as Marconi. By pressing the key, the operator could send messages in Morse code by energizing a rotating commutating spark gap. The rotating commutator produced a tone in the receiver, where a simple spark gap would produce a hiss, indistinguishable from static. Spark gap transmitters are now illegal, because their transmissions span several hundred megahertz. This is very wasteful of both radio frequencies and power.

The next advance was continuous wave telegraphy, or CW (Continuous Wave), in which a pure radio frequency, produced by a vacuum tube electronic oscillator was switched on and off by a key. A receiver with a local oscillator would “heterodyne” with the pure radio frequency, creating a whistle-like audio tone. CW uses less than 100 Hz of bandwidth. CW is still used, these days primarily by amateur radio operators (hams). Strictly, on-off keying of a carrier should be known as “Interrupted Continuous Wave” or ICW or on-off keying (OOK).

Radio teletypes usually operate on short-wave (HF) and are much loved by the military because they create written information without a skilled operator. They send a bit as one of two tones. Groups of five or seven bits become a character printed by a teletype. From about 1925 to 1975, radio teletype was how most commercial messages were sent to less developed countries. These are still used by the military and weather services.

Aircraft use a 1200 Baud radioteletype service over VHF to send their ID, altitude and position, and get gate and connecting-flight data. Microwave dishes on satellites, telephone exchanges and TV stations usually use quadrature amplitude modulation (QAM). QAM sends data by changing both the phase and the amplitude of the radio signal. Engineers like QAM because it packs the most bits into a radio signal when given an exclusive (non-shared) fixed narrowband frequency range. Usually the bits are sent in “frames” that repeat. A special bit pattern is used to locate the beginning of a frame.

Communication systems that limit themselves to a fixed narrowband frequency range are vulnerable to jamming.

A variety of jamming-resistant spread spectrum techniques were initially developed for military use, most famously for Global Positioning System satellite transmissions. Commercial use of spread spectrum begin in the 1980s.

Bluetooth, most cell phones, and the 802.11b version of Wi-Fi each use various forms of spread spectrum.

Systems that need reliability, or that share their frequency with other services, may use “coded orthogonal frequency-division multiplexing” or COFDM. COFDM breaks a digital signal into as many as several hundred slower subchannels. The digital signal is often sent as QAM on the subchannels. Modern COFDM systems use a small computer to make and decode the signal with digital signal processing, which is more flexible and far less expensive than older systems that implemented separate electronic channels. COFDM resists fading and ghosting because the narrow-channel QAM signals can be sent slowly. An adaptive system, or one that sends error-correction codes can also resist interference, because most interference can affect only a few of the QAM channels. COFDM is used for WiFi, some cell phones, Digital Radio Mondiale, Eureka 147, and many other local area network, digital TV and radio standards.


Radio-frequency energy generated for heating of objects is generally not intended to radiate outside of the generating equipment, to prevent interference with other radio signals. Microwave ovens use intense radio waves to heat food. Diathermy equipment is used in surgery for sealing of blood vessels. Induction furnaces are used for melting metal for casting.

Amateur radio service

Amateur radio (nicknamed Ham radio) is a hobby in which enthusiasts are licensed to transmit radio signals for their own enjoyment. They may also provide an emergency and public-service radio service. This has been very beneficial in emergencies, saving lives in many instances.[citation needed] Radio amateurs are licensed to use frequencies in a wide range of narrow bands throughout the radio spectrum. They use all forms of encoding, including nostalgic and experimental ones. Several forms of radio were pioneered by radio amateurs and later became commercially important including FM, single-sideband (SSB), AM, digital packet radio and satellite repeaters. Some amateur frequencies may be disrupted by power-line internet service.

Unlicensed radio services

Government-authorized personal radio services such as Citizens’ Band Radio, Family Radio Service, Multi-Use Radio Service and others exist in North America to provide simple, (usually) short range communication for individuals and small groups, without the overhead of licensing. Similar services exist in other parts of the world. These radio services involve the use of handheld units.

Unauthorized, unlicensed radio broadcasting is known as Free or pirate radio. The main difference between the two is that a Free radio station does not advertise or make any money, while the Pirate station could not exist without adverts, payolas, etc.[citation needed]

Radio control (RC)

Radio remote controls use radio waves to transmit control data to a remote object as in some early forms of guided missile, some early TV remotes and a range of model boats, cars and airplanes. Large industrial remote-controlled equipment such as cranes and switching locomotives now usually use digital radio techniques to ensure safety and reliability.

In Madison Square Garden, at the Electrical Exhibition of 1898, Nikola Tesla successfully demonstrated a radio-controlled boat.[7] He was awarded U.S. patent No. 613,809 for a “Method of and Apparatus for Controlling Mechanism of Moving Vessels or Vehicles.”[8]

The electromagnetic spectrum

Radio waves are a form of electromagnetic radiation that are created when a charged object, such as an electron, accelerates with a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. In radio, this acceleration is caused by an alternating current in an antenna. Radio frequencies occupy the range from a few tens of hertz to three hundred gigahertz, although commercially important uses of radio use only a small part of this spectrum.[9] Other types of electromagnetic radiation, with frequencies above the RF range, are microwave, infrared, visible light, ultraviolet, X-rays and gamma rays. Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation.


Energy autarkic radio technology consists of a small radio transmitter powered by environmental energy (push of a button, temperature differences, light, vibrations, etc.). A number of schemes have been proposed for Wireless energy transfer. Various plans included transmitting power using microwaves, and the technique has been demonstrated. (See Microwave power transmission). These schemes include, for example, solar power stations in orbit beaming energy down to terrestrial users.



Historians estimate that over twenty inventors worked toward the creation and design of the light bulb

Let there be light

light bulb in orange background

Today the light bulb is one of the most common illuminating devices around but this simple luxury was designed less than 200 years ago. Similar to any other great invention, like the invention of the internet, many scientists contributed to the invention of the light bulb, including the famous Thomas Edison. A glimpse into the 1800s provides details o

n just how the light bulb became what it is today.

Converting Electricity to Light Before the light bulb was invented, people had to rely on candles and torches during the evening hours. Oil lamps were also used, however they left a messy residue of soot on anything close to


Starting in the early 1800s, inventors looked for ways to convert electricity into light. Sir Humphry Davy, an English physician, successfully passed an electric current through platinum strips in 1801. Unfortunately, the strips evaporated quickly and Davy was unable to create a light that lasted more than a few minutes.

In 1809 Davy created what would become known as the Arc lamp. He made an electrical connection between two charcoal rods connected to a battery. The light from this was very bright but small.

For the next 50 years, others sought ways to lengthen the amount of time the light source would remain. In 1840 Warren de la Rue, a British scientist, placed a platinum coil in a vaccum tube. When he passed an electric current through it, light was formed. This design was efficient and the light lasted longer, but platinum was very expensive which made it impossible to be distributed on a commercial level.

In 1841 Frederick de Moleyns of England was given the first patent for an incandescent lamp. His design used powdered charcoal. He heated this material between two platinum wires in a vacuum bulb.
Joseph Wilson Swan Joseph Wilson Swan was born in 1828 in England. He worked as a physicist and chemist. Swan wanted to produce a practical, long-lasting light source. He used a carbon paper filament in his light bulbs. In 1878 he received a British patent for his light bulb. Swan began placing light bulbs in homes throughout England. By the early 1880s he had started his own light bulb company.

Thomas Edison While Swan worked in England, Thomas Edison was busy in the United States. He experimented with thousands of different filaments. His goal was to find materials that would light well and last for a long time. He brought in various metals and supplies from all over the world.

Then in October of 1879, Edison had a breakthrough. He carbonized a piece of sewing thread. Using this as a filament, he was able to produce a light bulb that burned for thirteen and a half hours. By bending the filament, he could make the lamp burn for over 100 hours. Eventually Edison invented a bulb that could glow for more than 1200 hours. He received a patent in 1880 for his light bulb. It had the same features of today’s modern light bulbs: an incandescent filament in a glass bulb with a screw base.

The Real Inventor of the Light Bulb When the question is asked, who invented the light bulb, Joseph Swan and Thomas Edison are usually given credit. However, both of these men worked off of previous inventions. Historians estimate that over twenty inventors worked toward the creation and design of the light bulb. Of these, Edison’s version was the most efficient.

When studying who invented the light bulb, it is appropriate to credit numerous inventors that lived during the 1800s. Even after Swan and Edison, others continued to improve the light source. The light bulb, as we know it today, is a result of much time and effort. Remember that the next time you flip on the switch!


AT A GLANCE: The modern world is an electrified world. The light bulb, in particular, profoundly changed human existence by illuminating the night and making it hospitable to a wide range of human activity. The electric light, one of the everyday conveniences that most affects our lives, was invented in 1879 by Thomas Alva Edison. He was neither the first nor the only person trying to invent an incandescent light bulb.
Invention: electric light bulb in 1879
Elecric Lamp image courtesy General Electric
Definition: noun / electric light bulb / incandescent lamp
Function: An electric lamp in which a filament is heated to incandescence by an electric current. Today’s incandescent light bulbs use filaments made of tungsten rather than carbon of the 1880’s.
Patent: 223,898 (US) issued January 27, 1880
Inventor: Thomas Alva Edison
Thomas Alva Edison photo courtesy General Electric
Criteria: First practical. Modern prototype. Entrepreneur.
Birth: February 11, 1847 in Milan, Ohio
Death: October 18, 1931 in West Orange, New Jersey
Nationality: American
1850 Joseph W. Swan began working on a light bulb using carbonized paper filaments
1860 Swan obtained a UK patent covering a partial vacuum, carbon filament incandescent lamp
1877 Edward Weston forms Weston Dynamo Machine Company, in Newark, New Jersey.
1878 Thomas Edison founded the Edison Electric Light Company
1878 Hiram Maxim founded the United States Electric Lighting Company
1878 205,144 William Sawyer and Albon Man 6/18 for Improvements in Electric Lamps
1878 Swan receives a UK patent for an improved incandescent lamp in a vacuum tube
1879 Swan began installing light bulbs in homes and landmarks in England.
1880 223,898 Thomas Edison 1/27 for Electric Lamp and Manufacturing Process
1880 230,309 Hiram Maxim 7/20 for Process of Manufacturing Carbon Conductors
1880 230,310 Hiram Maxim 7/20 for Electrical Lamp
1880 230,953 Hiram Maxim 7/20 for Electrical Lamp
1880 233,445 Joseph Swan 10/19 for Electric Lamp
1880 234,345 Joseph Swan 11/9 for Electric Lamp
1880 Weston Dynamo Machine Company renamed Weston Electric Lighting Company
1880 Elihu Thomson and Edwin Houston form American Electric Company
1880 Charles F. Brush forms the Brush Electric Company
1881 Joseph W. Swan founded the Swan Electric Light Company
1881 237,198 Hiram Maxim 2/1 for Electrical Lamp assigned to U.S. Electric Lighting Company
1881 238,868 Thomas Edison 3/15 for Manufacture of Carbons for Incandescent Lamps
1881 247,097 Joseph Nichols and Lewis Latimer 9/13 for Electric Lamp
1881 251, 540 Thomas Edison 12/27 for Bamboo Carbons Filament for Incandescent Lamps
1882 252,386 Lewis Latimer 1/17 for Process of Manufacturing Carbons assigned to U.S. E. L. Co.
1882 Edison’s UK operation merged with Swan to form the Edison & Swan United Co. or “Edi-swan”
1882 Joesph Swan sold his United States patent rights to the Brush Electric Company
1883 American Electric Company renamed Thomson-Houston Electric Company
1884 Sawyer & Man Electric Co formed by Albon Man a year after William Edward Sawyer death
1886 George Westinghouse formed the Westinghouse Electric Company
1886 The National Carbon Co. was founded by the then Brush Electric Co. executive W. H. Lawrence
1888 United States Electric Lighting Co. was purchased by Westinghouse Electric Company
1886 Sawyer & Man Electric Co. was purchased by Thomson-Houston Electric Company
1889 Brush Electric Company merged into the Thomson-Houston Electric Company
1889 Edison Electric Light Company consolidated and renamed Edison General Electric Company.
1890 Edison, Thomson-Houston, and Westinghouse, the “Big 3” of the American lighting industry.
1892 Edison Electric Light Co. and Thomson-Houston Electric Co. created General Electric Co.
light bulb, electric lamp, incandescent lamp, electric globe, Thomas Edison, Joseph Swan, Hiram Maxim, Humphrey Davy, James Joule, George Westinghouse, Charles Brush, William Coolidge, invention, history, inventor of, history of, who invented, invention of, fascinating facts.

The Story:
By the time of Edison’s 1879 lamp invention, gas lighting was a mature, well-established industry. The gas infrastructure was in place, franchises had been granted, and manufacturing facilities for both gas and equipment were in profitable operation. Perhaps as important, people had grown accustomed to the idea of lighting with gas.

Incandescent lamps make light by using electricity to heat a thin strip of material (called a filament) until it gets hot enough to glow. Many inventors had tried to perfect incandescent lamps to “sub-divide” electric light or make it smaller and weaker than it was in the existing electric arc lamps, which were too bright to be used for small spaces such as the rooms of a house.

Edison was neither the first nor the only person trying to invent an incandescent electric lamp. Many inventors had tried and failed some were discouraged and went on to invent other devices. Among those inventors who made a step forward in understanding the eclectic light were Sir Humphrey Davy, Warren De la Rue, James Bowman Lindsay, James Prescott Joule, Frederick de Moleyns and Heinrich Göbel.

Between the years 1878 and 1892 the electric light industry was growing in terms of installed lights but shrinking in terms of company competition as both Thomas Edison and George Westinghouse determined to control the industry and its advancement. They even formed the Board of Patent Control, a joint arrangement between General Electric and the Westinghouse Company to defend the patents of the two companies in litigation. This proved to be a wise decision as over 600 lawsuits for patent infringement were filed.

The easiest way to understand those turbulent times in the early lighting industry is to follow the company’s involved. Of the hundreds of companies in the business, we only cover the major players. We show the flow of inventor’s patents and inventor’s companies and how the industry ended up monopolized by GE and Westinghouse. Company names listed in GREEN ultimately became part of General Electric. Company names listed in RED ultimately became part of Westinghouse.

American Electric Company.
In the late 1870’s high school teachers Elihu Thomson and Edwin Houston began experimenting with and patenting improvements on existing arc lamp and dynamo designs. In 1880 after being approached by a group of businessmen from New Britain CT, They all agreed to the formation of a company that would engage in the commercial manufacture of lighting systems (both arc and incandescent) based on their own patents. This was the American Electric Company which existed until 1883 when it was reorganized and was renamed the Thomson-Houston Electric Company.

Brush Electric Company
In 1880, Charles F. Brush forms the Brush Electric Company. That same year he installs the first complete eclectic arc-lighting system in Wabash, Indiana. Wabash was the first American city to be lit solely by electricity and to own its own municipal power plant (that small dynamo driven by a threshing machine engine). The installation in Cleveland the year before had been a demonstration, but Cleveland would soon begin lighting its streets with arc lamps as well. In 1876 Charles F. Brush invented a new type of simple, reliable, self-regulating arc lamp, as well as a new dynamo designed to power it. Earlier attempts at self regulation had often depended on complex clockwork mechanisms that, among other things, could not automatically re-strike an arc if there were an interruption in power. The simpler Brush design for a lamp/dynamo system made central station lighting a possibility for the first time.  Joseph Swan sold his United States patent rights to the Brush Electric Company in June 1882. In 1889, Brush Electric Company merged into the Thomson-Houston Electric Company.

Edison Electric Light Company
In the period from 1878 to 1880 Edison and his associates worked on at least three thousand different theories to develop an efficient incandescent lamp.

Edison’s lamp would consist of a filament housed in a glass vacuum bulb. He had his own glass blowing shed where the fragile bulbs were carefully crafted for his experiments. Edison was trying to come up with a high resistance system that would require far less electrical power than was used for the arc lamps. This could eventually mean small electric lights suitable for home use.

By January 1879, at his laboratory in Menlo Park, New Jersey, Edison had built his first high resistance, incandescent electric light. It worked by passing electricity through a thin platinum filament in the glass vacuum bulb, which delayed the filament from melting. Still, the lamp only burned for a few short hours. In order to improve the bulb, Edison needed all the persistence he had learned years before in his basement laboratory. He tested thousands and thousands of other materials to use for the filament. He even thought about using tungsten, which is the metal used for light bulb filaments now, but he couldn’t work with it given the tools available at that time.

He tested the carbonized filaments of every plant imaginable, including bay wood, boxwood, hickory, cedar, flax, and bamboo. He even contacted biologists who sent him plant fibers from places in the tropics. Edison acknowledged that the work was tedious and very demanding, especially on his workers helping with the experiments. He always recognized the importance of hard work and determination. “Before I got through,” he recalled, “I tested no fewer than 6,000 vegetable growths, and ransacked the world for the most suitable filament material.”

Edison decided to try a carbonized cotton thread filament. When voltage was applied to the completed bulb, it began to radiate a soft orange glow. Just about fifteen hours later, the filament finally burned out. Further experimentation produced filaments that could burn longer and longer with each test. By the end of 1880, he had produced a 16-watt bulb that could last for 1500 hours and he began to market his new invention.

In Britain, Swan took Edison to court for patent infringement. Edison lost and as part of the settlement, Edison was forced to take Swan in as a partner in his British electric works. The company was called the Edison and Swan United Electric Company (later known as Ediswan which was then incorporated into Thorn Lighting Ltd). Eventually, Edison acquired all of Swan’s interest in the company. Swan sold his United States patent rights to the Brush Electric Company in June 1882.

In 1889 the Edison Electric Light Company merged with several other Edison companies to become the Edison General Electric Company. When the Edison General Electric Company merged with Thomson-Houston in 1892, a bitter struggle developed, Edison’s name was dropped, and Edison himself had no more involvement with the newly formed General Eclectic Company beyond defending his patents.

In 1903 Willis Whitnew invented a filament that would not blacken the inside of a light bulb. It was a metal-coated carbon filament. In 1906, the General Electric Company was the first to patent a method of making tungsten filaments for use in incandescent light bulbs. The filaments were costly, but by 1910 William David Coolidge had invented an improved method of making tungsten filaments. The tungsten filament outlasted all other types of filaments and Coolidge made the costs practical.

Edison & Swan United Electric Company
In Britain, Joseph Swan took Edison to court for patent infringement. Edison lost and as part of the settlement, Edison was forced to take Swan in as a partner in his British electric works. The company was called the Edison and Swan United Electric Company (later known as Ediswan). Eventually, Edison acquired all of Swan’s interest in the company.

General Electric Company
In 1892, a merger of Edison General Electric Company and Thomson-Houston Electric Company created General Electric Company. General Electric, GE is the only company listed in the Dow Jones Industrial Index today that was also included in the original index in 1896.

Sawyer & Man Electric Company
William Sawyer and Albon Man are issued Patent No, 205,144 on June 18, 1878 for Improvements in Electric Lamps. In 1884, Albon Man formed the Sawyer & Man Electric Co for the purpose of protecting the  Sawyer-Man electric lamp patent. William Sawyer had died the previous year. In 1886, the Thomson-Houston Electric Company purchased the Sawyer & Man Electric Company and began making incandescent lamps under the Sawyer-Man patents.

Swan Electric Light Company
Joseph Wilson Swan (1828-1914) was a physicist and chemist born in Sunderland, England. Swan was the first to construct an electric light bulb, but he had trouble maintaining a vacuum in his bulb. In 1850 he began working on a light bulb using carbonized paper filaments in an evacuated glass bulb. By 1860 he was able to demonstrate a working device, and obtained a UK patent covering a partial vacuum, carbon filament incandescent lamp. However, the lack of good vacuum and an adequate electric source resulted in a short lifetime for the bulb and an inefficient light.

Fifteen years later, in 1875, Swan returned to consider the problem of the light bulb and, with the aid of a better vacuum and a carbonized thread as a filament. The most significant feature of Swan’s lamp was that there was little residual oxygen in the vacuum tube to ignite the filament, thus allowing the filament to glow almost white-hot without catching fire. Swan received a British patent for his device in 1878
Swan had reported success to the Newcastle Chemical Society and at a lecture in Newcastle in February 1879 he demonstrated a working lamp. Starting that year he began installing light bulbs in homes and landmarks in England. In 1880, Swan gave the world’s first large-scale public exhibition of electric lamps at Newcastle upon Tyne England. In 1881 he had started his own company, The Swan Electric Light Company, and started commercial production.

Swan took Edison to court in Britain for patent infringement. Edison lost and as part of the settlement, Edison was forced to take Swan in as a partner in his British electric works. The company was called the Edison and Swan United Electric Company (later known as Ediswan). Eventually, Edison acquired all of Swan’s interest in the company. Also in 1882 Joseph Swan sold his United States patent rights to the Brush Electric Company, a successful “arc” street light manufacture.

Thomson-Houston Electric Company
In the late 1870’s high school teachers Elihu Thomson, a teacher of physics and chemistry, and Edwin Houston, a science teacher, began experimenting with and patenting improvements on existing arc lamp and dynamo designs. In 1880 after being approached by a group of businessmen from New Britain CT, Thomson & Houston agreed to the formation of a company that would engage in the commercial manufacture of lighting systems (both arc and incandescent) based on their own patents. This was the American Electric Company which existed until 1883 when it was reorganized and was renamed the Thomson-Houston Electric Company. .

The company became quite successful and diversified into other electrical markets. In 1886 they purchased the Sawyer & Man Electric Co. and began making incandescent lamps under the Sawyer-Man patents. In 1889 in an attempt to avoid patent disputes over a double-carbon arc lamp design, Thomson-Houston negotiated the purchase of a controlling interest in the Brush company. The Swan Incandescent Light Company was part of the Brush plant so it was included in the takeover. In 1892 Thomson-Houston merged with the Edison companies to form the giant General Electric Company.

United States Electric Lighting Company
Founded in 1878 by the prolific inventor Hiram Maxim, the United States Electric Lighting soon established itself as Thomas Edison’s chief rival in the field of incandescent lighting. The company made some of the earliest installations of this new technology using Maxim’s patent on a carbon-filament lamp, which was similar to that invented by Edison in 1879. When Maxim left USEL in 1881 to pursue other lines of invention, the company purchased the Weston Electric Lighting Company in Newark, NJ, and the services of its founder Edward Weston. The inventor of a successful “arc” lighting system, Weston, as works manager and chief designer of USEL, developed a comprehensive arc and incandescent system which the USEL began to market in 1882. In January 1882, Lewis Latimer, an employee of USEL, received a patent for the “Process of Manufacturing Carbons,” an improved method for the production of light bulb filaments which yielded longer lasting bulbs than Edison’s technique. In 1888, United States Electric Lighting Co. was purchased by Westinghouse Electric Company.

Westinghouse Electric Company
1886, George Westinghouse formed the Westinghouse Electric Company. The main function of the Electric & Manufacturing Company was to develop and produce “apparatus for the generation, transmission and application of alternating current electricity.” The company also produced electric railway motors, producing approximately 75,000 by 1905.

Weston Electric Lighting Company
Founded in New Jersey by Edward Weston in 1880, the company’s innovations included the Weston standard cell, the first accurate portable voltmeters and ammeters, the first portable light meter, and many other electrical developments. In 1881, the United States Electric Lighting Company purchased the Weston Electric Lighting Company, and the services of its founder Edward Weston. The inventor of a successful “arc” lighting system, Weston, as works manager and chief designer of USEL, developed a comprehensive arc and incandescent system which the USEL began to market in 1882.

Woodward and Evans Light
On July 24, 1874 a Canadian patent was filed for the Woodward and Evans Light by a Toronto medical electrician named Henry Woodward and a colleague Mathew Evans, who was described in the patent as a “Gentleman” but in reality a hotel keeper. They built their lamp with a shaped rod of carbon held between electrodes in a glass globe filled with nitrogen. Woodward and Evans found it impossible to raise financial support for the development of their invention and in 1875 Woodward sold a share of their Canadian patent to Thomas Edison.

The Edison Vision
The economic effect of electric lighting went far beyond increasing the workday. Profits generated by the electric lamp, in effect, paid for a network of generators and wires. This infrastructure then became available for a whole new class of inventions: appliances and equipment that by the 1930s had transformed the home and the workplace.

Edison didn’t just invent a light bulb, either. He put together what he knew about electricity with what he knew about gas lights and invented a whole system of electric lighting. This meant light bulbs, electricity generators, wires to get the electricity from the power station to the homes, fixtures (lamps, sockets, switches) for the light bulbs, and more. It was like a big jigsaw puzzle–and Edison made up the pieces as well as fitted them together. He did it his way.

Alexander Graham Bell and Elisha Gray raced to invent the telephone.

By Mary Bellis,

Alexander Graham Bell

Alexander Graham Bell

In the 1870s, two inventors Elisha Gray and Alexander Graham Bell both independently designed devices that could transmit speech electrically (the telephone). Both men rushed their respective designs to the patent office within hours of each other, Alexander Graham Bell patented his telephone first. Elisha Gray and Alexander Graham Bell entered into a famous legal battle over the invention of the telephone, which Bell won.

Alexander Graham Bell – Evolution of the Telegraph into the Telephone

The telegraph and telephone are both wire-based electrical systems, and Alexander Graham Bell’s success with the telephone came as a direct result of his attempts to improve the telegraph.

When Bell began experimenting with electrical signals, the telegraph had been an established means of communication for some 30 years. Although a highly successful system, the telegraph, with its dot-and-dash Morse code, was basically limited to receiving and sending one message at a time. Bell’s extensive knowledge of the nature of sound and his understanding of music enabled him to conjecture the possibility of transmitting multiple messages over the same wire at the same time. Although the idea of a multiple telegraph had been in existence for some time, Bell offered his own musical or harmonic approach as a possible practical solution. His “harmonic telegraph” was based on the principle that several notes could be sent simultaneously along the same wire if the notes or signals differed in pitch.

Alexander Graham Bell – Talk with Electricity

By October 1874, Bell’s research had progressed to the extent that he could inform his future father-in-law, Boston attorney Gardiner Greene Hubbard, about the possibility of a multiple telegraph. Hubbard, who resented the absolute control then exerted by the Western Union Telegraph Company, instantly saw the potential for breaking such a monopoly and gave Bell the financial backing he needed. Bell proceeded with his work on the multiple telegraph, but he did not tell Hubbard that he and Thomas Watson, a young electrician whose services he had enlisted, were also exploring an idea that had occurred to him that summer – that of developing a device that would transmit speech electrically.

While Alexander Graham Bell and Thomas Watson worked on the harmonic telegraph at the insistent urging of Hubbard and other backers, Bell nonetheless met in March 1875 with Joseph Henry, the respected director of the Smithsonian Institution, who listened to Bell’s ideas for a telephone and offered encouraging words. Spurred on by Henry’s positive opinion, Bell and Watson continued their work. By June 1875 the goal of creating a device that would transmit speech electrically was about to be realized. They had proven that different tones would vary the strength of an electric current in a wire. To achieve success they therefore needed only to build a working transmitter with a membrane capable of varying electronic currents and a receiver that would reproduce these variations in audible frequencies.

First Sounds – Twang

On June 2, 1875, Alexander Graham Bell while experimenting with his technique called “harmonic telegraph” discovered he could hear sound over a wire. The sound was that of a twanging clock spring.

Bell’s greatest success was achieved on March 10, 1876, marked not only the birth of the telephone but the death of the multiple telegraph as well. The communications potential contained in his demonstration of being able to “talk with electricity” far outweighed anything that simply increasing the capability of a dot-and-dash system could imply.

First Voice – Mr. Watson, come here. I want to see you.

Alexander Graham Bell’s notebook entry of 10 March 1876 describes his successful experiment with the telephone. Speaking through the instrument to his assistant, Thomas A. Watson, in the next room, Bell utters these famous first words, “Mr. Watson — come here — I want to see you.”

Alexander Graham Bell – Brief Biography

Born on March 3, 1847, in Edinburgh, Scotland, Alexander Graham Bell was the son and grandson of authorities in elocution and the correction of speech. Educated to pursue a career in the same specialty, his knowledge of the nature of sound led him not only to teach the deaf, but also to invent the telephone.

Alexander Graham Bell – Other Inventions

Bell’s unceasing scientific curiosity led to invention of the photophone, to significant commercial improvements in Thomas Edison’s phonograph, and to development of his own flying machine just six years after the Wright Brothers launched their plane at Kitty Hawk. As President James Garfield lay dying of an assassin’s bullet in 1881, Bell hurriedly invented a metal detector in an unsuccessful attempt to locate the fatal slug.

Read more about Alexander Graham Bell – Biography

Who is the inventor of television? You have really opened up a can of worms with that question! Probably no other invention in history has been so hotly disputed as the prestigious claim to the invention of ‘Tele-vision or ‘long-distance sight’ by wireless.”

Since Marconi’s invention of wireless telegraphy in 1897, the imagination of many inventors have been sparked with the notion of sending images as well as sound, wirelessly. The first documented notion of sending components of pictures over a series of multiple circuits is credited to George Carey. Another inventor, W. E. Sawyer, suggested the possibility of sending an image over a single wire by rapidly scanning parts of the picture in succession.

On December 2, 1922, in Sorbonne, France, Edwin Belin, an Englishman, who held the patent for the transmission of photographs by wire as well as fiber optics and radar, demonstrated a mechanical scanning device that was an early precursor to modern television. Belin’s machine took flashes of light and directed them at a selenium element connected to an electronic device that produced sound waves. These sound waves could be received in another location and remodulated into flashes of light on a mirror.

Up until this point, the concept behind television was established, but it wasn’t until electronic scanning of imagery (the breaking up of images into tiny points of light for transmission over radio waves), was invented, that modern television received its start. But here is where the controversy really heats up.

The credit as to who was the inventor of modern television really comes down to two different people in two different places both working on the same problem at about the same time: Vladimir Kosma Zworykin, a Russian-born American inventor working for Westinghouse, and Philo Taylor Farnsworth, a privately backed farm boy from the state of Utah.

“Zworykin had a patent, but Farnsworth had a picture…”

Zworykin and his televisionZworykin is usually credited as being the father of modern television. This was because the patent for the heart of the TV, the electron scanning tube, was first applied for by Zworykin in 1923, under the name of an iconoscope. The iconoscope was an electronic image scanner – essentially a primitive television camera. Farnsworth was the first of the two inventors to successfully demonstrate the transmission of television signals, which he did on September 7, 1927, using a scanning tube of his own design. Farnsworth received a patent for his electron scanning tube in 1930. Zworykin was not able to duplicate Farnsworth’s achievements until 1934 and his patent for a scanning tube was not issued until 1938. The truth of the matter is this, that while Zworykin applied for the patent for his iconoscope in 1923, the invention was not functional until some years later and all earlier efforts were of such poor quality that Westinghouse officials ordered him to work on something “more useful.”

Baird and his mechanical televisionAnother player of the times was John Logie Baird, a Scottish engineer and entrepreneur who ‘achieved his first transmissions of simple face shapes in 1924 using mechanical television. On March 25, 1925, Baird held his first public demonstration of ‘television’ at the London department store Selfridges on Oxford Street in London. In this demonstration, he had not yet obtained adequate half-tones in the moving pictures, and only silhouettes were visible.’ – MZTV

In the late thirties, when RCA and Zworykin, who was now working for RCA, tried to claim rights to the essence of television, it became evident that Farnsworth held the priority patent in the technology. The president of RCA sought to control television the same way that they controlled radio and vowed that, “RCA earns royalties, it does not pay them,” and a 50 million dollar legal battle subsequently ensued.

Farnsworth with his televisionIn the height of the legal battle for patent priority, Farnsworth’s high school science teacher was subpoenaed and traveled to Washington to testify that as a 14 year old, Farnsworth had shared his ideas of his television scanning tube with his teacher.

With patent priority status ruled in favor of Farnsworth, RCA for the first time in its history, began paying royalties for television in 1939.

Philo Farnsworth was recently named one of TIME Magazine’s 100 Greatest Scientists and Thinkers of the 20th Century.


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