Sejarah Radio dan Wireless (Dalam Bahasa Inggris)

The pre-history and early history of radio is the history of technology that produced instruments that use radio waves. Later radio history increasingly involves matters of programming and content.

Various scientists proposed that electricity and magnetism, both capable of causing attraction and repulsion of objects, 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 widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass needle. Ørsted’s experiments discovered the relationship between electricity and magnetism in a very simple experiment. Ørsted’s work influenced André-Marie Ampère to produce a theory of electromagnetism. In the history of radio and development of “wireless telegraphy”, several people are claimed to have “invented the radio”. The most commonly accepted claims are:

* Jagadish Chandra Bose
* Alexander Stepanovich Popov
* Nikola Tesla, who developed means to reliably produce radio frequency currents, publicly demonstrated the principles of radio, and transmitted long distance signals. In 1943 the US Supreme Court upheld Tesla’s patent number U.S. Patent 645,576 in effect recognizing him as the inventor of radio.
* Guglielmo Marconi, who equipped ships with life-saving wireless communications, conducted a reported transatlantic radio communications experiments in 1901 and established the first commercial transatlantic radio service in 1907.

  • Wireless prehistory (19th century)

In the late 19th century it was clear to various scientists and experimenters that wireless communication was possible. Various theoretical and experimental innovations led to the development of radio and the communication system we know today. Some early work was done by local effects and experiments of electromagnetic induction. Many understood that there was nothing similar to the “ethereal telegraphy”and telegraphy by induction; the phenomena being wholly distinct. Wireless telegraphy was beginning to take hold and the practice of transmitting messages without wires was being developed. Many people worked on developing the devices and improvements.

Faraday

In 1831, Michael Faraday began a series of experiments in which he discovered electromagnetic induction. The relation was mathematically modelled by Faraday’s law, which subsequently became one of the four Maxwell equations. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal.
William Henry Ward

In April 1872 William Henry Ward received U.S. Patent 126,356 for radio development.

Maxwell

Between 1861 and 1865, James Clerk Maxwell made experiments with electromagnetic waves. In 1873, as a result of experiments, Maxwell first described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society, “A Dynamical Theory of the Electromagnetic Field.”

Mahlon Loomis

Mahlon Loomis of West Virginia has the oldest and most documented claim of inventing radio. Loomis received U.S. Patent 129,971 for a “wireless telegraph” in July 1872. This patent utilizes atmospheric electricity to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods. It is substantially similar to William Henry Ward’s patent.

Edison (1875)

Towards the end of 1875, while experimenting with the telegraph, Thomas Edison noted a phenomenon that he termed “etheric force”, announcing it to the press on November 28. He abandoned this research when Elihu Thomson, among others, ridiculed the idea.

David E. Hughes

In 1878, David E. Hughes was the first to transmit and receive radio waves when he noticed that his induction balance caused noise in the receiver of his homemade telephone. He demonstrated his discovery to the Royal Society in 1880 but was told it was merely induction.

Calzecchi-Onesti

In 1884, Temistocle Calzecchi-Onesti at Fermo in Italy invented a primitive device that responded to radio waves. It consisted of a tube filled with iron filings, called a “coherer”. This device was a critical discovery because it would later be developed to become the first practical radio detector.

Edouard Branly

Between 1884 and 1886, Edouard Branly of France produced an improved version of the coherer.

Edison (1885)

In 1885, Edison took out U.S. Patent 465,971 on a system of radio communication between ships (which later he sold to Marconi).

Hertz

Between 1886 and 1888, Heinrich Rudolf Hertz validated Maxwell’s theory through experiment. He demonstrated that radio radiation had all the properties of waves (now called Hertzian waves), and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation. But he saw no practical use for his discovery. For more information see Hertz’s radio work.

Stubblefield

Claims have been made that Murray, Kentucky farmer Nathan Stubblefield invented radio between 1885 and 1892, before either Tesla or Marconi, but his devices seemed to have worked by induction transmission rather than radio transmission.

Landell de Moura

Between 1893 and 1894, Roberto Landell de Moura, a Brazilian priest and scientist, conducted experiments in wireless transmissions. He did not publicize his achievement until 1900, where he held a public demonstration of a wireless transmission of voice in São Paulo, Brazil in June 3, 2009.

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Marconi, orang yang disebut sangat berjasa bagi perkembangan teknologi wireless
  • Beginnings of radio

There are varying disputed claims about who invented radio, which in the beginning was called “wireless telegraphy”. The key invention for the beginning of “wireless transmission of data using the entire frequency spectrum”, known as the spark-gap transmitter, has been attributed to various men. Marconi equipped ships with lifesaving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequency electrical currents, publicly demonstrated the principles of radio, and transmitted long distance signals.
Nikola Tesla developed means to reliably produce radio frequencies, publicly demonstrated the principles of radio, and transmitted long distant signals. He holds the US patent for the invention of the radio, as defined as “wireless transmission of data”.
Nikola Tesla developed means to reliably produce radio frequencies, publicly demonstrated the principles of radio, and transmitted long distant signals. He holds the US patent for the invention of the radio, as defined as “wireless transmission of data”.

Nikola Tesla

In 1891 Tesla began his research into radio. He later published an article, “The True Wireless”, concerning this research.In 1892 he gave a lecture called “Experiments with Alternate Currents of High Potential and High Frequency”, in London (Available at Project Gutenberg).In 1893, at St. Louis, Missouri, Tesla gave a public demonstration of “wireless” radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described in detail the principles of radio communication.The apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the “oscillation valve”, the early vacuum tube.

Tesla was the first to apply the mechanism of electrical conduction to wireless practices. Also, he initially used sensitive electromagnetic receivers,[6] that were unlike the less responsive coherers later used by Marconi and other early experimenters. Afterwards, the principle of radio communication (sending signals through space to receivers) was publicized widely. Various scientists, inventors, and experimenters began to investigate wireless methods. He was re-awarded the patent rights, after holding them initially, for radio by the United States Supreme Court after his death in 1943. For more information see Tesla’s wireless work.

Oliver Lodge

Oliver Lodge transmitted radio signals on August 14, 1894 (one year after Tesla, five years after Heinrich Hertz and one year before Marconi) at a meeting of the British Association for the Advancement of Science at Oxford University.[7] (In 1995, the Royal Society recognized this scientific breakthrough at a special ceremony at Oxford University. For more information, see Past Years: An Autobiography, New York: Charles Scribner’s Sons, p231.)

On 19 August 1894 Lodge demonstrated the reception of Morse code signalling via radio waves using a “coherer”. He improved Edouard Branly’s coherer radio wave detector by adding a “trembler” which dislodged clumped filings, thus restoring the device’s sensitivity.In August 1898 he got U.S. Patent 609,154 , “Electric Telegraphy”, that made wireless signals using Ruhmkorff coils or Tesla coils for the transmitter and a Branly coherer for the detector. This was key to the “syntonic” tuning concept. In 1912 Lodge sold the patent to Marconi.

Jagdish Chandra Bose

In November 1894, the Bengali Indian physicist, Jagdish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work.[9] Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires.

The 1895 public demonstration by Bose in Calcutta was before Marconi’s wireless signalling experiment on Salisbury Plain in England in May 1897.

In 1896, the Daily Chronicle of England reported on his UHF experiments: “The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel.”

Alexander Popov

Popov was the first man to demonstrate the practical applications of radio waves.
In 1895, the Russian physicist Alexander Popov built a coherer. On May 7, 1895, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer:this day has since been celebrated in Russia as “Radio Day”. He did not apply for a patent for this invention. Popov’s early experiments were transmissions of only 600 yards. Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.
Around March 1896 Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg Physical Society. (This was before the public demonstration of the Marconi system around September 1896). Per other accounts, however, Popov achieved these results only in December, 1897; that is, after publication of Marconi’s patent.In 1898 his signal was received 6 miles away, and in 1899 30 miles away. In 1900, Popov stated at the Congress of Russian Electrical Engineers that,

“the emission and reception of signals by Marconi by means of electric oscillations was nothing new, as in America Nikola Tesla did the same experiments in 1893.”

Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945.

In February 1893, Tesla delivers “On Light and Other High Frequency Phenomena” before the Franklin Institute in Philadelphia. In 1895, Marconi receives a telegraph message without wires a short distance (below a mile), but he did not send his voice over the airwaves. In March 1895, Popov transmitted radio waves between campus buildings in Saint Petersburg, but did not apply for a patent. In 1896, Tesla detected transmissions from his New York lab of low frequency (50,000 cycle per second) undamped waves with a receiver located at West Point, “a distance of about 30 miles.”

Ernest Rutherford

The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson was instrumental in the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford was encouraged in his work by Sir Robert Ball, who had been scientific adviser to the body maintaining lighthouses on the Irish coast; he wished to solve the difficult problem of a ship’s inability to detect a lighthouse in fog. Sensing fame and fortune, Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves over a distance of several hundred meters. The commercial development, though, of wireless technology was left for others, as Rutherford continued purely scientific research. Thomson quickly realised that Rutherford was a researcher of exceptional ability and invited him to join in a study of the electrical conduction of gases.

Marconi

Guglielmo Marconi was an electrical engineer and Nobel laureate known for the development of a practical wireless telegraphy system.
Guglielmo Marconi was an electrical engineer and Nobel laureate known for the development of a practical wireless telegraphy system.

In 1896, Guglielmo Marconi was awarded a patent for radio with British Patent 12039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. This was the initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched.

In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. In 1897, Marconi established the radio station at Niton, Isle of Wight, England. In 1897, Tesla applied for two key radio patents in the USA. Those two patents were issued in early 1900. In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Bose announced his invention of the “iron-mercury-iron coherer with telephone detector” in a paper presented at Royal Society, London.

Julio Cervera Baviera

Recent studies in Spain credit Julio Cervera Baviera as the inventor of the radio (in 1902).Cervera Baviera obtained patents in England, Germany, Belgium, and Spain. In May-June 1899, Cervera had, with the blessing of the Spanish Army, visited Marconi’s radiotelegraphic installations on the English Channel, and worked to develop his own system. He began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who had worked with Marconi and his assistant George Kemp in 1899, resolved the difficulties of wireless telegraph and obtained his first patents prior to the end of that year. On March 22, 1902, Cervera founded the Spanish Wireless Telegraph and Telephone Corporation and brought to his corporation the patents he had obtained in Spain, Belgium, Germany and England.He established the second and third regular radiotelegraph service in the history of the world in 1901 and 1902 by maintaining regular transmissions between Tarifa and Ceuta for three consecutive months, and between Javea (Cabo de la Nao) and Ibiza (Cabo Pelado). This is after Marconi established the radiotelegraphic service between the Isle of Wight and Bournemouth in 1898. In 1906, Domenico Mazzotto wrote: “In Spain the Minister of War has applied the system perfected by the commander of military engineering, Julio Cervera Baviera (English patent No. 20084 (1899)).”Cervera thus achieved some success in this field, but his radiotelegraphic activities ceased suddenly, the reasons for which are unclear to this day.

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Om Waxwell, berjasa menemukan gelombang elektromagnetik

Turn of the century

Around the turn of the century, the Slaby-Arco wireless system was developed by Adolf Slaby and Georg von Arco (later incorporated into Telefunken). In 1900, Reginald Fessenden made a weak transmission of voice over the airwaves. Around 1900, Tesla opened the Wardenclyffe Tower facility and advertised services. In 1901, Marconi conducted the first successful transatlantic experimental radio communications. In 1903, Wardenclyffe Tower neared completion. Various theories exist on how Tesla intended to achieve the goals of this wireless system (reportedly, a 200 kW system). Tesla claimed that Wardenclyffe, as part of a World System of transmitters, would have allowed secure multichannel transceiving of information, universal navigation, time synchronization, and a global location system.

In 1904, The U.S. Patent Office reversed its decision, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi’s financial backers in the States, who included Thomas Edison and Andrew Carnegie. This also allowed the U.S. government (among others) to avoid having to pay the royalties that were being claimed by Tesla for use of his patents. For more information see Marconi’s radio work. In 1907, Marconi established the first commercial transatlantic radio communications service, between Clifden, Ireland and Glace Bay, Newfoundland.

  • Early radio telegraphy and telephony

British Marconi

Using various patents, the company called British Marconi was established and began communication between coast radio stations and ships at sea. This company along with its subsidiary American Marconi, had a stranglehold on ship to shore communication. It operated much the way American Telephone and Telegraph operated until 1983, owning all of its equipment and refusing to communicate with non-Marconi equipped ships. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus the first seeds of broadcasting were planted.

Reginald Fessenden

The invention of amplitude-modulated (AM) radio, so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of the spectrum) is attributed to Reginald Fessenden and Lee de Forest. On Christmas Eve 1906, Reginald Fessenden used an Alexanderson alternator and rotary spark-gap transmitter to make the first radio audio broadcast, from 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.

Karl Braun

In 1909, Marconi and Karl Ferdinand Braun were awarded the Nobel Prize in Physics for “contributions to the development of wireless telegraphy”.

Charles David Herrold

In April 1909 Charles David Herrold, an electronics instructor in San Jose, California constructed a broadcasting station. It used spark gap technology, but modulated the carrier frequency with the human voice, and later music. The station “San Jose Calling” (there were no call letters), continued to eventually become today’s KCBS in San Francisco. Herrold, the son of a Santa Clara Valley farmer, coined the terms “narrowcasting” and “broadcasting”, respectively to identify transmissions destined for a single receiver such as that on board a ship, and those transmissions destined for a general audience. (The term “broadcasting” had been used in farming to define the tossing of seed in all directions.) Charles Herrold did not claim to be the first to transmit the human voice, but he claimed to be the first to conduct “broadcasting”. To help the radio signal to spread in all directions, he designed some omnidirectional antennas, which he mounted on the rooftops of various buildings in San Jose. Herrold also claims to be the first broadcaster to accept advertising (he exchanged publicity for a local record store for records to play on his station), though this dubious honour usually is foisted on WEAF (1922).

In 1912, the RMS Titanic sank in the northern Atlantic Ocean. After this, wireless telegraphy using spark-gap transmitters quickly became universal on large ships. In 1913, the International Convention for the Safety of Life at Sea was convened and produced a treaty requiring shipboard radio stations to be manned 24 hours a day. A typical high-power spark gap was a rotating commutator with six to twelve contacts per wheel, nine inches to a foot wide, driven by about 2000 volts DC. As the gaps made and broke contact, the radio wave was audible as a tone in a crystal set. The telegraph key often directly made and broke the 2000 volt supply. One side of the spark gap was directly connected to the antenna. Receivers with thermionic valves became commonplace before spark-gap transmitters were replaced by continuous wave transmitters.

  • Audio broadcasting (1919 to 1950s)

Crystal sets

In the 1920s, the United States government publication, “Construction and Operation of a Simple Homemade Radio Receiving Outfit”, showed how almost any person handy with simple tools could a build an effective crystal radio receiver.
In the 1920s, the United States government publication, “Construction and Operation of a Simple Homemade Radio Receiving Outfit”, showed how almost any person handy with simple tools could a build an effective crystal radio receiver.

The most common type of receiver before vacuum tubes was the crystal set, although some early radios used some type of amplification through electric current or battery. Inventions of the triode amplifier, motor-generator, and detector enabled audio radio. The use of amplitude modulation (AM), with which more than one station can simultaneously send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of spectra) was pioneered by Fessenden and Lee de Forest.

To this day there is a small but avid base of fans of this technology who study and practice the art and science of designing and making crystal sets as a hobby; the Boy Scouts of America have often undertaken such craft projects to introduce boys to electronics and radio, and quite a number of them having grown up remain staunch fans of a radio that ‘runs on nothing, forever’. As the only energy available is that gathered by the antenna system, there are inherent limitations on how much sound even an ideal set could produce, but with only moderately decent antenna systems remarkable performance is possible with a superior set.

The first vacuum tubes

During the mid 1920s, amplifying vacuum tubes (or thermionic valves in the UK) revolutionized radio receivers and transmitters. John Ambrose Fleming developed an earlier tube known as an “oscillation valve” (it was a diode). Lee De Forest placed a screen, the “grid” electrode, between the filament and plate electrode. The Dutch engineer Hanso Schotanus à Steringa Idzerda made the first regular wireless broadcast for entertainment from his home in The Hague on 6 November 1919. He broadcast his popular program four nights per week until 1924 when he ran into financial troubles.

On 27 August 1920, regular wireless broadcasts for entertainment began in Argentina, pioneered by the group around Enrique Telémaco Susini, and spark gap telegraphy stopped. On 31 August 1920 the first known radio news program was broadcast by station 8MK, the unlicensed predecessor of WWJ (AM) in Detroit, Michigan. In 1922 regular wireless broadcasts for entertainment began in the UK from the Marconi Research Centre 2MT at Writtle near Chelmsford, England. Early radios ran the entire power of the transmitter through a carbon microphone. In the 1920s, the Westinghouse company bought Lee De Forest’s and Edwin Armstrong’s patent. During the mid 1920s, Amplifying vacuum tubes (US)/thermionic valves (UK) revolutionized radio receivers and transmitters. Westinghouse engineers developed a more modern vacuum tube.

Licensed commercial public radio stations

The question of the ‘first’ publicly-targeted licensed radio station in the U.S. has more than one answer and depends on semantics. Settlement of this ‘first’ question may hang largely upon what constitutes ‘regular’ programming.

* It is commonly attributed to KDKA in Pittsburgh, Pennsylvania, which in October 1920 received its license and went on the air as the first US licensed commercial broadcasting station. (Their engineer Frank Conrad had been broadcasting from his own station since 1916.) Technically, KDKA was the first of several already-extant stations to receive a ‘limited commercial’ license.
* On February 17, 1919, station 9XM at the University of Wisconsin in Madison had already broadcast the first human speech to the public at large. That station is still on the air today as WHA.
* 9XM sent music over the air two years earlier, was originally licensed in 1914 and sent its first transmission in 1916.
* On August 20, 1920, at least two months before KDKA, E.W. Scripps’s WBL (now WWJ) in Detroit started broadcasting. It has carried a regular schedule of programming to the present.
* There is the history noted above of Charles David Herrold’s radio services (eventually KCBS) going back to 1909.

Broadcasting was not yet supported by advertising or listener sponsorship. The stations owned by manufacturers and department stores were established to sell radios and those owned by newspapers to sell newspapers and express the opinions of the owners. In the 1920s, Radio was first used to transmit pictures visible as television. During the early 1930s, single sideband (SSB) and frequency modulation (FM) were invented by amateur radio operators. By 1940, they were established commercial modes.

Westinghouse was brought into the patent allies group, General Electric, American Telephone and Telegraph, and Radio Corporation of America, and became a part owner of RCA. All radios made by GE and Westinghouse were sold under the RCA label 60% GE and 40% Westinghouse. ATT’s Western Electric would build radio transmitters. The patent allies attempted to set up a monopoly, but they failed due to successful competition. Much to the dismay of the patent allies, several of the contracts for inventor’s patents held clauses protecting “amateurs” and allowing them to use the patents. Whether the competing manufacturers were really amateurs was ignored by these competitors.

These features arose:

* Commercial (United States) or governmental (Europe) station networks
* Federal Radio Commission
* Federal Communications Commission
* CCIR
* Birth of the soap opera
* Race towards shorter waves and FM

Dates of first radio stations

This is a listing of radio stations in broadcast networks. The earliest radio stations were simply radio telegraph systems which did not carry audio are not listed. The included first radio station encompass AM and FM stations; these include both commercial, public and nonprofit varieties found throughout the world.

FM and television start

In 1933, FM radio was patented by inventor Edwin H. Armstrong. FM uses frequency modulation of the radio wave to minimize static and interference from electrical equipment and the atmosphere, in the audio program. In 1937, W1XOJ, the first experimental FM radio station, was granted a construction permit by the FCC. In the 1930s, standard analog television transmissions started in Europe, and then in the 1940s in North America.

Marconi/Tesla priority dispute

In 1943, Tesla’s patent (number 645576) was reinstated as holding priority in the “invention” of modern radio by the U.S. Supreme Court shortly after Tesla’s death. The validity of the patent was never in question in the case. This decision was based on the fact that prior art existed before the establishment of Marconi’s patent. Ignoring Tesla’s prior art, the decision may have enabled the U.S. government to avoid having to pay damages that were being claimed by the Marconi Company for use of its patents during World War I (as, it is speculated, the government’s initial reversal to grant Marconi the patent right in order to nullify any claims Tesla had for compensation).

FM in Europe

After World War II, the FM radio broadcast was introduced in Germany. In 1948, a new wavelength plan was set up for Europe at a meeting in Copenhagen. Because of the recent war, Germany (which did not exist as a state and so was not invited) was only given a small number of medium-wave frequencies, which are not very good for broadcasting. For this reason Germany began broadcasting on UKW (“Ultrakurzwelle”, i.e. ultra short wave, nowadays called VHF) which was not covered by the Copenhagen plan. After some amplitude modulation experience with VHF, it was realized that FM radio was a much better alternative for VHF radio than AM. Because of this history FM Radio is still referred to as “UKW Radio” in Germany. Other European nations followed a bit later, when the superior sound quality of FM and the ability to run many more local stations because of the more limited range of VHF broadcasts were realized.

Later 20th century developments

In 1954 Regency introduced a pocket transistor radio, the TR-1, powered by a “standard 22.5V Battery”. In the early 1960s, VOR systems finally became widespread for aircraft navigation; before that, aircraft used commercial AM radio stations for navigation. (AM stations are still marked on U.S. aviation charts). In 1960 Sony introduced their 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 twenty years, transistors displaced tubes almost completely except for very high power, or very high frequency, uses.

Color television and digital

* 1963: Color television was commercially transmitted, and the first (radio) communication satellite, Telstar, was launched.
* Late 1960s: The USA long-distance telephone network began to convert to a digital network, employing digital radios for many of its links.
* 1970s: LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation.
* 1987: The GPS constellation of satellites was launched.
* Early 1990s: amateur radio experimenters began to use personal computers with audio cards to process radio signals.
* 1994: The U.S. Army and DARPA launched an aggressive successful project to construct a software radio that could become a different radio on the fly by changing software.
* Late 1990s: Digital transmissions began to be applied to broadcasting.

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radio 2 arah

Telex on radio

Telegraphy did not go away on radio. Instead, the degree of automation increased. On land-lines in the 1930s, Teletypewriters automated encoding, and were adapted to pulse-code dialing to automate routing, a service called telex. For thirty years, telex was the absolute cheapest form of long-distance communication, because up to 25 telex channels could occupy the same bandwidth as one voice channel. For business and government, it was an advantage that telex directly produced written documents.

Telex systems were adapted to short-wave radio by sending tones over single sideband. CCITT R.44 (the most advanced pure-telex standard) incorporated character-level error detection and retransmission as well as automated encoding and routing. For many years, telex-on-radio (TOR) was the only reliable way to reach some third-world countries. TOR remains reliable, though less-expensive forms of e-mail are displacing it. Many national telecom companies historically ran nearly pure telex networks for their governments, and they ran many of these links over short wave radio.

  • 21st century development

Internet radio

Internet radio consists of sending radio-style audio programming over streaming Internet connections: no radio transmitters need be involved at any point in the process.

* Early technology wars: Push or pull, streaming media or multicast

Digital audio broadcasting

Digital audio broadcasting (DAB): appears to be set to grow in importance relative to FM radio for airborne broadcasts in several countries.

Legal issues with radio

When radio was first introduced in the 1930’s many predicted the end of records. Radio was a free medium for the public to hear music for which they would normally pay. While some companies saw radio as a new avenue for promotion, other feared it would cut into profits from record sales and live performances. Many companies had their major stars sign agreements that they would not appear on radio.

Indeed, the music recording industry had a severe drop in profits after the introduction of the radio. For a while, it appeared as though radio was a definite threat to the record industry. Radio ownership grew from 2 out of 5 homes in 1931 to 4 out of 5 homes in 1938. Meanwhile record sales fell from $75 million in 1929 to $26 million in 1938 (with a low point of $5 million in 1933). Although it should be noted that the economics of the situation were also affected by the fact this took place during the Great Depression.

The copyright owners of these songs were concerned that they would see no gain from the popularity of radio and the ‘free’ music it provided. Luckily, everything they needed to make this new medium work for them already existed in previous copyright law. The copyright holder for a song had control over all public performances ‘for profit.’ The problem now was proving that the radio industry, which was just figuring out for itself how to make money from advertising and currently offered free music to anyone with a receiver, was making a profit from the songs.

The test case was against Bamberger Department Store in Newark, New Jersey in 1922. The store was broadcasting music throughout its store on the radio station WOR. No advertisements were heard, except for at the beginning of the broadcast which announced “L. Bamberger and Co., One of America’s Great Stores, Newark, New Jersey.” It was determined through this and previous cases (such as the lawsuit against Shanley’s Restaurant) that Bamberger was using the songs for commercial gain, thus making it a public performance for profit, which meant the copyright owners were due payment.

With this ruling the American Society of Composers, Authors and Publishers (ASCAP) began collecting licensing fees from radio stations in 1923. The beginning sum was $230 for all music protected under ASCAP, but for larger stations the price soon ballooned up to $5,000. Edward Samuel’s reports in his book The Illustrated Story of Copyright that “radio and TV licensing represents the single greatest source of revenue for ASCAP and its composers […] and average member of ASCAP gets about $150-$200 per work per year, or about $5,000-$6,000 for all of a member’s compositions. Not long after the Bamberger ruling, ASCAP had to once again defend their right to charge fees in 1924. The Dill Radio Bill would have allowed radio stations to play music without paying and licensing fees to ASCAP or any other music-licensing corporations. The bill did not pass.

The term wireless is normally used to refer to any type of electrical or electronic operation which is accomplished without the use of a “hard wired” connection. Wireless communication is the transfer of information over a distance without the use of electrical conductors or “wires”.The distances involved may be short (a few meters as in television remote control) or very long (thousands or even millions of kilometers for radio communications). When the context is clear the term is often simply shortened to “wireless”. Wireless communications is generally considered to be a branch of telecommunications.

It encompasses various types of fixed, mobile, and portable two way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, garage door openers and or garage doors, wireless computer mice and keyboards, satellite television and cordless telephones.

Introduction to modern wireless

Wireless operations permits services, such as long range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g., radio transmitters and receivers, remote controls, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF), infrared light, laser light, visible light, acoustic energy, etc.) to transfer information without the use of wires.Information is transferred in this manner over both short and long distances.

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wireless radio device

Wireless communication

The term “wireless” has become a generic and all-encompassing word used to describe communications in which electromagnetic waves or RF (rather than some form of wire) carry a signal over part or the entire communication path. Common examples of wireless equipment in use today include:

* Professional LMR (Land Mobile Radio) and SMR (Specialized Mobile Radio) typically used by business, industrial and Public Safety entities
* Consumer Two Way Radio including FRS (Family Radio Service), GMRS (General Mobile Radio Service)
* Amateur (“Ham”) and Citizens band (“CB”) radios
* Consumer and professional Marine VHF radios
* Cellular telphones and pagers: provide connectivity for portable and mobile applications, both personal and business.
* Global Positioning System (GPS): allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth.
* Cordless computer peripherals: the cordless mouse is a common example; keyboards and printers can also be linked to a computer via wireless.
* Cordless telephone sets: these are limited-range devices, not to be confused with cell phones.
* Satellite television: allows viewers in almost any location to select from hundreds of channels.

Wireless networking (i.e. the various flavors of unlicensed 2.4 GHz WiFi devices) is used to meet a variety of needs. Perhaps the most common use is to connect laptop users who travel from location to location. Another common use is for mobile networks that connect via satellite. A wireless transmission method is a logical choice to network a LAN segment that must frequently change locations. The following situations justify the use of wireless technology:

* To span a distance beyond the capabilities of typical cabling,
* To avoid obstacles such as physical structures, EMI, or RFI,
* To provide a backup communications link in case of normal network failure,
* To link portable or temporary workstations,
* To overcome situations where normal cabling is difficult or financially impractical, or
* To remotely connect mobile users or networks.

 

transreceiver1.jpg

radio transreceiver

Wireless communication may be via:

* radio frequency communication,
* microwave communication, for example long-range line-of-sight via highly directional antennas, or short-range communication, or
* infrared (IR) short-range communication, for example from remote controls or via IRDA,

Applications may involve point-to-point communication, point-to-multipoint communication, broadcasting , cellular networks and other wireless networks.

The term “wireless” should not be confused with the term “cordless”, which is generally used to refer to powered electrical or electronic devices that are able to operate from a portable power source (e.g., a battery pack) without any cable or cord to limit the mobility of the cordless device through a connection to the mains power supply. Some cordless devices, such as cordless telephones, are also wireless in the sense that information is transferred from the cordless telephone to the telephone’s base unit via some type of wireless communications link. This has caused some disparity in the usage of the term “cordless”, for example in Digital Enhanced Cordless Telecommunications.

In the last 50 years, wireless communications industry experienced drastic changes driven by many technology innovations.

Applications of wireless technology

  • Security systems

Wireless technology may supplement or replace hard wired implementations in security systems for homes or office buildings

  • Television remote control

Modern televisions use wireless (generally infrared) remote control units.

  • Cellular telephones

Perhaps the best known example of wireless technology is the cellular telephone. These instruments use radio waves to enable the operator to make phone calls from many locations world-wide. They can be used anywhere that there is a cellular telephone site to house the equipment that is required to transmit and receive the signal that is used to transfer both voice and data to and from these instruments.

gpsreceiver.jpg

sistem penerima GPS (Radio GPS receiver)

Environmental concerns and health hazards

Recently there have been concerns risen and research conducted concerning usage of wireless communications and its possible relation to poor concentration, memory loss, nausea, premature senility and even cancer.

On the PBS show Nature there was a show dedicated to Colony Collapse Disorder where there was mention of some blame on the phenomenon of missing bees particularly due to the wide use of cellphones as the cause of the collapse.However, one interviewed person asserted that the cellphones were not the cause due to misinterpreted report.

On the basis of current evidence, the HPA does not consider there to be a problem with the safety of WLAN. If an explicit statement that exposures are within the ICNIRP guidelines is required, this would have to be obtained from the manufacturers; however, it could be argued that this is implicit in the CE marking.

Categories of wireless implementations, devices and standards
* Broadcasting
* Amateur radio
* Communication radio
* Cordless telephony:DECT (Digital Enhanced Cordless Telecommunications)
* Cellular systems:0G, 1G, 2G, 3G, Beyond 3G (4G), Future wireless
* Short-range point-to-point communication : Wireless microphones, Remote controls, IrDA, RFID (Radio Frequency Identification), Wireless USB, DSRC (Dedicated Short Range Communications), EnOcean, Near Field Communication
* Wireless sensor networks : ZigBee, EnOcean; Personal area networks, Bluetooth, Ultra-wideband (UWB from WiMedia Alliance).
* Wireless computer networks: Wireless Local Area Networks (WLAN), (IEEE 802.11 branded as WiFi and HIPERLAN), Wireless Metropolitan Area Networks (WMAN) and Broadband Fixed Access (BWA) (LMDS, WiMAX, and HIPERMAN)


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