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92-564: The commission in its advisory capacity to the federal government regularly adopts scientific research methods to gather data, analyze trends in line with the dynamism of the industry and advise government accordingly. It is also the responsibility of the commission to receive, process and consider applications for the establishment, ownership or operation of radio and television stations including cable television service , direct satellite broadcast and any other medium of broadcasting; radio and television stations owned, established or operated by

184-471: A directional antenna transmits radio waves in a beam in a particular direction, or receives waves from only one direction. Radio waves travel at the speed of light in vacuum and at slightly lower velocity in air. The other types of electromagnetic waves besides radio waves, infrared , visible light , ultraviolet , X-rays and gamma rays , can also carry information and be used for communication. The wide use of radio waves for telecommunication

276-457: A flag , for raising or dropping it, at the same time, and so up to 19 different actions. In 1904, Torres chose to carry out the first test on a three-wheeled land vehicle with a range of 20 to 30 meters. In 1906, in the presence of an audience which included King Alfonso XIII of Spain, Torres demonstrated the invention in the Port of Bilbao , guiding the electrically powered launch Vizcaya from

368-418: A microphone , a video signal representing moving images from a video camera , or a digital signal consisting of a sequence of bits representing binary data from a computer. The modulation signal is applied to a radio transmitter . In the transmitter, an electronic oscillator generates an alternating current oscillating at a radio frequency , called the carrier wave because it serves to generate

460-497: A radar screen . Doppler radar can measure a moving object's velocity, by measuring the change in frequency of the return radio waves due to the Doppler effect . Radar sets mainly use high frequencies in the microwave bands, because these frequencies create strong reflections from objects the size of vehicles and can be focused into narrow beams with compact antennas. Parabolic (dish) antennas are widely used. In most radars

552-632: A transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave . They can be received by other antennas connected to a radio receiver ; this is the fundamental principle of radio communication. In addition to communication, radio is used for radar , radio navigation , remote control , remote sensing , and other applications. In radio communication , used in radio and television broadcasting , cell phones, two-way radios , wireless networking , and satellite communication , among numerous other uses, radio waves are used to carry information across space from

644-474: A " push to talk " button on their radio which switches off the receiver and switches on the transmitter. Or the radio link may be full duplex , a bidirectional link using two radio channels so both people can talk at the same time, as in a cell phone. One way, unidirectional radio transmission is called simplex . This is radio communication between a spacecraft and an Earth-based ground station, or another spacecraft. Communication with spacecraft involves

736-627: A Service Regulation specifying that "Radiotelegrams shall show in the preamble that the service is 'Radio ' ". The switch to radio in place of wireless took place slowly and unevenly in the English-speaking world. Lee de Forest helped popularize the new word in the United States—in early 1907, he founded the DeForest Radio Telephone Company, and his letter in the 22 June 1907 Electrical World about

828-412: A controller device control the actions of a remote device. The existence of radio waves was first proven by German physicist Heinrich Hertz on 11 November 1886. In the mid-1890s, building on techniques physicists were using to study electromagnetic waves, Italian physicist Guglielmo Marconi developed the first apparatus for long-distance radio communication, sending a wireless Morse Code message to

920-697: A couple thousand dollars , all the way down to under US$ 30 for some. Some manufacturers even offer conversion kits for older digital 72 MHz or 35 MHz receivers and radios. As the emerging multitude of 2.4 GHz band spread spectrum RC systems usually use a "frequency-agile" mode of operations, like FHSS that do not stay on one set frequency any longer while in use, the older "exclusive use" provisions at model flying sites needed for VHF-band RC control systems' frequency control, for VHF-band RC systems that only used one set frequency unless serviced to change it, are not as mandatory as before. Remote control military applications are typically not radio control in

1012-421: A given bandwidth than analog modulation , by using data compression algorithms, which reduce redundancy in the data to be sent, and more efficient modulation. Other reasons for the transition is that digital modulation has greater noise immunity than analog, digital signal processing chips have more power and flexibility than analog circuits, and a wide variety of types of information can be transmitted using

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1104-548: A government license, such as the general radiotelephone operator license in the US, obtained by taking a test demonstrating adequate technical and legal knowledge of safe radio operation. Exceptions to the above rules allow the unlicensed operation by the public of low power short-range transmitters in consumer products such as cell phones, cordless phones , wireless devices , walkie-talkies , citizens band radios , wireless microphones , garage door openers , and baby monitors . In

1196-512: A human operator. An industrial radio remote control can either be operated by a person, or by a computer control system in a machine to machine (M2M) mode. For example, an automated warehouse may use a radio-controlled crane that is operated by a computer to retrieve a particular item. Industrial radio controls for some applications, such as lifting machinery, are required to be of a fail-safe design in many jurisdictions. Industrial remote controls work differently from most consumer products. When

1288-587: A large economic cost, but it can also be life-threatening (for example, in the case of interference with emergency communications or air traffic control ). To prevent interference between different users, the emission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU), which allocates bands in the radio spectrum for different uses. Radio transmitters must be licensed by governments, under

1380-595: A metal conductor called an antenna . As they travel farther from the transmitting antenna, radio waves spread out so their signal strength ( intensity in watts per square meter) decreases (see Inverse-square law ), so radio transmissions can only be received within a limited range of the transmitter, the distance depending on the transmitter power, the antenna radiation pattern , receiver sensitivity, background noise level, and presence of obstructions between transmitter and receiver . An omnidirectional antenna transmits or receives radio waves in all directions, while

1472-461: A minimum of three control dimensions (yaw, pitch and motor speed), as opposed to boats, which required only two or one. As the electronics revolution took off, single-signal channel circuit design became redundant, and instead radios provided proportionally coded signal streams which a servomechanism could interpret, using pulse-width modulation (PWM). More recently, high-end hobby systems using pulse-code modulation (PCM) features have come on

1564-427: A more limited information-carrying capacity and so work best with audio signals (speech and music), and the sound quality can be degraded by radio noise from natural and artificial sources. The shortwave bands have a greater potential range but are more subject to interference by distant stations and varying atmospheric conditions that affect reception. In the very high frequency band, greater than 30 megahertz,

1656-535: A number of commando raids to collect the missile radio sets. Jammers were then installed on British ships, and the weapons basically "stopped working". The German development teams then turned to wire-guided missiles once they realized what was going on, but the systems were not ready for deployment until the war had already moved to France. The German Kriegsmarine operated FL-Boote ( ferngelenkte Sprengboote ) which were radio controlled motor boats filled with explosives to attack enemy shipping from 1944. Both

1748-526: A number of different relays when a particular frequency was received. The relays would in turn then activate various actuators acting on the control surfaces of the missile. The controller's radio transmitter would transmit the different frequencies in response to the movements of a control stick; these were typically on/off signals. The radio gear used to control the rudder function on the American-developed Azon guided ordnance, however,

1840-470: A primitive spark-gap transmitter . Experiments by Hertz and physicists Jagadish Chandra Bose , Oliver Lodge , Lord Rayleigh , and Augusto Righi , among others, showed that radio waves like light demonstrated reflection, refraction , diffraction , polarization , standing waves , and traveled at the same speed as light, confirming that both light and radio waves were electromagnetic waves, differing only in frequency. In 1895, Guglielmo Marconi developed

1932-420: A public audience. Analog audio is the earliest form of radio broadcast. AM broadcasting began around 1920. FM broadcasting was introduced in the late 1930s with improved fidelity . A broadcast radio receiver is called a radio . Most radios can receive both AM and FM. Television broadcasting is the transmission of moving images by radio, which consist of sequences of still images, which are displayed on

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2024-459: A radio signal is usually concentrated in narrow frequency bands called sidebands ( SB ) just above and below the carrier frequency. The width in hertz of the frequency range that the radio signal occupies, the highest frequency minus the lowest frequency, is called its bandwidth ( BW ). For any given signal-to-noise ratio , an amount of bandwidth can carry the same amount of information ( data rate in bits per second) regardless of where in

2116-489: A receiver that is typically colocated with the transmitter. In radio navigation systems such as GPS and VOR , a mobile navigation instrument receives radio signals from multiple navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones , garage door openers , and keyless entry systems , radio signals transmitted from

2208-533: A recipient over a kilometer away in 1895, and the first transatlantic signal on 12 December 1901. The first commercial radio broadcast was transmitted on 2 November 1920, when the live returns of the Harding-Cox presidential election were broadcast by Westinghouse Electric and Manufacturing Company in Pittsburgh, under the call sign KDKA . The emission of radio waves is regulated by law, coordinated by

2300-673: A reference to the radiotelegraph and radiotelegraphy . The use of radio as a standalone word dates back to at least 30 December 1904, when instructions issued by the British Post Office for transmitting telegrams specified that "The word 'Radio'... is sent in the Service Instructions." This practice was universally adopted, and the word "radio" introduced internationally, by the 1906 Berlin Radiotelegraphic Convention, which included

2392-446: A screen on a television receiver (a "television" or TV) along with a synchronized audio (sound) channel. Television ( video ) signals occupy a wider bandwidth than broadcast radio ( audio ) signals. Analog television , the original television technology, required 6 MHz, so the television frequency bands are divided into 6 MHz channels, now called "RF channels". The current television standard, introduced beginning in 2006,

2484-517: A small boat that used a coherer -based radio control. With an eye towards selling the idea to the US government as a torpedo, Tesla's 1898 patent included a clockwork frequency changer so an enemy could not take control of the device. In 1903, the Spanish engineer Leonardo Torres Quevedo introduced a radio based control system called the " Telekino " at the Paris Academy of Sciences . In

2576-441: A smaller bandwidth than the old analog channels, saving scarce radio spectrum space. Therefore, each of the 6 MHz analog RF channels now carries up to 7 DTV channels – these are called "virtual channels". Digital television receivers have different behavior in the presence of poor reception or noise than analog television, called the " digital cliff " effect. Unlike analog television, in which increasingly poor reception causes

2668-582: A target otherwise both difficult and dangerous to attack. However, by the end of the war, the Luftwaffe was having similar problems attacking Allied bombers and developed a number of radio command guided surface-to-air anti-aircraft missiles , none of which saw service. The effectiveness of the Luftwaffe 's systems, primarily comprising the series of Telefunken Funk-Gerät (or FuG) 203 Kehl twin-axis, single joystick-equipped transmitters mounted in

2760-416: A television (video) signal has a greater data rate than an audio signal . The radio spectrum , the total range of radio frequencies that can be used for communication in a given area, is a limited resource. Each radio transmission occupies a portion of the total bandwidth available. Radio bandwidth is regarded as an economic good which has a monetary cost and is in increasing demand. In some parts of

2852-460: A transmitter capable of sending a family of different code words by means of a binary telegraph key signal, and a receiver, which was able to set up a different state of operation in the device being used, depending on the code word. It was able to select different positions for the steering engine and different velocities for the propelling engine independently, and also to act over other mechanisms such an electric light , for switching it, and

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2944-400: A transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location to

3036-652: A transmitter to control the actions of a device at a remote location. Remote control systems may also include telemetry channels in the other direction, used to transmit real-time information on the state of the device back to the control station. Uncrewed spacecraft are an example of remote-controlled machines, controlled by commands transmitted by satellite ground stations . Most handheld remote controls used to control consumer electronics products like televisions or DVD players actually operate by infrared light rather than radio waves, so are not examples of radio remote control. A security concern with remote control systems

3128-541: A variant of the Aerial Target’s radio control system to control from ‘mother’ aircraft different types of naval vessels including a submarine. During World War I American inventor John Hays Hammond, Jr. developed many techniques used in subsequent radio control including developing remote controlled torpedoes, ships, anti-jamming systems and even a system allowing his remote-controlled ship targeting an enemy ship's searchlights. In 1922 he installed radio control gear on

3220-435: A variety of license classes depending on use, and are restricted to certain frequencies and power levels. In some classes, such as radio and television broadcasting stations, the transmitter is given a unique identifier consisting of a string of letters and numbers called a call sign , which must be used in all transmissions. In order to adjust, maintain, or internally repair radiotelephone transmitters, individuals must hold

3312-551: A vehicle are the Mars Exploration Rovers such as Sojourner . Today radio control is used in industry for such devices as overhead cranes and switchyard locomotives . Radio-controlled teleoperators are used for such purposes as inspections, and special vehicles for disarming of bombs . Some remotely controlled devices are loosely called robots , but are more properly categorized as teleoperators since they do not operate autonomously, but only under control of

3404-413: Is amplified in the transmitter and applied to a transmitting antenna which radiates the energy as radio waves. The radio waves carry the information to the receiver location. At the receiver, the radio wave induces a tiny oscillating voltage in the receiving antenna which is a weaker replica of the current in the transmitting antenna. This voltage is applied to the radio receiver , which amplifies

3496-703: Is spoofing , in which an unauthorized person transmits an imitation of the control signal to take control of the device. Examples of radio remote control: Radio jamming is the deliberate radiation of radio signals designed to interfere with the reception of other radio signals. Jamming devices are called "signal suppressors" or "interference generators" or just jammers. During wartime, militaries use jamming to interfere with enemies' tactical radio communication. Since radio waves can pass beyond national borders, some totalitarian countries which practice censorship use jamming to prevent their citizens from listening to broadcasts from radio stations in other countries. Jamming

3588-445: Is a digital format called high-definition television (HDTV), which transmits pictures at higher resolution, typically 1080 pixels high by 1920 pixels wide, at a rate of 25 or 30 frames per second. Digital television (DTV) transmission systems, which replaced older analog television in a transition beginning in 2006, use image compression and high-efficiency digital modulation such as OFDM and 8VSB to transmit HDTV video within

3680-433: Is an audio transceiver , a receiver and transmitter in the same device, used for bidirectional person-to-person voice communication with other users with similar radios. An older term for this mode of communication is radiotelephony . The radio link may be half-duplex , as in a walkie-talkie , using a single radio channel in which only one radio can transmit at a time, so different users take turns talking, pressing

3772-410: Is called "tuning". The oscillating radio signal from the desired station causes the tuned circuit to resonate , oscillate in sympathy, and it passes the signal on to the rest of the receiver. Radio signals at other frequencies are blocked by the tuned circuit and not passed on. A modulated radio wave, carrying an information signal, occupies a range of frequencies . The information ( modulation ) in

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3864-427: Is called an uplink , while a link that transmits data from the spacecraft to the ground is called a downlink. Radar is a radiolocation method used to locate and track aircraft, spacecraft, missiles, ships, vehicles, and also to map weather patterns and terrain. A radar set consists of a transmitter and receiver. The transmitter emits a narrow beam of radio waves which is swept around the surrounding space. When

3956-462: Is control of unmanned aerial vehicles (UAVs or drones) for both civilian and military uses, although these have more sophisticated control systems than traditional applications. The idea of controlling unmanned vehicles (for the most part in an attempt to improve the accuracy of torpedoes for military purposes) predates the invention of radio. The latter half of the 1800s saw development of many such devices, connected to an operator by wires, including

4048-565: Is in radio clocks and watches, which include an automated receiver that periodically (usually weekly) receives and decodes the time signal and resets the watch's internal quartz clock to the correct time, thus allowing a small watch or desk clock to have the same accuracy as an atomic clock. Government time stations are declining in number because GPS satellites and the Internet Network Time Protocol (NTP) provide equally accurate time standards. A two-way radio

4140-417: Is mainly due to their desirable propagation properties stemming from their longer wavelength. In radio communication systems, information is carried across space using radio waves. At the sending end, the information to be sent is converted by some type of transducer to a time-varying electrical signal called the modulation signal. The modulation signal may be an audio signal representing sound from

4232-399: Is pioneering the digital switch over (DSO) . This broadcasting -related article is a stub . You can help Misplaced Pages by expanding it . Radio Radio is the technology of communicating using radio waves . Radio waves are electromagnetic waves of frequency between 3  hertz (Hz) and 300  gigahertz (GHz). They are generated by an electronic device called

4324-524: Is the one-way transmission of information from a transmitter to receivers belonging to a public audience. Since the radio waves become weaker with distance, a broadcasting station can only be received within a limited distance of its transmitter. Systems that broadcast from satellites can generally be received over an entire country or continent. Older terrestrial radio and television are paid for by commercial advertising or governments. In subscription systems like satellite television and satellite radio

4416-505: Is the use of control signals transmitted by radio to remotely operate a device. Examples of simple radio control systems are garage door openers and keyless entry systems for vehicles, in which a small handheld radio transmitter unlocks or opens doors. Radio control is also used for control of model vehicles from a hand-held radio transmitter . Industrial , military , and scientific research organizations make use of radio-controlled vehicles as well. A rapidly growing application

4508-507: Is usually accomplished by a powerful transmitter which generates noise on the same frequency as the target transmitter. US Federal law prohibits the nonmilitary operation or sale of any type of jamming devices, including ones that interfere with GPS, cellular, Wi-Fi and police radars. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km Radio control Radio control (often abbreviated to RC )

4600-595: The International Telecommunication Union (ITU), which allocates frequency bands in the radio spectrum for various uses. The word radio is derived from the Latin word radius , meaning "spoke of a wheel, beam of light, ray". It was first applied to communications in 1881 when, at the suggestion of French scientist Ernest Mercadier  [ fr ] , Alexander Graham Bell adopted radiophone (meaning "radiated sound") as an alternate name for his photophone optical transmission system. Following Hertz's discovery of

4692-517: The de Havilland " Tiger Moth " aircraft for Navy fleet gunnery firing practice. The "Queen Bee" was superseded by the similarly named Airspeed Queen Wasp , a purpose-built target aircraft of higher performance. Radio control was further developed during World War II, primarily by the Germans who used it in a number of missile projects. Their main effort was the development of radio-controlled missiles and glide bombs for use against shipping,

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4784-504: The ionosphere without refraction , and at microwave frequencies the high-gain antennas needed to focus the radio energy into a narrow beam pointed at the receiver are small and take up a minimum of space in a satellite. Portions of the UHF , L , C , S , k u and k a band are allocated for space communication. A radio link that transmits data from the Earth's surface to a spacecraft

4876-400: The radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10 ) metres, with corresponding frequency of 3 times a power of ten, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name: It can be seen that the bandwidth , the range of frequencies, contained in each band is not equal but increases exponentially as

4968-531: The 1920s with the introduction of broadcasting. Electromagnetic waves were predicted by James Clerk Maxwell in his 1873 theory of electromagnetism , now called Maxwell's equations , who proposed that a coupled oscillating electric field and magnetic field could travel through space as a wave, and proposed that light consisted of electromagnetic waves of short wavelength . On 11 November 1886, German physicist Heinrich Hertz , attempting to confirm Maxwell's theory, first observed radio waves he generated using

5060-744: The British and US also developed radio control systems for similar tasks, to avoid the huge anti-aircraft batteries set up around German targets. However, no system proved usable in practice, and the one major US effort, Operation Aphrodite , proved to be far more dangerous to its users than to the target. The American Azon guided free-fall ordnance, however, proved useful in both the European and CBI Theaters of World War II. Radio control systems of this era were generally electromechanical in nature, using small metal "fingers" or " reeds " with different resonant frequencies each of which would operate one of

5152-474: The Earth's atmosphere has less of an effect on the range of signals, and line-of-sight propagation becomes the principal mode. These higher frequencies permit the great bandwidth required for television broadcasting. Since natural and artificial noise sources are less present at these frequencies, high-quality audio transmission is possible, using frequency modulation . Radio broadcasting means transmission of audio (sound) to radio receivers belonging to

5244-596: The US, these fall under Part 15 of the Federal Communications Commission (FCC) regulations. Many of these devices use the ISM bands , a series of frequency bands throughout the radio spectrum reserved for unlicensed use. Although they can be operated without a license, like all radio equipment these devices generally must be type-approved before the sale. Below are some of the most important uses of radio, organized by function. Broadcasting

5336-405: The air simultaneously without interfering with each other because each transmitter's radio waves oscillate at a different rate, in other words, each transmitter has a different frequency , measured in hertz (Hz), kilohertz (kHz), megahertz (MHz) or gigahertz (GHz). The receiving antenna typically picks up the radio signals of many transmitters. The receiver uses tuned circuits to select

5428-414: The beam strikes a target object, radio waves are reflected back to the receiver. The direction of the beam reveals the object's location. Since radio waves travel at a constant speed close to the speed of light , by measuring the brief time delay between the outgoing pulse and the received "echo", the range to the target can be calculated. The targets are often displayed graphically on a map display called

5520-668: The continuous waves which were needed for audio modulation , so radio was used for person-to-person commercial, diplomatic and military text messaging. Starting around 1908 industrial countries built worldwide networks of powerful transoceanic transmitters to exchange telegram traffic between continents and communicate with their colonies and naval fleets. During World War I the development of continuous wave radio transmitters, rectifying electrolytic, and crystal radio receiver detectors enabled amplitude modulation (AM) radiotelephony to be achieved by Reginald Fessenden and others, allowing audio to be transmitted. On 2 November 1920,

5612-629: The current requirements at low voltage were greatly reduced and the high voltage battery was eliminated. In both tube and early transistor sets the model's control surfaces were usually operated by an electromagnetic ' escapement ' controlling the stored energy in a rubber-band loop, allowing simple on/off rudder control (right, left, and neutral) and sometimes other functions such as motor speed. Crystal-controlled superheterodyne receivers with better selectivity and stability made control equipment more capable and at lower cost. Multi-channel developments were of particular use to aircraft, which really needed

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5704-466: The customer pays a monthly fee. In these systems, the radio signal is encrypted and can only be decrypted by the receiver, which is controlled by the company and can be deactivated if the customer does not pay. Broadcasting uses several parts of the radio spectrum, depending on the type of signals transmitted and the desired target audience. Longwave and medium wave signals can give reliable coverage of areas several hundred kilometers across, but have

5796-450: The deploying aircraft, and Telefunken's companion FuG 230 Straßburg receiver placed in the ordnance to be controlled during deployment and used by both the Fritz X unpowered, armored anti-ship bomb and the powered Henschel Hs 293 guided bomb, was greatly reduced by British efforts to jam their radio signals, eventually with American assistance. After initial successes, the British launched

5888-437: The direct sense, directly operating flight control surfaces and propulsion power settings, but instead take the form of instructions sent to a completely autonomous , computerized automatic pilot . Instead of a "turn left" signal that is applied until the aircraft is flying in the right direction, the system sends a single instruction that says "fly to this point". Some of the most outstanding examples of remote radio control of

5980-570: The existence of radio waves in 1886, the term Hertzian waves was initially used for this radiation. The first practical radio communication systems, developed by Marconi in 1894–1895, transmitted telegraph signals by radio waves, so radio communication was first called wireless telegraphy . Up until about 1910 the term wireless telegraphy also included a variety of other experimental systems for transmitting telegraph signals without wires, including electrostatic induction , electromagnetic induction and aquatic and earth conduction , so there

6072-679: The federal, state and local government; and stations run under private ownership. The commission recommends these applications after due consideration, through the Minister of Information to the President, Commander-In-Chief of the Armed Forces , for the grant of radio and television licenses. It is headed by Bello Shehu Ilelah, the current director general of the commission. In March 2015, Inview Technology based in Northwich , UK ,

6164-413: The first commercial radio broadcast was transmitted by Westinghouse Electric and Manufacturing Company in Pittsburgh, under the call sign KDKA featuring live coverage of the Harding-Cox presidential election . Radio waves are radiated by electric charges undergoing acceleration . They are generated artificially by time-varying electric currents , consisting of electrons flowing back and forth in

6256-507: The first practical application invented by German engineer Werner von Siemens in 1870. Getting rid of the wires via using a new wireless technology, radio, appeared in the late 1890s. In 1897 British engineer Ernest Wilson and C. J. Evans patented a radio-controlled torpedo or demonstrated radio-controlled boats on the Thames river (accounts of what they did vary). At an 1898 exhibition at Madison Square Garden , Nikola Tesla demonstrated

6348-592: The first radio communication system, using a spark-gap transmitter to send Morse code over long distances. By December 1901, he had transmitted across the Atlantic Ocean. Marconi and Karl Ferdinand Braun shared the 1909 Nobel Prize in Physics "for their contributions to the development of wireless telegraphy". During radio's first two decades, called the radiotelegraphy era, the primitive radio transmitters could only transmit pulses of radio waves, not

6440-618: The frequency increases; each band contains ten times the bandwidth of the preceding band. The term "tremendously low frequency" (TLF) has been used for wavelengths from 1–3 Hz (300,000–100,000 km), though the term has not been defined by the ITU. The airwaves are a resource shared by many users. Two radio transmitters in the same area that attempt to transmit on the same frequency will interfere with each other, causing garbled reception, so neither transmission may be received clearly. Interference with radio transmissions can not only have

6532-488: The individual signal characteristics of a particular PWM-type RC transmitter's emissions alone, without needing a special "code" transmitted along with the control information as PCM encoding has always required. In the early 21st century, 2.4 gigahertz spread spectrum RC control systems have become increasingly utilized in control of model vehicles and aircraft. Now, these 2.4 GHz systems are being made by most radio manufacturers. These radio systems range in price from

6624-402: The longest transmission distances of any radio links, up to billions of kilometers for interplanetary spacecraft . In order to receive the weak signals from distant spacecraft, satellite ground stations use large parabolic "dish" antennas up to 25 metres (82 ft) in diameter and extremely sensitive receivers. High frequencies in the microwave band are used, since microwaves pass through

6716-453: The market that provide a computerized digital data bit -stream signal to the receiving device, instead of the earlier PWM encoding type. However, even with this coding, loss of transmission during flight has become more common , in part because of the ever more wireless society. Some more modern FM-signal receivers that still use "PWM" encoding instead can, thanks to the use of more advanced computer chips in them, be made to lock onto and use

6808-472: The need for legal restrictions warned that "Radio chaos will certainly be the result until such stringent regulation is enforced." The United States Navy would also play a role. Although its translation of the 1906 Berlin Convention used the terms wireless telegraph and wireless telegram , by 1912 it began to promote the use of radio instead. The term started to become preferred by the general public in

6900-597: The obsolete US Navy battleship USS Iowa so it could be used as a target ship (sunk in gunnery exercise in March 1923). The Soviet Red Army used remotely controlled teletanks during the 1930s in the Winter War against Finland and fielded at least two teletank battalions at the beginning of the Great Patriotic War . A teletank is controlled by radio from a control tank at a distance of 500–1500 m,

6992-505: The picture quality to gradually degrade, in digital television picture quality is not affected by poor reception until, at a certain point, the receiver stops working and the screen goes black. Government standard frequency and time signal services operate time radio stations which continuously broadcast extremely accurate time signals produced by atomic clocks , as a reference to synchronize other clocks. Examples are BPC , DCF77 , JJY , MSF , RTZ , TDF , WWV , and YVTO . One use

7084-451: The radio frequency spectrum it is located, so bandwidth is a measure of information-carrying capacity . The bandwidth required by a radio transmission depends on the data rate of the information (modulation signal) being sent, and the spectral efficiency of the modulation method used; how much data it can transmit in each kilohertz of bandwidth. Different types of information signals carried by radio have different data rates. For example,

7176-409: The radio signal desired out of all the signals picked up by the antenna and reject the others. A tuned circuit (also called resonant circuit or tank circuit) acts like a resonator , similar to a tuning fork . It has a natural resonant frequency at which it oscillates. The resonant frequency of the receiver's tuned circuit is adjusted by the user to the frequency of the desired radio station; this

7268-451: The radio spectrum, the right to use a frequency band or even a single radio channel is bought and sold for millions of dollars. So there is an incentive to employ technology to minimize the bandwidth used by radio services. A slow transition from analog to digital radio transmission technologies began in the late 1990s. Part of the reason for this is that digital modulation can often transmit more information (a greater data rate) in

7360-456: The radio waves that carry the information through the air. The modulation signal is used to modulate the carrier, varying some aspect of the carrier wave, impressing the information in the modulation signal onto the carrier. Different radio systems use different modulation methods: Many other types of modulation are also used. In some types, a carrier wave is not transmitted but just one or both modulation sidebands . The modulated carrier

7452-427: The receiver receives the radio signal which the transmitter sent, it checks it so that it is the correct frequency and that any security codes match. Once the verification is complete, the receiver sends an instruction to a relay which is activated. The relay activates a function in the application corresponding to the transmitters button. This could be to engage an electrical directional motor in an overhead crane . In

7544-481: The same digital modulation. Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to use it more effectively is driving many additional radio innovations such as trunked radio systems , spread spectrum (ultra-wideband) transmission, frequency reuse , dynamic spectrum management , frequency pooling, and cognitive radio . The ITU arbitrarily divides

7636-413: The same package. While early control systems might have two or three channels using amplitude modulation , modern systems include twenty or more using frequency modulation . The first general use of radio control systems in models started in the early 1950s with single-channel self-built equipment; commercial equipment came later. The advent of transistors greatly reduced the battery requirements, since

7728-410: The same year, he applied for several patents in other countries. It was intended as a way of testing Astra-Torres airship , a dirigible of his own design, without risking human lives. Unlike the previous mechanisms, which carried out actions of the 'on/off' type, Torres established a system for controlling any mechanical or electrical device with different states of operation. This method required

7820-441: The shore with people on board, which was controlled at a distance over 2 km. In 1904, Bat , a Windermere steam launch, was controlled using experimental radio control by its inventor, [Jack Kitchen]. In 1909 French inventor [Gabet] demonstrated what he called his " Torpille Radio-Automatique ", a radio-controlled torpedo. In 1917, Archibald Low , as head of the secret Royal Flying Corps (RFC) experimental works at Feltham ,

7912-431: The transmitting antenna also serves as the receiving antenna; this is called a monostatic radar . A radar which uses separate transmitting and receiving antennas is called a bistatic radar . Radiolocation is a generic term covering a variety of techniques that use radio waves to find the location of objects, or for navigation. Radio remote control is the use of electronic control signals sent by radio waves from

8004-479: The two constituting a telemechanical group . There were also remotely controlled cutters and experimental remotely controlled planes in the Red Army. The United Kingdom's World War One development of their radio-controlled 1917 'Aerial Target' (AT) and 1918 'Distant Control Boat' (DCB) using Low's control systems led eventually to their 1930s fleet of "Queen Bee" . This was a remotely controlled unmanned version of

8096-510: The weak radio signal so it is stronger, then demodulates it, extracting the original modulation signal from the modulated carrier wave. The modulation signal is converted by a transducer back to a human-usable form: an audio signal is converted to sound waves by a loudspeaker or earphones, a video signal is converted to images by a display , while a digital signal is applied to a computer or microprocessor, which interacts with human users. The radio waves from many transmitters pass through

8188-504: Was a fully proportional control, with the "ailerons", solely under the control of an on-board gyroscope, serving merely to keep the ordnance from rolling. These systems were widely used until the 1960s, when the increasing use of solid state systems greatly simplified radio control. The electromechanical systems using reed relays were replaced by similar electronic ones, and the continued miniaturization of electronics allowed more signals, referred to as control channels , to be packed into

8280-543: Was a need for a more precise term referring exclusively to electromagnetic radiation. The French physicist Édouard Branly , who in 1890 developed the radio wave detecting coherer , called it in French a radio-conducteur . The radio- prefix was later used to form additional descriptive compound and hyphenated words, especially in Europe. For example, in early 1898 the British publication The Practical Engineer included

8372-496: Was appointed by the NBC to enable digital switchover from analogue throughout the country and provide a conditional access system, set-top boxes with full electronic program guide , push video on demand on digital terrestrial television and carry out audience measurement data. NBC further licensed 10 set-top box manufacturers of which Gospell Digital Technology Nigeria a leading indigenous IT company led by Sir. Godfrey Ohuabunwa

8464-477: Was the first person to use radio control successfully on an aircraft, a 1917 Aerial Target . It was "piloted" from the ground by future world aerial speed record holder Henry Segrave . Low's systems encoded the command transmissions as a countermeasure to prevent enemy intervention. By 1918 the secret D.C.B. Section of the Royal Navy's Signals School, Portsmouth under the command of Eric Robinson V.C. used

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