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A radio receiver is an electronic circuit that receives its input from an antenna, uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, amplifies it to a level suitable for further processing, and finally converts through demodulation and decoding the signal into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into Electronic filters are Electronic circuits which perform Signal processing functions specifically intended to remove unwanted signal components and/or enhance wanted An electronic amplifier is a device for increasing the power and/or Amplitude of a signal. Demodulation is the act of removing the Modulation from an analog signal to get the original Baseband signal back Decoding is the reverse of Encoding, which is the process of transforming information from one format into another [1]

Old-fashioned radio receiver--wireless Truetone model from about 1940
Old-fashioned radio receiver--wireless Truetone model from about 1940

In consumer electronics, the terms radio and radio receiver are often used specifically for receivers designed for the sound signals transmitted by radio broadcasting services – historically the first mass-market radio application. Wireless communication is the transfer of information over a distance without the use of electrical conductors or " Wires quot Consumer electronics include electronic equipment intended for everyday use This article is about radio broadcasting for other uses see Radio (disambiguation.

Contents

Types of radio receivers

Various types of radio receivers may include:

Consumer audio receivers

In the context of home audio systems, the term "receiver" often refers to a combination of a tuner, a preamplifier, and a power amplifier all on the same chassis. A tuner is an adjustable device which passes one Radio Frequency, or band of frequencies and excludes others by using electrical Resonance. A preamplifier (preamp or control amp in some parts of the world is an Electronic amplifier which precedes another amplifier to prepare an electronic Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. Audiophiles will refer to such a device as an integrated receiver, while a single chassis that implements only one of the three component functions is called a discrete component. Some audio purists still prefer three discreet units - tuner, preamplifier and power amplifier - but the integrated receiver has, for some years, been the mainstream choice for music listening. The first integrated stereo receiver was made by the Harman Kardon company, and came onto the market in 1958. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical Harman Kardon, a division of Harman International Industries, is a manufacturer of home and car Audio equipment. It had undistinguished performance, but it represented a breakthrough to the "all in one" concept of a receiver, and rapidly improving designs gradually made the receiver the mainstay of the marketplace. Many radio receivers also include a loudspeaker. For the Marty Friedman album see Loudspeaker (album A loudspeaker, speaker, or speaker system is an electroacoustical

Hi-Fi / Home theater

Main article: Home cinema

Today AV receivers are a common component in a high-fidelity or home-theatre system. Home cinema, also called home theater, are entertainment systems that seek to reproduce cinema quality video and audio in a private home AV receivers or audio-video receivers are one of the many Consumer electronics components typically found within a Home theatre system High fidelity or hi-fi reproduction is a term used by home stereo listeners and home audio enthusiasts ( Audiophiles to refer to high-quality reproduction Home cinema, also called home theater, are entertainment systems that seek to reproduce cinema quality video and audio in a private home The receiver is generally the nerve centre of a sophisticated home-theatre system providing selectable inputs for a number of different audio components like turntables, compact-disc players and recorders, and tape decks ( like video-cassette recorders) and video components (DVD players and recorders, video-game systems, and televisions). The phonograph, or gramophone, was the most common device for playing recorded Sound from the 1870s through the 1980s A Compact Disc player (often written as compact disc player) or CD player, is an electronic device which plays audio Compact Discs CD players are often Compact Disc ReWritable (CD-RW is a rewritable Optical disc format This article deals mainly with analog tape recorders for audio applications information on digital recording, recording of video signals, and PLEASE BEAR IN MIND THAT THIS IS A GENERAL ARTICLE ABOUT VCRs/VIDEOCASSETTE RECORDERS Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images This page relates to a Hardware device used to play DVDs For the Apple Software program, see DVD Player (Apple. A DVD recorder (also known as a DVDR mainly outside of the UK and Ireland is an Optical disc recorder that records video onto blank writeable DVD media Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic

With the decline of vinyl discs, modern receivers tend to omit inputs for turntables, which have separate requirements of their own. A vinyl compound is any Organic compound that contains a vinyl group (also called ethenyl) &minus C[[Hydrogen H]] =CH sub>2 The phonograph, or gramophone, was the most common device for playing recorded Sound from the 1870s through the 1980s All other common audio/visual components can use any of the identical line-level inputs on the receiver for playback, regardless of how they are marked (the "name" on each input is mostly for the convenience of the user. ) For instance, a second CD player can be plugged into an "Aux" input, and will work the same as it will in the "CD" input jacks.

Some receivers can also provide signal processors to give a more realistic illusion of listening in a concert hall. A digital signal processor ( DSP or DSP micro) is a specialized Microprocessor designed specifically for Digital signal processing, generally An auditory illusion is an Illusion of hearing, the aural equivalent of an optical illusion the listener hears either sounds which are not present in the stimulus A concert hall is a cultural building which serves as performance venue chiefly for classical instrumental music Digital audio S/PDIF and USB connections are also common today. Digital audio uses Digital signals for Sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage S/PDIF specifies a Data Link Layer protocol and choice of Physical Layer specifications for carrying Digital audio The home theater receiver, in the vocabulary of consumer electronics, comprises both the 'radio receiver' and other functions, such as control, sound processing, and power amplification. The standalone radio receiver is usually known in consumer electronics as a tuner.

Some modern integrated receivers can send audio out to seven loudspeakers and an additional channel for a subwoofer and often include connections for headphones. A subwoofer is a Woofer, or a complete Loudspeaker dedicated to the reproduction of bass audio frequencies, from perhaps 150 Hz down Headphones (also known as earphones, earbuds, stereophones, headsets) are a pair of small Loudspeakers or less commonly a single Receivers vary greatly in price, and support stereophonic or surround sound. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical 51, Multichannel audio, Multichannel music Surround 3D Surround 5 A high-quality receiver for dedicated audio-only listening (two channel stereo) can be relatively inexpensive; excellent ones can be purchased for $300 US or less. The United States of America —commonly referred to as the Because modern receivers are purely electronic devices with no moving parts unlike electromechanical devices like turntables and cassette decks, they tend to offer many years of trouble-free service. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical In Engineering, electromechanics combines the Sciences of Electromagnetism of Electrical engineering and mechanics. A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun In recent years, the home theater in a box has become common, which often integrates a surround-capable receiver with a DVD player. A " home theater in a box " (HTIB is an integrated Home theater package which "bundles" together a combination DVD The user simply connects it to a television, perhaps other components, and a set of loudspeakers.

Portable radios

Portable radios include simple transistor radios that are typically monoaural and receive the AM, FM, and/or short wave broadcast bands. This article is about an electronic device For the fourth studio album by M Broadcast band commonly refers to several segments of the Radio spectrum. FM, and often AM, radios are sometimes included as a feature of portable CD, MP3 CD, and USB key players, as well as cassette player/recorders. A Compact Disc (also known as a CD) is an Optical disc used to store digital data, originally developed for storing digital audio An MP3 CD is a Compact disc (usually a CD-R or CD-RW) that contains Digital audio in the MP3 File format. The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a Magnetic tape sound

A Boombox (or Boom-box) – also sometimes known as a Ghettoblaster or a Jambox, or (in parts of Europe) as a "radio-cassette" – is a name given to larger portable stereo systems capable of playing radio stations and recorded music. BoomBox is an American Rock band, which was founded in 2004 by singer/songwriter Zion Godchaux on the Guitar / Lead vocals and producer/DJ

Self-powered portable radios, such as clockwork radios are used in developing nations or as part of an emergency preparedness kit. A clockwork radio or windup radio is a radio that is powered by human muscle power rather than batteries or the Electrical grid. [2]

History of radio receivers

For the history of radio transmitting, see radio. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light.
For the inventors of radio technology, see Invention of radio. This article covers the main arguments about who had what part in the early development of radio

Early development

While James Clerk Maxwell was the first person to prove electromagnetic waves existed, a German named Heinrich Hertz demonstrated these new waves by using spark gap equipment to transmit and receive radio or "Hertzian waves", as they were first called. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Heinrich Rudolf Hertz ( February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory A spark gap consists of an arrangement of two conducting Electrodes separated by a gap usually filled with a Gas such as Air.

The world’s first radio receiver (thunderstorm register) was designed by Alexander Stepanovich Popov, and it was first seen at the All-Russia exhibition 1896. Alexander Stepanovich Popov (Александр Степанович Попов (Gregorian March 16 1859 - January 13 1906, Julian March The All-Russia industrial and art exhibition 1896 in Nizhny Novgorod was held from May 28 (June 9 till October 1 (13 1896. He was the first to demonstrate the practical application of electromagnetic (radio) waves,[3] although he did not care to apply for a patent for his invention. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light.

A device called a coherer became the basis for receiving radio signals. coherer was a primitive form of radio signal detector used in the late nineteenth and early twentieth centuries consisting of a capsule of metal filings in the space between The first person to use the device to detect radio waves was a Frenchman named Edouard Branly, and Oliver Lodge popularised it when he gave a lecture in 1898 in honour of Hertz. Sir Oliver Joseph Lodge, FRS ( June 12, 1851 - August 22, 1940) born at Penkhull in Stoke-on-Trent and educated Lodge also made improvements to the coherer. Guglielmo Marconi believed that these new waves could be used to communicate over great distances and made significant improvements to both radio receiving and transmitting apparatus. Marchese Guglielmo Marconi mar'koni (25 April 1874 – 20 July 1937 was an Italian inventor best known for his development of a Radiotelegraph system In 1895 Marconi demonstrated the first viable radio system, leading to transatlantic radio communication in December 1901.

John Ambrose Fleming's development of an early thermionic valve to help detect radio waves was based upon a discovery of Thomas Edison's (called "The Edison effect", which essentially modified an early light bulb). Sir John Ambrose Fleming ( November 29, 1849 - April 18, 1945) was an English Electrical engineer and Physicist This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general Fleming called it his "oscillation valve" because it acted in the same way as water valve in only allowing flow in one direction. While Fleming's valve was a great stride forward it would take some years before thermionic, or vacuum tube technology was fully adopted. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall.

Around this time work on other types of detectors started to be undertaken and it resulted in what was later known as the cat's whisker. A detector is a device that recovers Information of interest contained in a Modulated wave Cat’s whisker refers to a thin Wire that lightly touches a semiconducting crystal to make an imperfect contact-junction detector in a Crystal radio It consisted of a crystal of a material such as galena with a small springy piece of wire brought up against it. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Galena is the natural mineral form of Lead sulfide. It is the most important Lead Ore mineral The detector was constructed so that the wire contact could be moved to different points on the crystal, and thereby obtain the best point for rectifying the signal and the best detection. A rectifier is an electrical device that converts Alternating current (AC to Direct current (DC a process known as rectification. They were never very reliable as the "whisker" needed to be moved periodically to enable it to detect the signal properly. [4]

Valves

An American named Lee de Forest, a competitor to Marconi, set about to develop receiver technology that did not infringe any patents to which Marconi had access. Lee De Forest, ( August 26, 1873 – June 30, 1961) was an American Inventor with over 300 patents to his credit He took out a number of patents in the period between 1905 and 1907 covering a variety of developments that culminated in the form of the triode valve in which there was a third electrode called a grid. A triode is an electronic amplification device having three active electrodes An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e He called this an audion tube. The Audion is an electronic Amplifier device invented by Lee De Forest in 1906 One of the first areas in which valves were used was in the manufacture of telephone repeaters, and although the performance was poor, they gave significant improvement in long distance telephone receiving circuits. Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information

With the discovery that triode valves could amplify signals it was soon noticed that they would also oscillate, a fact that was exploited in generating signals. Once the triode was established as an amplifier it made a tremendous difference to radio receiver performance as it allowed the incoming signals to be amplified. One way that proved very successful was introduced in 1913 and involved the use of positive feedback in the form of a regenerative detector. This gave significant improvements in the levels of gain that could be achieved, greatly increasing selectivity, enabling this type of receiver to outperform all other types of the era. 
With the outbreak of the First World War, there was a great impetus to develop radio receiving technology further. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All An American named Irving Langmuir helped introduce a new generation of totally air-evacuated "hard" valves. Irving Langmuir ( January 31, 1881 in Brooklyn New York – August 16, 1957 in Woods Hole Massachusetts) was an H. J. Round undertook some work on this and in 1916 he produced a number valves with the grid connection taken out of the top of the envelope away from the anode connection. Captain Henry Joseph Round ( 2 June 1881, Kingswinford, Staffordshire, England &ndash 17 August 1966, Bognor An anode is an Electrode through which Electric current flows into a polarized electrical device [4]

Autodyne and superheterodyne

By the 1920s, the tuned radio frequency receiver (TRF) represented a major improvement in performance over what had been available before, it still fell short of the needs for some of the new applications. A tuned radio frequency receiver (TRF receiver is a Radio receiver that is usually composed of several tuned radio frequency Amplifiers followed by circuits to detect To enable receiver technology to meet the needs placed upon it a number of new ideas started to surface. One of these was a new form of direct conversion receiver. Here an internal or local oscillator was used to beat with the incoming signal to produce and audible signal that could be amplified by an audio amplifier. An audio amplifier is an Electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 Hertz to

H. J. Round developed a receiver he called an autodyne in which the same valve was used as a mixer and an oscillator, Whilst the set used fewer valves it was difficult to optimise the circuit for both the mixer and oscillator functions. Captain Henry Joseph Round ( 2 June 1881, Kingswinford, Staffordshire, England &ndash 17 August 1966, Bognor The autodyne circuit was an improvement to radio signal amplification using the De Forest Audion light bulb type amplifier

The next leap forward in receiver technology was a new type of receiver known as the superheterodyne, or supersonic heterodyne receiver. In Electronics, the superheterodyne receiver (also known by its full name the supersonic heterodyne receiver, or by the abbreviated form superhet) is a A Frenchman named Lucien Levy was investigating ways in which receiver selectivity could be improved and in doing this he devised a system whereby the signals were converted down to a lower frequency where the filter bandwidths could be made narrower. A further advantage was that the gain of valves was considerably greater at the lower frequencies used after the frequency conversion, and there were fewer problems with the circuits bursting into oscillation. Oscillation is the repetitive variation typically in Time, of some measure about a central value (often a point of Equilibrium) or between two or more different states

The idea for developing a receiver with a fixed intermediate frequency amplifier and filter is credited to Edwin Armstrong. Edwin Howard Armstrong ( December 18, 1890 &ndash January 31, 1954) was an American Electrical engineer and Inventor Working for the American Expeditionary Force in Europe in 1918, Armstrong thought that if the incoming signals were mixed with a variable frequency oscillator, a low frequency fix tuned amplifier could be used. The American Expeditionary Forces or AEF was the United States military force sent to Europe in World War I. Armstrong's original receiver consisted of a total of eight valves. Several tuned circuits could be cascaded to improve selectivity, and being on a fixed frequency they did not all need to be changed in line with one another. The filters could be preset and left correctly tuned. Armstrong was not the only person working on the idea of a superhet. Alexander Meissner in Germany took out a patent for the idea six months before Armstrong, but as Meissner did not prove the idea in practice and did not build a superhet radio, the idea is credited to Armstrong. Alexander Meissner (in German Alexander Meißner) ( September 14 1883 – January 3 1958) was Austrian engineer and physicist

The need for the increased performance of the superhet receiver was first felt in America, and by the late 1920s most sets were superhets. However in Europe the number of broadcast stations did not start to rise as rapidly until later. Even so by the mid 1930s virtually all receiving sets in Europe as well were using the superhet principle. In 1926 the tetrode valve was introduced, and enabled further improvements in performance. A tetrode is an electronic device having four active Electrodes The term most commonly applies to a two-grid Vacuum tube. [4]

War and postwar developments


In 1939 the outbreak of war gave a new impetus to receiver development. During this time a number of classic communications receivers were designed. A communications receiver is a type of radio receiver used as a component of radio communication link Some like the National HRO are still sought by enthusiasts today and although they are relatively large by today's standards, they can still give a good account of themselves under current crowded band conditions. The original National HRO was a 9-tube Shortwave general coverage Communications receiver manufactured by the National Radio Company of Malden Massachusetts In the late 1940s the transistor was discovered. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals Initially the devices were not widely used because of their expense, and the fact that valves were being made smaller, and performed better. However by the early 1960s portable transistor broadcast receivers (transistor radios) were hitting the market place. This article is about an electronic device For the fourth studio album by M These radios were ideal for broadcast reception on the long and medium wave bands. They were much smaller than their valve equivalents, they were portable and could be powered from batteries. In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy Although some valve portable receivers were available, batteries for these were expensive and did not last for long. The power requirements for transistor radios were very much less, resulting in batteries lasting for much longer and being considerably cheaper. [4]

Semiconductors

Further developments in semiconductor technology lead to the introduction of the integrated circuit in the late 1950s. Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside [5] This enabled radio receiver technology to move forward even further. Integrated circuits enabled high performance circuits to be built for less cost, and significant amounts of space could be saved.

As a result of these developments new techniques could be introduced. One of these was the frequency synthesizer that was used to generate the local oscillator signal for the receiver. A frequency synthesizer is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator. By using a synthesizer it was possible to generate a very accurate and stable local oscillator signal. Also the ability of synthesizers to be controlled by microprocessors meant that many new facilities could be introduced apart from the significant performance improvements offered by synthesizers. A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated [4]

Digital technologies

Receiver technology is still moving forward. Digital signal processing where many of the functions performed by an analog intermediate frequency stage can be performed digitally by converting the signal to a digital stream that is manipulated mathematically is now widespread. Digital signal processing ( DSP) is concerned with the representation of the signals by a sequence of numbers or symbols and the processing of these signals Analogue electronics (or analog in American English) are those electronic systems with a continuously Variable signal The new digital audio broadcasting standard being introduced can only be used when the receiver can manipulate the signal digitally. Digital Audio Broadcasting ( DAB) also known as Eureka 147, is a Digital radio technology for Broadcasting Radio stations used in

While today's radios are miracles of modern technology, filled with low power high performance integrated circuits crammed into the smallest spaces, the basic principle of the radio is usually the superhet, the same idea which was developed by Edwin Armstrong back in 1918. [4]

Manufacturers

Consumer electronics

Measurement receivers

References

  1. ^ http://www.radio-electronics.com/info/receivers/index.php Radio-Electronics, Radio Receiver Technology
  2. ^ http://radio.electrical-guide.info/types/ The Radio Guide, Types of Portable Radios
  3. ^ Early Radio Transmission Recognized as Milestone. was a Japanese consumer Electronics company, founded in 1951. is a Japanese Electronics company that originated Digital Audio technology while specializing in manufacturing of High-fidelity professional and consumer Harman Kardon, a division of Harman International Industries, is a manufacturer of home and car Audio equipment. Jyutping: on1 kiu4) ( is a Japanese consumer Electronics manufacturer specializing in Home cinema and Audio equipment ( usually referred to as JVC, is an International consumer and professional electronics Corporation based in Yokohama, Japan which was founded Marantz is a company that develops and sells upper-mid range to High-end audio products NAD Electronics ( NAD originally was an Acronym for New Acoustic Dimension) is a Canadian producer of low-cost home audiophile Amplifiers is a historic Japanese High end audio company most famous for its innovative and very high quality cassette decks Jyutping: on1 kiu4) ( is a Japanese consumer Electronics manufacturer specializing in Home cinema and Audio equipment ( is a Multinational Corporation that specializes in digital entertainment products based in Tokyo, Japan. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with TEAC Corporation (ティアック is an electronics company based in Japan. Bang & Olufsen ( B&O,) is a Danish company that designs and manufactures high end Audio products Television sets and Telephones Agilent Technologies ( or Agilent, is a measurement and instrument company headquartered in Santa Clara, California. Rohde & Schwarz (ʁoːdə ʊnt ʃvaʁts in German; anglicized pronunciation ənd ʃwɔ(ɹts is an independent group of companies specializing in electronics IEEE. The Institute of Electrical and Electronics Engineers or IEEE (read eye-triple-e) is an international Non-profit, professional organization Retrieved on 16 July, 2006.
  4. ^ a b c d e f History of the Radio Receiver. Radio-Electronics. Com. Retrieved on 2007-11-23. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 800 - Charlemagne arrives at Rome to investigate the alleged crimes of
  5. ^ http://www.ti.com/corp/docs/kilbyctr/jackbuilt.shtml Texas Instruments, The Chip That Jack Built

See also

In Telecommunication, a direct-conversion receiver (DCR also known as homodyne, synchrodyne, or zero-IF receiver, is a Radio receiver The receiver in Information theory is the receiving end of a Communication channel. The regenerative circuit (or self-regenerative circuit) allows an electronic signal to be amplified many times by the same Vacuum tube or other active component Global Navigation Satellite System (GNSS is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage The Neutrodyne was a particular type of Tuned Radio Frequency (TRF Radio receiver, in which the instability-causing inter-electrode Capacitance of the Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Table radio is a term used to describe a small self-contained radio receiver used as an entertainment device Television receive-only, or TVRO is a term used in North America to refer to the reception of Satellite television from FSS -type satellites A tuned radio frequency receiver (TRF receiver is a Radio receiver that is usually composed of several tuned radio frequency Amplifiers followed by circuits to detect A tuner is an adjustable device which passes one Radio Frequency, or band of frequencies and excludes others by using electrical Resonance. This article is about an electronic device For the fourth studio album by M
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