187:
2111:
2121:
2100:
2131:
256:
296:(1948) shows the maximum distance for 1 kW over salt water to be 1,500 miles, and this distance was routinely covered by ships at sea, where signals from ships and nearby coastal stations would cause congestion, covering up distant and weaker signals. During the silence, a distress signal could more easily be heard at great distances.
179:. Most two-way radio contacts were to be initiated on this frequency, although once established, the participating stations could shift to another frequency to avoid the congestion on 500 kHz. To facilitate communication between operators speaking different languages, standardized abbreviations were used, including a set of "
248:
International refinements for the use of 500 kHz were specified in later agreements, including the 1932 Madrid Radio
Conference. In later years, except for distress traffic, stations shifted to nearby "working frequencies" to exchange messages once contact was established: 425, 454, 468, 480,
244:
are required, during the hours the station is in operation, to 'listen in' at intervals of not more than 15 minutes and for a period not less than 2 minutes, with the receiving apparatus tuned to receive this wave length, for the purpose of determining if any distress signals or messages
219:
Coastal stations engaged in the transmission of long radiograms shall suspend the transmission at the end of each period of 15 minutes, and remain silent for a period of three minutes before resuming the transmission. Coastal and shipboard stations working under the conditions specified in
170:
The
Service Regulations, affixed to the 1912 convention, established 500 kHz as the primary frequency for seagoing communication, and the standard ship frequency was changed from 1,000 kHz to 500 kHz, to match the coastal station standard. Communication was generally conducted in
274:
In addition, during this silent period all coastal and ship stations were required to monitor the frequency, listening for any distress signals. All large ships at sea had to monitor 500 kHz at all times, either with a licensed radio operator or with equipment (called an auto-alarm) that
214:
There was a potential problem if a ship transmitted a distress call: The use of 500 kHz as a common frequency often led to heavy congestion, especially around major ports and shipping lanes, and it was possible the distress message would be drowned out by the bedlam of ongoing commercial
83:
calls and medical emergencies at sea were handled via this frequency. However, as the use of Morse code over radio is now obsolete in commercial shipping, 500 kHz is obsolete as a Morse distress frequency. Beginning in the late 1990s, most nations ended monitoring of transmissions on
144:"Two wave lengths, one of 300 meters and the other of 600 meters, are authorized for general public service. Every coastal station opened to such service shall use one or the other of these two wave lengths."
331:
used by NAVTEX) and is therefore capable of much higher data throughput. This allows NAVDAT broadcasts to carry images and other data as well as plain text, further allowing this data to be presented directly on an
220:
Article XXXV, par. 2, shall suspend work at the end of each period of 15 minutes and listen in with a wave length of 600 meters during a period of 3 minutes before resuming the transmission.
292:
At night, transmission ranges of 3,000–4,000 miles (4,500–6,500 kilometers) were typical. Daytime ranges were much shorter, on the order of 300–1,500 miles (500–2,500 kilometers).
224:
During distress working all non-distress traffic was banned from 500 kHz and adjacent coast stations then monitored 512 kHz as an additional calling frequency for ordinary traffic.
252:
Twice each hour, all stations operating on 500 kHz were required to maintain a strictly enforced three-minute silent period, starting at 15 and 45 minutes past the hour.
267:
between h+15ᵐ to h+18ᵐ and h+45ᵐ to h+48ᵐ in RED. Similar sectors between h+00ᵐ to h+03ᵐ and h+30ᵐ to h+33ᵐ are marked in GREEN which is the corresponding silence period for the
563:"Characteristics of a digital system, named Navigational Data for broadcasting maritime safety and security related information from shore-to-ship in the 500 kHz band"
281:
140:
The second service regulation affixed to this
Convention designated 500 kHz as one of the standard frequencies to be employed by shore stations, specifying that
333:
289:
Shore stations throughout the world operated on this frequency to exchange messages with ships and to issue warning about weather and other navigational warnings.
157:
130:
2083:
2055:
2050:
1075:
573:
630:
245:
are being sent and to determine if the transmitting operations of the 'listening station' are causing interference with other radio communication."
545:
280:
679:
2077:
305:
232:
The silent and monitoring periods were soon expanded and standardized. For example, Regulation 44, from the 27 July 1914, edition of
110:
85:
2072:
2062:
2042:
1844:
569:
500:
473:
358:
919:
2067:
1913:
929:
309:
1839:
211:
distress call was heard, all transmissions unrelated to the emergency had to immediately cease until the emergency was declared over.
1933:
982:
790:
2165:
1718:
1266:
1068:
49:
279:
2155:
1829:
324:
1824:
1375:
72:
1849:
899:
2134:
2124:
1885:
1782:
1325:
1092:
780:
727:
402:
2114:
1621:
1061:
795:
672:
361:
472–479 kHz amateur allocation, most countries no longer using it have allocate frequencies near 500 kHz to
263:
As a visual memory aid, a typical clock in a ship's radio room would have the silence periods marked by shading the
1973:
1895:
1834:
1541:
987:
161:
167:. This meeting produced an agreement which was signed on 5 July 1912, and became effective 1 July 1913.
2160:
1745:
1706:
1551:
1451:
1380:
1313:
1140:
1012:
843:
805:
76:
562:
365:
use on a secondary basis, although the primary allocation of the band remains with the maritime mobile service.
2104:
1346:
1281:
1234:
1120:
1037:
853:
1943:
1928:
1772:
1723:
1646:
1546:
1224:
1110:
1105:
997:
747:
634:
249:
and 512 kHz were used by ships while the coast stations had their own individual working frequencies.
1865:
1651:
1466:
1411:
1406:
1219:
1184:
707:
665:
191:
1767:
1571:
1536:
1456:
1436:
1358:
1246:
1167:
742:
538:
176:
56:
maritime communication. For much of its early history, this frequency was referred to by its equivalent
186:
1681:
1641:
1611:
1368:
1303:
1194:
1007:
858:
722:
717:
603:
79:, once maintained 24 hour watches on this frequency, staffed by skilled radio operators. Many
2170:
1691:
1631:
1390:
1352:
1209:
1150:
1135:
1042:
889:
775:
712:
593:
215:
traffic. To help address this problem, the
Service Regulation's Article XXXII specified that
1918:
1875:
1806:
1676:
1606:
1581:
1516:
1363:
1084:
399: – a maritime weather and safety text broadcast on 518 kHz and 490 kHz
357:
Maritime traffic currently displaced from the 500 kHz band in most countries, and with the
308:
in 1999 and the subsequent obsolescence of 500 kHz as a Morse distress frequency, the 2019
1958:
1880:
1794:
1777:
1740:
1626:
1586:
1416:
1385:
1251:
1145:
949:
944:
909:
496:
490:
469:
463:
438:
433:
1963:
1923:
1903:
1870:
1799:
1757:
1671:
1526:
1511:
1486:
1461:
1421:
1271:
1130:
1125:
1115:
894:
428:
340:
319:
NAVDAT is intended for the broadcast of data from shore-to-ship and may thus be compared to
98:
65:
1591:
1446:
1214:
1177:
1027:
977:
650:
413:
264:
1189:
1789:
1661:
1636:
1596:
1566:
1441:
1276:
1162:
848:
391:
369:
352:
118:
96:
The 500 kHz frequency has now been allocated to the maritime
Navigational Data or
31:
2149:
1938:
1711:
1701:
1616:
1506:
1501:
1491:
1476:
1298:
1157:
863:
833:
702:
688:
407:
362:
114:
1816:
1656:
1601:
1531:
1496:
1431:
1330:
1320:
1172:
1002:
939:
838:
828:
195:
516:
2016:
1666:
1576:
1561:
1521:
1481:
1340:
1032:
1022:
1017:
156:
International standards for the use of 500 kHz were expanded by the second
137:, which was signed 3 November 1906, and became effective 1 July 1908.
129:
International standards for the use of 500 kHz first appeared in the first
2021:
1728:
1426:
1335:
1291:
1261:
1239:
1229:
1204:
172:
148:
These regulations also specified that ship stations normally used 1 MHz.
57:
53:
2006:
1471:
1286:
992:
336:. This presents a significant improvement over the text-only NAVTEX system.
84:
500 kHz and emergency traffic on 500 kHz has been replaced by the
38:
614:
275:
detected an automatically sent distress signal consisting of long dashes.
2001:
1991:
1908:
1733:
1556:
934:
879:
800:
381:
268:
105:
The nearby frequencies of 518 kHz and 490 kHz are used for the
30:
This article is about the maritime band. For the amateur radio band, see
368:
Full details of these allocations can be found under the article on the
117:
use resulted in the international allocation of 472–479 kHz to the
1996:
1981:
954:
785:
732:
255:
201:
Article XXI of the
Service Regulations required that whenever an
17:
2026:
1986:
1308:
1100:
1053:
959:
924:
810:
757:
752:
737:
622:
423:
396:
320:
180:
134:
106:
615:"Excellent first hand account of distress frequency communications"
2011:
1948:
1256:
418:
328:
277:
254:
185:
1953:
657:
1057:
661:
113:. Proposals to allocate frequencies at or near 500 kHz to
1199:
443:
205:
80:
339:
As of
February 2023, no maritime authorities have begun
384: – the international distress frequency for
44:
From early in the 20th century, the radio frequency of
410: – for emergency frequencies in current use
610:— (Includes the 1912 London Radiotelegraphic Convention)
544:. ITU World Radiocommunication Conference 2019 (WRC-19).
468:. Institution of Electrical Engineers. pp. 256 ff.
334:
Electronic Chart
Display and Information System (ECDIS)
37:"auto alarm" redirects here. For automobile alarm, see
64:, or, using the earlier frequency unit name, 500
236:, stated: "The international standard wave length is
71:
Maritime authorities of many nations, including the
2035:
1972:
1894:
1858:
1815:
1756:
1690:
1399:
1091:
968:
908:
872:
819:
766:
695:
572:. January 2019. ITU Recommendation ITU-R M.2010-1.
259:
Ship's radio room clock with silence periods marked
190:500 kHz transmitter and receiver position on
595:Berlin International Radiotelegraphic Convention
605:Radio Laws and Regulations of the United States
1069:
673:
234:Radio Communication Laws of the United States
183:" specified by the 1912 Service Regulations.
8:
527:. Vol. 4. Kalmbach Publishing Co. 1954.
50:international calling and distress frequency
2084:Global telecommunications regulation bodies
492:The Worldwide History of Telecommunications
2120:
1076:
1062:
1054:
680:
666:
658:
495:. John Wiley & Sons. pp. 358 ff.
623:"International Telecommunication Union"
454:
271:voice communications distress signals.
240: meters, and the operators of all
158:International Radiotelegraph Convention
131:International Radiotelegraph Convention
86:Global Maritime Distress Safety System
570:International Telecommunication Union
160:, which was held in London after the
121:, now implemented in many countries.
7:
2130:
579:from the original on 7 January 2022.
489:Huurdeman, Anton A. (31 July 2003).
310:World Radiocommunication Conference
294:Terman's Radio Engineering Handbook
27:Maritime radio frequency at 500 kHz
551:from the original on 8 April 2020.
429:Medium frequency radio propagation
25:
791:Common traffic advisory frequency
2129:
2119:
2110:
2109:
2098:
1719:Free-space optical communication
316:to the maritime NAVDAT service.
651:"Merchant Shipping Regulations"
462:Beauchamp, Ken (January 2001).
631:"Marine and Coastguard Agency"
73:Maritime and Coastguard Agency
1:
900:Maritime mobile amateur radio
68:(per second) or 500 kc.
2105:Telecommunication portal
1886:Telecommunications equipment
1043:Voting (diversity combining)
781:Aircraft emergency frequency
728:General Mobile Radio Service
403:Aircraft emergency frequency
285:Simulated auto-alarm signal.
119:630-meter amateur radio band
1622:Alexander Stepanovich Popov
796:Mandatory frequency airport
2187:
1326:Telecommunications history
988:Automatic vehicle location
608:. Govt. print. off. 1914 .
598:. Govt. print. off. 1907 .
350:
304:Following the adoption of
36:
29:
2093:
1934:Public Switched Telephone
1746:telecommunication circuit
1707:Fiber-optic communication
1452:Francis Blake (telephone)
1247:Optical telecommunication
1013:Dynamic range compression
930:Dual-tone multi-frequency
844:Professional mobile radio
806:Single Frequency Approach
77:United States Coast Guard
1845:Orbital angular-momentum
1282:Satellite communications
1121:Communications satellite
1038:Radiotelephony procedure
854:Specialized Mobile Radio
519:[no title cited]
2166:Emergency communication
1724:Molecular communication
1547:Gardiner Greene Hubbard
1376:Undersea telegraph line
1111:Cable protection system
748:Multi-Use Radio Service
323:. However, NAVDAT uses
2156:Maritime communication
1866:Communication protocol
1652:Charles Sumner Tainter
1467:Walter Houser Brattain
1412:Edwin Howard Armstrong
1220:Information revolution
820:Land-based commercial
708:Amateur radio repeater
388:maritime communication
327:(in comparison to the
286:
260:
198:
194:, a World War II
177:spark-gap transmitters
48:(500 kHz) was an
1840:Polarization-division
1572:Narinder Singh Kapany
1537:Erna Schneider Hoover
1457:Jagadish Chandra Bose
1437:Alexander Graham Bell
1168:online video platform
822:and government mobile
769:(aeronautical mobile)
465:History of Telegraphy
372:amateur radio band.
284:
258:
189:
1682:Vladimir K. Zworykin
1642:Almon Brown Strowger
1612:Charles Grafton Page
1267:Prepaid mobile phone
1195:Electrical telegraph
859:Trunked radio system
723:Public Radio Service
718:Family Radio Service
696:Amateur and hobbyist
637:on 27 September 2007
1632:Johann Philipp Reis
1391:Wireless revolution
1353:The Telephone Cases
1210:Hydraulic telegraph
890:Coast radio station
776:Air traffic control
713:Citizens band radio
312:(WRC-19) allocated
192:SS Jeremiah O'Brien
162:sinking of the RMS
1830:Frequency-division
1807:Telephone exchange
1677:Charles Wheatstone
1607:Jun-ichi Nishizawa
1582:Innocenzo Manzetti
1517:Reginald Fessenden
1252:Optical telegraphy
1085:Telecommunications
873:Marine (shipboard)
758:UHF CB (Australia)
287:
261:
199:
175:, initially using
102:broadcast system.
46:500 kilohertz
2143:
2142:
1881:Store and forward
1876:Data transmission
1790:Network switching
1741:Transmission line
1587:Guglielmo Marconi
1552:Internet pioneers
1417:Mohamed M. Atalla
1386:Whistled language
1051:
1050:
912:Selective calling
525:Ships and the Sea
502:978-0-471-20505-0
475:978-0-85296-792-8
439:Radio propagation
434:Radio Act of 1912
282:
152:Expanded policies
16:(Redirected from
2178:
2161:History of radio
2133:
2132:
2123:
2122:
2113:
2112:
2103:
2102:
2101:
1974:Notable networks
1964:Wireless network
1904:Cellular network
1896:Types of network
1871:Computer network
1758:Network topology
1672:Thomas A. Watson
1527:Oliver Heaviside
1512:Philo Farnsworth
1487:Daniel Davis Jr.
1462:Charles Bourseul
1422:John Logie Baird
1131:Data compression
1126:Computer network
1078:
1071:
1064:
1055:
969:System elements
895:Marine VHF radio
682:
675:
668:
659:
654:
646:
644:
642:
633:. Archived from
626:
618:
609:
599:
581:
580:
578:
567:
559:
553:
552:
550:
543:
535:
529:
528:
520:
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479:
459:
315:
283:
210:
209:
208:
125:Initial adoption
21:
2186:
2185:
2181:
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2179:
2177:
2176:
2175:
2146:
2145:
2144:
2139:
2099:
2097:
2089:
2031:
1968:
1890:
1854:
1811:
1760:
1752:
1693:
1686:
1592:Robert Metcalfe
1447:Tim Berners-Lee
1395:
1215:Information Age
1087:
1082:
1052:
1047:
1028:Rayleigh fading
970:
964:
911:
904:
868:
821:
815:
768:
762:
691:
686:
649:
640:
638:
629:
621:
613:
602:
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541:
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532:
518:
515:
514:
510:
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488:
487:
483:
476:
461:
460:
456:
452:
414:Distress signal
378:
355:
349:
313:
302:
278:
230:
204:
203:
202:
154:
127:
94:
62:600 meters
42:
35:
28:
23:
22:
15:
12:
11:
5:
2184:
2182:
2174:
2173:
2168:
2163:
2158:
2148:
2147:
2141:
2140:
2138:
2137:
2127:
2117:
2107:
2094:
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2080:
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2065:
2060:
2059:
2058:
2053:
2045:
2039:
2037:
2033:
2032:
2030:
2029:
2024:
2019:
2014:
2009:
2004:
1999:
1994:
1989:
1984:
1978:
1976:
1970:
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1967:
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1961:
1956:
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1941:
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1926:
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1825:Space-division
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1698:
1696:
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1662:Camille Tissot
1659:
1654:
1649:
1644:
1639:
1637:Claude Shannon
1634:
1629:
1627:Tivadar Puskás
1624:
1619:
1614:
1609:
1604:
1599:
1597:Antonio Meucci
1594:
1589:
1584:
1579:
1574:
1569:
1567:Charles K. Kao
1564:
1559:
1554:
1549:
1544:
1542:Harold Hopkins
1539:
1534:
1529:
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1519:
1514:
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1504:
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1442:Emile Berliner
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1429:
1424:
1419:
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1403:
1401:
1397:
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1393:
1388:
1383:
1381:Videotelephony
1378:
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1277:Radiotelephone
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1165:
1163:Internet video
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1138:
1128:
1123:
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1113:
1108:
1103:
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1089:
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1080:
1073:
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1049:
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1020:
1015:
1010:
1005:
1000:
995:
990:
985:
980:
974:
972:
971:and principles
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869:
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851:
849:Radio repeater
846:
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823:
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619:
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600:
588:
587:External links
585:
583:
582:
568:. Geneva, CH:
554:
530:
508:
501:
481:
474:
453:
451:
448:
447:
446:
441:
436:
431:
426:
421:
416:
411:
405:
400:
394:
392:630-meter band
389:
377:
374:
353:630-meter band
348:
345:
325:QAM modulation
301:
298:
242:coast stations
229:
228:Later policies
226:
222:
221:
153:
150:
146:
145:
126:
123:
93:
92:Current status
90:
32:630-meter band
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2183:
2172:
2169:
2167:
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2054:
2052:
2049:
2048:
2046:
2044:
2041:
2040:
2038:
2034:
2028:
2025:
2023:
2020:
2018:
2015:
2013:
2010:
2008:
2005:
2003:
2000:
1998:
1995:
1993:
1990:
1988:
1985:
1983:
1980:
1979:
1977:
1975:
1971:
1965:
1962:
1960:
1957:
1955:
1952:
1950:
1947:
1945:
1942:
1940:
1937:
1935:
1932:
1930:
1927:
1925:
1922:
1920:
1917:
1915:
1912:
1910:
1907:
1905:
1902:
1901:
1899:
1897:
1893:
1887:
1884:
1882:
1879:
1877:
1874:
1872:
1869:
1867:
1864:
1863:
1861:
1857:
1851:
1850:Code-division
1848:
1846:
1843:
1841:
1838:
1836:
1835:Time-division
1833:
1831:
1828:
1826:
1823:
1822:
1820:
1818:
1814:
1808:
1805:
1801:
1798:
1796:
1793:
1792:
1791:
1788:
1784:
1781:
1780:
1779:
1776:
1774:
1771:
1769:
1766:
1765:
1763:
1761:and switching
1759:
1755:
1747:
1744:
1743:
1742:
1739:
1735:
1732:
1731:
1730:
1727:
1725:
1722:
1720:
1717:
1713:
1712:optical fiber
1710:
1709:
1708:
1705:
1703:
1702:Coaxial cable
1700:
1699:
1697:
1695:
1689:
1683:
1680:
1678:
1675:
1673:
1670:
1668:
1665:
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1660:
1658:
1655:
1653:
1650:
1648:
1645:
1643:
1640:
1638:
1635:
1633:
1630:
1628:
1625:
1623:
1620:
1618:
1617:Radia Perlman
1615:
1613:
1610:
1608:
1605:
1603:
1600:
1598:
1595:
1593:
1590:
1588:
1585:
1583:
1580:
1578:
1575:
1573:
1570:
1568:
1565:
1563:
1560:
1558:
1555:
1553:
1550:
1548:
1545:
1543:
1540:
1538:
1535:
1533:
1530:
1528:
1525:
1523:
1520:
1518:
1515:
1513:
1510:
1508:
1507:Lee de Forest
1505:
1503:
1502:Thomas Edison
1500:
1498:
1495:
1493:
1492:Donald Davies
1490:
1488:
1485:
1483:
1480:
1478:
1477:Claude Chappe
1475:
1473:
1470:
1468:
1465:
1463:
1460:
1458:
1455:
1453:
1450:
1448:
1445:
1443:
1440:
1438:
1435:
1433:
1430:
1428:
1425:
1423:
1420:
1418:
1415:
1413:
1410:
1408:
1405:
1404:
1402:
1398:
1392:
1389:
1387:
1384:
1382:
1379:
1377:
1374:
1370:
1367:
1365:
1362:
1361:
1360:
1357:
1355:
1354:
1350:
1348:
1345:
1342:
1339:
1337:
1334:
1332:
1329:
1327:
1324:
1322:
1321:Smoke signals
1319:
1315:
1312:
1310:
1307:
1305:
1302:
1301:
1300:
1299:Semiconductor
1297:
1293:
1290:
1289:
1288:
1285:
1283:
1280:
1278:
1275:
1273:
1270:
1268:
1265:
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1260:
1258:
1255:
1253:
1250:
1248:
1245:
1241:
1238:
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1233:
1231:
1228:
1226:
1223:
1221:
1218:
1216:
1213:
1211:
1208:
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1203:
1201:
1198:
1196:
1193:
1191:
1188:
1186:
1183:
1179:
1176:
1174:
1171:
1169:
1166:
1164:
1161:
1160:
1159:
1158:Digital media
1156:
1152:
1149:
1147:
1144:
1142:
1139:
1137:
1134:
1133:
1132:
1129:
1127:
1124:
1122:
1119:
1117:
1114:
1112:
1109:
1107:
1104:
1102:
1099:
1098:
1096:
1094:
1090:
1086:
1079:
1074:
1072:
1067:
1065:
1060:
1059:
1056:
1044:
1041:
1039:
1036:
1034:
1031:
1029:
1026:
1024:
1021:
1019:
1016:
1014:
1011:
1009:
1006:
1004:
1001:
999:
996:
994:
991:
989:
986:
984:
981:
979:
976:
975:
973:
967:
961:
958:
956:
953:
951:
948:
946:
943:
941:
938:
936:
933:
931:
928:
926:
923:
921:
918:
917:
915:
913:
907:
901:
898:
896:
893:
891:
888:
886:
883:
881:
878:
877:
875:
871:
865:
864:Walkie-talkie
862:
860:
857:
855:
852:
850:
847:
845:
842:
840:
837:
835:
834:Business band
832:
830:
827:
826:
824:
818:
812:
809:
807:
804:
802:
799:
797:
794:
792:
789:
787:
784:
782:
779:
777:
774:
773:
771:
765:
759:
756:
754:
751:
749:
746:
744:
741:
739:
736:
734:
731:
729:
726:
724:
721:
719:
716:
714:
711:
709:
706:
704:
703:Amateur radio
701:
700:
698:
694:
690:
689:Two-way radio
683:
678:
676:
671:
669:
664:
663:
660:
652:
648:
636:
632:
628:
624:
620:
616:
612:
607:
606:
601:
597:
596:
591:
590:
586:
575:
571:
564:
558:
555:
547:
540:
534:
531:
526:
522:
512:
509:
504:
498:
494:
493:
485:
482:
477:
471:
467:
466:
458:
455:
449:
445:
442:
440:
437:
435:
432:
430:
427:
425:
422:
420:
417:
415:
412:
409:
408:Call for help
406:
404:
401:
398:
395:
393:
390:
387:
383:
382:2182 kHz
380:
379:
375:
373:
371:
366:
364:
363:amateur radio
360:
354:
347:Amateur radio
346:
344:
342:
337:
335:
330:
326:
322:
317:
311:
307:
299:
297:
295:
290:
276:
272:
270:
269:2182 kHz
266:
257:
253:
250:
246:
243:
239:
235:
227:
225:
218:
217:
216:
212:
207:
197:
193:
188:
184:
182:
178:
174:
168:
166:
165:
159:
151:
149:
143:
142:
141:
138:
136:
132:
124:
122:
120:
116:
115:amateur radio
112:
109:component of
108:
103:
101:
100:
91:
89:
87:
82:
78:
74:
69:
67:
63:
59:
55:
51:
47:
40:
33:
19:
1817:Multiplexing
1692:Transmission
1657:Nikola Tesla
1647:Henry Sutton
1602:Samuel Morse
1532:Robert Hooke
1497:Amos Dolbear
1432:John Bardeen
1351:
1331:Telautograph
1235:Mobile phone
1190:Edholm's law
1173:social media
1106:Broadcasting
950:Quik-Call II
940:Push-to-talk
910:Signaling /
884:
839:Mobile radio
829:Base station
639:. Retrieved
635:the original
604:
594:
557:
539:"Final Acts"
533:
524:
511:
491:
484:
464:
457:
385:
367:
356:
343:broadcasts.
338:
318:
314:500 ± 5 kHz
303:
293:
291:
288:
273:
262:
251:
247:
241:
237:
233:
231:
223:
213:
200:
196:Liberty ship
169:
163:
155:
147:
139:
128:
104:
97:
95:
70:
61:
45:
43:
2017:NPL network
1729:Radio waves
1667:Alfred Vail
1577:Hedy Lamarr
1562:Dawon Kahng
1522:Elisha Gray
1482:Yogen Dalal
1407:Nasir Ahmed
1341:Teleprinter
1205:Heliographs
1033:Tone remote
1023:Link budget
1018:Fade margin
945:Quik-Call I
2171:Morse code
2150:Categories
2063:Antarctica
2022:Toasternet
1944:Television
1427:Paul Baran
1359:Television
1343:(teletype)
1336:Telegraphy
1314:transistor
1292:Phryctoria
1262:Photophone
1240:Smartphone
1230:Mass media
743:Mobile rig
450:References
351:See also:
173:Morse code
66:kilocycles
58:wavelength
54:Morse code
2047:Americas
2036:Locations
2007:Internet2
1768:Bandwidth
1472:Vint Cerf
1369:streaming
1347:Telephone
1287:Semaphore
1178:streaming
1003:DC remote
993:Call sign
767:Aviation
370:630 metre
88:(GMDSS).
39:car alarm
2115:Category
2002:Internet
1992:CYCLADES
1909:Ethernet
1859:Concepts
1783:terminal
1734:wireless
1557:Bob Kahn
1400:Pioneers
1225:Internet
1116:Cable TV
1008:Dispatch
935:MDC-1200
880:2182 kHz
801:MULTICOM
574:Archived
546:Archived
376:See also
75:and the
2135:Commons
2125:Outline
2078:Oceania
1997:FidoNet
1982:ARPANET
1795:circuit
1364:digital
1093:History
978:Antenna
955:Selcall
885:500 kHz
786:Airband
733:KDR 444
641:3 March
265:sectors
181:Q codes
164:Titanic
2073:Europe
2043:Africa
2027:Usenet
1987:BITNET
1924:Mobile
1800:packet
1309:MOSFET
1304:device
1101:Beacon
960:SELCAL
925:D-STAR
811:UNICOM
753:PMR446
738:LPD433
499:
472:
424:Mayday
397:Navtex
341:NAVDAT
321:NAVTEX
300:NAVDAT
135:Berlin
107:NAVTEX
99:NAVDAT
18:500kHz
2056:South
2051:North
2012:JANET
1949:Telex
1939:Radio
1778:Nodes
1773:Links
1694:media
1272:Radio
1257:Pager
1185:Drums
1151:video
1146:image
1136:audio
920:CTCSS
577:(PDF)
566:(PDF)
549:(PDF)
542:(PDF)
419:GMDSS
386:voice
329:SITOR
306:GMDSS
111:GMDSS
2068:Asia
1954:UUCP
1914:ISDN
983:APRS
643:2007
497:ISBN
470:ISBN
52:for
1959:WAN
1929:NGN
1919:LAN
1200:Fax
1141:DCT
998:CAD
444:SOS
359:ITU
238:600
206:SOS
133:in
81:SOS
2152::
523:.
60:,
2086:)
2082:(
1077:e
1070:t
1063:v
681:e
674:t
667:v
653:.
645:.
625:.
617:.
521:"
517:"
505:.
478:.
41:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
