491:
The standard "quarter wave" antenna in the 25-50 MHz range can be over nine feet long. A 900 MHz antenna may be three inches long for a quarter wavelength. A transit bus may have a ruggedized antenna, which looks like a white plastic blade or fin, on its roof. Some vehicles with concealed radio installations have antennas designed to look like the original AM/FM antenna, a rearview mirror, or may be installed inside windows, or hidden on the floor pan or underside of a vehicle. Aircraft antennas look like blades or fins, the size and shape being determined by frequencies used. Microwave antennas may look like flat panels on the aircraft's skin. Temporary installations may have antennas which clip on to vehicle parts or are attached to steel body parts by a strong magnet.
471:
mike into the glove box and shut it, causing the push-to-talk button to be depressed and locking the transmitter on. On taxi systems, a driver may be upset when a dispatcher assigns a call (s)he wanted to another driver and may deliberately hold the transmit button down (for which the owner can be fined by the FCC). Radios with time-out timers transmit for the preset amount of time, usually 30–60 seconds, after which the transmitter automatically turns off and a loud tone comes out of the radio speaker. The volume level of the tone on some radios is loud and cannot be adjusted. As soon as the push-to-talk button is released, the tone stops and the timer resets.
584:. Each vehicle is equipped with a charger system console. The walkie talkie inserted into a vehicular charger or converter while the user is in the vehicle. The charger or converter (1) connects the walkie talkie to the vehicle's two-way radio antenna, (2) connects an amplified speaker, (3) connects a mobile microphone, and (4) charges the walkie talkie's battery. The weak point of these systems has been connector technology which has been proven unreliable in some installations. Receiver performance is a problem in congested radio signal and urban areas. These installations are sometimes referred to as
42:
541:
50:
376:. A computer and software is typically required to program the features and channels of the mobile radio. Menus of options may be several levels deep and offer a complicated array of possibilities. Some mobile radios have alphanumeric displays that translate channel numbers (F1, F2) to a phrase more meaningful to the user, such as "Providence Base", "Boston Base", etc. Radios are now designed with a myriad of features to preclude the need for custom design. For example,
307:(LSI) provided a practical and economic solution for radio technology, and was used in mobile radio systems by the early 1970s. Channel spacing narrowed to 20–30 kHz with modulation deviation dropping to ±5 kHz. This was done to allow more radio spectrum availability to accommodate the rapidly growing national group of two-way radio users. By the mid-1970s, tube-type transmitter power amplifiers had been replaced with
288:
2251:
280:
technically approved, by the FCC before it could be offered for sale. In order to be type accepted, the radio set had to be equipped with an indicator light, usually green or yellow, that showed power was applied and the radio was ready to transmit. Radios were also required to have a lamp (usually red) indicating when the transmitter was on. These traits continue in the design of modern radios.
2261:
2240:
2271:
470:
systems is the stuck microphone: A radio locked on transmit, which disrupts communications on a two-way radio system. One example of this problem occurred in a car with a concealed two-way radio installation where the microphone and coiled cord were hidden inside the glove box. An operator tossed the
571:
Each radio works over a single band of frequencies. If a tow car company had a frequency on the same band as its auto club, a single radio with scanning might be employed for both systems. Since a mobile radio typically works on a single frequency band, multiple radios may be required in cases where
442:
Mobile radios installed on motorcycles are subject to extreme vibration and weather. Professional equipment designed for use on motorcycles is weather and vibration resistant. Shock mounting systems are used to reduce the radio's exposure to vibration imparted by the motorcycle's modal, or resonant,
217:
was superior for its ability to cope with vehicle ignition and power line noise. The frequency range used by most early radio systems, 25–50 MHz (vhf "low band") is particularly susceptible to the problem of electrical noise. This plus the need for more channels led to the eventual expansion of
490:
A mobile radio must have an associated antenna. The most common antennas are stainless steel wire or rod whips which protrude vertically from the vehicle. Physics defines the antenna length: length relates to frequency and cannot be arbitrarily lengthened or shortened (more likely) by the end user.
434:
Commercial and professional mobile radios are often purchased from an equipment supplier or dealer whose staff will install the equipment into the user's vehicles. Large fleet users may buy radios directly from an equipment manufacturer and may even employ their own technical staff for installation
406:
As use of mobile radio equipment has virtually exploded, channel spacing has had to be narrowed again to 12.5–15 kHz with modulation deviation dropped to ±2.5 kilohertz. In order to fit into smaller, more economical vehicles, today's radios are trending toward radically smaller sizes than
98:: a transmitter-receiver (transceiver) used for radio communications from a vehicle. Mobile radios are mounted to a motor vehicle usually with the microphone and control panel in reach of the driver. In the US, such a device is typically powered by the host vehicle's 12 Volt electrical system.
462:
and radios in heavy equipment use noise-canceling headsets. These protect the occupant's hearing and reduce background noise in the transmitted audio. Noise-canceling microphones require the operator speak directly into the front of the microphone. Hole arrays in the back of the microphone pick up
283:
Early tube-type radios operated on 50 kHz channel spacing with ±15 kHz modulation deviation. This meant that the number of radio channels that could be accommodated in the available radio frequency spectrum were limited to a certain number, dictated by the bandwidth of the signal on each
221:
One of the major challenges in early mobile radio technology was that of converting the six or twelve volt power supply of the vehicle to the high voltage needed to operate the vacuum tubes in the radio. Early tube-type radios used dynamotors - essentially a six or twelve volt motor that turned a
725:
In many fields of communications equipment design, MOS LSI custom built circuits provide the only practical and economic solution. (...) A complete list of all applications is beyond the scope of this paper since new MOS developments are constantly being initiated in the various technical areas.
494:
Though initially relatively inexpensive mobile radio system components, frequently damaged antennas can be costly to replace since they are usually not included in maintenance contracts for mobile radio fleets. Some types of vehicles in 24-hour use, with stiff suspensions, tall heights, or rough
438:
A modern mobile radio consists of a radio transceiver, housed in a single box, and a microphone with a push-to-talk button. Each installation would also have a vehicle-mounted antenna connected to the transceiver by a coaxial cable. Some models may have an external, separate speaker which can be
409:
The traditional analogue radio communications have been surpassed by digital radio voice communications capabilities that provide greater clarity of transmission, enable security features such as encryption and, within the network, allow low band data transmissions to accommodate simple text or
279:
regulations. The requirement that unauthorized persons be prohibited from using the radio transmitter meant that many radios were wired so they could not transmit unless the vehicle ignition was on. Persons without a key to the vehicle could not transmit. Equipment had to be "type accepted", or
101:
Some mobile radios are mounted in aircraft (aeronautical mobile), shipboard (maritime mobile), on motorcycles, or railroad locomotives. Power may vary with each platform. For example, a mobile radio installed in a locomotive would run off of 72 or 30 Volt DC power. A large ship with
250:
in the power supplies. These high voltage power supplies were inefficient, and the filaments of the vacuum tubes added to current demands, taxing vehicle electrical systems. Sometimes, a generator or alternator upgrade was needed to support the current required for a tube-type mobile radio.
439:
positioned and oriented facing the driver to overcome ambient road noise present when driving. The installer would have to locate this equipment in a way that does not interfere with the vehicle's sun roof, electronic engine management system, vehicle stability computer, or air bags.
195:
cab and grabbing train orders while rolling past a station, voice communications with rolling trains became possible. Radios linked the caboose with the locomotive cab. Early police radio systems were initially one way using MF frequencies above the AM broadcast band, (1.7
463:
ambient noise. This is applied, out-of-phase, to the back of the microphone, effectively reducing or canceling any sound which is present both in front and back of the microphone. Ideally, only the voice present on the front side of the microphone goes out on the air.
507:
guidelines for non-ionizing radio energy generally say the radio antenna must be two feet from any vehicle occupants. This rule of thumb is intended to prevent passengers from being exposed to unsafe levels of radio frequency energy when the radio transmits.
222:
generator to provide the high voltages required by the vacuum tubes. Some early mobile radios were the size of a suitcase or had separate boxes for the transmitter and receiver. As time went on, power supply technology evolved to use first electromechanical
560:. A data terminal radio allows data communications to take place over the separate radio. In the same way that a facsimile machine has a separate phone line, this means data and voice communication can take place simultaneously over a separate radio. Early
617:
for a system which accomplishes all three of these tasks. Some
Converta-Com systems allow the attachment of signaling devices or external devices not usually compatible with walkie talkies. One historic example is the NLN-4470A for MT-500 series
162:
tool intended to communicate in simplex or half-duplex modes using push-to-talk, and primarily intended to communicate with other radios rather than telephones. These systems run on push-to-talk-based infrastructure such as Nextel's
482:(EIA/TIA). These specifications have been developed to help assure the user that mobile radio equipment performs as expected and to prevent the sale and distribution of inferior equipment which could degrade communications.
499:
vibrations may damage antennas quickly. The location and type of antenna can affect system performance drastically. Large fleets usually test a few vehicles before making a commitment to a certain antenna location or type.
129:
is becoming blurred as the two technologies merge. The backbone or infrastructure supporting the system defines which category or taxonomy applies. A parallel to this concept is the convergence of computing and telephones.
371:
Custom design for a particular customer is a thing of the past. Modern mobile radio equipment is "feature rich". A mobile radio may have 100 or more channels, be microprocessor controlled and have built-in options such as
291:
In the early 1970s, the
California Department of Forestry requirement for 6 frequency transmit, 3 frequency receive, scanning, and a 5 tone burst encoder was unusual, leading to this custom-built mobile
771:. National Highway Traffic Safety Administration. Evaluating Regional Alternatives. Vol. 2: Regional-level Planning Guide. Washington, DC: Department of Transportation. 1995. pp. 45–49.
75:
frequencies), and where the path of communications is movable on either end. There are a variety of views about what constitutes mobile equipment. For US licensing purposes, mobiles may include
604:
Cited in many references including on escutcheons and silk-screened face plates on 1960s
Motorola products including early HT-200 and Dispatcher-series mobiles. Later HT-200s dropped the term.
446:
Some mobile radios use noise-canceling microphones or headsets. At speeds over 100 MPH, the ambient road and wind noise can make radio communications difficult to understand. For example,
238:(AC) which could be passed through a transformer to make high voltage. The power supply then rectified this high voltage to make the high voltage DC required for the vacuum tubes, (called
548:
US ambulances often have radios with dual controls and dual microphones allowing the radio to be used from the patient care area in the rear or from the vehicle's cab.
311:. From the 1960s to the 1980s, large system users with specialized requirements often had custom built radios designed for their unique systems. Systems with multiple-
380:'s HM68X mobile radio, which was introduced in September 2022, offers a variety of features, including GPS location, emergency alarm, noise cancellation, and more.
504:
242:
in
British English). The power supplies needed to power vacuum tube radios resulted in a common trait of tube-type mobile radios: their heavy weight due to the
2223:
2195:
2190:
1215:
171:, Enhanced Specialized Mobile Radio (ESMR) or conventional two-way systems. Certain modern two-way radio systems may have full-duplex telephone capability.
315:
tone encoders and more than two channels were unusual. Manufacturers of mobile radios built customized equipment for large radio fleets such as the
819:
479:
218:
two-way radio communications into the VHF "high band" (150–174 MHz) and UHF (450–470 MHz). The UHF band has since been expanded again.
2217:
2212:
2202:
2182:
1984:
652:
Model T31BAT-3100B-SP3 'Dispatcher' Radiophone 25-54 MC 12 W RF Power 12 VDC, State of
California Radio Communications System
1059:
2207:
2053:
1069:
524:, may have several radios in each vehicle. For example, tow cars may have one radio for towing company communications and a second for
1979:
300:
2073:
1122:
930:
475:
316:
276:
137:
1858:
1406:
1208:
113:, a mobile radio is "A station in the mobile service intended to be used while in motion or during halts at unspecified points."
1969:
41:
1964:
1515:
136:
are full-duplex (simultaneous talk and listen), circuit switched, and primarily communicate with telephones connected to the
35:
1989:
1039:
580:
Intended as a cost savings, some systems employ vehicular chargers instead of a mobile radio. Each radio user is issued a
213:
to convey intelligence through the communications channel. In time, problems with sources of electrical noise showed that
2274:
650:
It was also seen on some Kaar
Engineering mobile products. One example is the title on a special products service manual
2264:
2025:
1922:
1465:
1232:
920:
867:
145:
2254:
1761:
1201:
935:
812:
544:
A mobile radio in a US ambulance often has two sets of controls: one in the patient area and another near the driver.
2295:
2113:
2035:
1974:
1681:
1127:
529:
1885:
1846:
1691:
1591:
1520:
1453:
1280:
1152:
983:
945:
447:
415:
320:
2244:
1486:
1421:
1374:
1260:
1177:
993:
720:
631:
466:
Many radios are equipped with transmitter time-out timers which limit the length of a transmission. A bane of
2083:
2068:
1912:
1863:
1786:
1686:
1364:
1250:
1245:
1137:
887:
304:
2005:
1791:
1606:
1551:
1546:
1359:
1324:
847:
805:
525:
296:
67:
refer to wireless communications systems and devices which are based on radio frequencies (using commonly
179:
Early users of mobile radio equipment included transportation and government. These systems used one-way
1907:
1711:
1676:
1596:
1576:
1498:
1386:
1307:
882:
540:
227:
226:, then solid-state power supplies to provide high voltage for the vacuum tubes. These circuits, called "
223:
49:
1821:
1781:
1751:
1508:
1443:
1334:
1147:
998:
862:
857:
557:
423:
214:
210:
159:
556:
Both tow cars and ambulances may have an additional radio which transmits and receives to support a
1831:
1771:
1530:
1492:
1349:
1290:
1275:
1182:
1029:
915:
852:
235:
202:
191:) communications (similar to the AM broadcast band) to improve safety. Instead of hanging out of a
2058:
2015:
1946:
1816:
1746:
1721:
1656:
1503:
1224:
451:
2098:
2020:
1934:
1917:
1880:
1766:
1726:
1556:
1525:
1391:
1285:
1089:
1084:
1049:
373:
747:
2103:
2063:
2043:
2010:
1939:
1897:
1811:
1666:
1651:
1626:
1601:
1561:
1411:
1270:
1265:
1255:
1034:
308:
188:
1731:
1586:
1354:
1317:
1167:
1117:
275:
Equipment from different US manufacturers had similar traits. This was partly dictated by
140:. The connection sets up based on the user dialing. The connection is taken down when the
1329:
528:
communications. Ambulances may have a similar arrangement with one radio for government
1929:
1801:
1776:
1736:
1706:
1581:
1416:
1302:
988:
785:. Macro Corporation and The State of Arizona. 2004. Paragraph 2.4(e), pp. 15.
231:
122:
287:
2289:
2078:
1851:
1841:
1756:
1646:
1641:
1631:
1616:
1438:
1297:
1003:
973:
842:
828:
783:
Arizona Phase II Final Report: Statewide Radio
Interoperability Needs Assessment
581:
568:
button which, when acknowledged, allowed voice communication to the dispatch center.
126:
76:
31:
17:
1956:
1796:
1741:
1671:
1636:
1571:
1470:
1460:
1312:
1142:
1079:
968:
467:
180:
103:
713:"MOS LSI Custom Circuits Offer New Prospects for Communications Equipment Design"
712:
2156:
1806:
1716:
1701:
1661:
1621:
1480:
1172:
1162:
1157:
496:
459:
299:
equipment arrived in the 1960s, with more efficient circuitry and smaller size.
255:
247:
200:). Some early systems talked back to dispatch on a 30-50 MHz link, (called
2161:
1868:
1566:
1475:
1431:
1401:
1379:
1369:
1344:
455:
411:
192:
694:
2146:
1611:
1426:
1132:
521:
517:
268:
General
Electric Progress Line (Early models without "T-Power" power supply)
474:
Mobile radio equipment is manufactured to specifications developed by the
2141:
2131:
2048:
1873:
1696:
1074:
1019:
940:
265:
Motorola Twin-V, named for its "universal" 6 or 12 Volt power supply
184:
168:
54:
572:
communications take place over systems on more than one frequency band.
30:
This article is about professional equipment. For mobile radios used in
2136:
2121:
1094:
1024:
925:
872:
748:"Hytera launches MNC360 PoC Mobile Radio for In-Vehicle Communication"
564:
radio systems used a single radio for data and voice. The radio had a
144:
button is pressed. They run on telephony-based infrastructure such as
2166:
2126:
1448:
1240:
1193:
1099:
1064:
950:
897:
892:
877:
450:
mobile radios have noise-canceling microphones which reduce road and
377:
667:
conflicts with some uses, saying radiophone is interchangeable with
2151:
2088:
1396:
561:
539:
419:
312:
286:
48:
40:
2093:
797:
243:
164:
1197:
801:
726:
Typical examples of completed and present MOS developments are:
1339:
197:
149:
110:
90:
A sales person or radio repair shop would understand the word
72:
68:
326:
Examples of US hybrid partially solid state mobile radios:
254:
Examples of US 1950s-1960s tube-type mobile radios with no
383:
Examples of US microprocessor-controlled mobile radios:
27:
Wireless communications systems using radio frequencies
45:
National Guard operating a mobile radio station (1922)
654:, (Chicago: Motorola Communications Division, 1965).
2175:
2112:
2034:
1998:
1955:
1896:
1830:
1539:
1231:
1108:
1048:
1012:
959:
906:
835:
576:Walkie talkie converters in place of mobile radios
613:For example, Motorola has trademarked the name
1209:
813:
505:Occupational Safety and Health Administration
8:
410:picture messaging as an example. (Examples:
2224:Global telecommunications regulation bodies
763:
761:
2260:
1216:
1202:
1194:
820:
806:
798:
769:Planning Emergency Medical Communications
684:says radiophone is an, "obsolete term."
643:
597:
532:dispatch and one for company dispatch.
480:Telecommunications Industry Association
277:Federal Communications Commission (FCC)
262:Motorola FMTRU-140D (dynamotor powered)
117:Nomenclature: Two-way versus telephone
102:117 V AC power might have a
7:
2270:
746:Anthony Davis (September 28, 2022).
516:Dispatch-reliant services, such as
183:instead of two-way conversations.
167:, Specialized Mobile Radio (SMR),
83:), equipment. An obsolete term is
25:
931:Common traffic advisory frequency
476:Electronic Industries Association
317:California Department of Forestry
138:public switched telephone network
109:According to article 1.67 of the
2269:
2259:
2250:
2249:
2238:
1859:Free-space optical communication
711:Zeidler, G.; Becker, D. (1974).
271:Kaar Engineering Model 501
536:Multiple controls, microphones
230:", changed the 6 or 12 V
106:mounted on the ship's bridge.
36:amateur radio mobile operation
1:
1040:Maritime mobile amateur radio
187:used medium frequency range (
2245:Telecommunication portal
2026:Telecommunications equipment
1183:Voting (diversity combining)
921:Aircraft emergency frequency
868:General Mobile Radio Service
345:Transistorized Progress Line
1762:Alexander Stepanovich Popov
936:Mandatory frequency airport
682:Newton's Telecom Dictionary
2312:
1466:Telecommunications history
1128:Automatic vehicle location
530:emergency medical services
407:their tube-type ancestors.
29:
2233:
2074:Public Switched Telephone
1886:telecommunication circuit
1847:Fiber-optic communication
1592:Francis Blake (telephone)
1387:Optical telecommunication
1153:Dynamic range compression
1070:Dual-tone multi-frequency
984:Professional mobile radio
946:Single Frequency Approach
695:"R15-WRC15-C-0000!!MSW-E"
680:The 11th edition of
665:Oxford English Dictionary
448:California Highway Patrol
416:Terrestrial Trunked Radio
340:IMTS Car Telephone (1963)
321:California Highway Patrol
301:Metal–oxide–semiconductor
215:frequency modulation (FM)
211:amplitude modulation (AM)
209:Early mobile radios used
53:Mobile radio on board of
1985:Orbital angular-momentum
1422:Satellite communications
1261:Communications satellite
1178:Radiotelephony procedure
994:Specialized Mobile Radio
721:Western Electric Company
717:Electrical Communication
389:Astro Digital Spectra W9
121:The distinction between
1864:Molecular communication
1687:Gardiner Greene Hubbard
1516:Undersea telegraph line
1251:Cable protection system
888:Multi-Use Radio Service
562:Federal Express (FedEx)
305:large-scale integration
2006:Communication protocol
1792:Charles Sumner Tainter
1607:Walter Houser Brattain
1552:Edwin Howard Armstrong
1360:Information revolution
960:Land-based commercial
848:Amateur radio repeater
545:
526:emergency road service
309:high-power transistors
297:Solid-state electronic
293:
57:
46:
1980:Polarization-division
1712:Narinder Singh Kapany
1677:Erna Schneider Hoover
1597:Jagadish Chandra Bose
1577:Alexander Graham Bell
1308:online video platform
962:and government mobile
909:(aeronautical mobile)
543:
290:
52:
44:
1822:Vladimir K. Zworykin
1782:Almon Brown Strowger
1752:Charles Grafton Page
1407:Prepaid mobile phone
1335:Electrical telegraph
999:Trunked radio system
863:Public Radio Service
858:Family Radio Service
836:Amateur and hobbyist
558:mobile data terminal
79:, (sometimes called
18:Mobile radio station
1772:Johann Philipp Reis
1531:Wireless revolution
1493:The Telephone Cases
1350:Hydraulic telegraph
1030:Coast radio station
916:Air traffic control
853:Citizens band radio
512:Multiple radio sets
454:noise heard by the
236:alternating current
1970:Frequency-division
1947:Telephone exchange
1817:Charles Wheatstone
1747:Jun-ichi Nishizawa
1722:Innocenzo Manzetti
1657:Reginald Fessenden
1392:Optical telegraphy
1225:Telecommunications
1013:Marine (shipboard)
898:UHF CB (Australia)
546:
351:MASTR Professional
294:
58:
47:
2296:Mobile technology
2283:
2282:
2021:Store and forward
2016:Data transmission
1930:Network switching
1881:Transmission line
1727:Guglielmo Marconi
1692:Internet pioneers
1557:Mohamed M. Atalla
1526:Whistled language
1191:
1190:
1052:Selective calling
632:Land mobile radio
435:and maintenance.
401:mobile-radio-m94g
349:General Electric
343:General Electric
16:(Redirected from
2303:
2273:
2272:
2263:
2262:
2253:
2252:
2243:
2242:
2241:
2114:Notable networks
2104:Wireless network
2044:Cellular network
2036:Types of network
2011:Computer network
1898:Network topology
1812:Thomas A. Watson
1667:Oliver Heaviside
1652:Philo Farnsworth
1627:Daniel Davis Jr.
1602:Charles Bourseul
1562:John Logie Baird
1271:Data compression
1266:Computer network
1218:
1211:
1204:
1195:
1109:System elements
1035:Marine VHF radio
822:
815:
808:
799:
787:
786:
779:
773:
772:
765:
756:
755:
743:
737:
736:
708:
702:
701:
699:
691:
685:
678:
672:
661:
655:
648:
619:
611:
605:
602:
566:request-to-speak
21:
2311:
2310:
2306:
2305:
2304:
2302:
2301:
2300:
2286:
2285:
2284:
2279:
2239:
2237:
2229:
2171:
2108:
2030:
1994:
1951:
1900:
1892:
1833:
1826:
1732:Robert Metcalfe
1587:Tim Berners-Lee
1535:
1355:Information Age
1227:
1222:
1192:
1187:
1168:Rayleigh fading
1110:
1104:
1051:
1044:
1008:
961:
955:
908:
902:
831:
826:
796:
791:
790:
781:
780:
776:
767:
766:
759:
745:
744:
740:
734:— mobile radios
733:
731:
729:
727:
710:
709:
705:
697:
693:
692:
688:
679:
675:
662:
658:
649:
645:
640:
628:
623:
622:
612:
608:
603:
599:
594:
578:
554:
538:
514:
488:
432:
408:
369:
355:MASTR Executive
177:
158:is primarily a
134:Radiotelephones
123:radiotelephones
119:
96:vehicle-mounted
39:
28:
23:
22:
15:
12:
11:
5:
2309:
2307:
2299:
2298:
2288:
2287:
2281:
2280:
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2277:
2267:
2257:
2247:
2234:
2231:
2230:
2228:
2227:
2220:
2215:
2210:
2205:
2200:
2199:
2198:
2193:
2185:
2179:
2177:
2173:
2172:
2170:
2169:
2164:
2159:
2154:
2149:
2144:
2139:
2134:
2129:
2124:
2118:
2116:
2110:
2109:
2107:
2106:
2101:
2096:
2091:
2086:
2081:
2076:
2071:
2066:
2061:
2056:
2051:
2046:
2040:
2038:
2032:
2031:
2029:
2028:
2023:
2018:
2013:
2008:
2002:
2000:
1996:
1995:
1993:
1992:
1987:
1982:
1977:
1972:
1967:
1965:Space-division
1961:
1959:
1953:
1952:
1950:
1949:
1944:
1943:
1942:
1937:
1927:
1926:
1925:
1915:
1910:
1904:
1902:
1894:
1893:
1891:
1890:
1889:
1888:
1878:
1877:
1876:
1866:
1861:
1856:
1855:
1854:
1844:
1838:
1836:
1828:
1827:
1825:
1824:
1819:
1814:
1809:
1804:
1802:Camille Tissot
1799:
1794:
1789:
1784:
1779:
1777:Claude Shannon
1774:
1769:
1767:Tivadar Puskás
1764:
1759:
1754:
1749:
1744:
1739:
1737:Antonio Meucci
1734:
1729:
1724:
1719:
1714:
1709:
1707:Charles K. Kao
1704:
1699:
1694:
1689:
1684:
1682:Harold Hopkins
1679:
1674:
1669:
1664:
1659:
1654:
1649:
1644:
1639:
1634:
1629:
1624:
1619:
1614:
1609:
1604:
1599:
1594:
1589:
1584:
1582:Emile Berliner
1579:
1574:
1569:
1564:
1559:
1554:
1549:
1543:
1541:
1537:
1536:
1534:
1533:
1528:
1523:
1521:Videotelephony
1518:
1513:
1512:
1511:
1506:
1496:
1489:
1484:
1478:
1473:
1468:
1463:
1458:
1457:
1456:
1451:
1446:
1436:
1435:
1434:
1424:
1419:
1417:Radiotelephone
1414:
1409:
1404:
1399:
1394:
1389:
1384:
1383:
1382:
1372:
1367:
1362:
1357:
1352:
1347:
1342:
1337:
1332:
1327:
1322:
1321:
1320:
1315:
1310:
1305:
1303:Internet video
1295:
1294:
1293:
1288:
1283:
1278:
1268:
1263:
1258:
1253:
1248:
1243:
1237:
1235:
1229:
1228:
1223:
1221:
1220:
1213:
1206:
1198:
1189:
1188:
1186:
1185:
1180:
1175:
1170:
1165:
1160:
1155:
1150:
1145:
1140:
1135:
1130:
1125:
1120:
1114:
1112:
1111:and principles
1106:
1105:
1103:
1102:
1097:
1092:
1087:
1082:
1077:
1072:
1067:
1062:
1056:
1054:
1046:
1045:
1043:
1042:
1037:
1032:
1027:
1022:
1016:
1014:
1010:
1009:
1007:
1006:
1001:
996:
991:
989:Radio repeater
986:
981:
976:
971:
965:
963:
957:
956:
954:
953:
948:
943:
938:
933:
928:
923:
918:
912:
910:
904:
903:
901:
900:
895:
890:
885:
880:
875:
870:
865:
860:
855:
850:
845:
839:
837:
833:
832:
827:
825:
824:
817:
810:
802:
795:
794:External links
792:
789:
788:
774:
757:
752:Highways Today
738:
730:— multiplexers
703:
686:
673:
669:radiotelephone
656:
642:
641:
639:
636:
635:
634:
627:
624:
621:
620:
606:
596:
595:
593:
590:
577:
574:
553:
550:
537:
534:
513:
510:
487:
484:
431:
428:
404:
403:
397:
391:
368:
365:
364:
363:
357:
347:
341:
334:
273:
272:
269:
266:
263:
232:direct current
176:
173:
118:
115:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2308:
2297:
2294:
2293:
2291:
2276:
2268:
2266:
2258:
2256:
2248:
2246:
2236:
2235:
2232:
2225:
2221:
2219:
2216:
2214:
2211:
2209:
2206:
2204:
2201:
2197:
2194:
2192:
2189:
2188:
2186:
2184:
2181:
2180:
2178:
2174:
2168:
2165:
2163:
2160:
2158:
2155:
2153:
2150:
2148:
2145:
2143:
2140:
2138:
2135:
2133:
2130:
2128:
2125:
2123:
2120:
2119:
2117:
2115:
2111:
2105:
2102:
2100:
2097:
2095:
2092:
2090:
2087:
2085:
2082:
2080:
2077:
2075:
2072:
2070:
2067:
2065:
2062:
2060:
2057:
2055:
2052:
2050:
2047:
2045:
2042:
2041:
2039:
2037:
2033:
2027:
2024:
2022:
2019:
2017:
2014:
2012:
2009:
2007:
2004:
2003:
2001:
1997:
1991:
1990:Code-division
1988:
1986:
1983:
1981:
1978:
1976:
1975:Time-division
1973:
1971:
1968:
1966:
1963:
1962:
1960:
1958:
1954:
1948:
1945:
1941:
1938:
1936:
1933:
1932:
1931:
1928:
1924:
1921:
1920:
1919:
1916:
1914:
1911:
1909:
1906:
1905:
1903:
1901:and switching
1899:
1895:
1887:
1884:
1883:
1882:
1879:
1875:
1872:
1871:
1870:
1867:
1865:
1862:
1860:
1857:
1853:
1852:optical fiber
1850:
1849:
1848:
1845:
1843:
1842:Coaxial cable
1840:
1839:
1837:
1835:
1829:
1823:
1820:
1818:
1815:
1813:
1810:
1808:
1805:
1803:
1800:
1798:
1795:
1793:
1790:
1788:
1785:
1783:
1780:
1778:
1775:
1773:
1770:
1768:
1765:
1763:
1760:
1758:
1757:Radia Perlman
1755:
1753:
1750:
1748:
1745:
1743:
1740:
1738:
1735:
1733:
1730:
1728:
1725:
1723:
1720:
1718:
1715:
1713:
1710:
1708:
1705:
1703:
1700:
1698:
1695:
1693:
1690:
1688:
1685:
1683:
1680:
1678:
1675:
1673:
1670:
1668:
1665:
1663:
1660:
1658:
1655:
1653:
1650:
1648:
1647:Lee de Forest
1645:
1643:
1642:Thomas Edison
1640:
1638:
1635:
1633:
1632:Donald Davies
1630:
1628:
1625:
1623:
1620:
1618:
1617:Claude Chappe
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:
1544:
1542:
1538:
1532:
1529:
1527:
1524:
1522:
1519:
1517:
1514:
1510:
1507:
1505:
1502:
1501:
1500:
1497:
1495:
1494:
1490:
1488:
1485:
1482:
1479:
1477:
1474:
1472:
1469:
1467:
1464:
1462:
1461:Smoke signals
1459:
1455:
1452:
1450:
1447:
1445:
1442:
1441:
1440:
1439:Semiconductor
1437:
1433:
1430:
1429:
1428:
1425:
1423:
1420:
1418:
1415:
1413:
1410:
1408:
1405:
1403:
1400:
1398:
1395:
1393:
1390:
1388:
1385:
1381:
1378:
1377:
1376:
1373:
1371:
1368:
1366:
1363:
1361:
1358:
1356:
1353:
1351:
1348:
1346:
1343:
1341:
1338:
1336:
1333:
1331:
1328:
1326:
1323:
1319:
1316:
1314:
1311:
1309:
1306:
1304:
1301:
1300:
1299:
1298:Digital media
1296:
1292:
1289:
1287:
1284:
1282:
1279:
1277:
1274:
1273:
1272:
1269:
1267:
1264:
1262:
1259:
1257:
1254:
1252:
1249:
1247:
1244:
1242:
1239:
1238:
1236:
1234:
1230:
1226:
1219:
1214:
1212:
1207:
1205:
1200:
1199:
1196:
1184:
1181:
1179:
1176:
1174:
1171:
1169:
1166:
1164:
1161:
1159:
1156:
1154:
1151:
1149:
1146:
1144:
1141:
1139:
1136:
1134:
1131:
1129:
1126:
1124:
1121:
1119:
1116:
1115:
1113:
1107:
1101:
1098:
1096:
1093:
1091:
1088:
1086:
1083:
1081:
1078:
1076:
1073:
1071:
1068:
1066:
1063:
1061:
1058:
1057:
1055:
1053:
1047:
1041:
1038:
1036:
1033:
1031:
1028:
1026:
1023:
1021:
1018:
1017:
1015:
1011:
1005:
1004:Walkie-talkie
1002:
1000:
997:
995:
992:
990:
987:
985:
982:
980:
977:
975:
974:Business band
972:
970:
967:
966:
964:
958:
952:
949:
947:
944:
942:
939:
937:
934:
932:
929:
927:
924:
922:
919:
917:
914:
913:
911:
905:
899:
896:
894:
891:
889:
886:
884:
881:
879:
876:
874:
871:
869:
866:
864:
861:
859:
856:
854:
851:
849:
846:
844:
843:Amateur radio
841:
840:
838:
834:
830:
829:Two-way radio
823:
818:
816:
811:
809:
804:
803:
800:
793:
784:
778:
775:
770:
764:
762:
758:
753:
749:
742:
739:
735:
728:— crosspoints
722:
718:
714:
707:
704:
696:
690:
687:
683:
677:
674:
670:
666:
660:
657:
653:
647:
644:
637:
633:
630:
629:
625:
616:
610:
607:
601:
598:
591:
589:
587:
583:
582:walkie talkie
575:
573:
569:
567:
563:
559:
551:
549:
542:
535:
533:
531:
527:
523:
519:
511:
509:
506:
501:
498:
492:
485:
483:
481:
477:
472:
469:
464:
461:
457:
453:
449:
444:
440:
436:
429:
427:
425:
421:
417:
413:
402:
398:
396:
392:
390:
386:
385:
384:
381:
379:
375:
366:
362:
361:Super Carfone
358:
356:
352:
348:
346:
342:
339:
335:
333:
329:
328:
327:
324:
322:
318:
314:
310:
306:
302:
298:
289:
285:
281:
278:
270:
267:
264:
261:
260:
259:
257:
252:
249:
245:
241:
237:
233:
229:
225:
219:
216:
212:
207:
205:
204:
199:
194:
190:
186:
182:
174:
172:
170:
166:
161:
157:
156:Two-way radio
153:
151:
147:
143:
139:
135:
131:
128:
127:two-way radio
124:
116:
114:
112:
107:
105:
99:
97:
93:
88:
86:
82:
78:
74:
70:
66:
62:
56:
51:
43:
37:
33:
32:amateur radio
19:
1957:Multiplexing
1832:Transmission
1797:Nikola Tesla
1787:Henry Sutton
1742:Samuel Morse
1672:Robert Hooke
1637:Amos Dolbear
1572:John Bardeen
1491:
1471:Telautograph
1375:Mobile phone
1330:Edholm's law
1313:social media
1246:Broadcasting
1090:Quik-Call II
1080:Push-to-talk
1050:Signaling /
979:Mobile radio
978:
969:Base station
782:
777:
768:
751:
741:
724:
716:
706:
689:
681:
676:
668:
664:
659:
651:
646:
615:Converta-Com
614:
609:
600:
586:jerk-and-run
585:
579:
570:
565:
555:
547:
515:
502:
493:
489:
473:
468:push-to-talk
465:
460:fire engines
445:
441:
437:
433:
405:
400:
399:PositionPTT
394:
388:
382:
370:
360:
354:
350:
344:
337:
331:
325:
295:
282:
274:
253:
248:transformers
239:
220:
208:
201:
181:broadcasting
178:
155:
154:
141:
133:
132:
120:
108:
104:base station
100:
95:
91:
89:
84:
80:
77:hand-carried
64:
61:Mobile radio
60:
59:
2157:NPL network
1869:Radio waves
1807:Alfred Vail
1717:Hedy Lamarr
1702:Dawon Kahng
1662:Elisha Gray
1622:Yogen Dalal
1547:Nasir Ahmed
1481:Teleprinter
1345:Heliographs
1173:Tone remote
1163:Link budget
1158:Fade margin
1085:Quik-Call I
497:engine idle
414:(APCO-25),
256:transistors
2203:Antarctica
2162:Toasternet
2084:Television
1567:Paul Baran
1499:Television
1483:(teletype)
1476:Telegraphy
1454:transistor
1432:Phryctoria
1402:Photophone
1380:Smartphone
1370:Mass media
883:Mobile rig
638:References
552:Data radio
522:ambulances
456:dispatcher
412:Project 25
193:locomotive
85:radiophone
2187:Americas
2176:Locations
2147:Internet2
1908:Bandwidth
1612:Vint Cerf
1509:streaming
1487:Telephone
1427:Semaphore
1318:streaming
1143:DC remote
1133:Call sign
907:Aviation
723:: 88–92.
719:. 49–50.
588:systems.
443:shaking.
387:Motorola
336:Motorola
330:Motorola
284:channel.
228:inverters
224:vibrators
203:crossband
185:Railroads
2290:Category
2255:Category
2142:Internet
2132:CYCLADES
2049:Ethernet
1999:Concepts
1923:terminal
1874:wireless
1697:Bob Kahn
1540:Pioneers
1365:Internet
1256:Cable TV
1148:Dispatch
1075:MDC-1200
1020:2182 kHz
941:MULTICOM
732:— modems
626:See also
518:tow cars
393:Kenwood
319:and the
234:(DC) to
169:MPT-1327
160:dispatch
94:to mean
81:portable
55:Zeppelin
2275:Commons
2265:Outline
2218:Oceania
2137:FidoNet
2122:ARPANET
1935:circuit
1504:digital
1233:History
1118:Antenna
1095:Selcall
1025:500 kHz
926:Airband
873:KDR 444
618:radios.
495:diesel
486:Antenna
458:. Most
430:Details
374:unit ID
175:History
65:mobiles
2213:Europe
2183:Africa
2167:Usenet
2127:BITNET
2064:Mobile
1940:packet
1449:MOSFET
1444:device
1241:Beacon
1100:SELCAL
1065:D-STAR
951:UNICOM
893:PMR446
878:LPD433
395:TK-690
378:Hytera
332:Motrac
303:(MOS)
292:radio.
246:-core
240:valves
92:mobile
34:, see
2196:South
2191:North
2152:JANET
2089:Telex
2079:Radio
1918:Nodes
1913:Links
1834:media
1412:Radio
1397:Pager
1325:Drums
1291:video
1286:image
1276:audio
1060:CTCSS
698:(PDF)
592:Notes
503:U.S.
452:siren
420:TETRA
367:Today
313:CTCSS
2208:Asia
2094:UUCP
2054:ISDN
1123:APRS
663:The
359:RCA
353:and
244:iron
165:iDEN
146:AMPS
125:and
2099:WAN
2069:NGN
2059:LAN
1340:Fax
1281:DCT
1138:CAD
520:or
426:.)
424:DMR
422:),
206:).
198:MHz
150:GSM
148:or
142:end
111:ITU
73:VHF
71:or
69:UHF
63:or
2292::
760:^
750:.
715:.
338:MJ
323:.
258::
189:MF
152:.
87:.
2226:)
2222:(
1217:e
1210:t
1203:v
821:e
814:t
807:v
754:.
700:.
671:.
478:/
418:(
38:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
