178:
535:
642:
285:
2586:
826:
797:
391:
847:
2596:
244:
2575:
137:
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.
2606:
461:
809:
559:
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.
785:
116:
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
938:
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
578:
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
558:
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
713:
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
360:
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
700:
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
599:
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
229:
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
542:
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:
432:
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.
402:
364:
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
1296:
343:
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
814:
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
531:, 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.
436:
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
600:
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
369:
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
939:
examined the similarities among coherers and electrolytic RF detectors, MOM (Metal-Oxide-Metal) 'diodes' used in laser heterodyning, and the STM (Scanning
Tunneling Microscope).
324:. 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
1488:
445:
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,
410:
The coherer as developed by
Marconi consisted of metal filings (dots) enclosed between two slanted electrodes (black) a few millimeters apart, connected to terminals.
356:
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
1850:
97:
1325:"Sir J. C. Bose's Diode Detector Received Marconi's First Transatlantic Wireless Signal of December 1901 (The "Italian Navy Coherer" Scandal Revisited)"
687:
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:
547:. 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.
570:
ahead of the train were occupied the oscillations were interrupted and the coherer, acting through a relay, showed a warning and applied the brakes.
744:
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:
802:
A "ball" coherer, designed by Branly in 1899. This imperfect contact type had a series of lightly touching metal balls set between two electrodes.
566:
for rail locomotives, patented in 1907, used a coherer to detect electrical oscillations in a continuous aerial running along the track. If the
2558:
2530:
2525:
1550:
158:
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
914:
1310:
225:
One minor use of the coherer in modern times was by Japanese tin-plate toy manufacturer Matsudaya Toy Co. who beginning 1957 used a
1448:
993:
Peter Samuel Munk af Rosenschold lecture assistant in Chemistry at the University of Lund was born at Lund in 1804 and died in 1860
1479:
2552:
1010:
Falcon, Eric; Castaing, Bernard (2005). "Electrical conductivity in granular media and Branly's coherer: A simple experiment".
721:(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
931:. A comprehensive description of radio detectors up to the development of the vacuum tube, with many unusual types of coherer.
2547:
2537:
2517:
2319:
177:
2630:
100:
noticed a change of resistance in a mixture of metal filings in the presence of spark discharge from a Leyden jar. In 1850
1684:
2609:
2542:
2388:
1523:
1191:
185:, UK. The coherer is on right, with the decoherer mechanism behind it. The relay is in the cylindrical metal container
2314:
1458:
1117:
676:
Because they are threshold voltage detectors, coherers had difficulty discriminating between the impulsive signals of
538:
A coherer with electromagnet-operated "tapper" (decoherer), built by early radio researcher Emile Guarini around 1904.
2408:
1090:
986:
965:
264:
1507:
2193:
1741:
1543:
182:
2304:
563:
207:
built a "Hertzian wave" (radio wave) based lightning detector using a coherer. That same year, Italian inventor
2645:
2299:
1174:
1164:
924:
361:
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
2324:
1497:
1238:
Falcon, E.; Castaing, B.; Creyssels, M. (2004). "Nonlinear electrical conductivity in a 1D granular medium".
865:
332:
125:
in Italy began studying the anomalous change in the resistance of thin metallic films and metal particles at
1358:
979:
The letters of Faraday and Schoenbein 1836-1862: With notes, comments and references to contemporary letters
328:. The coherer was the most successful of many detector devices that were tried in the early days of radio.
2599:
2360:
2257:
1800:
1595:
1567:
258:
2589:
2096:
1536:
204:
122:
2635:
2448:
2370:
2309:
2016:
935:
706:
292:
Unlike modern AM radio stations that transmit a continuous radio frequency, whose amplitude (power) is
1516:
2220:
2181:
2026:
1926:
1855:
1788:
1615:
1291:
626:
554:
In later practical receivers the decoherer was a clapper similar to an electric bell, operated by an
163:
159:
1224:
2579:
1821:
1756:
1709:
1669:
68:
288:
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder.
2418:
2403:
2247:
2198:
2121:
2021:
1699:
1585:
1580:
1329:
567:
352:, or a mark on a paper tape, to record the signal. Unfortunately, the reduction in the coherer's
2340:
2126:
1941:
1886:
1881:
1694:
1659:
1149:
1417:
1133:
652:
2242:
2046:
2011:
1931:
1911:
1833:
1721:
1642:
875:
749:
677:
588:
509:
505:
493:
353:
226:
215:
73:
1575:
211:
demonstrated a wireless telegraphy system using Hertzian waves (radio), based on a coherer.
2156:
2116:
2086:
1843:
1778:
1600:
1257:
1029:
890:
718:
580:
489:
105:
1294:, Frank Wyatt Prentice, "Electric Signaling System", published 5 February 1907
8:
2166:
2106:
1865:
1827:
1625:
1610:
726:
454:
305:
118:
44:
1261:
1033:
551:, for example, invented a coherer in which the tube rotated continually along its axis.
534:
2640:
2393:
2350:
2281:
2151:
2081:
2056:
1991:
1838:
1559:
1388:
1273:
1247:
1045:
1019:
852:
753:
745:
692:
579:
by Marconi for the first transatlantic radio message. An earlier form was invented by
370:
113:
2433:
2355:
2269:
2252:
2215:
2061:
1891:
1860:
1726:
1620:
1454:
1170:
1113:
1086:
982:
961:
920:
819:) detectors, because Branly reported it could produce a DC current without a battery.
584:
525:
349:
301:
208:
24:
2101:
1392:
1277:
1166:
Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits
1049:
89:
48:
2438:
2398:
2378:
2345:
2274:
2232:
2146:
2001:
1986:
1961:
1936:
1896:
1746:
1605:
1590:
1378:
1370:
1338:
1265:
1145:
1078:
1070:
1037:
880:
860:
757:
325:
219:
93:
77:
36:
1073:; Salazar-Palma, Magdalena; Sengupta, Dipak L. (2006). "Wireless before Marconi".
2066:
1921:
1689:
1664:
1652:
1269:
900:
895:
738:
481:
366:
340:
339:(cling together), they conduct electricity much better after being subjected to
309:
60:
976:
2264:
2136:
2111:
2071:
2041:
1916:
1751:
1704:
1679:
1637:
1374:
741:
374:
345:
167:
40:
790:
One of the first coherers designed by Édouard Branly. Built by his assistant.
336:
64:
63:
signal is applied to the device, the metal particles would cling together or "
2624:
2413:
2186:
2176:
2091:
1981:
1976:
1966:
1951:
1773:
1632:
885:
870:
765:
722:
617:
612:
555:
313:
153:
the neighbourhood of the circuit, a large deviation was seen on the attached
130:
56:
1404:
457:
to prevent the RF signal power from leaking away through the relay circuit.
348:
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
2291:
2131:
2076:
2006:
1971:
1906:
1805:
1795:
1647:
1082:
1066:
734:
583:
in 1899. The device consisted of a small metallic cup containing a pool of
548:
317:
199:
154:
141:
284:
2491:
2141:
2051:
2036:
1996:
1956:
1815:
1252:
1024:
761:
420:, which was about half filled with sharply cut metal filings, often part
171:
1383:
641:
214:
The coherer was replaced in receivers by the simpler and more sensitive
2496:
2203:
1901:
1810:
1766:
1736:
1714:
1311:
Jagadish Chandra Bose: The Real Inventor of Marconi’s Wireless Receiver
321:
293:
1041:
2481:
1946:
1761:
1528:
1342:
825:
796:
730:
606:
429:
52:
1324:
1134:"The Development of the Coherer And Some Theories of Coherer Action"
784:
416:
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 "
2476:
2466:
2383:
2208:
2031:
846:
508:
is received, the filings tend to cling to each other, reducing the
2471:
2456:
1674:
1065:
504:, is also attached to the two electrodes. When the signal from a
136:
390:
2501:
2461:
1783:
773:
769:
460:
425:
421:
417:
320:
signal, "dots" and "dashes", that spelled out text messages in
92:'s 1890 paper and even before there was proof of the theory of
1369:. New York: Inst. of Electrical and Electronic Engineers: 64.
516:
supplies enough current through the coherer to activate relay
257:
The explanation is unclear and confusing, as critiqued by the
2486:
2423:
1731:
1450:
The Continuous Wave: Technology and American Radio, 1900-1932
816:
808:
297:
126:
717:
More important for the future, the coherer could not detect
2428:
977:
Faraday, Michael; Schoenbein, Christian Friedirich (1899).
596:
331:
The operation of the coherer is based on the phenomenon of
512:
of the coherer. When the coherer conducts better, battery
401:
189:
to shield the coherer from the RF noise from its contacts.
19:
592:
1237:
1104:
1102:
1502:". The Century Magazine. April, 1898. Pages 867–874.
1500:, Recent experiments in telegraphy with sparks.
842:
316:) to produce different length pulses of unmodulated
148:In 1890, French physicist Édouard Branly published
1169:. London: Cambridge University Press. p. 11.
1127:
1125:
1099:
464:A radio receiver circuit using a coherer detector
377:across an imperfect junction between conductors.
2622:
1290:
1110:Wireless: From Marconi's Black-box to the Audion
1122:
603: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
1009:
1544:
1428:(2). New York: The Review of Reviews Co.: 192
1322:
573:
253:needs attention from an expert in Electronics
140:Branly's electrical circuit tube filled with
1131:
2559:Global telecommunications regulation bodies
1005:
1003:
1001:
480:, in the left diagram) is connected to the
2595:
1551:
1537:
1483:". World of Wireless, Virtual radiomuseum.
1150:10.1038/scientificamerican10271917-268supp
760:around 1907, and then around 1912–1918 by
671:
312:), the transmitter was turned on and off (
1505:Hirakawa Institute of Technology(Japan),"
1382:
1251:
1023:
919:. London: Inst. of Electrical Engineers.
55:spaced a small distance apart with loose
1061:
1059:
998:
912:
756:around 1902. These were replaced by the
680:, and other impulsive electrical noise:
595:; above the surface of the oil, a small
533:
468:. The "tapper" (decoherer) is not shown.
459:
283:
176:
135:
18:
1440:
1356:
1190:Findlay, David A. (September 1, 1957).
1189:
960:, Butterworth-Heinemann. pp. 2–3, 2–4.
831:Another tripod detector built by Branly
2623:
1558:
1453:. Princeton Univ. Press. p. 190.
1446:
1183:
981:. Williams & Norgate. p. 54.
267:may be able to help recruit an expert.
1532:
1415:
1409:
1192:"Radio Controlled Toys Use Spark Gap"
1056:
958:Electronics Engineer's Reference Book
35:was a primitive form of radio signal
2605:
1323:Bondyopadhyay, P.K. (January 1998).
636:
623:Detector for electrical disturbances
237:
166:proven to exist by German physicist
1162:
866:Electrical contact resistance (ECR)
13:
1422:American Monthly Review of Reviews
1416:Maver, William Jr. (August 1904).
1225:"Early Electromechanical Circuits"
1156:
906:
335:. Specifically as metal particles
222:around 1907, and became obsolete.
23:Metal filings coherer designed by
14:
2657:
1471:
615:, London. He also later received
2604:
2594:
2585:
2584:
2573:
2194:Free-space optical communication
1524:Coherer: history & operation
845:
824:
807:
795:
783:
714:paper tape machines at 100 WPM.
701:required a brilliant imagination
640:
400:
389:
242:
183:Museum of the History of Science
1349:
1316:
1303:
1284:
1240:The European Physical Journal B
1231:
729:transmitters, but it could not
605:iron-mercury-iron coherer with
1217:
1138:Scientific American Supplement
970:
950:
632:
611:" in a paper presented at the
380:
1:
943:
333:electrical contact resistance
67:", reducing the initial high
59:in the space between. When a
2580:Telecommunication portal
2361:Telecommunications equipment
1418:"Wireless Telegraphy To-Day"
1357:Douglas, Alan (April 1981).
913:Phillips, Vivian J. (1980).
492:. A series combination of a
233:
96:. In 1835 Swedish scientist
7:
2631:History of radio technology
2097:Alexander Stepanovich Popov
1492:". Marconi Calling Company.
1012:American Journal of Physics
838:
766:Fleming's oscillation valve
304:transmitted information by
255:. The specific problem is:
123:Temistocle Calzecchi-Onesti
10:
2662:
1801:Telecommunications history
1517:Tesla's US Patent: 613,809
1447:Aitken, Hugh G.J. (2014).
1375:10.1109/MSPEC.1981.6369482
1270:10.1140/epjb/e2004-00142-9
934:Cuff, Thomas Mark (1993).
916:Early Radio Wave Detectors
707:Greenleaf Whittier Pickard
574:Imperfect junction coherer
144:(later called a "coherer")
83:
2568:
2510:
2447:
2409:Public Switched Telephone
2369:
2333:
2290:
2231:
2221:telecommunication circuit
2182:Fiber-optic communication
2165:
1927:Francis Blake (telephone)
1874:
1722:Optical telecommunication
1566:
1144:. Munn and Company: 268.
625:" (1904), for a specific
520:, which connects battery
484:and the other electrode,
164:electromagnetic radiation
16:Early radio wave detector
2320:Orbital angular-momentum
1757:Satellite communications
1596:Communications satellite
564:automatic braking system
2199:Molecular communication
2022:Gardiner Greene Hubbard
1851:Undersea telegraph line
1586:Cable protection system
1330:Proceedings of the IEEE
1163:Lee, Thomas H. (2004).
1069:; Mailloux, Robert J.;
672:Limitations of coherers
587:covered by a very thin
265:WikiProject Electronics
2341:Communication protocol
2127:Charles Sumner Tainter
1942:Walter Houser Brattain
1887:Edwin Howard Armstrong
1695:Information revolution
1359:"The crystal detector"
1083:10.1002/0471783021.ch7
711:
697:
678:spark-gap transmitters
649:This section is empty.
539:
469:
289:
190:
145:
28:
2646:Electronic amplifiers
2315:Polarization-division
2047:Narinder Singh Kapany
2012:Erna Schneider Hoover
1932:Jagadish Chandra Bose
1912:Alexander Graham Bell
1643:online video platform
1477:Web archive backup: "
1205:(9). McGraw-Hill: 190
1132:Green, E. C. (1917).
1108:Hong, Sungook (2010)
956:Turner, L. W. (2013)
876:Spark-gap transmitter
764:technologies such as
750:electrolytic detector
698:
682:
537:
506:spark gap transmitter
463:
354:electrical resistance
287:
227:spark-gap transmitter
180:
139:
22:
2157:Vladimir K. Zworykin
2117:Almon Brown Strowger
2087:Charles Grafton Page
1742:Prepaid mobile phone
1670:Electrical telegraph
1077:. pp. 261–262.
891:Camille Papin Tissot
768:and Lee De Forest's
581:Jagdish Chandra Bose
106:Samuel Alfred Varley
2107:Johann Philipp Reis
1866:Wireless revolution
1828:The Telephone Cases
1685:Hydraulic telegraph
1262:2004EPJB...38..475F
1112:. MIT Press. p. 4.
1075:History of Wireless
1034:2005AmJPh..73..302F
936:Coherers, a review.
727:wireless telegraphy
618:U.S. patent 755,840
476:, of the coherer, (
306:wireless telegraphy
119:David Edward Hughes
45:wireless telegraphy
2305:Frequency-division
2282:Telephone exchange
2152:Charles Wheatstone
2082:Jun-ichi Nishizawa
2057:Innocenzo Manzetti
1992:Reginald Fessenden
1727:Optical telegraphy
1560:Telecommunications
1498:The New Telegraphy
1495:Slaby, Adolphus, "
1489:Coherer / Receiver
1405:Stay Tuned website
853:Electronics portal
754:Reginald Fessenden
746:hot wire barretter
540:
470:
302:radio transmitters
300:signal, the first
290:
191:
146:
114:lightning arrester
39:used in the first
29:
2636:Radio electronics
2618:
2617:
2356:Store and forward
2351:Data transmission
2265:Network switching
2216:Transmission line
2062:Guglielmo Marconi
2027:Internet pioneers
1892:Mohamed M. Atalla
1861:Whistled language
1520:". ShareAPic.net.
1309:Aggarwal, Varun
1071:Oliner, Arthur A.
1042:10.1119/1.1848114
737:the waveforms of
669:
668:
526:telegraph sounder
350:telegraph sounder
282:
281:
259:ElectroBOOM video
220:crystal detectors
209:Guglielmo Marconi
98:Peter Samuel Munk
78:crystal detectors
25:Guglielmo Marconi
2653:
2608:
2607:
2598:
2597:
2588:
2587:
2578:
2577:
2576:
2449:Notable networks
2439:Wireless network
2379:Cellular network
2371:Types of network
2346:Computer network
2233:Network topology
2147:Thomas A. Watson
2002:Oliver Heaviside
1987:Philo Farnsworth
1962:Daniel Davis Jr.
1937:Charles Bourseul
1897:John Logie Baird
1606:Data compression
1601:Computer network
1553:
1546:
1539:
1530:
1529:
1465:
1464:
1444:
1438:
1437:
1435:
1433:
1413:
1407:
1402:
1400:
1399:
1386:
1353:
1347:
1346:
1343:10.1109/5.658778
1320:
1314:
1307:
1301:
1300:
1299:
1295:
1288:
1282:
1281:
1255:
1253:cond-mat/0311453
1235:
1229:
1228:
1227:. February 2017.
1221:
1215:
1214:
1212:
1210:
1196:
1187:
1181:
1180:
1160:
1154:
1153:
1129:
1120:
1106:
1097:
1096:
1067:Sarkar, Tapan K.
1063:
1054:
1053:
1027:
1025:cond-mat/0407773
1007:
996:
995:
974:
968:
954:
930:
861:Detector (radio)
855:
850:
849:
828:
811:
799:
787:
758:crystal detector
709:
695:
664:
661:
651:You can help by
644:
637:
620:
404:
393:
277:
274:
268:
246:
245:
238:
110:lightning bridge
94:electromagnetism
2661:
2660:
2656:
2655:
2654:
2652:
2651:
2650:
2621:
2620:
2619:
2614:
2574:
2572:
2564:
2506:
2443:
2365:
2329:
2286:
2235:
2227:
2168:
2161:
2067:Robert Metcalfe
1922:Tim Berners-Lee
1870:
1690:Information Age
1562:
1557:
1474:
1469:
1468:
1461:
1445:
1441:
1431:
1429:
1414:
1410:
1397:
1395:
1354:
1350:
1321:
1317:
1308:
1304:
1297:
1289:
1285:
1236:
1232:
1223:
1222:
1218:
1208:
1206:
1194:
1188:
1184:
1177:
1161:
1157:
1130:
1123:
1107:
1100:
1093:
1064:
1057:
1008:
999:
989:
975:
971:
955:
951:
946:
927:
909:
907:Further reading
901:Wetting voltage
896:Wetting current
851:
844:
841:
836:
835:
834:
833:
832:
829:
821:
820:
812:
804:
803:
800:
792:
791:
788:
752:, developed by
710:
705:
696:
693:Robert Marriott
691:
674:
665:
659:
656:
635:
627:electromagnetic
616:
576:
500:, and a relay,
472:One electrode,
414:
413:
412:
411:
407:
406:
405:
396:
395:
394:
383:
375:charge carriers
367:radio frequency
341:radio frequency
310:radiotelegraphy
278:
272:
269:
263:
247:
243:
236:
205:Alexander Popov
86:
61:radio frequency
41:radio receivers
17:
12:
11:
5:
2659:
2649:
2648:
2643:
2638:
2633:
2616:
2615:
2613:
2612:
2602:
2592:
2582:
2569:
2566:
2565:
2563:
2562:
2555:
2550:
2545:
2540:
2535:
2534:
2533:
2528:
2520:
2514:
2512:
2508:
2507:
2505:
2504:
2499:
2494:
2489:
2484:
2479:
2474:
2469:
2464:
2459:
2453:
2451:
2445:
2444:
2442:
2441:
2436:
2431:
2426:
2421:
2416:
2411:
2406:
2401:
2396:
2391:
2386:
2381:
2375:
2373:
2367:
2366:
2364:
2363:
2358:
2353:
2348:
2343:
2337:
2335:
2331:
2330:
2328:
2327:
2322:
2317:
2312:
2307:
2302:
2300:Space-division
2296:
2294:
2288:
2287:
2285:
2284:
2279:
2278:
2277:
2272:
2262:
2261:
2260:
2250:
2245:
2239:
2237:
2229:
2228:
2226:
2225:
2224:
2223:
2213:
2212:
2211:
2201:
2196:
2191:
2190:
2189:
2179:
2173:
2171:
2163:
2162:
2160:
2159:
2154:
2149:
2144:
2139:
2137:Camille Tissot
2134:
2129:
2124:
2119:
2114:
2112:Claude Shannon
2109:
2104:
2102:Tivadar Puskás
2099:
2094:
2089:
2084:
2079:
2074:
2072:Antonio Meucci
2069:
2064:
2059:
2054:
2049:
2044:
2042:Charles K. Kao
2039:
2034:
2029:
2024:
2019:
2017:Harold Hopkins
2014:
2009:
2004:
1999:
1994:
1989:
1984:
1979:
1974:
1969:
1964:
1959:
1954:
1949:
1944:
1939:
1934:
1929:
1924:
1919:
1917:Emile Berliner
1914:
1909:
1904:
1899:
1894:
1889:
1884:
1878:
1876:
1872:
1871:
1869:
1868:
1863:
1858:
1856:Videotelephony
1853:
1848:
1847:
1846:
1841:
1831:
1824:
1819:
1813:
1808:
1803:
1798:
1793:
1792:
1791:
1786:
1781:
1771:
1770:
1769:
1759:
1754:
1752:Radiotelephone
1749:
1744:
1739:
1734:
1729:
1724:
1719:
1718:
1717:
1707:
1702:
1697:
1692:
1687:
1682:
1677:
1672:
1667:
1662:
1657:
1656:
1655:
1650:
1645:
1640:
1638:Internet video
1630:
1629:
1628:
1623:
1618:
1613:
1603:
1598:
1593:
1588:
1583:
1578:
1572:
1570:
1564:
1563:
1556:
1555:
1548:
1541:
1533:
1527:
1526:
1521:
1512:
1503:
1493:
1484:
1473:
1472:External links
1470:
1467:
1466:
1460:978-1400854608
1459:
1439:
1408:
1348:
1337:(1): 259–285.
1315:
1302:
1283:
1246:(3): 475–483.
1230:
1216:
1182:
1175:
1155:
1121:
1118:978-0262514194
1098:
1091:
1055:
1018:(4): 302–307.
997:
987:
969:
948:
947:
945:
942:
941:
940:
932:
925:
908:
905:
904:
903:
898:
893:
888:
883:
881:Radio receiver
878:
873:
868:
863:
857:
856:
840:
837:
830:
823:
822:
813:
806:
805:
801:
794:
793:
789:
782:
781:
780:
779:
778:
742:radiotelephone
703:
689:
673:
670:
667:
666:
660:September 2015
647:
645:
634:
631:
575:
572:
449:. The coils,
409:
408:
399:
398:
397:
388:
387:
386:
385:
384:
382:
379:
280:
279:
273:September 2023
250:
248:
241:
235:
232:
170:(later called
168:Heinrich Hertz
102:Pierre Guitard
90:Édouard Branly
85:
82:
49:Édouard Branly
15:
9:
6:
4:
3:
2:
2658:
2647:
2644:
2642:
2639:
2637:
2634:
2632:
2629:
2628:
2626:
2611:
2603:
2601:
2593:
2591:
2583:
2581:
2571:
2570:
2567:
2560:
2556:
2554:
2551:
2549:
2546:
2544:
2541:
2539:
2536:
2532:
2529:
2527:
2524:
2523:
2521:
2519:
2516:
2515:
2513:
2509:
2503:
2500:
2498:
2495:
2493:
2490:
2488:
2485:
2483:
2480:
2478:
2475:
2473:
2470:
2468:
2465:
2463:
2460:
2458:
2455:
2454:
2452:
2450:
2446:
2440:
2437:
2435:
2432:
2430:
2427:
2425:
2422:
2420:
2417:
2415:
2412:
2410:
2407:
2405:
2402:
2400:
2397:
2395:
2392:
2390:
2387:
2385:
2382:
2380:
2377:
2376:
2374:
2372:
2368:
2362:
2359:
2357:
2354:
2352:
2349:
2347:
2344:
2342:
2339:
2338:
2336:
2332:
2326:
2325:Code-division
2323:
2321:
2318:
2316:
2313:
2311:
2310:Time-division
2308:
2306:
2303:
2301:
2298:
2297:
2295:
2293:
2289:
2283:
2280:
2276:
2273:
2271:
2268:
2267:
2266:
2263:
2259:
2256:
2255:
2254:
2251:
2249:
2246:
2244:
2241:
2240:
2238:
2236:and switching
2234:
2230:
2222:
2219:
2218:
2217:
2214:
2210:
2207:
2206:
2205:
2202:
2200:
2197:
2195:
2192:
2188:
2187:optical fiber
2185:
2184:
2183:
2180:
2178:
2177:Coaxial cable
2175:
2174:
2172:
2170:
2164:
2158:
2155:
2153:
2150:
2148:
2145:
2143:
2140:
2138:
2135:
2133:
2130:
2128:
2125:
2123:
2120:
2118:
2115:
2113:
2110:
2108:
2105:
2103:
2100:
2098:
2095:
2093:
2092:Radia Perlman
2090:
2088:
2085:
2083:
2080:
2078:
2075:
2073:
2070:
2068:
2065:
2063:
2060:
2058:
2055:
2053:
2050:
2048:
2045:
2043:
2040:
2038:
2035:
2033:
2030:
2028:
2025:
2023:
2020:
2018:
2015:
2013:
2010:
2008:
2005:
2003:
2000:
1998:
1995:
1993:
1990:
1988:
1985:
1983:
1982:Lee de Forest
1980:
1978:
1977:Thomas Edison
1975:
1973:
1970:
1968:
1967:Donald Davies
1965:
1963:
1960:
1958:
1955:
1953:
1952:Claude Chappe
1950:
1948:
1945:
1943:
1940:
1938:
1935:
1933:
1930:
1928:
1925:
1923:
1920:
1918:
1915:
1913:
1910:
1908:
1905:
1903:
1900:
1898:
1895:
1893:
1890:
1888:
1885:
1883:
1880:
1879:
1877:
1873:
1867:
1864:
1862:
1859:
1857:
1854:
1852:
1849:
1845:
1842:
1840:
1837:
1836:
1835:
1832:
1830:
1829:
1825:
1823:
1820:
1817:
1814:
1812:
1809:
1807:
1804:
1802:
1799:
1797:
1796:Smoke signals
1794:
1790:
1787:
1785:
1782:
1780:
1777:
1776:
1775:
1774:Semiconductor
1772:
1768:
1765:
1764:
1763:
1760:
1758:
1755:
1753:
1750:
1748:
1745:
1743:
1740:
1738:
1735:
1733:
1730:
1728:
1725:
1723:
1720:
1716:
1713:
1712:
1711:
1708:
1706:
1703:
1701:
1698:
1696:
1693:
1691:
1688:
1686:
1683:
1681:
1678:
1676:
1673:
1671:
1668:
1666:
1663:
1661:
1658:
1654:
1651:
1649:
1646:
1644:
1641:
1639:
1636:
1635:
1634:
1633:Digital media
1631:
1627:
1624:
1622:
1619:
1617:
1614:
1612:
1609:
1608:
1607:
1604:
1602:
1599:
1597:
1594:
1592:
1589:
1587:
1584:
1582:
1579:
1577:
1574:
1573:
1571:
1569:
1565:
1561:
1554:
1549:
1547:
1542:
1540:
1535:
1534:
1531:
1525:
1522:
1519:
1518:
1513:
1510:
1509:
1504:
1501:
1499:
1494:
1491:
1490:
1485:
1482:
1481:
1476:
1475:
1462:
1456:
1452:
1451:
1443:
1427:
1423:
1419:
1412:
1406:
1394:
1390:
1385:
1380:
1376:
1372:
1368:
1364:
1363:IEEE Spectrum
1360:
1352:
1344:
1340:
1336:
1332:
1331:
1326:
1319:
1312:
1306:
1293:
1287:
1279:
1275:
1271:
1267:
1263:
1259:
1254:
1249:
1245:
1241:
1234:
1226:
1220:
1204:
1200:
1193:
1186:
1178:
1172:
1168:
1167:
1159:
1151:
1147:
1143:
1139:
1135:
1128:
1126:
1119:
1115:
1111:
1105:
1103:
1094:
1092:9780471783022
1088:
1084:
1080:
1076:
1072:
1068:
1062:
1060:
1051:
1047:
1043:
1039:
1035:
1031:
1026:
1021:
1017:
1013:
1006:
1004:
1002:
994:
990:
988:9783744688895
984:
980:
973:
967:
966:9780408001687
963:
959:
953:
949:
937:
933:
928:
922:
918:
917:
911:
910:
902:
899:
897:
894:
892:
889:
887:
886:Antique radio
884:
882:
879:
877:
874:
872:
871:Crystal radio
869:
867:
864:
862:
859:
858:
854:
848:
843:
827:
818:
810:
798:
786:
777:
775:
771:
767:
763:
759:
755:
751:
747:
743:
740:
736:
732:
728:
724:
723:on-off keying
720:
715:
708:
702:
694:
688:
686:
681:
679:
663:
654:
650:
646:
643:
639:
638:
630:
628:
624:
619:
614:
613:Royal Society
610:
608:
601:
598:
594:
590:
586:
582:
571:
569:
565:
560:
557:
556:electromagnet
552:
550:
546:
536:
532:
530:
527:
523:
519:
515:
511:
507:
503:
499:
495:
491:
487:
483:
479:
475:
467:
462:
458:
456:
452:
448:
444:
440:
434:
431:
427:
423:
419:
403:
392:
378:
376:
372:
368:
362:
359:
355:
351:
347:
342:
338:
334:
329:
327:
323:
319:
315:
314:on-off keying
311:
307:
303:
299:
295:
286:
276:
266:
262:
260:
254:
251:This article
249:
240:
239:
231:
228:
223:
221:
217:
212:
210:
206:
201:
197:
188:
184:
179:
175:
173:
169:
165:
161:
160:George Forbes
156:
151:
143:
138:
134:
132:
131:Monterubbiano
128:
124:
120:
115:
111:
107:
103:
99:
95:
91:
81:
79:
75:
70:
66:
62:
58:
57:metal filings
54:
50:
46:
42:
38:
34:
26:
21:
2292:Multiplexing
2167:Transmission
2132:Nikola Tesla
2122:Henry Sutton
2077:Samuel Morse
2007:Robert Hooke
1972:Amos Dolbear
1907:John Bardeen
1826:
1806:Telautograph
1710:Mobile phone
1665:Edholm's law
1648:social media
1581:Broadcasting
1515:
1506:
1496:
1487:
1478:
1449:
1442:
1430:. Retrieved
1425:
1421:
1411:
1396:. Retrieved
1384:10366/158938
1366:
1362:
1351:
1334:
1328:
1318:
1305:
1286:
1243:
1239:
1233:
1219:
1209:November 11,
1207:. Retrieved
1202:
1198:
1185:
1165:
1158:
1141:
1137:
1109:
1074:
1015:
1011:
992:
978:
972:
957:
952:
915:
716:
712:
699:
685:
684:This device
683:
675:
657:
653:adding to it
648:
622:
604:
602:
577:
561:
553:
544:
541:
528:
521:
517:
513:
501:
497:
485:
477:
473:
471:
465:
453:, act as RF
450:
446:
442:
438:
435:
415:
363:
357:
330:
318:carrier wave
291:
270:
256:
252:
224:
216:electrolytic
213:
200:Oliver Lodge
195:
192:
186:
155:galvanometer
149:
147:
142:iron filings
87:
74:electrolytic
32:
30:
2492:NPL network
2204:Radio waves
2142:Alfred Vail
2052:Hedy Lamarr
2037:Dawon Kahng
1997:Elisha Gray
1957:Yogen Dalal
1882:Nasir Ahmed
1816:Teleprinter
1680:Heliographs
1480:The Coherer
1199:Electronics
762:vacuum tube
633:Anticoherer
381:Application
172:radio waves
43:during the
2625:Categories
2538:Antarctica
2497:Toasternet
2419:Television
1902:Paul Baran
1834:Television
1818:(teletype)
1811:Telegraphy
1789:transistor
1767:Phryctoria
1737:Photophone
1715:Smartphone
1705:Mass media
1432:January 2,
1398:2010-03-14
1355:quoted in
1176:0521835267
944:References
926:0906048249
735:demodulate
629:receiver.
589:insulating
510:resistance
441:and relay
430:electrodes
322:Morse code
230:popular).
117:scientist
69:resistance
53:electrodes
2641:Detectors
2522:Americas
2511:Locations
2482:Internet2
2243:Bandwidth
1947:Vint Cerf
1844:streaming
1822:Telephone
1762:Semaphore
1653:streaming
1313:. mit.edu
1292:US 843550
607:telephone
545:decoherer
428:. Silver
424:and part
418:evacuated
371:tunneling
358:decoherer
294:modulated
234:Operation
2590:Category
2477:Internet
2467:CYCLADES
2384:Ethernet
2334:Concepts
2258:terminal
2209:wireless
2032:Bob Kahn
1875:Pioneers
1700:Internet
1591:Cable TV
1393:44288637
1278:14855786
1050:19855739
839:See also
776:) tube.
704:—
690:—
609:detector
591:film of
326:detector
187:(center)
108:'s 1866
37:detector
2610:Commons
2600:Outline
2553:Oceania
2472:FidoNet
2457:ARPANET
2270:circuit
1839:digital
1568:History
1508:Coherer
1258:Bibcode
1030:Bibcode
731:rectify
585:mercury
524:to the
494:battery
482:antenna
84:History
33:coherer
2548:Europe
2518:Africa
2502:Usenet
2462:BITNET
2399:Mobile
2275:packet
1784:MOSFET
1779:device
1576:Beacon
1457:
1391:
1298:
1276:
1173:
1116:
1089:
1048:
985:
964:
923:
774:triode
770:Audion
490:ground
455:chokes
426:nickel
422:silver
337:cohere
296:by an
65:cohere
2531:South
2526:North
2487:JANET
2424:Telex
2414:Radio
2253:Nodes
2248:Links
2169:media
1747:Radio
1732:Pager
1660:Drums
1626:video
1621:image
1611:audio
1389:S2CID
1274:S2CID
1248:arXiv
1195:(PDF)
1046:S2CID
1020:arXiv
817:diode
568:block
549:Tesla
488:, to
298:audio
127:Fermo
2543:Asia
2429:UUCP
2389:ISDN
1455:ISBN
1434:2016
1211:2015
1171:ISBN
1114:ISBN
1087:ISBN
983:ISBN
962:ISBN
921:ISBN
748:and
733:nor
597:iron
218:and
112:, a
76:and
31:The
2434:WAN
2404:NGN
2394:LAN
1675:Fax
1616:DCT
1403:on
1379:hdl
1371:doi
1339:doi
1266:doi
1146:doi
1079:doi
1038:doi
725:of
655:.
621:, "
593:oil
562:An
466:(C)
373:of
174:).
2627::
1511:".
1426:30
1424:.
1420:.
1387:.
1377:.
1367:18
1365:.
1361:.
1335:86
1333:.
1327:.
1272:.
1264:.
1256:.
1244:38
1242:.
1203:30
1201:.
1197:.
1142:84
1140:.
1136:.
1124:^
1101:^
1085:.
1058:^
1044:.
1036:.
1028:.
1016:73
1014:.
1000:^
991:.
739:AM
719:AM
522:B2
514:B1
498:B1
496:,
439:B1
346:DC
80:.
27:.
2561:)
2557:(
1552:e
1545:t
1538:v
1514:"
1486:"
1463:.
1436:.
1401:.
1381::
1373::
1345:.
1341::
1280:.
1268::
1260::
1250::
1213:.
1179:.
1152:.
1148::
1095:.
1081::
1052:.
1040::
1032::
1022::
929:.
815:(
772:(
662:)
658:(
529:S
518:R
502:R
486:B
478:C
474:A
451:L
447:S
443:R
308:(
275:)
271:(
261:.
129:/
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
