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94-662: Majestic Radios was an American radio brand from 1927 to 1955, trademarked as "The Mighty Monarchs of the Air". Noted for their high quality, they were initially manufactured by the Grigsby-Grunow Company of Chicago. After Grigsby-Grunow's demise in 1934 during the Great Depression , Majestic Radios continued to be made through subsequent corporate ownership changes and reorganizations for another twenty-two years. The Majestic Radio & Television Corporation

188-415: A battery and relay . When the incoming radio wave reduced the resistance of the coherer, the current from the battery flowed through it, turning on the relay to ring a bell or make a mark on a paper tape in a siphon recorder . In order to restore the coherer to its previous nonconducting state to receive the next pulse of radio waves, it had to be tapped mechanically to disturb the metal particles. This

282-468: A digital signal rather than an analog signal as AM and FM do. Its advantages are that DAB has the potential to provide higher quality sound than FM (although many stations do not choose to transmit at such high quality), has greater immunity to radio noise and interference, makes better use of scarce radio spectrum bandwidth, and provides advanced user features such as electronic program guide , sports commentaries, and image slideshows. Its disadvantage

376-445: A feedback control system which monitors the average level of the radio signal at the detector, and adjusts the gain of the amplifiers to give the optimum signal level for demodulation. This is called automatic gain control (AGC). AGC can be compared to the dark adaptation mechanism in the human eye ; on entering a dark room the gain of the eye is increased by the iris opening. In its simplest form, an AGC system consists of

470-413: A radio frequency (RF) amplifier to increase its strength to a level sufficient to drive the demodulator; (3) the demodulator recovers the modulation signal (which in broadcast receivers is an audio signal , a voltage oscillating at an audio frequency rate representing the sound waves) from the modulated radio carrier wave ; (4) the modulation signal is amplified further in an audio amplifier , then

564-576: A rectifier which converts the RF signal to a varying DC level, a lowpass filter to smooth the variations and produce an average level. This is applied as a control signal to an earlier amplifier stage, to control its gain. In a superheterodyne receiver, AGC is usually applied to the IF amplifier , and there may be a second AGC loop to control the gain of the RF amplifier to prevent it from overloading, too. In certain receiver designs such as modern digital receivers,

658-410: A wireless modem , is applied as input to a computer or microprocessor , which interacts with human users. In the simplest type of radio receiver, called a tuned radio frequency (TRF) receiver , the three functions above are performed consecutively: (1) the mix of radio signals from the antenna is filtered to extract the signal of the desired transmitter; (2) this oscillating voltage is sent through

752-511: A 12-inch (30 cm) speaker. To promote its radio sales, Grigsby-Grunow sponsored The Majestic Theater of the Air musical show on the CBS radio network beginning in October, 1928. By 1928, the company enjoyed booming sales and had become the second largest U.S. radio manufacturer, behind RCA and ahead of Atwater-Kent . Grigsby-Grunow was producing 4,000 radios a day and shipping them by

846-444: A cable, as with rooftop television antennas and satellite dishes . Practical radio receivers perform three basic functions on the signal from the antenna: filtering , amplification , and demodulation : Radio waves from many transmitters pass through the air simultaneously without interfering with each other and are received by the antenna. These can be separated in the receiver because they have different frequencies ; that is,

940-420: A distance of 3500 km (2200 miles), which was received by a coherer. However the usual range of coherer receivers even with the powerful transmitters of this era was limited to a few hundred miles. The coherer remained the dominant detector used in early radio receivers for about 10 years, until replaced by the crystal detector and electrolytic detector around 1907. In spite of much development work, it

1034-605: A filter increases with its center frequency, so as the TRF receiver is tuned to different frequencies its bandwidth varies. Most important, the increasing congestion of the radio spectrum requires that radio channels be spaced very close together in frequency. It is extremely difficult to build filters operating at radio frequencies that have a narrow enough bandwidth to separate closely spaced radio stations. TRF receivers typically must have many cascaded tuning stages to achieve adequate selectivity. The Advantages section below describes how

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1128-543: A limited range of its transmitter. The range depends on the power of the transmitter, the sensitivity of the receiver, atmospheric and internal noise , as well as any geographical obstructions such as hills between transmitter and receiver. AM broadcast band radio waves travel as ground waves which follow the contour of the Earth, so AM radio stations can be reliably received at hundreds of miles distance. Due to their higher frequency, FM band radio signals cannot travel far beyond

1222-431: A lower price than before the split, the result can be a temporary increase in demand and the share price. Others contend that the management of a company, by initiating a stock split, is implicitly signaling its confidence in the future prospects of the company. In a market where there is a high minimum number of shares, or a penalty for trading in so-called odd lots (a non multiple of some arbitrary number of shares),

1316-458: A market capitalization of $ 5000 = 100 × $ 50. If the company splits its stock 2-for-1, there are now 200 shares of stock and each shareholder holds twice as many shares. The price of each share is adjusted to $ 25 = $ 5000 / 200. The market capitalization is 200 × $ 25 = $ 5000, the same as before the split. The analog in currency would be redenomination . This would be where a currency increases in value so that people have to use small fractions. Then

1410-552: A new technology were particularly attractive in the rush to buy common stocks during the Roaring Twenties . As Thurman Arnold wrote in 1965: "Economists argued that when you buy common stocks, you buy the future, not the present. Names like Auburn, Grigsby-Grunow, Kolster Radio – names you no longer hear of – flashed across the ticker tape". After the Wall Street Crash of 1929 , Grigsby-Grunow's stock began

1504-654: A new unit (such as dollar) can be introduced, such that an old unit is equal to 10 (or some number) new units. An example is with the Australian currency. In 1966 the Australian pound was split into two Australian dollars . When a stock splits, many charts show it similarly to a dividend payout and therefore do not show a dramatic dip in price. Taking the same example as above, a company with 100 shares of stock priced at $ 50 per share. The company splits its stock 2-for-1. There are now 200 shares of stock and each shareholder holds twice as many shares. The price of each share

1598-448: A paper tape machine. The coherer's poor performance motivated a great deal of research to find better radio wave detectors, and many were invented. Some strange devices were tried; researchers experimented with using frog legs and even a human brain from a cadaver as detectors. By the first years of the 20th century, experiments in using amplitude modulation (AM) to transmit sound by radio ( radiotelephony ) were being made. So

1692-578: A previous visit to the United States. At its peak in 1930, Grigsby-Grunow employed 11,000 workers at its Chicago factory and sales reached $ 61 million annually. Its stock price had reached dizzying heights and was called "the sensation of the Chicago Exchange " by Time magazine: a share purchased at $ 40 in 1928 had risen to $ 1,100 in value at its 1929 peak (taking into account multiple 4-for-1 stock splits ). Radio stocks as

1786-420: A reduced share price may attract more attention from small investors. Small investors such as these, however, will have negligible impact on the overall price. Ratios of 2-for-1 , 3-for-1 , and 3-for-2 splits are the most common, but any ratio is possible. Splits of 4-for-3, 5-for-2, and 5-for-4 are used, though less frequently. Investors will sometimes receive cash payments in lieu of fractional shares. In

1880-616: A related problem is DC offset of the signal. This is corrected by a similar feedback system. Radio waves were first identified in German physicist Heinrich Hertz 's 1887 series of experiments to prove James Clerk Maxwell's electromagnetic theory . Hertz used spark-excited dipole antennas to generate the waves and micrometer spark gaps attached to dipole and loop antennas to detect them. These primitive devices are more accurately described as radio wave sensors, not "receivers", as they could only detect radio waves within about 100 feet of

1974-423: A second goal of detector research was to find detectors that could demodulate an AM signal, extracting the audio (sound) signal from the radio carrier wave . It was found by trial and error that this could be done by a detector that exhibited "asymmetrical conduction"; a device that conducted current in one direction but not in the other. This rectified the alternating current radio signal, removing one side of

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2068-511: A single audio channel that is a combination (sum) of the left and right channels. While AM stereo transmitters and receivers exist, they have not achieved the popularity of FM stereo. Most modern radios are able to receive both AM and FM radio stations, and have a switch to select which band to receive; these are called AM/FM radios . Digital audio broadcasting (DAB) is an advanced radio technology which debuted in some countries in 1998 that transmits audio from terrestrial radio stations as

2162-641: A steep decline, eventually down to $ 18 per share. In April, 1930, the company announced the formation of Majestic Household Utilities, a new subsidiary to manufacture refrigerators and other appliances, such as vacuum cleaners and washing machines, and deliveries of Majestic refrigerators began in October. A $ 9 million plant expansion was undertaken to produce 600 all-electric refrigerators daily. A company distributor said Majestic's refrigerators would have "several new mechanical features" to make them silent-running and 30 percent more energy efficient that competing brands. Ominously, however, Time magazine

2256-412: A stock split to obtain the opposite strategy: by refusing to split the stock and keeping the price high, they reduce trading volume. Berkshire Hathaway is a notable example of this. As of 2023, the company has never split its stock and trades at over US$ 500,000. One possible explanation for increased trading volume is confusion. If some investors are unable to recognize that a split stock should trade at

2350-537: A subsidiary, Majestic Records , to produce phonograph records, beginning in 1945. Its studios were in New York City and the city's erstwhile mayor, Jimmy Walker , was named president. Although Majestic Records had some popular artists on its label, such as Bud Freeman and Louis Prima , it ceased pressing records in 1948 due to financial difficulties and its catalog was acquired by Mercury Records . The expected postwar demand for radios did not materialize and

2444-423: A voluntary reorganization plan after filing for bankruptcy on October 24, 1939. The company's plan to restructure its debt had the agreement of unsecured creditors, such as suppliers of vacuum tubes . The company stressed that business was strong and day-to-day operations would not be affected. During World War II , the company performed defense work, employing noted crystallographer George Switzer to ensure that

2538-444: Is a transmitter and receiver combined in one unit. Below is a list of a few of the most common types, organized by function. A radio receiver is connected to an antenna which converts some of the energy from the incoming radio wave into a tiny radio frequency AC voltage which is applied to the receiver's input. An antenna typically consists of an arrangement of metal conductors. The oscillating electric and magnetic fields of

2632-470: Is adjusted to $ 25. As a result, when looking at a historical chart, one might expect to see the stock dropping from $ 50 to $ 25. To avoid these discontinuities, many charts use what is known as an adjusted share price; that is, they divide all closing prices before the split by the split ratio. Thus, when looking at the charts it will seem as if the price was always $ 25. Both the Yahoo! historical price charts and

2726-436: Is applied to a loudspeaker or earphone to convert it to sound waves. Although the TRF receiver is used in a few applications, it has practical disadvantages which make it inferior to the superheterodyne receiver below, which is used in most applications. The drawbacks stem from the fact that in the TRF the filtering, amplification, and demodulation are done at the high frequency of the incoming radio signal. The bandwidth of

2820-443: Is called the intermediate frequency (IF). The IF signal also has the modulation sidebands that carry the information that was present in the original RF signal. The IF signal passes through filter and amplifier stages, then is demodulated in a detector, recovering the original modulation. The receiver is easy to tune; to receive a different frequency it is only necessary to change the local oscillator frequency. The stages of

2914-475: Is commonly called a "radio". However radio receivers are very widely used in other areas of modern technology, in televisions , cell phones , wireless modems , radio clocks and other components of communications, remote control, and wireless networking systems. The most familiar form of radio receiver is a broadcast receiver, often just called a radio , which receives audio programs intended for public reception transmitted by local radio stations . The sound

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3008-428: Is first mixed with one local oscillator signal in the first mixer to convert it to a high IF frequency, to allow efficient filtering out of the image frequency, then this first IF is mixed with a second local oscillator signal in a second mixer to convert it to a low IF frequency for good bandpass filtering. Some receivers even use triple-conversion . At the cost of the extra stages, the superheterodyne receiver provides

3102-537: Is not the degree of amplification but random electronic noise present in the circuit, which can drown out a weak radio signal. After the radio signal is filtered and amplified, the receiver must extract the information-bearing modulation signal from the modulated radio frequency carrier wave . This is done by a circuit called a demodulator ( detector ). Each type of modulation requires a different type of demodulator Many other types of modulation are also used for specialized purposes. The modulation signal output by

3196-411: Is reproduced either by a loudspeaker in the radio or an earphone which plugs into a jack on the radio. The radio requires electric power , provided either by batteries inside the radio or a power cord which plugs into an electric outlet . All radios have a volume control to adjust the loudness of the audio, and some type of "tuning" control to select the radio station to be received. Modulation

3290-402: Is so high that it becomes unwieldy when traded. One of the reasons is that a very high share price may deter small investors from buying the shares. Stock splits are usually initiated after a large run up in share price. The main effect of stock splits is an increase in the liquidity of a stock: there are more buyers and sellers for 10 shares at $ 10 than 1 share at $ 100. Some companies avoid

3384-445: Is that it is incompatible with previous radios so that a new DAB receiver must be purchased. As of 2017, 38 countries offer DAB, with 2,100 stations serving listening areas containing 420 million people. The United States and Canada have chosen not to implement DAB. DAB radio stations work differently from AM or FM stations: a single DAB station transmits a wide 1,500 kHz bandwidth signal that carries from 9 to 12 channels from which

3478-449: Is the process of adding information to a radio carrier wave . Two types of modulation are used in analog radio broadcasting systems; AM and FM. In amplitude modulation (AM) the strength of the radio signal is varied by the audio signal. AM broadcasting is allowed in the AM broadcast bands which are between 148 and 283 kHz in the longwave range, and between 526 and 1706 kHz in

3572-413: The amplitude (voltage or current) of the signal. In most modern receivers, the electronic components which do the actual amplifying are transistors . Receivers usually have several stages of amplification: the radio signal from the bandpass filter is amplified to make it powerful enough to drive the demodulator, then the audio signal from the demodulator is amplified to make it powerful enough to operate

3666-516: The crystal oscillators in aircraft transceivers were operating on the intended frequencies. Following the end of World War II , the company optimistically invested $ 600,000 in a new, 161,000-square-foot (15,000 m) factory on 69 acres (28 ha) in Elgin, Illinois . Majestic's product line included colorful, futuristic tabletop sets, as well as combination radio and phonograph consoles with FM tuners , beginning in 1947. The company also formed

3760-576: The loudspeaker grill cloth and a hand-rubbed mahogany cabinet, having a list price of $ 47.50. Nonetheless, Grigsby-Grunow declared bankruptcy in November, 1933, and ended production of Majestic Radios in February, 1934. When the bankruptcy court rejected its reorganization plan, Grigsby-Grunow was forced into liquidation in June, 1934, at the urging of creditors and bondholders. The bankruptcy court ordered

3854-463: The medium frequency (MF) range of the radio spectrum . AM broadcasting is also permitted in shortwave bands, between about 2.3 and 26 MHz, which are used for long distance international broadcasting. In frequency modulation (FM), the frequency of the radio signal is varied slightly by the audio signal. FM broadcasting is permitted in the FM broadcast bands between about 65 and 108 MHz in

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3948-418: The very high frequency (VHF) range. The exact frequency ranges vary somewhat in different countries. FM stereo radio stations broadcast in stereophonic sound (stereo), transmitting two sound channels representing left and right microphones . A stereo receiver contains the additional circuits and parallel signal paths to reproduce the two separate channels. A monaural receiver, in contrast, only receives

4042-909: The Charlotte, Michigan, factory. A line of eight Majestic radio models was offered, along with television sets. In August, 1954, Ashbach announced that Wilcox-Gay's Majestic radio and television subsidiary would begin importing Grundig FM radios from Germany as well, including an AM-FM-shortwave table model, added to the firm's Majestic product line. The Grundig radios were distributed by the existing network of Majestic dealers. However, just five months later in January, 1955, Wilcox-Gay filed for bankruptcy and ended its money-losing television production, although radios were still manufactured. The bankrupt firm eventually closed its Michigan plant in December, 1958, ending domestic production of Majestic radios, although

4136-592: The Majestic brand was "famous the world over for its excellent reception and colorful tone", with "striking yet tasteful cabinet designs". Indeed, so highly regarded were the radios that Graf Zeppelin navigator Max Pruss purchased a set in 1929 while his dirigible was moored at Lakehurst Naval Air Station , to take back to his home in Germany. Graf Zeppelin captain Hugo Eckener had purchased his own set on

4230-424: The above examples ‘y-for-x’ Shows the number of shares before (x) and after (y). Other common reporting nomenclatures are ‘x-y’ and ‘stock dividend’ of [=]y-x. In the above ‘3-for-1’ example (or 1-3 and 2 share stock dividend) would mean a stockholder holding 100 shares (on record date) will receive 200 new shares after the split for those 100 shares. A company which has 100 issued shares priced at $ 50 per share, has

4324-409: The advantage of greater selectivity than can be achieved with a TRF design. Where very high frequencies are in use, only the initial stage of the receiver needs to operate at the highest frequencies; the remaining stages can provide much of the receiver gain at lower frequencies which may be easier to manage. Tuning is simplified compared to a multi-stage TRF design, and only two stages need to track over

4418-440: The amplitude of the modulation does not vary with the radio signal strength, but in all types the demodulator requires a certain range of signal amplitude to operate properly. Insufficient signal amplitude will cause an increase of noise in the demodulator, while excessive signal amplitude will cause amplifier stages to overload (saturate), causing distortion (clipping) of the signal. Therefore, almost all modern receivers include

4512-431: The antenna is mixed with an unmodulated signal generated by a local oscillator (LO) in the receiver. The mixing is done in a nonlinear circuit called the " mixer ". The result at the output of the mixer is a heterodyne or beat frequency at the difference between these two frequencies. The process is similar to the way two musical notes at different frequencies played together produce a beat note . This lower frequency

4606-575: The auction block March 27–29, 1962. Majestic radios from the Grigsby-Grunow halcyon era of the late 1920s–early 1930s have become antique radio collectors' items, prized for their craftmanship and appearance. Some models, such as the Art Deco -styled model 161 produced in 1933, have been fully restored. Radio receiver Radio receivers are essential components of all systems that use radio . The information produced by

4700-416: The carrier cycles, leaving a pulsing DC current whose amplitude varied with the audio modulation signal. When applied to an earphone this would reproduce the transmitted sound. Below are the detectors that saw wide use before vacuum tubes took over around 1920. All except the magnetic detector could rectify and therefore receive AM signals: Stock split A stock split or stock divide increases

4794-412: The company had annual nationwide sales of $ 5 million in manufacturing products such as "Majestic" battery eliminators for home radios. The device, developed by inventor William Lear for Grigsby-Grunow, eliminated the need for a cumbersome array of lead-acid batteries and chargers to power radio receivers of the time. With the growing popularity of the new commercial broadcasting radio medium and

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4888-495: The company was unable to develop its envisioned line of televisions, leading to the company again filing for bankruptcy in February, 1948, including its Majestic Records subsidiary. On May 27, 1949, the Federal bankruptcy court judge ordered the company's liquidation, as recommended by the trustees who concluded reorganization was not feasible. They attributed the company's failure to declining radio sales and price cutting, as well as

4982-420: The demodulator is usually amplified to increase its strength, then the information is converted back to a human-usable form by some type of transducer . An audio signal , representing sound, as in a broadcast radio, is converted to sound waves by an earphone or loudspeaker . A video signal , representing moving images, as in a television receiver , is converted to light by a display . Digital data , as in

5076-450: The desired signal. A single tunable RF filter stage rejects the image frequency; since these are relatively far from the desired frequency, a simple filter provides adequate rejection. Rejection of interfering signals much closer in frequency to the desired signal is handled by the multiple sharply-tuned stages of the intermediate frequency amplifiers, which do not need to change their tuning. This filter does not need great selectivity, but as

5170-502: The development of nationwide networks in the prosperous 1920s, there was increasing consumer demand for better audio quality and console radios suitable for the living room or parlor of American households. In 1927, Grigsby-Grunow (by then, Hinds was no longer a part of the enterprise) began making "Majestic" radios featuring dynamic speakers with moving-coils and advanced circuitry employing screen-grid tubes for improved reception. The Majestic Model #71 introduced in 1927, for example,

5264-655: The earphone the signal sounded like a musical tone or buzz, and the Morse code "dots" and "dashes" sounded like beeps. The first person to use radio waves for communication was Guglielmo Marconi . Marconi invented little himself, but he was first to believe that radio could be a practical communication medium, and singlehandedly developed the first wireless telegraphy systems, transmitters and receivers, beginning in 1894–5, mainly by improving technology invented by others. Oliver Lodge and Alexander Popov were also experimenting with similar radio wave receiving apparatus at

5358-485: The filtering at the lower intermediate frequency. One of the most important parameters of a receiver is its bandwidth , the band of frequencies it accepts. In order to reject nearby interfering stations or noise, a narrow bandwidth is required. In all known filtering techniques, the bandwidth of the filter increases in proportion with the frequency, so by performing the filtering at the lower f IF {\displaystyle f_{\text{IF}}} , rather than

5452-399: The firm continued to be the sole U.S. importer of Grundig products through 1961. In September, 1961, a proposed merger with Davega Stores was not consummated because Wilcox-Gay failed to meet the merger agreement's cash terms. As 1961 drew to a close in late December, Wilcox-Gay was again bankrupt and went out of business completely, with its property, equipment, and remaining inventory going on

5546-476: The frequency of the original radio signal f RF {\displaystyle f_{\text{RF}}} , a narrower bandwidth can be achieved. Modern FM and television broadcasting, cellphones and other communications services, with their narrow channel widths, would be impossible without the superheterodyne. The signal strength ( amplitude ) of the radio signal from a receiver's antenna varies drastically, by orders of magnitude, depending on how far away

5640-522: The included AM radio. In 1948, Wilcox-Gay introduced the "Recordette", a portable version of the combination recorder, radio, and phonograph. The company also made wire recorders in the 1940s which, like phonograph home recorders, were made obsolete by the development of reel-to-reel magnetic tape recorders and discontinued in the early 1950s. With the acquisition of Majestic Radio & TV approved by Wilcox-Gay's shareholders on August 22, 1950, manufacturing of Majestic brand radios and televisions began at

5734-428: The incoming radio signal is at the resonant frequency, the resonant circuit has high impedance and the radio signal from the desired station is passed on to the following stages of the receiver. At all other frequencies the resonant circuit has low impedance, so signals at these frequencies are conducted to ground. The power of the radio waves picked up by a receiving antenna decreases with the square of its distance from

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5828-554: The intention of manufacturing Majestic radios and televisions at Wilcox-Gay's plant in Charlotte, Michigan (near Lansing ). Wilcox-Gay, a manufacturer of recording equipment, phonographs, and televisions at the time, traced its origin to 1910, when Wilcox began making transcription equipment and radio kits. One of the company's products was the "Recordio", introduced in 1939. It enabled the consumer to make home 78 rpm phonograph records, even recording off-the-air radio programs with

5922-533: The lack of success in television manufacturing. Pursuant to the court's order, the Elgin factory was sold at auction in November of that year, along with inventory, equipment, and goodwill . Leonard Ashbach, whose holding company owned Garod Radio Corporation, acquired the remaining assets of Majestic Radio & Television and a controlling share of stock in the Wilcox-Gay Corporation in 1950, with

6016-417: The listener can choose. Broadcasters can transmit a channel at a range of different bit rates , so different channels can have different audio quality. In different countries DAB stations broadcast in either Band III (174–240 MHz) or L band (1.452–1.492 GHz). The signal strength of radio waves decreases the farther they travel from the transmitter, so a radio station can only be received within

6110-408: The number of shares in a company . For example, after a 2-for-1 split, each investor will own double the number of shares, and each share will be worth half as much. A stock split causes a decrease of market price of individual shares, but does not change the total market capitalization of the company: stock dilution does not occur. A company may split its stock when the market price per share

6204-416: The radio transmitter is, how powerful it is, and propagation conditions along the path of the radio waves. The strength of the signal received from a given transmitter varies with time due to changing propagation conditions of the path through which the radio wave passes, such as multipath interference ; this is called fading . In an AM receiver, the amplitude of the audio signal from the detector, and

6298-410: The radio wave from each transmitter oscillates at a different rate. To separate out the desired radio signal, the bandpass filter allows the frequency of the desired radio transmission to pass through, and blocks signals at all other frequencies. The bandpass filter consists of one or more resonant circuits (tuned circuits). The resonant circuit is connected between the antenna input and ground. When

6392-401: The radio wave push the electrons in the antenna back and forth, creating an oscillating voltage. The antenna may be enclosed inside the receiver's case, as with the ferrite loop antennas of AM radios and the flat inverted F antenna of cell phones; attached to the outside of the receiver, as with whip antennas used on FM radios , or mounted separately and connected to the receiver by

6486-565: The radio wave to demodulate the later amplitude modulated (AM) radio transmissions that carried sound. In a long series of experiments Marconi found that by using an elevated wire monopole antenna instead of Hertz's dipole antennas he could transmit longer distances, beyond the curve of the Earth, demonstrating that radio was not just a laboratory curiosity but a commercially viable communication method. This culminated in his historic transatlantic wireless transmission on December 12, 1901, from Poldhu, Cornwall to St. John's, Newfoundland ,

6580-448: The receiver after the mixer operates at the fixed intermediate frequency (IF) so the IF bandpass filter does not have to be adjusted to different frequencies. The fixed frequency allows modern receivers to use sophisticated quartz crystal , ceramic resonator , or surface acoustic wave (SAW) IF filters that have very high Q factors , to improve selectivity. The RF filter on the front end of

6674-420: The receiver is needed to prevent interference from any radio signals at the image frequency . Without an input filter the receiver can receive incoming RF signals at two different frequencies,. The receiver can be designed to receive on either of these two frequencies; if the receiver is designed to receive on one, any other radio station or radio noise on the other frequency may pass through and interfere with

6768-466: The receiver is tuned to different frequencies it must "track" in tandem with the local oscillator. The RF filter also serves to limit the bandwidth applied to the RF amplifier, preventing it from being overloaded by strong out-of-band signals. To achieve both good image rejection and selectivity, many modern superhet receivers use two intermediate frequencies; this is called a dual-conversion or double-conversion superheterodyne. The incoming RF signal

6862-431: The receiver may be in the form of sound, video ( television ), or digital data . A radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device. The most familiar type of radio receiver for most people is a broadcast radio receiver, which reproduces sound transmitted by radio broadcasting stations, historically the first mass-market radio application. A broadcast receiver

6956-467: The same time in 1894–5, but they are not known to have transmitted Morse code during this period, just strings of random pulses. Therefore, Marconi is usually given credit for building the first radio receivers. The first radio receivers invented by Marconi, Oliver Lodge and Alexander Popov in 1894-5 used a primitive radio wave detector called a coherer , invented in 1890 by Edouard Branly and improved by Lodge and Marconi. The coherer

7050-420: The sound volume, is proportional to the amplitude of the radio signal, so fading causes variations in the volume. In addition as the receiver is tuned between strong and weak stations, the volume of the sound from the speaker would vary drastically. Without an automatic system to handle it, in an AM receiver, constant adjustment of the volume control would be required. With other types of modulation like FM or FSK

7144-402: The speaker. The degree of amplification of a radio receiver is measured by a parameter called its sensitivity , which is the minimum signal strength of a station at the antenna, measured in microvolts , necessary to receive the signal clearly, with a certain signal-to-noise ratio . Since it is easy to amplify a signal to any desired degree, the limit to the sensitivity of many modern receivers

7238-476: The superheterodyne receiver overcomes these problems. The superheterodyne receiver, invented in 1918 by Edwin Armstrong is the design used in almost all modern receivers except a few specialized applications. In the superheterodyne, the radio frequency signal from the antenna is shifted down to a lower " intermediate frequency " (IF), before it is processed. The incoming radio frequency signal from

7332-479: The trainload nationwide, newspapers reported. Majestic's trademarked slogan was "The Mighty Monarch of the Air" and its advertising in 1930 touted a 40 percent market share of U.S. and Canada radio sales. Prices ranged from $ 126.50 to $ 235 in 1930 (equivalent to $ 1,890–$ 3,500 in 2020), with installment purchase plans offered by retail dealers. In a March, 1930, review, the Charlotte Observer said

7426-683: The transmitter, and were not used for communication but instead as laboratory instruments in scientific experiments. The first radio transmitters , used during the initial three decades of radio from 1887 to 1917, a period called the spark era , were spark gap transmitters which generated radio waves by discharging a capacitance through an electric spark . Each spark produced a transient pulse of radio waves which decreased rapidly to zero. These damped waves could not be modulated to carry sound, as in modern AM and FM transmission. So spark transmitters could not transmit sound, and instead transmitted information by radiotelegraphy . The transmitter

7520-404: The transmitting antenna. Even with the powerful transmitters used in radio broadcasting stations, if the receiver is more than a few miles from the transmitter the power intercepted by the receiver's antenna is very small, perhaps as low as picowatts or femtowatts . To increase the power of the recovered signal, an amplifier circuit uses electric power from batteries or the wall plug to increase

7614-569: The trustee to establish a Refrigeration Service Department to service Majestic refrigerators and sell parts, along with parts for Majestic radios. In 1936, the assets of the defunct Grigsby-Grunow company were acquired by a new investment group, led by Zenith Radio . Included in the acquisition were the trademarks "Majestic Radio" and "The Mighty Monarch of the Air", along with unsold inventory, manufacturing equipment, and Grigsby-Grunow's former Chicago factory, which Zenith needed for its own expansion plans. The Majestic Radio & Television Corporation

7708-427: The tuning range. The total amplification of the receiver is divided between three amplifiers at different frequencies; the RF, IF, and audio amplifier. This reduces problems with feedback and parasitic oscillations that are encountered in receivers where most of the amplifier stages operate at the same frequency, as in the TRF receiver. The most important advantage is that better selectivity can be achieved by doing

7802-464: The visual horizon to about 30–40 miles (48–64 km). Radios are manufactured in a range of styles and functions: Radio receivers are essential components of all systems that use radio . Besides the broadcast receivers described above, radio receivers are used in a huge variety of electronic systems in modern technology. They can be a separate piece of equipment (a radio ), or a subsystem incorporated into other electronic devices. A transceiver

7896-605: The visual horizon; limiting reception distance to about 40 miles (64 km), and can be blocked by hills between the transmitter and receiver. However FM radio is less susceptible to interference from radio noise ( RFI , sferics , static) and has higher fidelity ; better frequency response and less audio distortion , than AM. So in countries that still broadcast AM radio, serious music is typically only broadcast by FM stations, and AM stations specialize in radio news , talk radio , and sports radio . Like FM, DAB signals travel by line of sight so reception distances are limited by

7990-489: Was a tuned radio frequency receiver with a 9-inch (23 cm) speaker, powered from AC house current . This was a considerable improvement over previous radios having typically poor selectivity and producing inferior sound from old-fashioned horn speakers or earphones. Majestic radios were highly regarded for their handsome cabinetry and superior loudspeaker quality. Model #131, a floor console made in 1930, had an 8-tube circuit for high sensitivity and selectivity, along with

8084-415: Was a glass tube with metal electrodes at each end, with loose metal powder between the electrodes. It initially had a high resistance . When a radio frequency voltage was applied to the electrodes, its resistance dropped and it conducted electricity. In the receiver the coherer was connected directly between the antenna and ground. In addition to the antenna, the coherer was connected in a DC circuit with

8178-418: Was a very crude unsatisfactory device. It was not very sensitive, and also responded to impulsive radio noise ( RFI ), such as nearby lights being switched on or off, as well as to the intended signal. Due to the cumbersome mechanical "tapping back" mechanism it was limited to a data rate of about 12-15 words per minute of Morse code , while a spark-gap transmitter could transmit Morse at up to 100 WPM with

8272-406: Was called a " detector ". Since there were no amplifying devices at this time, the sensitivity of the receiver mostly depended on the detector. Many different detector devices were tried. Radio receivers during the spark era consisted of these parts: The signal from the spark gap transmitter consisted of damped waves repeated at an audio frequency rate, from 120 to perhaps 4000 per second, so in

8366-415: Was done by a "decoherer", a clapper which struck the tube, operated by an electromagnet powered by the relay. The coherer is an obscure antique device, and even today there is some uncertainty about the exact physical mechanism by which the various types worked. However it can be seen that it was essentially a bistable device, a radio-wave-operated switch, and so it did not have the ability to rectify

8460-469: Was forced out as president in 1931 as sales declined. He went on to start General Household Utilities in 1933 to manufacture Grunow refrigerators and radios, but it went out of business in 1939. The Majestic "Smart Set" line of less expensive, but stylish, table radios was introduced in mid-1933 and enjoyed strong sales. The model 161 (pictured at top) produced in 1933 was a superheterodyne receiver with Art Deco -style chrome decorative trim adorning

8554-904: Was formed to produce the radios in the 1930s and 1940s. Following Majestic Radio & Television's liquidation in 1949, Majestic-brand radios were made by a division of the Wilcox-Gay Corporation at their Michigan factory in the 1950s. Before embarking on radio manufacturing, the Grigsby-Grunow Company had started in 1921 as the Grigsby-Grunow-Hinds Company in Chicago , making such automotive aftermarket items as its "Premier" brand of sun visors. co-founded by Bertram James Grigsby and William Carl Grunow, an Army major in World War I . By 1927,

8648-404: Was formed, with stock in the new company offered at $ 3.75 per share in October, 1936, to raise working capital and facilitate business expansion. Davega Stores became a principal stockholder, owning 175,000 shares. Early in his career, inventor Otis Boykin began working for the company as a laboratory assistant, eventually becoming plant foreman. Majestic Radio & Television submitted

8742-412: Was reporting on the unsold inventory of Majestic radios and decreasing company revenue by June, 1930, as consumers curtailed spending on luxury items, saying, "the radio industry is a ... sufferer in time of depression". As the Great Depression worsened, the company faced a number of patent infringement lawsuits and declining sales for its expensive console models. Grunow, notoriously irascible by nature,

8836-500: Was switched on and off rapidly by the operator using a telegraph key , creating different length pulses of damped radio waves ("dots" and "dashes") to spell out text messages in Morse code . Therefore, the first radio receivers did not have to extract an audio signal from the radio wave like modern receivers, but just detected the presence of the radio signal, and produced a sound during the "dots" and "dashes". The device which did this

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