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133:. He found that copper filings between two brass plates would cling together, becoming conductive, when he applied a voltage to them. He also found that other types of metal filings would have the same reaction to electric sparks occurring at a distance, a phenomenon that he thought could be used for detecting lightning strikes. Calzecchi-Onesti's papers were published in il Nuovo Cimento in 1884, 1885 and 1886.
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arm sprang back. If the radio signal was still present, the coherer would immediately turn on again, pulling the clapper over to give it another tap, which would turn it off again. The result was a constant "trembling" of the clapper during the period that the radio signal was on, during the "dots" and "dashes" of the Morse code signal.
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attached to telegraph lines consisting of a piece of wood with two metal spikes extending into a chamber. The space was filled with powdered carbon that would not allow the low voltage telegraph signals to pass through but it would conduct and ground a high voltage lightning strike. In 1879 the Welsh
942:
Philadelphia, PA, Temple
University, Master's Thesis. A technical historical account of the discovery and development of coherers and coherer-like behaviors from the 1800s to 1993, including the investigations, in the 1950s, of using coherers in the, then, new field of digital computers. This thesis
582:
There are several variations of what is known as the imperfect junction coherer. The principle of operation (microwelding) suggested above for the filings coherer may be less likely to apply to this type because there is no need for decohering. An iron and mercury variation on this device was used
157:
needle. He noted the filings in the tube would react to the electric discharge even when the tube was placed in another room 20 yards away. Branly went on to devise many types of these devices based on "imperfect" metal contacts. Branly's filings tube came to light in 1892 in Great
Britain when it
152:
in a French
Journal where he described his thorough investigation of the effect of minute electrical charges on metal and many types of metal filings. In one type of circuit, filings were placed in a tube of glass or ebonite, held between two metal plates. When an electric discharge was produced in
71:
of the device, thereby allowing a much greater direct current to flow through it. In a receiver, the current would activate a bell, or a Morse paper tape recorder to make a record of the received signal. The metal filings in the coherer remained conductive after the signal (pulse) ended so that the
562:
powered by the coherer current itself. When the radio wave turned on the coherer, the DC current from the battery flowed through the electromagnet, pulling the arm over to give the coherer a tap. This returned the coherer to the nonconductive state, turning off the electromagnet current, and the
717:
Coherers were also finicky to adjust and not very sensitive. Another problem was that, because of the cumbersome mechanical "decohering" mechanism, the coherer was limited to a receiving speed of 12 – 15 words per minute of Morse code, while telegraph operators could send at rates of 50 WPM, and
364:
mechanism was added to tap the coherer, mechanically disturbing the particles to reset it to the high resistance state. If a dash is being transmitted then the radio frequency is still being received when the tap happens, and the coherer immediately becomes conductive again and the whole process
193:
In 1893 physicist W.B. Croft exhibited Branly's experiments at a meeting of the
Physical Society in London. It was unclear to Croft and others whether the filings in the Branly tube were reacting to sparks or the light from the sparks. George Minchin noticed the Branly tube might be reacting to
704:
All was fish that came to the coherer net, and the recorder wrote down dot and dash combinations quite impartially for legitimate signals, static disturbances, a slipping trolley several blocks away, and even the turning on and off of lights in the building. Translation of the tape frequently
603:
disc is suspended. By means of an adjusting screw the lower edge of the disc is made to touch the oil-covered mercury with a pressure small enough not to puncture the film of oil. Its principle of operation is not well understood. The action of detection occurs when the radio frequency signal
233:
and coherer-based receiver in a range of radio-controlled (RC) toys, called
Radicon (abbreviation for Radio-Controlled) toys. Several different types using the same RC system were commercially sold, including a Radicon Boat (very rare), Radicon Oldsmobile Car (rare) and a Radicon Bus (the most
546:
The problem of the filings continuing to cling together and conduct after the removal of the signal was solved by tapping or shaking the coherer after the arrival of each signal, shaking the filings and raising the resistance of the coherer to the original value. This apparatus was called a
202:
who saw this as a way to build a much improved
Hertzian wave detector. On 1 June 1894, a few months after the death of Heinrich Hertz, Oliver Lodge delivered a memorial lecture on Hertz where he demonstrated the properties of "Hertzian waves" (radio), including transmitting them over a short
72:
coherer had to be "decohered" by tapping it with a clapper actuated by an electromagnet, each time a signal was received, thereby restoring the coherer to its original state. Coherers remained in widespread use until about 1907, when they were replaced by more sensitive
20:
436:
made contact with the metal particles on both ends. In some coherers, the electrodes were slanted so the width of the gap occupied by the filings could be varied by rotating the tube about its long axis, thus adjusting its sensitivity to the prevailing conditions.
406:
368:
Coherence of particles by radio waves is an obscure phenomenon that is not well understood even today. Recent experiments with particle coherers seem to have confirmed the hypothesis that the particles cohere by a micro-weld phenomenon caused by
1326:
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electricity. The radio signal from the antenna was applied directly across the coherer's electrodes. When the radio signal from a "dot" or "dash" came in, the coherer would become conductive. The coherer's electrodes were also attached to a
818:
Tripod coherer, built by Branly in 1902, another imperfect contact type. Although most coherers functioned as "switches" that turned on a DC current from a battery in the presence of radio waves, this may be one of the first rectifying
535:, giving an audible click. In some applications, a pair of headphones replaced the telegraph sounder, being much more sensitive to weak signals, or a Morse recorder which recorded the dots and dashes of the signal on paper tape.
440:
In operation, the coherer is included in two separate electrical circuits. One is the antenna-ground circuit shown in the untuned receiver circuit diagram below. The other is the battery-sounder relay circuit including battery
604:
somehow breaks down the insulating film of oil, allowing the device to conduct, operating the receiving sounder wired in series. This form of coherer is self-restoring and needs no decohering.
203:
distance, using an improved version of Branly's filings tube, which Lodge had named the "coherer", as a detector. In May 1895, after reading about Lodge's demonstrations, the
Russian physicist
373:
electricity flowing across the small contact area between particles. The underlying principle of so-called "imperfect contact" coherers is also not well understood, but may involve a kind of
121:
found that loose contacts between a carbon rod and two carbon blocks as well as the metallic granules in a microphone he was developing responded to sparks generated in a nearby apparatus.
104:
found that when dusty air was electrified, the particles would tend to collect in the form of strings. The idea that particles could react to electricity was used in
English engineer
943:
examined the similarities among coherers and electrolytic RF detectors, MOM (Metal-Oxide-Metal) 'diodes' used in laser heterodyning, and the STM (Scanning
Tunneling Microscope).
328:. As a result, early radio receiving apparatus merely had to detect the presence or absence of the radio signal, not convert it to audio. The device that did this was called a
1518:
449:
in the diagram. A radio signal from the antenna-ground circuit "turns on" the coherer, enabling current flow in the battery-sounder circuit, activating the sounder,
414:
The coherer as developed by
Marconi consisted of metal filings (dots) enclosed between two slanted electrodes (black) a few millimeters apart, connected to terminals.
360:
persisted after the radio signal was removed. This was a problem because the coherer had to be ready immediately to receive the next "dot" or "dash". Therefore, a
1880:
1167:
97:
1355:"Sir J. C. Bose's Diode Detector Received Marconi's First Transatlantic Wireless Signal of December 1901 (The "Italian Navy Coherer" Scandal Revisited)"
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was publicized as wonderful, and it was wonderfully erratic and bad. It would not work when it should, and it worked overtime when it should not have.
109:
551:. This process was referred to as 'decohering' the device and was subject to much innovation during the life of the popular use of this component.
574:
ahead of the train were occupied the oscillations were interrupted and the coherer, acting through a relay, showed a warning and applied the brakes.
748:
signals, which began to be experimented with in the first years of the 20th century. This problem was solved by the rectification capability of the
101:
806:
A "ball" coherer, designed by Branly in 1899. This imperfect contact type had a series of lightly touching metal balls set between two electrodes.
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for rail locomotives, patented in 1907, used a coherer to detect electrical oscillations in a continuous aerial running along the track. If the
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2555:
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was described by Dr. Dawson Turner at a meeting of the British Association in Edinburgh. The Scottish electrical engineer and astronomer
88:
The behavior of particles or metal filings in the presence of electricity or electric sparks was noticed in many experiments well before
918:
1340:
229:
One minor use of the coherer in modern times was by Japanese tin-plate toy manufacturer Matsudaya Toy Co. who beginning 1957 used a
1478:
997:
Peter Samuel Munk af Rosenschold lecture assistant in Chemistry at the University of Lund was born at Lund in 1804 and died in 1860
1509:
2582:
1014:
Falcon, Eric; Castaing, Bernard (2005). "Electrical conductivity in granular media and Branly's coherer: A simple experiment".
725:(radio) transmissions. As a simple switch that registered the presence or absence of radio waves, the coherer could detect the
51:
and adapted by other physicists and inventors over the next ten years. The device consists of a tube or capsule containing two
935:. A comprehensive description of radio detectors up to the development of the vacuum tube, with many unusual types of coherer.
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noticed a change of resistance in a mixture of metal filings in the presence of spark discharge from a Leyden jar. In 1850
1714:
2639:
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2418:
1553:
1221:
185:, UK. The coherer is on right, with the decoherer mechanism behind it. The relay is in the cylindrical metal container
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1121:
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Because they are threshold voltage detectors, coherers had difficulty discriminating between the impulsive signals of
542:
A coherer with electromagnet-operated "tapper" (decoherer), built by early radio researcher Emile Guarini around 1904.
211:
demonstrated a wireless telegraphy system using Hertzian waves (radio), based on a coherer. The Russian radio pioneer
2438:
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built a "Hertzian wave" (radio wave) based lightning detector using a coherer. That same year, Italian inventor
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1204:
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repeats for another mark on the tape. As a result, dash is marked on the tape as multiple dots close together.
162:
suggested that Branly's filings tube might be reacting in the presence of Hertzian waves, a type of air-borne
47:
era at the beginning of the 20th century. Its use in radio was based on the 1890 findings of French physicist
2354:
1527:
1268:
Falcon, E.; Castaing, B.; Creyssels, M. (2004). "Nonlinear electrical conductivity in a 1D granular medium".
869:
336:
125:
in Italy began studying the anomalous change in the resistance of thin metallic films and metal particles at
1388:
983:
The letters of Faraday and Schoenbein 1836-1862: With notes, comments and references to contemporary letters
332:. The coherer was the most successful of many detector devices that were tried in the early days of radio.
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Unlike modern AM radio stations that transmit a continuous radio frequency, whose amplitude (power) is
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In later practical receivers the decoherer was a clapper similar to an electric bell, operated by an
163:
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1851:
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1739:
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68:
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The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder.
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2228:
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2051:
1729:
1615:
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356:, or a mark on a paper tape, to record the signal. Unfortunately, the reduction in the coherer's
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1911:
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1324:, Frank Wyatt Prentice, "Electric Signaling System", published 5 February 1907
8:
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1895:
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309:
118:
44:
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555:, for example, invented a coherer in which the tube rotated continually along its axis.
538:
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by Marconi for the first transatlantic radio message. An earlier form was invented by
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1890:
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823:) detectors, because Branly reported it could produce a DC current without a battery.
588:
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353:
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212:
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24:
2131:
1422:
1307:
1196:
Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits
1053:
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used a cohere in his initial laboratory which established as hobby pursuit in 1904.
89:
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1991:
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329:
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93:
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36:
1077:; Salazar-Palma, Magdalena; Sengupta, Dipak L. (2006). "Wireless before Marconi".
2096:
1951:
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343:(cling together), they conduct electricity much better after being subjected to
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60:
980:
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1946:
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1404:
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349:
167:
40:
794:
One of the first coherers designed by Édouard Branly. Built by his assistant.
340:
64:
63:
signal is applied to the device, the metal particles would cling together or "
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2443:
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2011:
2006:
1996:
1981:
1803:
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559:
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the neighbourhood of the circuit, a large deviation was seen on the attached
130:
56:
1434:
461:
to prevent the RF signal power from leaking away through the relay circuit.
352:
circuit powered by a battery that created a "click" sound in earphones or a
196:
The Action of Electromagnetic Radiation on Films containing Metallic Powders
150:
On the Changes in Resistance of Bodies under Different Electrical Conditions
2321:
2161:
2106:
2036:
2001:
1936:
1835:
1825:
1677:
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in 1899. The device consisted of a small metallic cup containing a pool of
552:
321:
199:
154:
141:
288:
2521:
2171:
2081:
2066:
2026:
1986:
1845:
1282:
1028:
765:
424:, which was about half filled with sharply cut metal filings, often part
171:
1413:
645:
218:
The coherer was replaced in receivers by the simpler and more sensitive
2526:
2233:
1931:
1840:
1796:
1766:
1744:
1341:
Jagadish Chandra Bose: The Real Inventor of Marconi’s Wireless Receiver
325:
297:
1045:
2511:
1976:
1791:
1558:
1372:
829:
800:
734:
610:
433:
52:
1354:
1138:"The Development of the Coherer And Some Theories of Coherer Action"
788:
420:
The coherer used in practical receivers was a glass tube, sometimes
194:
Hertzian waves the same way his solar cell did and wrote the paper "
2506:
2496:
2413:
2238:
2061:
850:
512:
is received, the filings tend to cling to each other, reducing the
2501:
2486:
1704:
1174:. Directory of enterprises, companies and firms of St. Petersburg
1069:
508:, is also attached to the two electrodes. When the signal from a
136:
394:
2531:
2491:
1813:
777:
773:
464:
429:
425:
421:
324:
signal, "dots" and "dashes", that spelled out text messages in
92:'s 1890 paper and even before there was proof of the theory of
1399:. New York: Inst. of Electrical and Electronic Engineers: 64.
520:
supplies enough current through the coherer to activate relay
261:
The explanation is unclear and confusing, as critiqued by the
2516:
2453:
1761:
1480:
The Continuous Wave: Technology and American Radio, 1900-1932
820:
812:
301:
126:
721:
More important for the future, the coherer could not detect
2458:
981:
Faraday, Michael; Schoenbein, Christian Friedirich (1899).
600:
335:
The operation of the coherer is based on the phenomenon of
516:
of the coherer. When the coherer conducts better, battery
405:
189:
to shield the coherer from the RF noise from its contacts.
19:
596:
1168:"Русское общество беспроволочных телеграфов и телефонов"
1267:
1108:
1106:
1532:". The Century Magazine. April, 1898. Pages 867–874.
1530:, Recent experiments in telegraphy with sparks.
846:
320:) to produce different length pulses of unmodulated
148:In 1890, French physicist Édouard Branly published
1199:. London: Cambridge University Press. p. 11.
1131:
1129:
1103:
468:A radio receiver circuit using a coherer detector
381:across an imperfect junction between conductors.
2652:
1320:
1114:Wireless: From Marconi's Black-box to the Audion
1126:
607:In 1899, Bose announced the development of an "
198:". These papers were read by English physicist
181:Marconi's 1896 coherer receiver, at the Oxford
1013:
1574:
1458:(2). New York: The Review of Reviews Co.: 192
1352:
577:
257:needs attention from an expert in Electronics
140:Branly's electrical circuit tube filled with
1135:
2589:Global telecommunications regulation bodies
1009:
1007:
1005:
484:, in the left diagram) is connected to the
2625:
1581:
1567:
1513:". World of Wireless, Virtual radiomuseum.
1154:10.1038/scientificamerican10271917-268supp
764:around 1907, and then around 1912–1918 by
675:
316:), the transmitter was turned on and off (
1535:Hirakawa Institute of Technology(Japan),"
1412:
1281:
1027:
923:. London: Inst. of Electrical Engineers.
55:spaced a small distance apart with loose
1160:
1065:
1063:
1002:
916:
760:around 1902. These were replaced by the
684:, and other impulsive electrical noise:
599:; above the surface of the oil, a small
537:
472:. The "tapper" (decoherer) is not shown.
463:
287:
176:
135:
18:
1470:
1386:
1220:Findlay, David A. (September 1, 1957).
1219:
964:, Butterworth-Heinemann. pp. 2–3, 2–4.
835:Another tripod detector built by Branly
2653:
1588:
1483:. Princeton Univ. Press. p. 190.
1476:
1213:
985:. Williams & Norgate. p. 54.
271:may be able to help recruit an expert.
1562:
1445:
1439:
1222:"Radio Controlled Toys Use Spark Gap"
1060:
962:Electronics Engineer's Reference Book
35:was a primitive form of radio signal
2635:
1353:Bondyopadhyay, P.K. (January 1998).
640:
627:Detector for electrical disturbances
241:
166:proven to exist by German physicist
1192:
870:Electrical contact resistance (ECR)
13:
1452:American Monthly Review of Reviews
1446:Maver, William Jr. (August 1904).
1255:"Early Electromechanical Circuits"
1186:
910:
339:. Specifically as metal particles
226:around 1907, and became obsolete.
23:Metal filings coherer designed by
14:
2687:
1501:
619:, London. He also later received
2634:
2624:
2615:
2614:
2603:
2224:Free-space optical communication
1554:Coherer: history & operation
849:
828:
811:
799:
787:
718:paper tape machines at 100 WPM.
705:required a brilliant imagination
644:
404:
393:
246:
183:Museum of the History of Science
1379:
1346:
1333:
1314:
1270:The European Physical Journal B
1261:
1247:
733:transmitters, but it could not
609:iron-mercury-iron coherer with
1142:Scientific American Supplement
974:
954:
636:
615:" in a paper presented at the
384:
1:
947:
337:electrical contact resistance
67:", reducing the initial high
59:in the space between. When a
2610:Telecommunication portal
2391:Telecommunications equipment
1448:"Wireless Telegraphy To-Day"
1387:Douglas, Alan (April 1981).
917:Phillips, Vivian J. (1980).
496:. A series combination of a
237:
96:. In 1835 Swedish scientist
7:
2661:History of radio technology
2127:Alexander Stepanovich Popov
1522:". Marconi Calling Company.
1016:American Journal of Physics
842:
770:Fleming's oscillation valve
308:transmitted information by
259:. The specific problem is:
123:Temistocle Calzecchi-Onesti
10:
2692:
1831:Telecommunications history
1547:Tesla's US Patent: 613,809
1477:Aitken, Hugh G.J. (2014).
1405:10.1109/MSPEC.1981.6369482
1300:10.1140/epjb/e2004-00142-9
938:Cuff, Thomas Mark (1993).
920:Early Radio Wave Detectors
711:Greenleaf Whittier Pickard
578:Imperfect junction coherer
144:(later called a "coherer")
83:
2598:
2540:
2477:
2439:Public Switched Telephone
2399:
2363:
2320:
2261:
2251:telecommunication circuit
2212:Fiber-optic communication
2195:
1957:Francis Blake (telephone)
1904:
1752:Optical telecommunication
1596:
1148:. Munn and Company: 268.
629:" (1904), for a specific
524:, which connects battery
488:and the other electrode,
164:electromagnetic radiation
16:Early radio wave detector
2350:Orbital angular-momentum
1787:Satellite communications
1626:Communications satellite
568:automatic braking system
2229:Molecular communication
2052:Gardiner Greene Hubbard
1881:Undersea telegraph line
1616:Cable protection system
1360:Proceedings of the IEEE
1193:Lee, Thomas H. (2004).
1073:; Mailloux, Robert J.;
676:Limitations of coherers
591:covered by a very thin
269:WikiProject Electronics
2371:Communication protocol
2157:Charles Sumner Tainter
1972:Walter Houser Brattain
1917:Edwin Howard Armstrong
1725:Information revolution
1389:"The crystal detector"
1087:10.1002/0471783021.ch7
715:
701:
682:spark-gap transmitters
653:This section is empty.
543:
473:
293:
190:
145:
28:
2676:Electronic amplifiers
2345:Polarization-division
2077:Narinder Singh Kapany
2042:Erna Schneider Hoover
1962:Jagadish Chandra Bose
1942:Alexander Graham Bell
1673:online video platform
1507:Web archive backup: "
1235:(9). McGraw-Hill: 190
1136:Green, E. C. (1917).
1112:Hong, Sungook (2010)
960:Turner, L. W. (2013)
880:Spark-gap transmitter
768:technologies such as
754:electrolytic detector
702:
686:
541:
510:spark gap transmitter
467:
358:electrical resistance
291:
231:spark-gap transmitter
180:
139:
22:
2187:Vladimir K. Zworykin
2147:Almon Brown Strowger
2117:Charles Grafton Page
1772:Prepaid mobile phone
1700:Electrical telegraph
1081:. pp. 261–262.
895:Camille Papin Tissot
772:and Lee De Forest's
585:Jagdish Chandra Bose
106:Samuel Alfred Varley
2137:Johann Philipp Reis
1896:Wireless revolution
1858:The Telephone Cases
1715:Hydraulic telegraph
1292:2004EPJB...38..475F
1116:. MIT Press. p. 4.
1079:History of Wireless
1038:2005AmJPh..73..302F
940:Coherers, a review.
731:wireless telegraphy
622:U.S. patent 755,840
480:, of the coherer, (
310:wireless telegraphy
119:David Edward Hughes
45:wireless telegraphy
2335:Frequency-division
2312:Telephone exchange
2182:Charles Wheatstone
2112:Jun-ichi Nishizawa
2087:Innocenzo Manzetti
2022:Reginald Fessenden
1757:Optical telegraphy
1590:Telecommunications
1528:The New Telegraphy
1525:Slaby, Adolphus, "
1519:Coherer / Receiver
1435:Stay Tuned website
1172:www.companybest.ru
857:Electronics portal
758:Reginald Fessenden
750:hot wire barretter
544:
474:
306:radio transmitters
304:signal, the first
294:
191:
146:
114:lightning arrester
39:used in the first
29:
2666:Radio electronics
2648:
2647:
2386:Store and forward
2381:Data transmission
2295:Network switching
2246:Transmission line
2092:Guglielmo Marconi
2057:Internet pioneers
1922:Mohamed M. Atalla
1891:Whistled language
1550:". ShareAPic.net.
1339:Aggarwal, Varun
1075:Oliner, Arthur A.
1046:10.1119/1.1848114
741:the waveforms of
673:
672:
530:telegraph sounder
354:telegraph sounder
286:
285:
263:ElectroBOOM video
224:crystal detectors
213:Simeon Aisenstein
209:Guglielmo Marconi
98:Peter Samuel Munk
78:crystal detectors
25:Guglielmo Marconi
2683:
2638:
2637:
2628:
2627:
2618:
2617:
2608:
2607:
2606:
2479:Notable networks
2469:Wireless network
2409:Cellular network
2401:Types of network
2376:Computer network
2263:Network topology
2177:Thomas A. Watson
2032:Oliver Heaviside
2017:Philo Farnsworth
1992:Daniel Davis Jr.
1967:Charles Bourseul
1927:John Logie Baird
1636:Data compression
1631:Computer network
1583:
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1283:cond-mat/0311453
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1257:. February 2017.
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1071:Sarkar, Tapan K.
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1029:cond-mat/0407773
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978:
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865:Detector (radio)
859:
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762:crystal detector
713:
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655:You can help by
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110:lightning bridge
94:electromagnetism
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2097:Robert Metcalfe
1952:Tim Berners-Lee
1900:
1720:Information Age
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911:Further reading
905:Wetting voltage
900:Wetting current
855:
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756:, developed by
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697:Robert Marriott
695:
678:
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639:
631:electromagnetic
620:
580:
504:, and a relay,
476:One electrode,
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379:charge carriers
371:radio frequency
345:radio frequency
314:radiotelegraphy
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205:Alexander Popov
86:
61:radio frequency
41:radio receivers
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2167:Camille Tissot
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2142:Claude Shannon
2139:
2134:
2132:Tivadar Puskás
2129:
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2119:
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2102:Antonio Meucci
2099:
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2072:Charles K. Kao
2069:
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2047:Harold Hopkins
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2019:
2014:
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1502:External links
1500:
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1490:978-1400854608
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1367:(1): 259–285.
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1276:(3): 475–483.
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664:September 2015
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453:. The coils,
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284:
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277:September 2023
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170:(later called
168:Heinrich Hertz
102:Pierre Guitard
90:Édouard Branly
85:
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49:Édouard Branly
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2122:Radia Perlman
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2012:Lee de Forest
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2007:Thomas Edison
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1997:Donald Davies
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1804:Semiconductor
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890:Antique radio
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875:Crystal radio
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318:on-off keying
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255:This article
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160:George Forbes
156:
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134:
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131:Monterubbiano
128:
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115:
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107:
103:
99:
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81:
79:
75:
70:
66:
62:
58:
57:metal filings
54:
50:
46:
42:
38:
34:
26:
21:
2322:Multiplexing
2197:Transmission
2162:Nikola Tesla
2152:Henry Sutton
2107:Samuel Morse
2037:Robert Hooke
2002:Amos Dolbear
1937:John Bardeen
1856:
1836:Telautograph
1740:Mobile phone
1695:Edholm's law
1678:social media
1611:Broadcasting
1545:
1536:
1526:
1517:
1508:
1479:
1472:
1460:. Retrieved
1455:
1451:
1441:
1426:. Retrieved
1414:10366/158938
1396:
1392:
1381:
1364:
1358:
1348:
1335:
1316:
1273:
1269:
1263:
1249:
1239:November 11,
1237:. Retrieved
1232:
1228:
1215:
1195:
1188:
1178:27 September
1176:. Retrieved
1171:
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1145:
1141:
1113:
1078:
1019:
1015:
996:
982:
976:
961:
956:
919:
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716:
703:
689:
688:This device
687:
679:
661:
657:adding to it
652:
626:
608:
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565:
557:
548:
545:
532:
525:
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457:, act as RF
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367:
361:
334:
322:carrier wave
295:
274:
260:
256:
228:
220:electrolytic
217:
200:Oliver Lodge
195:
192:
186:
155:galvanometer
149:
147:
142:iron filings
87:
74:electrolytic
32:
30:
2522:NPL network
2234:Radio waves
2172:Alfred Vail
2082:Hedy Lamarr
2067:Dawon Kahng
2027:Elisha Gray
1987:Yogen Dalal
1912:Nasir Ahmed
1846:Teleprinter
1710:Heliographs
1510:The Coherer
1229:Electronics
766:vacuum tube
637:Anticoherer
385:Application
172:radio waves
43:during the
2655:Categories
2568:Antarctica
2527:Toasternet
2449:Television
1932:Paul Baran
1864:Television
1848:(teletype)
1841:Telegraphy
1819:transistor
1797:Phryctoria
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1735:Mass media
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1428:2010-03-14
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1874:streaming
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1343:. mit.edu
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432:. Silver
428:and part
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1423:44288637
1308:14855786
1054:19855739
843:See also
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694:—
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595:film of
330:detector
187:(center)
108:'s 1866
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2640:Commons
2630:Outline
2583:Oceania
2502:FidoNet
2487:ARPANET
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1869:digital
1598:History
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