129:
486:
141:
262:
198:
432:
2573:
250:
210:
373:
32:
2583:
389:
2562:
2593:
174:" button, which turns off the receiver and turns on the transmitter; when the button is released, the receiver is activated again. Multiple channels are provided so separate user groups can communicate in the same area without interfering with each other and some radios are designed to scan the channels in order to find a valid transmission. Other two-way radio systems operate in
170:, in which transmission can only be sent in one direction, and full-duplex, which allows transmission in both directions simultaneously.) This requires users in a group to take turns talking. The radio is normally in receive mode so the user can hear all other transmissions on the channel. When the user wants to talk, they press a "
364:, and estimate how well signals will penetrate buildings. These models will be backed-up by drive testing and actual field signal level measurements. Designers adjust antenna patterns, add or move equipment sites, and design antenna networks in a way that will accomplish the intended level of performance.
493:
Typical two-way radios work on fixed radio frequency channels, though some can scan multiple channels in order to find a valid transmission. In an analog, conventional system, (the simplest type of system) a frequency or channel serves as a physical medium or link carrying communicated information.
325:
Analog systems may communicate a single condition, such as water level in a livestock tank. A transmitter at the tank site continually sends a signal with a constant audio tone. The tone would change in pitch to indicate the tank's water level. A meter at the remote end would vary, corresponding to
409:
In government systems, equipment may be replaced based on budgeting rather than any plan or expected service life. Funding in government agencies may be cyclical or sporadic. Managers may replace computing systems, vehicles, or budget computer and vehicle support costs while ignoring two-way radio
343:
button, sending data in the opposite direction and flagging the call as received by the driver. They can be used for analog telemetry systems, such as the livestock tank levels, as described above. Another possibility is the lubricating oil pressure in a transit bus engine, or the current speed of
417:
Another source says system backbone equipment like consoles and base stations are expected to have a fifteen-year life. Mobile radios are expected to last ten years. Walkie talkies typically last eight. In a State of
California document, the Department of General Services reports expected service
384:
Many mobile and handhelds have a limited duty cycle. Duty Cycle is the ratio of listening time to transmit time and is generally dependent on how well the transmitter can shed the heat from the heat sink on the rear of the radio. A 10% duty cycle (common on handhelds) translates to 10 seconds of
359:
or standard. They are designed as systems with all equipment matched to perform together. For example, a modern, local government two-way radio system in the US may be designed to provide 95% area coverage in an urban area. System designers use radio frequency models, terrain models, and signal
413:
One document says "seven years" is beyond the expected lifetime of walkie-talkies in police service. Batteries are cited as needing replacement more often. Twelve-year-old dispatch consoles mentioned in the same document were identified as usable. These were compared to problematic 21-year-old
315:
Disadvantage: If a radio cannot reach the repeater, it cannot communicate. This can be mitigated with a "talk around" or "car to car" setting where stations out of range of the base can speak directly to each other, alternating transmitting and receiving roles in simplex fashion on a single
832:, Soviet Military Thought Series #18, (Washington, D.C.: Superintendent of Documents, 1977) Library of Congress Control Number: 84602565. This is a US Air Force translation of a Soviet-era, Russian-language book. See also, "Inadequate System Capacity,"
229:
were the first in the world to use wireless communication in cars, putting an end to the inefficient status reports via public telephone boxes which had been used until that time. The first sets occupied about half of the floor in the back seat of the
330:. In the US, mid-band 72–76 MHz or UHF 450–470 MHz interstitial channels are often used for these systems. Some systems multiplex telemetry of several analog conditions by limiting each to a separate range of tone pitches, for example.
298:
set standards for channel access times and delays caused by system overhead. Scan features can further increase these delays. One study said delays of longer than 0.4 seconds (400 milliseconds) in emergency services are not recommended.
128:
338:
Digital systems may communicate text messages from computer-aided dispatch (CAD). For example, a display in a tow truck may give a textual location for a call and any related details. The tow truck driver may press an
311:
Advantage: duplex channels usually allow repeater operation which extends range (in most cases due to increased transmit power and improved aerial location / height) – especially where hand-held radios are in
967:, November 1964, pp. 2935-2971. 800 MHz trivia: this article shows that signal fades occur at audio frequencies near CTCSS tones, explaining why only DCS was used in Motorola 800 MHz systems in the 1970s.
919:
Planning
Emergency Medical Communications: Volume 2, Local/Regional-Level Planning Guide, (Washington, D.C.: National Highway Traffic Safety Administration, US Department of Transportation, 1995) pp. 48.
326:
the tone pitch, to indicate the amount of water present in the livestock tank. Similar methods can be used to telemeter any analog condition. This type of radio system serves a purpose equivalent to a
241:
police department successfully operated a two-way system between a central fixed station and radio transceivers installed in police cars; this allowed rapidly directing police response in emergencies.
344:
the bus. Analog conditions are translated into data words. Some systems send radio paging messages which can either 1) beep a paging receiver, 2) send a numeric message, or 3) send a text message.
166:
Two-way radios usually use a half-duplex communication channel, which permits two-way communication, albeit with the limitation that only one user can transmit at a time. (This is in contrast to
550:
has become an important activity of governments to regulate radio users in the interests of both efficient and non-interfering use of radio. Both bands are widely applied for different users.
360:
propagation modeling software in an attempt to accurately estimate where radios will work within a defined geographic area. The models help designers choose equipment, equipment locations,
163:), which is used for bidirectional person-to-person voice communication with other users with similar radios, in contrast to a broadcast receiver, which only receives transmissions.
494:
The performance of a radio system is partly dependent on the characteristics of frequency band used. The selection of a frequency for a two-way radio system is affected, in part, by:
385:
transmit time to 90 seconds of receive time. Some mobile and base equipment is specified at different power levels – for example 100% duty cycle at 25 watts and 15% at 40 watts.
307:
The term "half duplex" is applied to wired communication systems where the circuit can send information in one direction at a time but not both directions at the same time.
895:
USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire
Administration, 1999) pp. 25-26. This article also confirms the definition of the phrase talk around.
1837:
824:
One example of purpose-specific channel assignments is described in Ivanov, D. A., V. P. Savelyev, and P. V. Shemanski, "Organization of
Communications,"
813:
960:
Ossanna, Jr., Joseph F., "A Model For Mobile Radio Fading Due to
Building Reflections: Theoretical and Experimental Fading Waveform Power Spectra,"
185:
The first two-way radio was an AM-only device introduced by the Galvin
Manufacturing Corporation in 1940 for use by the police and military during
442:
987:
For one example, see: "Plan
Element S-7: Rationalized Funding" and "Plan Element L-2: Permanent Contra Costa Public Safety Radio Authority,"
2545:
2517:
2512:
1537:
930:
178:
mode, in which both parties can talk simultaneously. This requires either two separate radio channels or channel sharing methods such as
1141:
410:
equipment. Equipment may remain in use even though maintenance costs are unreasonable when viewed from an efficiency standpoint.
957:, 80-C477, (Sacramento, California: Department of General Services, Communications Technology Division, 1982,) pp. II-1 - II-34.
2539:
1008:, (Oklahoma City, Oklahoma: Oklahoma City Municipal Facilities Authority, Public Safety Capital Projects Office, 2000) pp. 56.
2534:
2524:
2504:
2306:
878:"IEEE 100 The Authoritative Dictionary of IEEE Standards Terms", Seventh Edition, IEEE Press, 2000, ISBN SBN 0-7381 -2601 -2
96:
1381:
742:
1671:
694:
565:
There are other factors that affect the range of a two-way radio such as weather, exact frequency used, and obstructions.
68:
2596:
2529:
2375:
1391:
2301:
771:
2395:
1444:
1252:
840:
USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire
Administration, 1999) pp. 18-19 and "5.2 Present System,"
801:
708:
677:
472:
115:
75:
2180:
1728:
1530:
189:, and followed by the company's 1943 introduction of the Walkie-Talkie, the best-known example of a two-way radio.
2291:
294:
Scan features are either not used or scan lists are intentionally kept short in emergency applications. Part of
2286:
82:
53:
49:
2617:
2311:
1361:
1204:
2586:
2347:
2244:
1787:
1582:
1554:
1242:
1189:
667:
64:
2576:
2083:
1523:
1411:
1257:
1134:
1034:"8000 Exhibits:Equipment Replacement Costs for a Typical Three Position CDF Command and Control Center,"
175:
1070:
253:
Several portable two-way radios designed for public services (police, fire, rescue) compatible with the
2435:
2357:
2296:
2003:
1449:
904:
For examples, see, Mikhailov, K. E. "Communications
Facilities on the Volga-Moscow Transmission Line,"
700:
737:
418:
life for a communications console used in the
Department of Forestry and Fire Protection is 10 years.
2207:
2168:
2013:
1913:
1842:
1775:
1602:
1474:
1305:
1267:
843:
624:
574:
2566:
1808:
1743:
1696:
1656:
1499:
1315:
629:
182:(TDD) to carry the two directions of the conversation simultaneously on a single radio frequency.
1084:
1038:, (Sacramento, California: State of California, Department of Forestry and Fire Protection, 2006)
2405:
2390:
2234:
2185:
2108:
2008:
1686:
1572:
1567:
1459:
1406:
1209:
42:
2327:
2113:
1928:
1873:
1868:
1681:
1646:
1169:
1127:
1110:
1022:
866:
849:
634:
133:
906:
Long-Distance Electrical Transmission between the V. I. Lenin Hydroelectric Station and Moscow
2229:
2033:
1998:
1918:
1898:
1820:
1708:
1629:
1464:
1039:
167:
16:
Radio that can both transmit and receive a signal, used for bidirectional voice communication
1562:
2143:
2103:
2073:
1830:
1765:
1587:
1469:
1320:
1184:
1179:
852:: Department of General Services, Communications Technology Division, 1982,) pp. V-4 - V-6.
594:
584:
535:
179:
89:
8:
2153:
2093:
1852:
1814:
1612:
1597:
1504:
1351:
1237:
1174:
1057:, (Sacramento, California: State of California EMS Authority, September 2000) pp.38. and
950:
For two examples of drive testing and field measurements of received signal levels, see:
827:
547:
531:
238:
2380:
2337:
2268:
2138:
2068:
2043:
1978:
1825:
1546:
454:
450:
273:
Two-way radio systems can be classified in several ways depending on their attributes.
1095:
2420:
2342:
2256:
2239:
2202:
2048:
1878:
1847:
1713:
1607:
1371:
992:
797:
732:
704:
673:
559:
266:
2088:
2425:
2385:
2365:
2332:
2261:
2219:
2133:
1988:
1973:
1948:
1923:
1883:
1733:
1592:
1577:
1356:
955:
The California Highway Patrol Communications Technology Research Project on 800 MHz
579:
521:
in the US, some frequencies require approval of a frequency coordination committee.
1059:
Arizona Phase II Final Report: Statewide Radio Inter-operability Needs Assessment,
225:
in 1923 by Senior Constable Frederick William Downie of the Victorian Police. The
19:
This article is about two-way radio in general. For hand-held two-way radios, see
2053:
1908:
1676:
1651:
1639:
1489:
1439:
361:
226:
2251:
2123:
2098:
2058:
2028:
1903:
1738:
1691:
1666:
1624:
1310:
646:
614:
539:
504:
terrain, since radio signals travel differently in forests and urban viewsheds.
485:
393:
140:
2611:
2400:
2173:
2163:
2078:
1968:
1963:
1953:
1938:
1760:
1619:
1325:
1295:
1164:
356:
20:
767:
2278:
2118:
2063:
1993:
1958:
1893:
1792:
1782:
1634:
1401:
1300:
1290:
641:
619:
543:
261:
202:
197:
186:
171:
2478:
2128:
2038:
2023:
1983:
1943:
1802:
1494:
1484:
1479:
962:
835:
609:
511:
156:
2483:
2190:
1888:
1797:
1753:
1723:
1701:
604:
377:
254:
249:
214:
160:
2468:
1933:
1748:
1515:
1454:
599:
372:
222:
209:
286:
In multi-channel systems, channels are used for separate purposes.
31:
2463:
2453:
2370:
2195:
2018:
1396:
1341:
1262:
1019:
San Rafael Police Radio Committee: Report to Mayor and City Council
863:
San Rafael Police Radio Committee: Report to Mayor and City Council
397:
388:
2458:
2443:
1661:
1416:
1346:
1247:
1194:
908:, (Jerusalem: Israeli Program for Scientific Translations, 1965).
327:
295:
1119:
221:
The first truly mobile two-way radio equipment was developed in
2488:
2448:
1770:
1421:
1386:
1272:
1219:
1214:
1199:
1114:
589:
231:
2473:
2410:
1718:
558:
The useful direct range of a two-way radio system depends on
441:
deal primarily with the United States and do not represent a
153:
144:
A variety of portable handheld two-way radios for private use
1096:"2-Way Radio Range: How Far Can Two-Way Radios Communicate?"
2415:
1004:
For one example, see: "3.2.10.1 Current System Problems,"
989:
Contra Costa County Public Safety Mobile Radio Master Plan
515:
367:
217:
used by firefighters to communicate with their dispatcher
542:. Because this part of the spectrum is heavily used for
507:
the presence of noise, interference, or intermodulation.
400:
mounted in Flightcase, 100% Duty cycle up to 40 W output
136:
communicates with aircraft over a two-way radio headset
1080:
1078:
893:
Special Report: Improving Firefighter Communications,
846:
Communications Technology Research Project on 800 MHz
530:
The most common two-way radio systems operate in the
931:"Spartan Training Bulletin - Volume One – Issue One"
794:
The People's Force, A history of the Victoria Police
1049:
1047:
347:
56:. Unsourced material may be challenged and removed.
1075:
289:
1061:Macro Corporation and The State of Arizona, 2004.
2609:
1044:
917:For an electrocardiogram telemetry example, see
501:local congestion or availability of frequencies.
1055:California EMS Communications Plan: Final Draft
995:: Federal Engineering, Inc., 2002,) pp. 45, 49.
562:conditions, which are a function of frequency.
510:sky wave interference below 50–60 MHz and
489:Two GMRS radios, a hand mic, and two FRS radios
376:Example of control arrangement on a configured
814:IEEE History Milestones retrieved Oct. 2, 2007
762:
760:
276:
1531:
1135:
861:"3.4.1 User Equipment General Deficiencies,"
439:The examples and perspective in this section
421:
414:consoles used elsewhere in the same system.
159:(a radio that can both transmit and receive
2546:Global telecommunications regulation bodies
1006:Trunked Radio System: Request For Proposals
757:
355:systems are designed to perform close to a
2582:
1538:
1524:
1142:
1128:
730:
457:, or create a new section, as appropriate.
953:"Section II: Radio Propagation Studies,"
692:
473:Learn how and when to remove this message
116:Learn how and when to remove this message
669:Modern Dictionary of Electronics, 7th Ed
484:
387:
371:
260:
248:
208:
196:
139:
127:
2610:
1545:
368:Options, duty cycle, and configuration
1519:
1123:
1053:See, "Appendix B - FCC Regulations,"
872:
745:from the original on January 18, 2023
498:government licensing and regulations.
2592:
869:: City of San Rafael, 1995,) pp. 12.
768:"A complete guide to Two-way Radios"
665:
425:
404:
54:adding citations to reliable sources
25:
1025:: City of San Rafael, 1995,) pp. 8.
978:Kenwood TKR-850 specification sheet
659:
13:
774:from the original on June 26, 2022
14:
2629:
1253:Common traffic advisory frequency
1149:
1104:
575:TETRA (Terrestrial Trunked Radio)
525:
2591:
2581:
2572:
2571:
2560:
2181:Free-space optical communication
1071:"VHF or UHF... Which Is Better?"
1040:Adobe PDF file on console costs.
693:Goldsmith, Andrea (8 Aug 2005).
430:
348:Engineered versus not engineered
30:
1089:
1064:
1028:
1011:
998:
981:
972:
944:
923:
911:
898:
881:
328:four-to-twenty milliampere loop
290:Scanning in conventional radios
281:
41:needs additional citations for
1036:8000 Telecommunications Manual
891:use, see "Problem Reporting,"
855:
818:
807:
796:. Melbourne University Press.
786:
731:Hall, Mark (October 3, 2022).
724:
686:
1:
1362:Maritime mobile amateur radio
770:. Crystal Radio Systems Ltd.
652:
546:and multiple competing uses,
2567:Telecommunication portal
2348:Telecommunications equipment
1505:Voting (diversity combining)
1243:Aircraft emergency frequency
1190:General Mobile Radio Service
7:
2084:Alexander Stepanovich Popov
1258:Mandatory frequency airport
1017:"2.4 Equipment Inventory,"
568:
453:, discuss the issue on the
277:Conventional versus trunked
10:
2634:
1788:Telecommunications history
1450:Automatic vehicle location
834:Special Report: Improving
701:Cambridge University Press
333:
192:
18:
2555:
2497:
2434:
2396:Public Switched Telephone
2356:
2320:
2277:
2218:
2208:telecommunication circuit
2169:Fiber-optic communication
2152:
1914:Francis Blake (telephone)
1861:
1709:Optical telecommunication
1553:
1475:Dynamic range compression
1430:
1392:Dual-tone multi-frequency
1370:
1334:
1306:Professional mobile radio
1281:
1268:Single Frequency Approach
1228:
1157:
844:California Highway Patrol
826:Fundamentals of Tactical
672:. Elsevier. p. 811.
625:Professional Mobile Radio
422:Two-way radio frequencies
380:-capable hand-held radio.
320:
302:
2307:Orbital angular-momentum
1744:Satellite communications
1583:Communications satellite
1500:Radiotelephony procedure
1316:Specialized Mobile Radio
792:Haldane, Robert. (1995)
666:Graf, Rudolf F. (1999).
630:Specialized Mobile Radio
553:
244:
2186:Molecular communication
2009:Gardiner Greene Hubbard
1838:Undersea telegraph line
1573:Cable protection system
1210:Multi-Use Radio Service
738:Encyclopædia Britannica
696:Wireless Communications
257:digital radio standard
2328:Communication protocol
2114:Charles Sumner Tainter
1929:Walter Houser Brattain
1874:Edwin Howard Armstrong
1682:Information revolution
1282:Land-based commercial
1170:Amateur radio repeater
1023:San Rafael, California
867:San Rafael, California
850:Sacramento, California
635:Mobile radio telephone
490:
401:
381:
270:
258:
218:
206:
145:
137:
134:air traffic controller
2302:Polarization-division
2034:Narinder Singh Kapany
1999:Erna Schneider Hoover
1919:Jagadish Chandra Bose
1899:Alexander Graham Bell
1630:online video platform
1284:and government mobile
1231:(aeronautical mobile)
488:
391:
375:
264:
252:
212:
200:
168:simplex communication
143:
131:
2618:Radio communications
2144:Vladimir K. Zworykin
2104:Almon Brown Strowger
2074:Charles Grafton Page
1729:Prepaid mobile phone
1657:Electrical telegraph
1321:Trunked radio system
1185:Public Radio Service
1180:Family Radio Service
1158:Amateur and hobbyist
595:Family Radio Service
585:Digital Mobile Radio
451:improve this section
180:time-division duplex
50:improve this article
2094:Johann Philipp Reis
1853:Wireless revolution
1815:The Telephone Cases
1672:Hydraulic telegraph
1352:Coast radio station
1238:Air traffic control
1175:Citizens band radio
1085:Two Way Radio Range
828:Command and Control
548:spectrum management
239:Bayonne, New Jersey
213:Two-way radio in a
2292:Frequency-division
2269:Telephone exchange
2139:Charles Wheatstone
2069:Jun-ichi Nishizawa
2044:Innocenzo Manzetti
1979:Reginald Fessenden
1714:Optical telegraphy
1547:Telecommunications
1335:Marine (shipboard)
1220:UHF CB (Australia)
887:For an example of
491:
402:
392:Motorola MOTOTRBO
382:
271:
259:
219:
207:
146:
138:
2605:
2604:
2343:Store and forward
2338:Data transmission
2252:Network switching
2203:Transmission line
2049:Guglielmo Marconi
2014:Internet pioneers
1879:Mohamed M. Atalla
1848:Whistled language
1513:
1512:
1374:Selective calling
993:Fairfax, Virginia
965:Technical Journal
560:radio propagation
483:
482:
475:
405:Life of equipment
126:
125:
118:
100:
2625:
2595:
2594:
2585:
2584:
2575:
2574:
2565:
2564:
2563:
2436:Notable networks
2426:Wireless network
2366:Cellular network
2358:Types of network
2333:Computer network
2220:Network topology
2134:Thomas A. Watson
1989:Oliver Heaviside
1974:Philo Farnsworth
1949:Daniel Davis Jr.
1924:Charles Bourseul
1884:John Logie Baird
1593:Data compression
1588:Computer network
1540:
1533:
1526:
1517:
1516:
1431:System elements
1357:Marine VHF radio
1144:
1137:
1130:
1121:
1120:
1098:
1093:
1087:
1082:
1073:
1068:
1062:
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1026:
1015:
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1002:
996:
985:
979:
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948:
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939:
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927:
921:
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909:
902:
896:
885:
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876:
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822:
816:
811:
805:
790:
784:
783:
781:
779:
764:
755:
754:
752:
750:
733:"Motorola, Inc."
728:
722:
721:
719:
717:
690:
684:
683:
663:
580:Astro (Motorola)
478:
471:
467:
464:
458:
434:
433:
426:
269:radio in a truck
121:
114:
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58:
34:
26:
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2316:
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2222:
2214:
2155:
2148:
2054:Robert Metcalfe
1909:Tim Berners-Lee
1857:
1677:Information Age
1549:
1544:
1514:
1509:
1490:Rayleigh fading
1432:
1426:
1373:
1366:
1330:
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838:Communications,
830:: A Soviet View
823:
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65:"Two-way radio"
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17:
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2124:Camille Tissot
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2099:Claude Shannon
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2089:Tivadar Puskás
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2029:Charles K. Kao
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2016:
2011:
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2004:Harold Hopkins
2001:
1996:
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1843:Videotelephony
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1105:External links
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615:Motorola Saber
612:
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540:radio spectrum
527:
526:UHF versus VHF
524:
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481:
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445:of the subject
443:worldwide view
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2079:Radia Perlman
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1969:Lee de Forest
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1964:Thomas Edison
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1954:Donald Davies
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1939:Claude Chappe
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1761:Semiconductor
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1326:Walkie-talkie
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1165:Amateur radio
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1151:Two-way radio
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1111:Two-Way_Radio
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802:0-522-84674-2
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710:9780521837163
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679:9780080511986
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541:
538:parts of the
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477:
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358:
357:specification
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329:
314:
310:
309:
308:
300:
297:
287:
274:
268:
263:
256:
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240:
237:In 1933, the
235:
234:patrol cars.
233:
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204:
199:
190:
188:
183:
181:
177:
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150:two-way radio
142:
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120:
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109:
98:
95:
91:
88:
84:
81:
77:
74:
70:
67: –
66:
62:
61:Find sources:
55:
51:
45:
44:
39:This article
37:
33:
28:
27:
22:
21:Walkie-talkie
2279:Multiplexing
2154:Transmission
2119:Nikola Tesla
2109:Henry Sutton
2064:Samuel Morse
1994:Robert Hooke
1959:Amos Dolbear
1894:John Bardeen
1813:
1793:Telautograph
1697:Mobile phone
1652:Edholm's law
1635:social media
1568:Broadcasting
1412:Quik-Call II
1402:Push-to-talk
1372:Signaling /
1301:Mobile radio
1291:Base station
1150:
1091:
1066:
1058:
1054:
1035:
1030:
1018:
1013:
1005:
1000:
988:
983:
974:
961:
954:
946:
934:. Retrieved
925:
918:
913:
905:
900:
892:
888:
883:
874:
862:
857:
848:, 80-C477, (
841:
833:
825:
820:
809:
793:
788:
776:. Retrieved
747:. Retrieved
736:
726:
714:. Retrieved
695:
688:
668:
661:
642:Police radio
620:Mobile radio
564:
557:
544:broadcasting
529:
512:tropospheric
492:
469:
463:October 2012
460:
440:
416:
412:
408:
396:DR3000 with
383:
352:
351:
340:
337:
324:
306:
293:
285:
282:Conventional
272:
236:
220:
203:marine radio
187:World War II
184:
172:push-to-talk
165:
149:
147:
112:
103:
93:
86:
79:
72:
60:
48:Please help
43:verification
40:
2479:NPL network
2191:Radio waves
2129:Alfred Vail
2039:Hedy Lamarr
2024:Dawon Kahng
1984:Elisha Gray
1944:Yogen Dalal
1869:Nasir Ahmed
1803:Teleprinter
1667:Heliographs
1495:Tone remote
1485:Link budget
1480:Fade margin
1407:Quik-Call I
963:Bell System
936:October 18,
889:talk around
836:Firefighter
778:January 17,
749:January 17,
610:Quik Call I
514:bending at
341:acknowledge
176:full-duplex
161:radio waves
157:transceiver
2525:Antarctica
2484:Toasternet
2406:Television
1889:Paul Baran
1821:Television
1805:(teletype)
1798:Telegraphy
1776:transistor
1754:Phryctoria
1724:Photophone
1702:Smartphone
1692:Mass media
1205:Mobile rig
653:References
605:Project 25
353:Engineered
316:frequency.
255:Project 25
215:fire truck
76:newspapers
2509:Americas
2498:Locations
2469:Internet2
2230:Bandwidth
1934:Vint Cerf
1831:streaming
1809:Telephone
1749:Semaphore
1640:streaming
1465:DC remote
1455:Call sign
1229:Aviation
600:GE Marc V
455:talk page
265:A mobile
223:Australia
205:on a ship
106:July 2022
2612:Category
2577:Category
2464:Internet
2454:CYCLADES
2371:Ethernet
2321:Concepts
2245:terminal
2196:wireless
2019:Bob Kahn
1862:Pioneers
1687:Internet
1578:Cable TV
1470:Dispatch
1397:MDC-1200
1342:2182 kHz
1263:MULTICOM
772:Archived
743:Archived
716:20 April
569:See also
449:You may
398:duplexer
394:Repeater
362:antennas
2597:Commons
2587:Outline
2540:Oceania
2459:FidoNet
2444:ARPANET
2257:circuit
1826:digital
1555:History
1440:Antenna
1417:Selcall
1347:500 kHz
1248:Airband
1195:KDR 444
334:Digital
193:History
90:scholar
2535:Europe
2505:Africa
2489:Usenet
2449:BITNET
2386:Mobile
2262:packet
1771:MOSFET
1766:device
1563:Beacon
1422:SELCAL
1387:D-STAR
1273:UNICOM
1215:PMR446
1200:LPD433
1115:Curlie
804:, 1995
800:
707:
676:
590:PMR446
321:Analog
303:Duplex
232:Lancia
132:Naval
92:
85:
78:
71:
63:
2518:South
2513:North
2474:JANET
2411:Telex
2401:Radio
2240:Nodes
2235:Links
2156:media
1734:Radio
1719:Pager
1647:Drums
1613:video
1608:image
1598:audio
1382:CTCSS
554:Range
245:Types
154:radio
152:is a
97:JSTOR
83:books
2530:Asia
2416:UUCP
2376:ISDN
1445:APRS
938:2017
842:The
798:ISBN
780:2023
751:2022
718:2016
705:ISBN
674:ISBN
534:and
312:use.
201:VHF
69:news
2421:WAN
2391:NGN
2381:LAN
1662:Fax
1603:DCT
1460:CAD
1113:at
1021:, (
991:, (
865:, (
536:UHF
532:VHF
516:VHF
378:P25
52:by
2614::
1077:^
1046:^
759:^
741:.
735:.
703:.
699:.
148:A
2548:)
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