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1082:. At the receiver, these pulses were sometimes directly recorded on paper tapes, but more common was audible reception. The pulses were audible as beeps in the receiver's earphones, which were translated back to text by an operator who knew Morse code. These spark-gap transmitters were used during the first three decades of radio (1887–1917), called the
1424:
1436:
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to get a signal at the desired frequency. Modern designs more commonly use an oscillator at the operating frequency which is stabilized by phase locking to a very stable lower frequency reference, usually a crystal oscillator.
582:
lines. The antenna in the center is two vertical metal rods, with an alternating current applied at its center from a radio transmitter (not shown). The voltage charges the two sides of the antenna alternately positive
1430:
One of the BBC's first broadcast transmitters, early 1920s, London. The 4 triode tubes, connected in parallel to form an oscillator, each produced around 4 kilowatts with 12 thousand volts on their anodes.
367:, which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as cell phones, walkie-talkies, and
934:
Two radio transmitters in the same area that attempt to transmit on the same frequency will interfere with each other, causing garbled reception, so neither transmission may be received clearly.
945:
For this reason, in most countries, use of transmitters is strictly controlled by law. Transmitters must be licensed by governments, under a variety of license classes depending on use such as
977:
consisting of a string of letters and numbers which must be used as an identifier in transmissions. The operator of the transmitter usually must hold a government license, such as a
1345:
854:
than AM or FM. In OFDM multiple radio carrier waves closely spaced in frequency are transmitted within the radio channel, with each carrier modulated with bits from the incoming
1066:
developed the first practical radio communication systems using these transmitters, and radio began to be used commercially around 1900. Spark transmitters could not transmit
1371:
transmitter which generated continuous waves using an electric arc in a magnetic field, a technology used for a brief period from 1903 until vacuum tubes took over in the 20s
654:
range above about 20 kHz, the oscillating coupled electric and magnetic fields will radiate away from the antenna into space as an electromagnetic wave, a radio wave.
938:
with radio transmissions can not only have a large economic cost, it can be life-threatening (for example, in the case of interference with emergency communications or
669:
alternating current to apply to the antenna, and the antenna radiates the energy from this current as radio waves. The transmitter also encodes information such as an
2711:
2683:
2678:
1703:
316:
of information over a distance. The information is provided to the transmitter in the form of an electronic signal called the modulation signal, such as an
862:
are being sent simultaneously, in parallel. At the receiver the carriers are demodulated and the bits are combined in the proper order into one bitstream.
819:
921:
range, free running oscillators are unstable at the output frequency. Older designs used an oscillator at a lower frequency, which was multiplied by
642:
around the conductor. The alternating voltage will also charge the ends of the conductor alternately positive and negative, creating an oscillating
681:, the waves excite similar (but less powerful) radio frequency currents in it. The radio receiver extracts the information from the received waves.
1544:
1574:
978:
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371:. In more powerful transmitters, the antenna may be located on top of a building or on a separate tower, and connected to the transmitter by a
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2700:
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2670:
2472:
962:
747:. This is done by varying some aspect of the carrier wave. The information is provided to the transmitter as an electronic signal called the
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in 1933, who showed that it was less vulnerable to noise and static than AM. The first FM radio station was licensed in 1937. Experimental
68:
2695:
2541:
909:, in which the power is reflected back from the antenna toward the transmitter, wasting power and sometimes overheating the transmitter.
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1584:
1554:
1275:
410:
35 kW, Continental 816R-5B FM transmitter, belonging to
American FM radio station KWNR broadcasting on 95.5 MHz in Las Vegas
811:) transmitter, which transmits digital data, the frequency of the carrier is shifted between two frequencies which represent the two
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1615:
1021:
90:
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1894:
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Exceptions to the above regulations allow the unlicensed use of low-power short-range transmitters in consumer products such as
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to the antenna), to transfer power efficiently to the antenna. If these impedances are not equal, it causes a condition called
2783:
2457:
429:, the ICOM IC-746PRO. It can transmit on the amateur bands from 1.8 MHz to 144 MHz with an output power of 100 W
504:
control contains a low-power 2.4 GHz transmitter that sends coded commands to the garage door mechanism to open or close.
2452:
2003:
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which turned the transmitter on-and-off to produce radio wave pulses spelling out text messages in telegraphic code, usually
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1953:
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because it produces the radio waves which "carry" the information through space. In most modern transmitters, this is a
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1607:
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Two short-lived competing transmitter technologies came into use after the turn of the century, which were the first
61:
55:
981:, which is obtained by passing a test demonstrating adequate technical and legal knowledge of safe radio operation.
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2523:
2462:
2169:
1492:
839:
344:. The information can be added to the carrier in several different ways, in different types of transmitters. In an
272:. This usage typically includes both the transmitter proper, the antenna, and often the building it is housed in.
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2334:
2179:
2079:
2008:
1941:
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1307:
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234:
183:
528:, automated microwave transmitters and receivers operating on 2.4 GHz which exchange data packets with the
72:
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1974:
1909:
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1748:
1503:
561:
1387:, a huge rotating machine used as a radio transmitter at very low frequency from about 1910 until World War 2
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2400:
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2174:
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in 1887 during his pioneering investigations of radio waves. These generated radio waves by a high voltage
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2094:
2039:
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which interfered with other transmitters. Damped wave emissions were banned by international law in 1934.
1024:(FCC) regulations. Although they can be operated without a license, these devices still generally must be
808:
269:
1672:
Major UK television transmitters including change of group information, see
Transmitter Planning section.
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are also used. In large transmitters the oscillator and modulator together are often referred to as the
2395:
2199:
2164:
2084:
2064:
1986:
1874:
1795:
1446:, New York City, used for secret tests 1934–1935. It transmitted on 41 MHz at a power of 2 kW.
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1329:
1125:
1051:
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257:
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into the radio frequency current to be carried by the radio waves. When they strike the antenna of a
494:
472:
A cellphone has several transmitters: a duplex cell transceiver, a Wi-Fi modem, and a
Bluetooth modem.
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2269:
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1996:
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922:
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and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as
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2018:
1980:
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524:(background) which connects it to the Internet, creating a home Wi-Fi network. Both have Wi-Fi
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2013:
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1325:
1287:
1063:
1046:
Hertz discovering radio waves in 1887 with his first primitive radio transmitter (background).
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376:
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equipment, are not usually called transmitters, even though they often have similar circuits.
152:
1090:, spark transmitters were electrically "noisy". Their energy was spread over a broad band of
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transmitting on 27 MHz with a power of 4 W, that can be operated without a license
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Transmitters are necessary component parts of all electronic devices that communicate by
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1247:) in portable devices operate automatically, in the background, to exchange data with
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transmission had been conducted by radio stations since the late 1920s, but practical
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circuit to add the information to be transmitted to the carrier wave produced by the
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earbud with microphone. It has a
Bluetooth modem to exchange audio with a cell phone
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595:. Loops of electric field (black lines) leave the antenna and travel away at the
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to various classes of users. In some classes, each transmitter is given a unique
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contain low power 2.4 GHz radio transmitters to communicate with each other.
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2204:
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1968:
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793:(strength) of the carrier wave is varied in proportion to the modulation signal.
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426:
309:
128:
599:; these are the radio waves. This animation shows the action slowed enormously
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and are restricted to certain frequencies and power levels. A body called the
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to increase the power of the signal, to increase the range of the radio waves.
870:
779:
748:
615:
348:(AM) transmitter, the information is added to the radio signal by varying its
341:
336:
signal which when applied to the antenna produces the radio waves, called the
293:
202:
156:
2634:
2099:
1914:
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allowed the development in the 1960s of small portable transmitters such as
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340:. It combines the carrier with the modulation signal, a process called
2624:
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1017:
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698:
112:
1442:
Armstrong's first experimental FM broadcast transmitter W2XDG, in the
728:
in which the frequency is precisely controlled by the vibrations of a
689:
A practical radio transmitter mainly consists of the following parts:
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2614:
1936:
1728:
1681:
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1415:
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851:
300:
A transmitter can be a separate piece of electronic equipment, or an
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1302:
algorithms. Other advantages of digital transmission are increased
736:
of the carrier wave is considered the frequency of the transmitter.
2639:
2576:
1884:
1462:
1243:
networks, in which integrated digital transmitters and receivers (
1240:
1181:
1041:
1001:
827:
756:
565:
279:
242:
226:
102:
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of the transmitter to match the impedance of the antenna (or the
2581:
1258:
is driving the development of new types of transmitters such as
1148:
in 1906. Vacuum tube transmitters were inexpensive and produced
638:
flowing back and forth in an antenna will create an oscillating
296:) to transport information (in this case sound) over a distance.
1685:
233:
is usually limited to equipment that generates radio waves for
1827:
1188:
motivated the evolution of high frequency transmitters in the
697:
circuit to transform the input electrical power to the higher
115:, Wayne State University, Detroit, US. It broadcasts at 101.9
40:
1332:, with which he performed the first experiments in practical
1254:
The need to conserve bandwidth in the increasingly congested
1231:(IC) in the 1970s made possible the current proliferation of
763:
which represents moving images, or for data in the form of a
634:
which are changing their velocity and thus accelerating. An
356:(FM) transmitter, it is added by varying the radio signal's
826:
methods very widely used in high bandwidth systems such as
256:
The term is popularly used more specifically to refer to a
398:
Elcom Bauer model 701B 1100 watt AM broadcast transmitter
363:
The radio signal from the transmitter is applied to the
360:
slightly. Many other types of modulation are also used.
182:. When excited by this alternating current, the antenna
304:
within another electronic device. A transmitter and a
1543:
Serway, Raymond; Faughn, Jerry; Vuille, Chris (2008).
1270:. A related trend has been an ongoing transition from
1180:
didn't begin until the late 1930s. The development of
665:
from a power source, a battery or mains power, into a
1458:
Transmitter assembly of a 20 kW, 9.375 GHz
2663:
2600:
2522:
2486:
2443:
2384:
2318:
2027:
1719:
1306:, and greater flexibility and processing power of
1290:; that is it can often transmit more information (
842:(DAB) to transmit digital data using a minimum of
804:of the carrier is varied by the modulation signal.
1473:produces microwaves which pass from the aperture
778:. Different types of transmitters use different
1662:Jim Hawkins' Radio and Broadcast Technology Page
1164:possible, which began in about 1920. Practical
1070:(sound) and instead transmitted information by
1050:The first primitive radio transmitters (called
1579:. Cambridge University Press. pp. 16–17.
1120:All these early technologies were replaced by
1697:
1677:Details of UK digital television transmitters
1196:ranges, using new active devices such as the
1117:around 1910, which were used into the 1920s.
332:from a computer. The transmitter generates a
8:
701:needed to produce the required power output.
630:flowing through a metal conductor called an
2712:Global telecommunications regulation bodies
1603:Antenna theory: Analysis and Design, 3rd Ed
1568:
1566:
1062:between two conductors. Beginning in 1895,
650:of the oscillations is high enough, in the
459:Consumer products that contain transmitters
2748:
1704:
1690:
1682:
1481:which conducts them to the dish antenna.
1124:transmitters in the 1920s, which used the
820:orthogonal frequency-division multiplexing
1500: – List of specific models of radios
913:In higher frequency transmitters, in the
284:A radio transmitter is usually part of a
91:Learn how and when to remove this message
229:sets and navigational beacons. The term
54:This article includes a list of general
30:For broader coverage of this topic, see
27:Electronic device that emits radio waves
1667:WCOV-TV's Transmitter Technical Website
1535:
1315:
1086:or "spark" era. Because they generated
979:general radiotelephone operator license
324:(TV) signal from a video camera, or in
312:. The purpose of most transmitters is
1657:International Telecommunication Union
1355:transmitter in Australia around 1910.
963:International Telecommunication Union
171:. The transmitter itself generates a
7:
2758:
320:(sound) signal from a microphone, a
751:. The modulation signal may be an
484:Both the handset and the base of a
1168:(FM) transmission was invented by
897:) circuit to transform the output
618:, electromagnetic waves of radio
60:it lacks sufficient corresponding
25:
1549:. Cengage Learning. p. 714.
1469:tube mounted between two magnets
1054:) were built by German physicist
1022:Federal Communications Commission
782:methods to transmit information:
712:signal. This usually generates a
308:combined in one unit is called a
2757:
2747:
2738:
2737:
2726:
2347:Free-space optical communication
1606:. John Wiley and Sons. pp.
1600:Balanis, Constantine A. (2005).
1451:
1435:
1423:
1392:
1376:
1360:
1344:
1318:
1156:to transmit audio (sound) using
622:, are generated by time-varying
537:
509:
493:
477:
465:
434:
415:
403:
391:
225:in aircraft, ships, spacecraft,
45:
770:which represents a sequence of
1631:Brain, Marshall (2000-12-07).
1016:. In the US, these fall under
693:In high power transmitters, a
646:around the conductor. If the
151:in technical documents) is an
1:
1573:Ellingson, Steven W. (2016).
1406:radio transmitters, built by
822:) is a family of complicated
111:transmitter at radio station
2789:Telecommunications equipment
2733:Telecommunication portal
2514:Telecommunications equipment
1278:radio transmission methods.
846:bandwidth. OFDM has higher
119:with a radiated power of 48
2250:Alexander Stepanovich Popov
1418:) tube is visible at right.
1074:: the operator tapped on a
2810:
1954:Telecommunications history
1493:List of transmission sites
1339:communication in 1895–1897
1144:) vacuum tube invented by
1136:around 1912, based on the
1035:
840:digital audio broadcasting
657:A radio transmitter is an
559:
445:transceiver in a truck, a
211:wireless computer networks
178:, which is applied to the
29:
2721:
2562:Public Switched Telephone
2374:telecommunication circuit
2335:Fiber-optic communication
2080:Francis Blake (telephone)
1875:Optical telecommunication
1576:Radio Systems Engineering
1308:digital signal processing
1227:. The development of the
530:internet service provider
2473:Orbital angular-momentum
1910:Satellite communications
1749:Communications satellite
1504:Radio transmitter design
708:circuit to generate the
562:Radio transmitter design
260:, a transmitter used in
2352:Molecular communication
2175:Gardiner Greene Hubbard
2004:Undersea telegraph line
1739:Cable protection system
1546:College Physics, 8th Ed
1385:Alexanderson alternator
1178:television broadcasting
1115:Alexanderson alternator
882:A radio frequency (RF)
850:and more resistance to
199:television broadcasting
75:more precise citations.
2784:Broadcast transmitters
2494:Communication protocol
2280:Charles Sumner Tainter
2095:Walter Houser Brattain
2040:Edwin Howard Armstrong
1848:Information revolution
1524:Television transmitter
1152:, and could be easily
1052:spark gap transmitters
1047:
809:frequency-shift keying
600:
297:
270:television transmitter
143:(often abbreviated as
124:
2468:Polarization-division
2200:Narinder Singh Kapany
2165:Erna Schneider Hoover
2085:Jagadish Chandra Bose
2065:Alexander Graham Bell
1796:online video platform
1444:Empire State Building
1351:High power spark gap
1330:spark gap transmitter
1264:trunked radio systems
1211:The invention of the
1045:
923:frequency multipliers
706:electronic oscillator
604:Electromagnetic waves
574:antenna transmitting
569:
290:electromagnetic waves
283:
258:broadcast transmitter
106:
2310:Vladimir K. Zworykin
2270:Almon Brown Strowger
2240:Charles Grafton Page
1895:Prepaid mobile phone
1823:Electrical telegraph
1217:wireless microphones
1166:frequency modulation
1158:amplitude modulation
994:wireless microphones
965:(ITU) allocates the
869:Many other types of
798:frequency modulation
787:amplitude modulation
354:frequency modulation
346:amplitude modulation
266:FM radio transmitter
163:with the purpose of
34:. For the band, see
2260:Johann Philipp Reis
2019:Wireless revolution
1981:The Telephone Cases
1838:Hydraulic telegraph
1635:. HowStuffWorks.com
1514:Transmitter station
1460:air traffic control
1410:in 1914. The early
1311:integrated circuits
1298:than analog, using
1284:spectral efficiency
1221:garage door openers
1206:traveling wave tube
1160:(AM). This made AM
1126:feedback oscillator
1084:wireless telegraphy
1010:garage door openers
990:cordless telephones
940:air traffic control
848:spectral efficiency
755:, which represents
636:alternating current
369:garage door openers
326:wireless networking
314:radio communication
286:radio communication
219:garage door openers
176:alternating current
165:signal transmission
32:Signal transmission
2458:Frequency-division
2435:Telephone exchange
2305:Charles Wheatstone
2235:Jun-ichi Nishizawa
2210:Innocenzo Manzetti
2145:Reginald Fessenden
1880:Optical telegraphy
1713:Telecommunications
1280:Digital modulation
1229:integrated circuit
1162:radio broadcasting
1134:Alexander Meissner
1113:) in 1904 and the
1105:transmitters: the
1048:
891:impedance matching
838:broadcasting, and
836:digital television
824:digital modulation
800:) transmitter the
789:) transmitter the
726:crystal oscillator
659:electronic circuit
601:
502:garage door opener
385:Radio transmitters
302:electrical circuit
298:
288:system which uses
133:telecommunications
125:
2771:
2770:
2509:Store and forward
2504:Data transmission
2418:Network switching
2369:Transmission line
2215:Guglielmo Marconi
2180:Internet pioneers
2045:Mohamed M. Atalla
2014:Whistled language
1633:"How Radio Works"
1399:One of the first
1326:Guglielmo Marconi
1288:analog modulation
1282:can have greater
1249:wireless networks
1064:Guglielmo Marconi
903:transmission line
749:modulation signal
661:which transforms
624:electric currents
377:transmission line
217:enabled devices,
153:electronic device
137:radio transmitter
101:
100:
93:
16:(Redirected from
2801:
2761:
2760:
2751:
2750:
2741:
2740:
2731:
2730:
2729:
2602:Notable networks
2592:Wireless network
2532:Cellular network
2524:Types of network
2499:Computer network
2386:Network topology
2300:Thomas A. Watson
2155:Oliver Heaviside
2140:Philo Farnsworth
2115:Daniel Davis Jr.
2090:Charles Bourseul
2050:John Logie Baird
1759:Data compression
1754:Computer network
1706:
1699:
1692:
1683:
1644:
1643:
1641:
1640:
1628:
1622:
1621:
1597:
1591:
1590:
1570:
1561:
1560:
1540:
1455:
1439:
1427:
1396:
1380:
1364:
1348:
1322:
1300:data compression
1233:wireless devices
1150:continuous waves
1038:History of radio
626:, consisting of
608:electric charges
606:are radiated by
593:
587:
572:half-wave dipole
541:
513:
497:
481:
469:
438:
419:
407:
395:
96:
89:
85:
82:
76:
71:this article by
62:inline citations
49:
48:
41:
36:The Transmitters
21:
2809:
2808:
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1268:cognitive radio
1260:spread spectrum
1245:wireless modems
1170:Edwin Armstrong
1130:Edwin Armstrong
1103:continuous wave
1072:radiotelegraphy
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710:radio frequency
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667:radio frequency
652:radio frequency
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570:Animation of a
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247:microwave ovens
173:radio frequency
155:which produces
109:FM broadcasting
97:
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67:Please help to
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2255:Tivadar Puskás
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2009:Videotelephony
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1651:External links
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1586:978-1316785164
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1556:978-0495386933
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1498:List of radios
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1304:noise immunity
1256:radio spectrum
1225:walkie-talkies
1056:Heinrich Hertz
1036:Main article:
1033:
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998:walkie-talkies
971:radio spectrum
931:
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907:standing waves
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844:radio spectrum
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768:digital signal
737:
730:quartz crystal
702:
686:
683:
679:radio receiver
663:electric power
644:electric field
640:magnetic field
610:when they are
597:speed of light
589:and negative
580:electric field
578:, showing the
560:Main article:
557:
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486:cordless phone
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338:carrier signal
330:digital signal
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223:two-way radios
207:walkie-talkies
169:radio receiver
99:
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26:
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2135:Lee de Forest
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2130:Thomas Edison
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2120:Donald Davies
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2105:Claude Chappe
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1367:1 MW US Navy
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813:binary digits
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447:two way radio
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239:radiolocation
237:purposes; or
236:
235:communication
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186:radio waves.
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19:
2445:Multiplexing
2320:Transmission
2285:Nikola Tesla
2275:Henry Sutton
2230:Samuel Morse
2160:Robert Hooke
2125:Amos Dolbear
2060:John Bardeen
1979:
1959:Telautograph
1863:Mobile phone
1818:Edholm's law
1801:social media
1734:Broadcasting
1637:. Retrieved
1626:
1602:
1595:
1575:
1545:
1538:
1474:
1470:
1253:
1210:
1186:World War II
1128:invented by
1119:
1100:
1088:damped waves
1049:
983:
951:marine radio
944:
936:Interference
933:
912:
874:
858:so multiple
761:video signal
753:audio signal
722:carrier wave
716:of constant
695:power supply
688:
675:video signal
656:
602:
590:
584:
375:, that is a
362:
299:
265:
262:broadcasting
255:
230:
197:(audio) and
188:
148:
144:
140:
136:
126:
87:
81:October 2022
78:
59:
18:Transmitters
2645:NPL network
2357:Radio waves
2295:Alfred Vail
2205:Hedy Lamarr
2190:Dawon Kahng
2150:Elisha Gray
2110:Yogen Dalal
2035:Nasir Ahmed
1969:Teleprinter
1833:Heliographs
1401:vacuum tube
1369:Poulsen arc
1237:cell phones
1122:vacuum tube
1111:Poulsen arc
1096:radio noise
1094:, creating
1092:frequencies
986:cell phones
807:In an FSK (
616:Radio waves
612:accelerated
576:radio waves
427:transceiver
328:devices, a
310:transceiver
294:radio waves
276:Description
231:transmitter
203:cell phones
157:radio waves
141:transmitter
129:electronics
107:Commercial
73:introducing
2778:Categories
2691:Antarctica
2650:Toasternet
2572:Television
2055:Paul Baran
1987:Television
1971:(teletype)
1964:Telegraphy
1942:transistor
1920:Phryctoria
1890:Photophone
1868:Smartphone
1858:Mass media
1639:2009-09-11
1530:References
1519:Transposer
1334:Morse code
1235:, such as
1213:transistor
1174:television
1080:Morse code
930:Regulation
871:modulation
832:cellphones
830:networks,
815:, 0 and 1.
796:In an FM (
785:In an AM (
780:modulation
745:oscillator
685:Components
342:modulation
241:, such as
201:stations,
193:, such as
56:references
2675:Americas
2664:Locations
2635:Internet2
2396:Bandwidth
2100:Vint Cerf
1997:streaming
1975:Telephone
1915:Semaphore
1806:streaming
1479:waveguide
1467:magnetron
1296:bandwidth
1292:data rate
1198:magnetron
1194:microwave
1154:modulated
1008:devices,
1006:Bluetooth
975:call sign
967:frequency
947:broadcast
919:microwave
899:impedance
884:amplifier
856:bitstream
802:frequency
791:amplitude
776:bitstream
741:modulator
734:frequency
718:amplitude
714:sine wave
648:frequency
628:electrons
620:frequency
556:Operation
546:Bluetooth
520:and home
373:feed line
358:frequency
350:amplitude
251:diathermy
215:Bluetooth
2743:Category
2630:Internet
2620:CYCLADES
2537:Ethernet
2487:Concepts
2411:terminal
2362:wireless
2185:Bob Kahn
2028:Pioneers
1853:Internet
1744:Cable TV
1509:Repeater
1487:See also
1202:klystron
699:voltages
443:CB radio
306:receiver
264:, as in
184:radiates
167:up to a
159:with an
139:or just
2763:Commons
2753:Outline
2706:Oceania
2625:FidoNet
2610:ARPANET
2423:circuit
1992:digital
1721:History
1477:into a
1471:(right)
1276:digital
1184:during
1032:History
1020:of the
1018:Part 15
959:Amateur
955:Airband
875:exciter
732:. The
632:antenna
422:Modern
365:antenna
352:. In a
180:antenna
161:antenna
113:WDET-FM
69:improve
2701:Europe
2671:Africa
2655:Usenet
2615:BITNET
2552:Mobile
2428:packet
1937:MOSFET
1932:device
1729:Beacon
1614:
1583:
1553:
1475:(left)
1416:triode
1412:Audion
1272:analog
1204:, and
1142:triode
1138:Audion
1012:, and
852:fading
818:OFDM (
765:binary
532:(ISP).
526:modems
58:, but
2794:Radar
2684:South
2679:North
2640:JANET
2577:Telex
2567:Radio
2406:Nodes
2401:Links
2322:media
1900:Radio
1885:Pager
1813:Drums
1779:video
1774:image
1764:audio
1463:radar
1286:than
1241:Wi-Fi
1182:radar
1068:audio
1060:spark
1002:Wi-Fi
828:Wi-Fi
757:sound
671:audio
322:video
318:audio
243:radar
227:radar
195:radio
191:radio
2696:Asia
2582:UUCP
2542:ISDN
1612:ISBN
1581:ISBN
1551:ISBN
1266:and
1239:and
1223:and
1192:and
1132:and
1004:and
917:and
860:bits
774:, a
772:bits
759:, a
145:XMTR
135:, a
131:and
2587:WAN
2557:NGN
2547:LAN
1828:Fax
1769:DCT
1383:An
1328:'s
1274:to
1190:UHF
942:).
915:UHF
889:An
704:An
673:or
592:(−)
586:(+)
268:or
249:or
147:or
127:In
117:MHz
2780::
1610:.
1608:10
1565:^
1404:AM
1313:.
1262:,
1251:.
1219:,
1208:.
1200:,
1000:,
996:,
992:,
988:,
957:,
953:,
949:,
834:,
739:A
614:.
544:A
516:A
500:A
441:A
379:.
221:,
213:,
209:,
205:,
149:TX
121:kW
2714:)
2710:(
1705:e
1698:t
1691:v
1642:.
1620:.
1589:.
1559:.
1414:(
1140:(
1109:(
893:(
877:.
292:(
123:.
94:)
88:(
83:)
79:(
65:.
38:.
20:)
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