480:
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.
460:
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.
31:
573:. 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
530:
39:
365:. 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,
277:
2240:
2250:
296:(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
2229:
2260:
269:
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.
459:
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
560:
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
431:
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,
206:
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
479:
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.
423:
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
395:
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
87:: 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.
451:
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
272:
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
210:
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
714:
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.
483:
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
427:
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
398:
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
268:
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
90:
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
239:
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.
428:
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.
184:
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
452:
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.
496:
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.
211:
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
549:. 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
606:
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
151:
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
471:(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.
488:
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.
118:
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.
360:
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
280:
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
760:. National Highway Traffic Safety Administration. Evaluating Regional Alternatives. Vol. 2: Regional-level Planning Guide. Washington, DC: Department of Transportation. 1995. pp. 45–49.
64:
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
593:
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.
435:
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,
227:(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
537:
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.
300:. 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-
369:'s HM68X mobile radio, which was introduced in September 2022, offers a variety of features, including GPS location, emergency alarm, noise cancellation, and more.
231:
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
160:, Enhanced Specialized Mobile Radio (ESMR) or conventional two-way systems. Certain modern two-way radio systems may have full-duplex telephone capability.
1504:
304:
tone encoders and more than two channels were unusual. Manufacturers of mobile radios built customized equipment for large radio fleets such as the
207:
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.
493:
641:
Model T31BAT-3100B-SP3 'Dispatcher' Radiophone 25-54 MC 12 W RF Power 12 VDC, State of
California Radio Communications System
2212:
2184:
2179:
1204:
513:, may have several radios in each vehicle. For example, tow cars may have one radio for towing company communications and a second for
808:
468:
102:, a mobile radio is "A station in the mobile service intended to be used while in motion or during halts at unspecified points."
2206:
2201:
2191:
2171:
1973:
125:
are full-duplex (simultaneous talk and listen), circuit switched, and primarily communicate with telephones connected to the
1048:
1338:
569:
Intended as a cost savings, some systems employ vehicular chargers instead of a mobile radio. Each radio user is issued a
202:
to convey intelligence through the communications channel. In time, problems with sources of electrical noise showed that
2263:
2196:
2042:
1058:
639:
It was also seen on some Kaar
Engineering mobile products. One example is the title on a special products service manual
1968:
2062:
1111:
919:
533:
A mobile radio in a US ambulance often has two sets of controls: one in the patient area and another near the driver.
464:
305:
289:
265:
126:
1847:
1395:
1197:
1958:
1953:
24:
455:
Many radios are equipped with transmitter time-out timers which limit the length of a transmission. A bane of
1978:
1028:
871:
2253:
2014:
1911:
1454:
1249:
1221:
909:
856:
134:
56:
refer to wireless communications systems and devices which are based on radio frequencies (using commonly
2243:
1750:
1190:
1078:
924:
801:
168:
Early users of mobile radio equipment included transportation and government. These systems used one-way
215:, then solid-state power supplies to provide high voltage for the vacuum tubes. These circuits, called "
2284:
2102:
2024:
1963:
1670:
1116:
518:
30:
1874:
1835:
1680:
1580:
1509:
1442:
1269:
1141:
972:
934:
436:
404:
309:
545:
Both tow cars and ambulances may have an additional radio which transmits and receives to support a
2233:
1475:
1410:
1363:
1323:
1166:
982:
709:
620:
180:) communications (similar to the AM broadcast band) to improve safety. Instead of hanging out of a
2072:
2057:
1901:
1852:
1775:
1675:
1353:
1239:
1234:
1126:
1073:
876:
293:
1994:
1780:
1595:
1540:
1535:
1348:
1313:
836:
794:
514:
285:
1896:
1700:
1665:
1585:
1565:
1487:
1375:
1296:
1131:
736:
216:
212:
1229:
1810:
1770:
1740:
1497:
1432:
1254:
1136:
987:
851:
846:
546:
412:
203:
199:
148:
264:
Equipment from different US manufacturers had similar traits. This was partly dictated by
129:. The connection sets up based on the user dialing. The connection is taken down when the
8:
1820:
1760:
1519:
1481:
1279:
1264:
1171:
1018:
904:
841:
224:
191:
517:
communications. Ambulances may have a similar arrangement with one radio for government
2047:
2004:
1935:
1805:
1735:
1710:
1645:
1492:
1213:
774:. Macro Corporation and The State of Arizona. 2004. Paragraph 2.4(e), pp. 15.
440:
529:
2087:
2009:
1923:
1906:
1869:
1715:
1545:
1514:
1380:
1274:
1038:
772:
Arizona Phase II Final Report: Statewide Radio
Interoperability Needs Assessment
557:
button which, when acknowledged, allowed voice communication to the dispatch center.
362:
38:
1755:
2092:
2052:
2032:
1999:
1928:
1886:
1800:
1655:
1640:
1615:
1590:
1550:
1400:
1259:
1244:
1023:
297:
177:
1720:
1575:
1343:
1318:
1306:
1156:
1106:
702:"MOS LSI Custom Circuits Offer New Prospects for Communications Equipment Design"
701:
288:
equipment arrived in the 1960s, with more efficient circuitry and smaller size.
189:). Some early systems talked back to dispatch on a 30-50 MHz link, (called
1918:
1790:
1765:
1725:
1695:
1570:
1405:
1358:
1333:
1291:
977:
220:
111:
2278:
2067:
1840:
1830:
1745:
1635:
1630:
1620:
1605:
1427:
1286:
992:
962:
831:
817:
683:
570:
115:
65:
20:
257:
General
Electric Progress Line (Early models without "T-Power" power supply)
1945:
1785:
1730:
1660:
1625:
1560:
1459:
1449:
1301:
1068:
957:
456:
169:
92:
463:
Mobile radio equipment is manufactured to specifications developed by the
2145:
1795:
1705:
1690:
1650:
1610:
1469:
1161:
1151:
1146:
485:
448:
254:
Motorola Twin-V, named for its "universal" 6 or 12 Volt power supply
244:
236:
561:
communications take place over systems on more than one frequency band.
276:
19:
This article is about professional equipment. For mobile radios used in
2150:
1857:
1555:
1464:
1420:
1390:
1368:
444:
400:
181:
737:"Hytera launches MNC360 PoC Mobile Radio for In-Vehicle Communication"
553:
radio systems used a single radio for data and voice. The radio had a
133:
button is pressed. They run on telephony-based infrastructure such as
2135:
1600:
1415:
1182:
1121:
564:
510:
506:
439:
mobile radios have noise-canceling microphones which reduce road and
656:
conflicts with some uses, saying radiophone is interchangeable with
2130:
2120:
2037:
1862:
1685:
1063:
1008:
929:
173:
157:
43:
2125:
2110:
1328:
1083:
1013:
914:
861:
786:
2155:
2115:
1437:
1088:
1053:
939:
886:
881:
866:
715:
Typical examples of completed and present MOS developments are:
366:
79:
A sales person or radio repair shop would understand the word
2140:
2077:
1385:
550:
408:
301:
2082:
315:
Examples of US hybrid partially solid state mobile radios:
243:
Examples of US 1950s-1960s tube-type mobile radios with no
232:
153:
186:
138:
105:
99:
61:
57:
372:
Examples of US microprocessor-controlled mobile radios:
16:
Wireless communications systems using radio frequencies
34:
National Guard operating a mobile radio station (1922)
643:, (Chicago: Motorola Communications Division, 1965).
565:Walkie talkie converters in place of mobile radios
524:
2276:
602:For example, Motorola has trademarked the name
1198:
802:
734:
699:
494:Occupational Safety and Health Administration
399:picture messaging as an example. (Examples:
2213:Global telecommunications regulation bodies
752:
750:
2249:
1205:
1191:
809:
795:
758:Planning Emergency Medical Communications
747:
528:
275:
37:
29:
673:says radiophone is an, "obsolete term."
521:dispatch and one for company dispatch.
469:Telecommunications Industry Association
266:Federal Communications Commission (FCC)
251:Motorola FMTRU-140D (dynamotor powered)
2277:
1212:
500:
106:Nomenclature: Two-way versus telephone
91:117 V AC power might have a
1186:
790:
2259:
735:Anthony Davis (September 28, 2022).
505:Dispatch-reliant services, such as
13:
172:instead of two-way conversations.
156:, Specialized Mobile Radio (SMR),
72:), equipment. An obsolete term is
14:
2296:
920:Common traffic advisory frequency
816:
782:
465:Electronic Industries Association
306:California Department of Forestry
127:public switched telephone network
98:According to article 1.67 of the
2258:
2248:
2239:
2238:
2227:
1848:Free-space optical communication
700:Zeidler, G.; Becker, D. (1974).
596:
260:Kaar Engineering Model 501
764:
728:
693:
676:
663:
646:
633:
587:
525:Multiple controls, microphones
219:", changed the 6 or 12 V
95:mounted on the ship's bridge.
25:amateur radio mobile operation
1:
1029:Maritime mobile amateur radio
626:
540:
176:used medium frequency range (
2234:Telecommunication portal
2015:Telecommunications equipment
1172:Voting (diversity combining)
910:Aircraft emergency frequency
857:General Mobile Radio Service
334:Transistorized Progress Line
7:
1751:Alexander Stepanovich Popov
925:Mandatory frequency airport
671:Newton's Telecom Dictionary
614:
10:
2301:
1455:Telecommunications history
1117:Automatic vehicle location
519:emergency medical services
474:
418:
396:their tube-type ancestors.
163:
18:
2222:
2164:
2101:
2063:Public Switched Telephone
2023:
1987:
1944:
1885:
1875:telecommunication circuit
1836:Fiber-optic communication
1819:
1581:Francis Blake (telephone)
1528:
1376:Optical telecommunication
1220:
1142:Dynamic range compression
1097:
1059:Dual-tone multi-frequency
1037:
1001:
973:Professional mobile radio
948:
935:Single Frequency Approach
895:
824:
684:"R15-WRC15-C-0000!!MSW-E"
669:The 11th edition of
654:Oxford English Dictionary
437:California Highway Patrol
405:Terrestrial Trunked Radio
329:IMTS Car Telephone (1963)
310:California Highway Patrol
290:Metal–oxide–semiconductor
204:frequency modulation (FM)
200:amplitude modulation (AM)
198:Early mobile radios used
42:Mobile radio on board of
1974:Orbital angular-momentum
1411:Satellite communications
1250:Communications satellite
1167:Radiotelephony procedure
983:Specialized Mobile Radio
710:Western Electric Company
706:Electrical Communication
580:
378:Astro Digital Spectra W9
355:
110:The distinction between
1853:Molecular communication
1676:Gardiner Greene Hubbard
1505:Undersea telegraph line
1240:Cable protection system
877:Multi-Use Radio Service
551:Federal Express (FedEx)
294:large-scale integration
1995:Communication protocol
1781:Charles Sumner Tainter
1596:Walter Houser Brattain
1541:Edwin Howard Armstrong
1349:Information revolution
949:Land-based commercial
837:Amateur radio repeater
534:
515:emergency road service
298:high-power transistors
286:Solid-state electronic
282:
46:
35:
1969:Polarization-division
1701:Narinder Singh Kapany
1666:Erna Schneider Hoover
1586:Jagadish Chandra Bose
1566:Alexander Graham Bell
1297:online video platform
951:and government mobile
898:(aeronautical mobile)
532:
279:
41:
33:
1811:Vladimir K. Zworykin
1771:Almon Brown Strowger
1741:Charles Grafton Page
1396:Prepaid mobile phone
1324:Electrical telegraph
988:Trunked radio system
852:Public Radio Service
847:Family Radio Service
825:Amateur and hobbyist
547:mobile data terminal
68:, (sometimes called
1761:Johann Philipp Reis
1520:Wireless revolution
1482:The Telephone Cases
1339:Hydraulic telegraph
1019:Coast radio station
905:Air traffic control
842:Citizens band radio
501:Multiple radio sets
443:noise heard by the
225:alternating current
1959:Frequency-division
1936:Telephone exchange
1806:Charles Wheatstone
1736:Jun-ichi Nishizawa
1711:Innocenzo Manzetti
1646:Reginald Fessenden
1381:Optical telegraphy
1214:Telecommunications
1002:Marine (shipboard)
887:UHF CB (Australia)
535:
340:MASTR Professional
283:
47:
36:
2285:Mobile technology
2272:
2271:
2010:Store and forward
2005:Data transmission
1919:Network switching
1870:Transmission line
1716:Guglielmo Marconi
1681:Internet pioneers
1546:Mohamed M. Atalla
1515:Whistled language
1180:
1179:
1041:Selective calling
621:Land mobile radio
424:and maintenance.
390:mobile-radio-m94g
338:General Electric
332:General Electric
2292:
2262:
2261:
2252:
2251:
2242:
2241:
2232:
2231:
2230:
2103:Notable networks
2093:Wireless network
2033:Cellular network
2025:Types of network
2000:Computer network
1887:Network topology
1801:Thomas A. Watson
1656:Oliver Heaviside
1641:Philo Farnsworth
1616:Daniel Davis Jr.
1591:Charles Bourseul
1551:John Logie Baird
1260:Data compression
1255:Computer network
1207:
1200:
1193:
1184:
1183:
1098:System elements
1024:Marine VHF radio
811:
804:
797:
788:
787:
776:
775:
768:
762:
761:
754:
745:
744:
732:
726:
725:
697:
691:
690:
688:
680:
674:
667:
661:
650:
644:
637:
608:
600:
594:
591:
555:request-to-speak
2300:
2299:
2295:
2294:
2293:
2291:
2290:
2289:
2275:
2274:
2273:
2268:
2228:
2226:
2218:
2160:
2097:
2019:
1983:
1940:
1889:
1881:
1822:
1815:
1721:Robert Metcalfe
1576:Tim Berners-Lee
1524:
1344:Information Age
1216:
1211:
1181:
1176:
1157:Rayleigh fading
1099:
1093:
1040:
1033:
997:
950:
944:
897:
891:
820:
815:
785:
780:
779:
770:
769:
765:
756:
755:
748:
733:
729:
723:— mobile radios
722:
720:
718:
716:
698:
694:
686:
682:
681:
677:
668:
664:
651:
647:
638:
634:
629:
617:
612:
611:
601:
597:
592:
588:
583:
567:
543:
527:
503:
477:
421:
397:
358:
344:MASTR Executive
166:
147:is primarily a
123:Radiotelephones
112:radiotelephones
108:
85:vehicle-mounted
28:
17:
12:
11:
5:
2298:
2288:
2287:
2270:
2269:
2267:
2266:
2256:
2246:
2236:
2223:
2220:
2219:
2217:
2216:
2209:
2204:
2199:
2194:
2189:
2188:
2187:
2182:
2174:
2168:
2166:
2162:
2161:
2159:
2158:
2153:
2148:
2143:
2138:
2133:
2128:
2123:
2118:
2113:
2107:
2105:
2099:
2098:
2096:
2095:
2090:
2085:
2080:
2075:
2070:
2065:
2060:
2055:
2050:
2045:
2040:
2035:
2029:
2027:
2021:
2020:
2018:
2017:
2012:
2007:
2002:
1997:
1991:
1989:
1985:
1984:
1982:
1981:
1976:
1971:
1966:
1961:
1956:
1954:Space-division
1950:
1948:
1942:
1941:
1939:
1938:
1933:
1932:
1931:
1926:
1916:
1915:
1914:
1904:
1899:
1893:
1891:
1883:
1882:
1880:
1879:
1878:
1877:
1867:
1866:
1865:
1855:
1850:
1845:
1844:
1843:
1833:
1827:
1825:
1817:
1816:
1814:
1813:
1808:
1803:
1798:
1793:
1791:Camille Tissot
1788:
1783:
1778:
1773:
1768:
1766:Claude Shannon
1763:
1758:
1756:Tivadar Puskás
1753:
1748:
1743:
1738:
1733:
1728:
1726:Antonio Meucci
1723:
1718:
1713:
1708:
1703:
1698:
1696:Charles K. Kao
1693:
1688:
1683:
1678:
1673:
1671:Harold Hopkins
1668:
1663:
1658:
1653:
1648:
1643:
1638:
1633:
1628:
1623:
1618:
1613:
1608:
1603:
1598:
1593:
1588:
1583:
1578:
1573:
1571:Emile Berliner
1568:
1563:
1558:
1553:
1548:
1543:
1538:
1532:
1530:
1526:
1525:
1523:
1522:
1517:
1512:
1510:Videotelephony
1507:
1502:
1501:
1500:
1495:
1485:
1478:
1473:
1467:
1462:
1457:
1452:
1447:
1446:
1445:
1440:
1435:
1425:
1424:
1423:
1413:
1408:
1406:Radiotelephone
1403:
1398:
1393:
1388:
1383:
1378:
1373:
1372:
1371:
1361:
1356:
1351:
1346:
1341:
1336:
1331:
1326:
1321:
1316:
1311:
1310:
1309:
1304:
1299:
1294:
1292:Internet video
1284:
1283:
1282:
1277:
1272:
1267:
1257:
1252:
1247:
1242:
1237:
1232:
1226:
1224:
1218:
1217:
1210:
1209:
1202:
1195:
1187:
1178:
1177:
1175:
1174:
1169:
1164:
1159:
1154:
1149:
1144:
1139:
1134:
1129:
1124:
1119:
1114:
1109:
1103:
1101:
1100:and principles
1095:
1094:
1092:
1091:
1086:
1081:
1076:
1071:
1066:
1061:
1056:
1051:
1045:
1043:
1035:
1034:
1032:
1031:
1026:
1021:
1016:
1011:
1005:
1003:
999:
998:
996:
995:
990:
985:
980:
978:Radio repeater
975:
970:
965:
960:
954:
952:
946:
945:
943:
942:
937:
932:
927:
922:
917:
912:
907:
901:
899:
893:
892:
890:
889:
884:
879:
874:
869:
864:
859:
854:
849:
844:
839:
834:
828:
826:
822:
821:
814:
813:
806:
799:
791:
784:
783:External links
781:
778:
777:
763:
746:
741:Highways Today
727:
719:— multiplexers
692:
675:
662:
658:radiotelephone
645:
631:
630:
628:
625:
624:
623:
616:
613:
610:
609:
595:
585:
584:
582:
579:
566:
563:
542:
539:
526:
523:
502:
499:
476:
473:
420:
417:
393:
392:
386:
380:
357:
354:
353:
352:
346:
336:
330:
323:
262:
261:
258:
255:
252:
221:direct current
165:
162:
107:
104:
15:
9:
6:
4:
3:
2:
2297:
2286:
2283:
2282:
2280:
2265:
2257:
2255:
2247:
2245:
2237:
2235:
2225:
2224:
2221:
2214:
2210:
2208:
2205:
2203:
2200:
2198:
2195:
2193:
2190:
2186:
2183:
2181:
2178:
2177:
2175:
2173:
2170:
2169:
2167:
2163:
2157:
2154:
2152:
2149:
2147:
2144:
2142:
2139:
2137:
2134:
2132:
2129:
2127:
2124:
2122:
2119:
2117:
2114:
2112:
2109:
2108:
2106:
2104:
2100:
2094:
2091:
2089:
2086:
2084:
2081:
2079:
2076:
2074:
2071:
2069:
2066:
2064:
2061:
2059:
2056:
2054:
2051:
2049:
2046:
2044:
2041:
2039:
2036:
2034:
2031:
2030:
2028:
2026:
2022:
2016:
2013:
2011:
2008:
2006:
2003:
2001:
1998:
1996:
1993:
1992:
1990:
1986:
1980:
1979:Code-division
1977:
1975:
1972:
1970:
1967:
1965:
1964:Time-division
1962:
1960:
1957:
1955:
1952:
1951:
1949:
1947:
1943:
1937:
1934:
1930:
1927:
1925:
1922:
1921:
1920:
1917:
1913:
1910:
1909:
1908:
1905:
1903:
1900:
1898:
1895:
1894:
1892:
1890:and switching
1888:
1884:
1876:
1873:
1872:
1871:
1868:
1864:
1861:
1860:
1859:
1856:
1854:
1851:
1849:
1846:
1842:
1841:optical fiber
1839:
1838:
1837:
1834:
1832:
1831:Coaxial cable
1829:
1828:
1826:
1824:
1818:
1812:
1809:
1807:
1804:
1802:
1799:
1797:
1794:
1792:
1789:
1787:
1784:
1782:
1779:
1777:
1774:
1772:
1769:
1767:
1764:
1762:
1759:
1757:
1754:
1752:
1749:
1747:
1746:Radia Perlman
1744:
1742:
1739:
1737:
1734:
1732:
1729:
1727:
1724:
1722:
1719:
1717:
1714:
1712:
1709:
1707:
1704:
1702:
1699:
1697:
1694:
1692:
1689:
1687:
1684:
1682:
1679:
1677:
1674:
1672:
1669:
1667:
1664:
1662:
1659:
1657:
1654:
1652:
1649:
1647:
1644:
1642:
1639:
1637:
1636:Lee de Forest
1634:
1632:
1631:Thomas Edison
1629:
1627:
1624:
1622:
1621:Donald Davies
1619:
1617:
1614:
1612:
1609:
1607:
1606:Claude Chappe
1604:
1602:
1599:
1597:
1594:
1592:
1589:
1587:
1584:
1582:
1579:
1577:
1574:
1572:
1569:
1567:
1564:
1562:
1559:
1557:
1554:
1552:
1549:
1547:
1544:
1542:
1539:
1537:
1534:
1533:
1531:
1527:
1521:
1518:
1516:
1513:
1511:
1508:
1506:
1503:
1499:
1496:
1494:
1491:
1490:
1489:
1486:
1484:
1483:
1479:
1477:
1474:
1471:
1468:
1466:
1463:
1461:
1458:
1456:
1453:
1451:
1450:Smoke signals
1448:
1444:
1441:
1439:
1436:
1434:
1431:
1430:
1429:
1428:Semiconductor
1426:
1422:
1419:
1418:
1417:
1414:
1412:
1409:
1407:
1404:
1402:
1399:
1397:
1394:
1392:
1389:
1387:
1384:
1382:
1379:
1377:
1374:
1370:
1367:
1366:
1365:
1362:
1360:
1357:
1355:
1352:
1350:
1347:
1345:
1342:
1340:
1337:
1335:
1332:
1330:
1327:
1325:
1322:
1320:
1317:
1315:
1312:
1308:
1305:
1303:
1300:
1298:
1295:
1293:
1290:
1289:
1288:
1287:Digital media
1285:
1281:
1278:
1276:
1273:
1271:
1268:
1266:
1263:
1262:
1261:
1258:
1256:
1253:
1251:
1248:
1246:
1243:
1241:
1238:
1236:
1233:
1231:
1228:
1227:
1225:
1223:
1219:
1215:
1208:
1203:
1201:
1196:
1194:
1189:
1188:
1185:
1173:
1170:
1168:
1165:
1163:
1160:
1158:
1155:
1153:
1150:
1148:
1145:
1143:
1140:
1138:
1135:
1133:
1130:
1128:
1125:
1123:
1120:
1118:
1115:
1113:
1110:
1108:
1105:
1104:
1102:
1096:
1090:
1087:
1085:
1082:
1080:
1077:
1075:
1072:
1070:
1067:
1065:
1062:
1060:
1057:
1055:
1052:
1050:
1047:
1046:
1044:
1042:
1036:
1030:
1027:
1025:
1022:
1020:
1017:
1015:
1012:
1010:
1007:
1006:
1004:
1000:
994:
993:Walkie-talkie
991:
989:
986:
984:
981:
979:
976:
974:
971:
969:
966:
964:
963:Business band
961:
959:
956:
955:
953:
947:
941:
938:
936:
933:
931:
928:
926:
923:
921:
918:
916:
913:
911:
908:
906:
903:
902:
900:
894:
888:
885:
883:
880:
878:
875:
873:
870:
868:
865:
863:
860:
858:
855:
853:
850:
848:
845:
843:
840:
838:
835:
833:
832:Amateur radio
830:
829:
827:
823:
819:
818:Two-way radio
812:
807:
805:
800:
798:
793:
792:
789:
773:
767:
759:
753:
751:
742:
738:
731:
724:
717:— crosspoints
711:
707:
703:
696:
685:
679:
672:
666:
659:
655:
649:
642:
636:
632:
622:
619:
618:
605:
599:
590:
586:
578:
576:
572:
571:walkie talkie
562:
558:
556:
552:
548:
538:
531:
522:
520:
516:
512:
508:
498:
495:
490:
487:
481:
472:
470:
466:
461:
458:
453:
450:
446:
442:
438:
433:
429:
425:
416:
414:
410:
406:
402:
391:
387:
385:
381:
379:
375:
374:
373:
370:
368:
364:
351:
350:Super Carfone
347:
345:
341:
337:
335:
331:
328:
324:
322:
318:
317:
316:
313:
311:
307:
303:
299:
295:
291:
287:
278:
274:
270:
267:
259:
256:
253:
250:
249:
248:
246:
241:
238:
234:
230:
226:
222:
218:
214:
208:
205:
201:
196:
194:
193:
188:
183:
179:
175:
171:
161:
159:
155:
150:
146:
145:Two-way radio
142:
140:
136:
132:
128:
124:
120:
117:
116:two-way radio
113:
103:
101:
96:
94:
88:
86:
82:
77:
75:
71:
67:
63:
59:
55:
51:
45:
40:
32:
26:
22:
21:amateur radio
1946:Multiplexing
1821:Transmission
1786:Nikola Tesla
1776:Henry Sutton
1731:Samuel Morse
1661:Robert Hooke
1626:Amos Dolbear
1561:John Bardeen
1480:
1460:Telautograph
1364:Mobile phone
1319:Edholm's law
1302:social media
1235:Broadcasting
1079:Quik-Call II
1069:Push-to-talk
1039:Signaling /
968:Mobile radio
967:
958:Base station
771:
766:
757:
740:
730:
713:
705:
695:
678:
670:
665:
657:
653:
648:
640:
635:
604:Converta-Com
603:
598:
589:
575:jerk-and-run
574:
568:
559:
554:
544:
536:
504:
491:
482:
478:
462:
457:push-to-talk
454:
449:fire engines
434:
430:
426:
422:
394:
389:
388:PositionPTT
383:
377:
371:
359:
349:
343:
339:
333:
326:
320:
314:
284:
271:
263:
242:
237:transformers
228:
209:
197:
190:
170:broadcasting
167:
144:
143:
130:
122:
121:
109:
97:
93:base station
89:
84:
80:
78:
73:
69:
66:hand-carried
53:
50:Mobile radio
49:
48:
2146:NPL network
1858:Radio waves
1796:Alfred Vail
1706:Hedy Lamarr
1691:Dawon Kahng
1651:Elisha Gray
1611:Yogen Dalal
1536:Nasir Ahmed
1470:Teleprinter
1334:Heliographs
1162:Tone remote
1152:Link budget
1147:Fade margin
1074:Quik-Call I
486:engine idle
403:(APCO-25),
245:transistors
2192:Antarctica
2151:Toasternet
2073:Television
1556:Paul Baran
1488:Television
1472:(teletype)
1465:Telegraphy
1443:transistor
1421:Phryctoria
1391:Photophone
1369:Smartphone
1359:Mass media
872:Mobile rig
627:References
541:Data radio
511:ambulances
445:dispatcher
401:Project 25
182:locomotive
74:radiophone
2176:Americas
2165:Locations
2136:Internet2
1897:Bandwidth
1601:Vint Cerf
1498:streaming
1476:Telephone
1416:Semaphore
1307:streaming
1132:DC remote
1122:Call sign
896:Aviation
712:: 88–92.
708:. 49–50.
577:systems.
432:shaking.
376:Motorola
325:Motorola
319:Motorola
273:channel.
217:inverters
213:vibrators
192:crossband
174:Railroads
2279:Category
2244:Category
2131:Internet
2121:CYCLADES
2038:Ethernet
1988:Concepts
1912:terminal
1863:wireless
1686:Bob Kahn
1529:Pioneers
1354:Internet
1245:Cable TV
1137:Dispatch
1064:MDC-1200
1009:2182 kHz
930:MULTICOM
721:— modems
615:See also
507:tow cars
382:Kenwood
308:and the
223:(DC) to
158:MPT-1327
149:dispatch
83:to mean
70:portable
44:Zeppelin
2264:Commons
2254:Outline
2207:Oceania
2126:FidoNet
2111:ARPANET
1924:circuit
1493:digital
1222:History
1107:Antenna
1084:Selcall
1014:500 kHz
915:Airband
862:KDR 444
607:radios.
484:diesel
475:Antenna
447:. Most
419:Details
363:unit ID
164:History
54:mobiles
2202:Europe
2172:Africa
2156:Usenet
2116:BITNET
2053:Mobile
1929:packet
1438:MOSFET
1433:device
1230:Beacon
1089:SELCAL
1054:D-STAR
940:UNICOM
882:PMR446
867:LPD433
384:TK-690
367:Hytera
321:Motrac
292:(MOS)
281:radio.
235:-core
229:valves
81:mobile
23:, see
2185:South
2180:North
2141:JANET
2078:Telex
2068:Radio
1907:Nodes
1902:Links
1823:media
1401:Radio
1386:Pager
1314:Drums
1280:video
1275:image
1265:audio
1049:CTCSS
687:(PDF)
581:Notes
492:U.S.
441:siren
409:TETRA
356:Today
302:CTCSS
2197:Asia
2083:UUCP
2043:ISDN
1112:APRS
652:The
348:RCA
342:and
233:iron
154:iDEN
135:AMPS
114:and
2088:WAN
2058:NGN
2048:LAN
1329:Fax
1270:DCT
1127:CAD
509:or
415:.)
413:DMR
411:),
195:).
187:MHz
139:GSM
137:or
131:end
100:ITU
62:VHF
60:or
58:UHF
52:or
2281::
749:^
739:.
704:.
327:MJ
312:.
247::
178:MF
141:.
76:.
2215:)
2211:(
1206:e
1199:t
1192:v
810:e
803:t
796:v
743:.
689:.
660:.
467:/
407:(
27:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
