579:) of a damped wave and its bandwidth; the longer the damped waves take to decay toward zero, the narrower the frequency band the radio signal occupies, so the less it interferes with other transmissions. As more transmitters began crowding the radio spectrum, reducing the frequency spacing between transmissions, government regulations began to limit the maximum damping or "decrement" a radio transmitter could have. Manufacturers produced spark transmitters which generated long "ringing" waves with minimal damping.
136:
1731:
25:
801:
812:
to transmit speech, and so CW radio telegraphy was the only form of communication available. CW still remains a viable form of radio communication many years after voice transmission was perfected, because simple, robust transmitters can be used, and because its signals are the simplest of the forms
896:
for the return; examples include police speed radars and microwave-type motion detectors and automatic door openers. This type of radar is effectively "blinded" by its own transmitted signal to stationary targets; they must move toward or away from the radar quickly enough to create a
Doppler shift
817:
able to penetrate interference. The low bandwidth of the code signal, due in part to low information transmission rate, allows very selective filters to be used in the receiver, which block out much of the radio noise that would otherwise reduce the intelligibility of the signal.
595:. An unbroken continuous sine wave theoretically has no bandwidth; all its energy is concentrated at a single frequency, so it doesn't interfere with transmissions on other frequencies. Continuous waves could not be produced with an electric spark, but were achieved with the
784:. The noise occurs in the part of the signal bandwidth further above and below the carrier than required for normal, less abrupt switching. The solution to the problem for CW is to make the transition between on and off to be more gradual, making the edges of pulses
912:) their transmitters rapidly enough to avoid self-interference with returns from objects beyond some minimum distance; this kind of radar can detect and range static targets. This approach is commonly used in
856:
in wires, sound, or light, for example. For radio signals, a carrier wave is keyed on and off to represent the dots and dashes of the code elements. The carrier's amplitude and frequency remain
662:
will be large; if the carrier turns on and off more gradually, the bandwidth will be smaller. The bandwidth of an on-off keyed signal is related to the data transmission rate as:
1187:
868:) to change the radio frequency impulses to sound. Almost all commercial traffic has now ceased operation using Morse, but it is still used by amateur radio operators.
696:
575:
This motivated efforts to produce radio frequency oscillations that decayed more slowly; had less damping. There is an inverse relation between the rate of decay (the
723:
418:
628:
Damped wave spark transmitters were replaced by continuous wave vacuum tube transmitters around 1920, and damped wave transmissions were finally outlawed in 1934.
852:
the terms "CW" and "Morse code" are often used interchangeably, despite the distinctions between the two. Aside from radio signals, Morse code may be sent using
767:
743:
382:
1110:
1691:
769:
is a constant related to the expected radio propagation conditions; K=1 is difficult for a human ear to decode, K=3 or K=5 is used when fading or
651:, so a "continuous wave" radiotelegraphy signal consists of pulses of sine waves with a constant amplitude interspersed with gaps of no signal.
1246:
1081:
411:
327:
1387:
1382:
1370:
1365:
1350:
1210:
1165:
1143:
486:
306:
108:
1430:
935:
use physically separate transmit and receive antennas to lessen the self-interference problems inherent in monostatic CW radars.
200:
42:
1755:
387:
301:
273:
240:
215:
167:
89:
1600:
1181:
404:
46:
61:
833:. However, instead of controlling the electricity in a cross-country wire, the switch controlled the power sent to a radio
659:
561:
569:
565:
897:
sufficient to allow the radar to isolate the outbound and return signal frequencies. This kind of CW radar can measure
655:
68:
1656:
884:
Morse code is all but extinct outside the amateur service, so in non-amateur contexts the term CW usually refers to a
205:
1460:
357:
177:
1284:
1195:
1024:
975:
873:
865:
230:
75:
1330:
1239:
1049:
367:
250:
1325:
615:
264:
57:
35:
1765:
1760:
1630:
1450:
1397:
1102:
869:
377:
372:
210:
195:
1518:
995:
991:
885:
842:
770:
599:
545:
523:
460:
362:
296:
1625:
1508:
1496:
1423:
1320:
1269:
1019:
909:
468:
444:
220:
157:
152:
1676:
1595:
1535:
1455:
1360:
1232:
967:
925:
921:
556:. The disadvantage of damped waves was that their energy was spread over an extremely wide band of
544:
to produce radio-frequency oscillations in the transmitting antenna. The signals produced by these
514:
245:
792:). Certain types of power amplifiers used in transmission may aggravate the effect of key clicks.
517:
radio transmission, CW waves were also known as "undamped waves", to distinguish this method from
1770:
1375:
1003:
987:
951:
that produces a continuous output beam, sometimes referred to as "free-running," as opposed to a
607:
278:
255:
235:
1274:
225:
892:
transmit and receive a single (non-swept) frequency, often using the transmitted signal as the
1696:
1570:
1545:
1161:
1139:
1073:
1039:
857:
665:
647:
to produce the different length pulses, "dots" and "dashes", that spell out text messages in
82:
1706:
1671:
1651:
1620:
893:
889:
789:
352:
347:
172:
162:
701:
135:
1734:
1615:
1416:
1191:
1007:
913:
822:
603:
588:
287:
1711:
1701:
1661:
1610:
1528:
1481:
1465:
983:
956:
932:
853:
804:
A commercially manufactured paddle for use with electronic keyer to generate Morse code
752:
728:
643:
In order to transmit information, the continuous wave must be turned off and on with a
1749:
1666:
1646:
1587:
1513:
1034:
979:
944:
849:
838:
644:
637:
576:
506:
1686:
1555:
1550:
1491:
1158:
We were burning : Japanese entrepreneurs and the forging of the electronic age
971:
490:
472:
392:
332:
311:
1206:
1219:
1716:
1577:
1560:
1540:
1294:
1029:
960:
917:
902:
834:
777:
619:
611:
596:
553:
518:
502:
24:
860:
during each code element. At the receiver, the received signal is mixed with a
1565:
1392:
1289:
1255:
952:
898:
861:
830:
814:
809:
648:
622:
510:
186:
143:
127:
654:
In on-off carrier keying, if the carrier wave is turned on or off abruptly,
1681:
1523:
1503:
1486:
826:
800:
557:
541:
456:
452:
448:
337:
1224:
1054:
999:
549:
124:
990:, commercialized by Japanese entrepreneurs, and opened up the field of
572:) that spread over the transmissions of stations at other frequencies.
1340:
1335:
1044:
552:
radio frequency oscillations which died out rapidly to zero, called
788:, appearing more rounded, or to use other modulation methods (e.g.
1439:
948:
636:"Key click" redirects here. For the sound of a Hammond organ, see
483:
464:
342:
463:
is considered to be of infinite duration. It may refer to e.g. a
1135:
998:. Optical communication in turn provided the hardware basis for
746:
1412:
1228:
876:
used in air navigation use Morse to transmit their identifier.
1315:
1310:
18:
1132:
The ARRL Handbook for Radio
Amateurs, Sixty Eighth Edition
888:
system, as opposed to one transmitting short pulses. Some
1408:
614:, transmitters capable of producing continuous wave, the
591:
communication would be a sine wave with zero damping, a
1183:
A History of
Engineering and Science in the Bell System
947:
and engineering, "continuous wave" or "CW" refers to a
780:
which abruptly switches a carrier on and off is called
493:
is switched on and off. This is more precisely called
908:
Other CW radars linearly or pseudo-randomly "chirp" (
755:
731:
704:
668:
829:, it worked by means of a simple switch to transmit
1639:
1586:
1474:
1349:
1303:
1262:
49:. Unsourced material may be challenged and removed.
1207:The Third Industrial Revolution Occurred in Sendai
761:
737:
717:
690:
974:in 1970. It led directly to the light sources in
745:is the keying rate in signal changes per second (
841:operators due to its narrow bandwidth and high
587:It was realized that the ideal radio wave for
1424:
1240:
920:and in oceanic and atmospheric research. The
412:
8:
471:having a continuous output, as opposed to a
1002:technology, laying the foundations for the
1431:
1417:
1409:
1247:
1233:
1225:
845:compared to other modes of communication.
505:is carried in the varying duration of the
419:
405:
120:
16:An electromagnetic wave that is not pulsed
754:
730:
709:
703:
673:
667:
109:Learn how and when to remove this message
1209:, Soh-VEHE International Patent Office,
799:
548:consisted of strings of brief pulses of
1692:Multiple-prism grating laser oscillator
1065:
963:laser, which has a pulsed output beam.
319:
286:
263:
185:
142:
123:
1130:L. D. Wolfgang, C. L. Hutchinson (ed)
994:, playing an important role in future
837:. This mode is still in common use by
808:Early radio transmitters could not be
1160:. New York: BasicBooks. p. 252.
890:monostatic (single antenna) CW radars
874:VHF omnidirectional radio range (VOR)
725:is the necessary bandwidth in hertz,
540:Very early radio transmitters used a
7:
638:Hammond organ § Tone generation
47:adding citations to reliable sources
970:was invented by Japanese physicist
1211:Japan Patent Attorneys Association
482:also refers to an early method of
14:
821:Continuous-wave radio was called
1730:
1729:
776:The spurious noise emitted by a
134:
23:
1113:from the original on 2023-04-10
1084:from the original on 2021-09-22
848:In military communications and
796:Persistence of radio telegraphy
34:needs additional citations for
1601:Amplified spontaneous emission
928:combined both CW radar types.
564:. As a result, they produced
509:of the signal, for example by
1:
1103:"Interrupted continuous wave"
870:Non-directional beacons (NDB)
566:electromagnetic interference
521:signals produced by earlier
1657:Chirped pulse amplification
625:, became widely available.
495:interrupted continuous wave
1787:
1461:List of laser applications
1196:AT&T Bell Laboratories
635:
602:, invented around 1913 by
328:Capacity-approaching codes
1725:
1446:
1285:Modulated continuous wave
976:fiber-optic communication
866:beat frequency oscillator
513:in early radio. In early
1331:Morse code abbreviations
1256:International Morse code
1050:Types of radio emissions
691:{\displaystyle B_{n}=BK}
1326:Prosigns for Morse code
1156:Johnstone, Bob (2000).
616:Alexanderson alternator
536:Transmissions before CW
478:By extension, the term
265:Hierarchical modulation
1756:Radio modulation modes
1451:List of laser articles
1398:Chinese telegraph code
1220:CW Bandwidth Described
1025:The CW Operators' Club
996:communication networks
805:
763:
739:
719:
692:
546:spark-gap transmitters
489:in which a sinusoidal
1351:Other writing systems
992:optical communication
886:continuous-wave radar
843:signal-to-noise ratio
803:
771:multipath propagation
764:
740:
720:
718:{\displaystyle B_{n}}
693:
656:communications theory
600:electronic oscillator
461:mathematical analysis
1626:Population inversion
1321:Morse code mnemonics
1270:Electrical telegraph
1263:Transmission methods
1020:Amplitude modulation
966:The continuous wave
753:
729:
702:
666:
469:particle accelerator
445:electromagnetic wave
43:improve this article
1677:Laser beam profiler
1596:Active laser medium
1536:Free-electron laser
1456:List of laser types
1361:American Morse code
1180:S. Millman (1983),
1107:The Free Dictionary
1078:The Free Dictionary
988:optical disc drives
968:semiconductor laser
926:Apollo Lunar Module
864:signal from a BFO (
527:type transmitters.
515:wireless telegraphy
437:continuous waveform
1190:2017-10-26 at the
1004:Digital Revolution
910:frequency modulate
806:
759:
735:
715:
688:
658:can show that the
608:Alexander Meissner
507:on and off periods
187:Digital modulation
1743:
1742:
1697:Optical amplifier
1546:Solid-state laser
1406:
1405:
1146:, pages 9-8, 9-9
1074:"Continuous wave"
1040:Periodic function
825:because like the
762:{\displaystyle K}
738:{\displaystyle B}
429:
428:
144:Analog modulation
119:
118:
111:
93:
58:"Continuous wave"
1778:
1733:
1732:
1707:Optical isolator
1672:Injection seeder
1652:Beam homogenizer
1631:Ultrashort pulse
1621:Lasing threshold
1433:
1426:
1419:
1410:
1249:
1242:
1235:
1226:
1213:
1204:
1198:
1178:
1172:
1171:
1153:
1147:
1128:
1122:
1121:
1119:
1118:
1099:
1093:
1092:
1090:
1089:
1070:
914:radar altimeters
894:local oscillator
790:phase modulation
768:
766:
765:
760:
744:
742:
741:
736:
724:
722:
721:
716:
714:
713:
697:
695:
694:
689:
678:
677:
589:radiotelegraphic
583:Transition to CW
560:; they had wide
421:
414:
407:
138:
121:
114:
107:
103:
100:
94:
92:
51:
27:
19:
1786:
1785:
1781:
1780:
1779:
1777:
1776:
1775:
1746:
1745:
1744:
1739:
1721:
1635:
1616:Laser linewidth
1606:Continuous wave
1582:
1475:Types of lasers
1470:
1442:
1437:
1407:
1402:
1371:Cyrillic script
1352:
1345:
1304:Notable signals
1299:
1280:Continuous wave
1258:
1253:
1216:
1205:
1201:
1192:Wayback Machine
1179:
1175:
1168:
1155:
1154:
1150:
1129:
1125:
1116:
1114:
1101:
1100:
1096:
1087:
1085:
1072:
1071:
1067:
1063:
1016:
1008:Information Age
984:barcode readers
941:
933:bistatic radars
882:
823:radiotelegraphy
798:
751:
750:
727:
726:
705:
700:
699:
669:
664:
663:
641:
634:
604:Edwin Armstrong
593:continuous wave
585:
538:
533:
480:continuous wave
433:continuous wave
425:
288:Spread spectrum
115:
104:
98:
95:
52:
50:
40:
28:
17:
12:
11:
5:
1784:
1782:
1774:
1773:
1768:
1763:
1758:
1748:
1747:
1741:
1740:
1738:
1737:
1726:
1723:
1722:
1720:
1719:
1714:
1712:Output coupler
1709:
1704:
1702:Optical cavity
1699:
1694:
1689:
1684:
1679:
1674:
1669:
1664:
1662:Gain-switching
1659:
1654:
1649:
1643:
1641:
1637:
1636:
1634:
1633:
1628:
1623:
1618:
1613:
1611:Laser ablation
1608:
1603:
1598:
1592:
1590:
1584:
1583:
1581:
1580:
1575:
1574:
1573:
1568:
1563:
1558:
1553:
1543:
1538:
1533:
1532:
1531:
1526:
1521:
1516:
1511:
1509:Carbon dioxide
1501:
1500:
1499:
1497:Liquid-crystal
1494:
1484:
1482:Chemical laser
1478:
1476:
1472:
1471:
1469:
1468:
1466:Laser acronyms
1463:
1458:
1453:
1447:
1444:
1443:
1438:
1436:
1435:
1428:
1421:
1413:
1404:
1403:
1401:
1400:
1395:
1390:
1385:
1380:
1379:
1378:
1368:
1366:Greek alphabet
1363:
1357:
1355:
1347:
1346:
1344:
1343:
1338:
1333:
1328:
1323:
1318:
1313:
1307:
1305:
1301:
1300:
1298:
1297:
1292:
1287:
1282:
1277:
1272:
1266:
1264:
1260:
1259:
1254:
1252:
1251:
1244:
1237:
1229:
1223:
1222:
1215:
1214:
1199:
1173:
1166:
1148:
1123:
1094:
1064:
1062:
1059:
1058:
1057:
1052:
1047:
1042:
1037:
1032:
1027:
1022:
1015:
1012:
980:laser printers
940:
937:
881:
878:
854:direct current
797:
794:
758:
734:
712:
708:
687:
684:
681:
676:
672:
633:
630:
584:
581:
537:
534:
532:
529:
455:, typically a
427:
426:
424:
423:
416:
409:
401:
398:
397:
396:
395:
390:
385:
380:
375:
370:
365:
360:
355:
350:
345:
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335:
330:
322:
321:
317:
316:
315:
314:
309:
304:
299:
291:
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284:
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276:
268:
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223:
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208:
203:
198:
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189:
183:
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181:
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165:
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155:
147:
146:
140:
139:
131:
130:
117:
116:
31:
29:
22:
15:
13:
10:
9:
6:
4:
3:
2:
1783:
1772:
1769:
1767:
1766:Laser science
1764:
1762:
1761:Amateur radio
1759:
1757:
1754:
1753:
1751:
1736:
1728:
1727:
1724:
1718:
1715:
1713:
1710:
1708:
1705:
1703:
1700:
1698:
1695:
1693:
1690:
1688:
1685:
1683:
1680:
1678:
1675:
1673:
1670:
1668:
1667:Gaussian beam
1665:
1663:
1660:
1658:
1655:
1653:
1650:
1648:
1647:Beam expander
1645:
1644:
1642:
1638:
1632:
1629:
1627:
1624:
1622:
1619:
1617:
1614:
1612:
1609:
1607:
1604:
1602:
1599:
1597:
1594:
1593:
1591:
1589:
1588:Laser physics
1585:
1579:
1576:
1572:
1569:
1567:
1564:
1562:
1559:
1557:
1554:
1552:
1549:
1548:
1547:
1544:
1542:
1539:
1537:
1534:
1530:
1527:
1525:
1522:
1520:
1517:
1515:
1512:
1510:
1507:
1506:
1505:
1502:
1498:
1495:
1493:
1490:
1489:
1488:
1485:
1483:
1480:
1479:
1477:
1473:
1467:
1464:
1462:
1459:
1457:
1454:
1452:
1449:
1448:
1445:
1441:
1434:
1429:
1427:
1422:
1420:
1415:
1414:
1411:
1399:
1396:
1394:
1391:
1389:
1388:Arabic script
1386:
1384:
1383:Hebrew script
1381:
1377:
1374:
1373:
1372:
1369:
1367:
1364:
1362:
1359:
1358:
1356:
1354:
1353:in Morse code
1348:
1342:
1339:
1337:
1334:
1332:
1329:
1327:
1324:
1322:
1319:
1317:
1314:
1312:
1309:
1308:
1306:
1302:
1296:
1293:
1291:
1288:
1286:
1283:
1281:
1278:
1276:
1275:On–off keying
1273:
1271:
1268:
1267:
1265:
1261:
1257:
1250:
1245:
1243:
1238:
1236:
1231:
1230:
1227:
1221:
1218:
1217:
1212:
1208:
1203:
1200:
1197:
1193:
1189:
1186:
1184:
1177:
1174:
1169:
1167:9780465091188
1163:
1159:
1152:
1149:
1145:
1144:0-87259-168-9
1141:
1137:
1133:
1127:
1124:
1112:
1108:
1104:
1098:
1095:
1083:
1079:
1075:
1069:
1066:
1060:
1056:
1053:
1051:
1048:
1046:
1043:
1041:
1038:
1036:
1035:On-off keying
1033:
1031:
1028:
1026:
1023:
1021:
1018:
1017:
1013:
1011:
1009:
1005:
1001:
997:
993:
989:
985:
981:
977:
973:
969:
964:
962:
958:
957:gain-switched
954:
950:
946:
945:laser physics
939:Laser physics
938:
936:
934:
929:
927:
923:
922:landing radar
919:
915:
911:
906:
904:
900:
895:
891:
887:
879:
877:
875:
871:
867:
863:
859:
855:
851:
850:amateur radio
846:
844:
840:
839:amateur radio
836:
832:
828:
824:
819:
816:
811:
802:
795:
793:
791:
787:
783:
779:
774:
773:is expected.
772:
756:
748:
732:
710:
706:
685:
682:
679:
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645:telegraph key
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582:
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577:time constant
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70:
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63:
60: –
59:
55:
54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
1687:Mode locking
1640:Laser optics
1605:
1279:
1202:
1182:
1176:
1157:
1151:
1131:
1126:
1115:. Retrieved
1106:
1097:
1086:. Retrieved
1077:
1068:
972:Izuo Hayashi
965:
942:
930:
907:
905:(distance).
883:
847:
820:
807:
785:
781:
775:
653:
642:
627:
592:
586:
574:
554:damped waves
539:
522:
498:
494:
491:carrier wave
487:transmission
479:
477:
447:of constant
440:
436:
432:
430:
393:Multiplexing
333:Demodulation
105:
96:
86:
79:
72:
65:
53:
41:Please help
36:verification
33:
1717:Q-switching
1578:X-ray laser
1571:Ti-sapphire
1541:Laser diode
1519:Helium–neon
1295:Signal lamp
1030:Damped wave
918:meteorology
835:transmitter
778:transmitter
749:rate), and
623:oscillators
620:vacuum tube
612:World War I
597:vacuum tube
558:frequencies
519:damped wave
503:Information
459:, that for
338:Line coding
99:August 2014
1750:Categories
1393:Wabun code
1290:Heliograph
1117:2023-04-10
1109:. Farlex.
1088:2023-04-10
1080:. Farlex.
1061:References
961:modelocked
953:q-switched
899:range rate
862:heterodyne
831:Morse code
815:modulation
782:key clicks
649:Morse code
632:Key clicks
550:sinusoidal
511:Morse code
128:modulation
69:newspapers
1771:Waveforms
1682:M squared
1504:Gas laser
1487:Dye laser
1185:, page 10
827:telegraph
810:modulated
660:bandwidth
562:bandwidth
542:spark gap
524:spark gap
457:sine wave
453:frequency
449:amplitude
1735:Category
1529:Nitrogen
1188:Archived
1138:, 1991)
1111:Archived
1082:Archived
1055:Waveform
1014:See also
1000:internet
901:but not
858:constant
610:. After
475:output.
443:) is an
320:See also
125:Passband
1514:Excimer
1376:Russian
924:on the
83:scholar
1556:Nd:YAG
1551:Er:YAG
1492:Bubble
1440:Lasers
1341:Z code
1336:Q code
1164:
1142:
1045:Tikker
986:, and
698:where
473:pulsed
246:SC-FDE
85:
78:
71:
64:
56:
1561:Raman
949:laser
916:, in
903:range
880:Radar
531:Radio
484:radio
465:laser
343:Modem
90:JSTOR
76:books
1566:Ruby
1162:ISBN
1140:ISBN
1136:ARRL
1006:and
872:and
786:soft
747:baud
618:and
606:and
451:and
383:OFDM
312:THSS
307:FHSS
302:DSSS
216:MFSK
201:APSK
62:news
1524:Ion
1316:CQD
1311:SOS
1134:, (
959:or
943:In
931:CW
813:of
570:RFI
501:).
499:ICW
467:or
435:or
388:FDM
378:ΔΣM
373:PWM
368:PDM
363:PCM
358:PAM
353:PoM
348:AnM
297:CSS
279:WDM
274:QAM
256:WDM
251:TCM
241:QAM
236:PSK
231:PPM
226:OOK
221:MSK
211:FSK
206:CPM
196:ASK
178:SSB
168:QAM
45:by
1752::
1194:,
1105:.
1076:.
1010:.
982:,
978:,
955:,
441:CW
431:A
173:SM
163:PM
158:FM
153:AM
1432:e
1425:t
1418:v
1248:e
1241:t
1234:v
1170:.
1120:.
1091:.
757:K
733:B
711:n
707:B
686:K
683:B
680:=
675:n
671:B
640:.
568:(
497:(
439:(
420:e
413:t
406:v
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
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