Radio - Wikipédia Sunda, énsiklopédi bébas

Radio - Wikipédia Sunda, énsiklopédi bébas
Lompat ke isi
Ti Wikipédia Sunda, énsiklopédi bébas
Radio
nyaéta
pangiriman sinyal nirkabel
, ku cara numpangkeun atawa nga-
modulasi
sinyal informasi kana
gelombang éléktromagnétik
dina jajaran
frékuénsi
handapeun frékuénsi
cahaya katémbong
Rambatan
gelombang éléktromagnétik dimungkinkeun ku cara ngaayunambing médan magnét. Ieu gelombang henteu merlukeun mediyeum pikeun ngaliwat. Informasi dibawa sacara sistematik ku cara ngarobah sababaraha sifat gelombang anu dipancarkeun, saperti amplitudo atawa frékuénsina. Mangsa gelombang radio ngaliwatan konduktor listrik, médan anu ngaayun-ambing ngahasilkeun arus listrik bulak-balik dina konduktor. Arus listrik ieu bisa didetéksi jeung dirobah jadi sinyal sora atawa sinyal liana.
Sanajan
Nikola Tesla
anu munggaran medar yén komunikasi nir-kabel bisa dilaksanakeun, persisna dina taun 1893,
Guglielmo Marconi
asal Italia, mangrupa panimu anu munggaran ngalakukeun komunikasi radio. Manéhna ngirim jeung narima sinyal radio munggaran di Italia dina taun 1895.
Radio
édit
édit sumber
Kecap radio asalna tina kecap radioteléografi anu disebut ogé 'wireless telegraphy', anu disingket 'wireless'. Préfiks
radio-
dina harti pangiriman sacara nirkabel munggaran dicutat dina kecap 'radioconductor
, anu ditimukeun ku fisikawan Perancis
Edouard Branly
dina taun 1897 sarta dumasar kana kecap gawe
to radiate
(dina basa Laten "radius" hartina "pancaran cahaya, sinar").
'Radio' minangka kecap barang cenah ditimukeun ku ahli iklan
Waldo Warren
(White 1944). Kecap kasebut, anu muncul dina hiji artikel nu diterbitkeun ku
Lee de Forest
taun 1907, digunakeun ku
Angkatan Laut Amérika Sarikat
dina taun 1912 sarta jadi ilahar nepi ka waktu munggaran ayana siaran komérsial di Amérika Sérikat dina taun 1920-an. Istilah éta terus digunakeun dina basa-basa lian di Éropah jeung Asia, sanajan nagara-nagara Persemakmuran Inggris mertahankeun istilah 'wireless' nepi ka tengah abad ka-20.
Kiwari istilah 'wireless' meunangkeun deui popularitas alatan tumuwuhna jaringan télékomunikasi jarak pondok anu lumangsung gancang, contona
WLAN
('Wireless Local Aréa Network'),
WiFi
jeung
Bluetooth
sarta telepon mobil, misalna
GSM
katut
UMTS
. Kiwari, istilah 'radio' mindeng nujul kana alat transceiver (alat pancar sakaligus panarima) atawa chip, sedengkeun 'wireless' nujul kana sistem jeung/atawa métode anu digunakeun pikeun komunikasi radio.
Panimuan
édit
édit sumber
Sanajan panimuan radio lila dikaitkeun jeung
Guglielmo Marconi
, jatidiri
panimu radio
anu mimiti, anu dina mangsa harita disebut
wireless telegraphy
, jadi bahan kontrovérsi
. Kamajuan ti mimiti percobaan di laboratorium nepi ka radio jadi barang kaperluan komérsial ngabutuhkeun waktu sabababaraha dasawarsa sarta merlukeun usaha ti para panalungtik. Kontrovérsi ngeunaan saha anu nimukeun radio, bisa kapanggih ku cara merhatikeun kronologi ditimukeunna radio saperti di handap ieu:
Dina taun 1887,
David E. Hughes
mancarkeun kode Morse maké radio dina handapeun daérah
Super low frequency
Dina taun 1888,
Heinrich Hertz
ngahasilkeun sarta ngukur jajaran
Ultra High Frequency
Dina taun 1891,
Nikola Tesla
ngamimitian panalungtikan nirkabel. Manéhna nyieun alat anu bisa diandelkeun pikeun ngahasilkeun frékuénsi radio, mintonkeun ka balaréa prinsip-prinsip radio, sarta ngirimkeun sinyal ka jarak anu jauh.
Antara taun 1893 jeung 1894,
Roberto Landell de Moura
, urang Brazil, ngalakukeun percobaan. Manéhna henteu nerbitkeun hasilna nepi ka taun 1900 tapi tungtungna meunangkeun patén ti nagarana.
Dina taun 1894 di
Kolkata
(Calcutta), Sir
Jagdish Chandra Bose (J. C. Bose)
nimukeun
coherer
jeung panarima (receiver)
telepon
Alexander Stepanovich Popov
, dina taun 1894, nyieun receiver radiona nu munggaran, anu ngandung hiji coherer tapi sabenerna coherer geus dipintonkeun saméméhna ku J.C. Bose. Popov. Popov satuluyna ngahadéan éta alat jadi hiji detéktor kilat sarta midangkeun dina Russian Physical and Chemical Society dina tanggal
7 Mei
, 1895.
Dina taun 1894,
Guglielmo Marconi
macaan tulisan ngeunaan hasil gawé Hertz jeung Tesla dina perkara wireless telegraphy, sarta ngamimitian percobaanna sorangan.
Dina bulan Désémber 1901
Guglielmo Marconi
ngagunakeun timuan J.C. Bose pikeun narima sinyal radio dina komunikasi transatlatik anu ngaliwatan jarak 2000 mil ti Poldhu, Inggris, ka St. Johns, Newfoundland. Marconi kasohor di sakuliah dunya lantara hasil anu dihontalna ieu. Henteu lila ti harita, Marconi narima patén, malah narima ogé panghargaan Nobel.
Dina awal taun 1900-an
Reginald Fessenden
sarta
Lee de Forest
nimukeun
modulasi amplitudo
AM
) radio) anu ngamungkinkeun sinyal audio bisa dikirim ngaliwatan jomantara.
Dina taun 1935
Edwin H. Armstrong
nimukeun
modulasi frékuénsi
FM
) radio, antukna sinyal audio anu dipancarkeun bisa nyingkahan listrik "statik," nyaéta interférensi tina alat-alat listrik katut gangguan atmosfir.
Dina taun 1943, Pangadilan Tinggi AS ngumumkeun yén gawé Marconi lain gawé asli jieunan manéhna, sarta kapamilikan patén dibikeun ka Nikola Tesla. Ngan, Tesla palastra teu lila saacan kaputusan kasebut dibéwarakeun.
Sajarah
édit
édit sumber
Pikeun leuwih jéntré ngeunaan jejer ieu, mangga tingal
Sajarah radio
Tesla keur mintonkeun pangiriman informasi nirkabel dina kuliah ngeunaan frékuénsi luhur dina taun 1891. Saenggeus ngalakukeun risét anu sinambung, Tesla ngajelaskeun dasar-dasar ngeunaan radio dina taun 1893.
Dina taun 1893, di
St. Louis
Missouri
Nikola Tesla
nyieun alat pikeun percobaan
listrik
. Biantara di hareupeun
Franklin Institute
di
Philadelphia
sarta
National Electric Light Association
, manéhna ngajelaskeun, mintonkeun sarta ngawincik prinsip-prinsip gawé nirkabelna.
Dina taun
1894
Alexander Stepanovich Popov
nyieun
radio receiver
, anu ngandung hiji
coherer
. Satuluyna manéhna nyampurnakeun éta alat jadi hiji
detektor cahaya
, anu dibébérkeun hareupeun
Russian Physical and Chemical Society
dina tanggal
May 7
1895
Pintonan telegrafi nirkabel munggaran hareupeun balaréa lumangsung di ruang kuliah muséum Sajarah Alam Oxford University dina tanggal 14 Agustus 1894, anu dilaksanakeun ku Profésor
Oliver Lodge
jeung
Alexander Muirhead
. Dina éta pintonan, hiji sinyal radio dikirim ti gedong laboratorium Clarendon, sarta ditarima ku alat anu ditempatkeun di ruang kuliah dimaksud.
Dina taun
1896
, Marconi dibéré
patent
12039 ku
Inggris
Improvements in transmitting electrical impulses and signals and in apparatus there-for
. Dina taun 1897 manéhna ngadegkeun stasiun radio munggaran di dunya di
Isle of Wight
Inggris
. Marconi muka pabrik "nirkabel" munggaran di dunya di Hall Street,
Chelmsford, Inggris
dina taun 1898, anu ngagawékeun kira-kira 50 urang.
Panimuan hébat satuluyna nyaéta detéktor
bungbung hapa
, anu katimu ku para insinyur
Westinghouse
. Dina tanggal 25 Désémber 1906,
Reginald Fessenden
ngagunakeun
synchronous rotary-spark transmitter
pikeun siaran program radiona munggaran, ti
Brant Rock, Massachusetts
. Kapal-kapal di laut ngadéngé siaran Fessenden anu ngamaénkeun
biola
. Program warta berita radio munggaran disiarkeun dina
31 Agustus
1920
ku stasiun 8MK di
Detroit, Michigan
. Stasiun radio kampus munggaran mitembeyan siaran dina tanggal
14 Oktober
, 1920, ti
Union College
Schenectady
New York
Archived
2008-05-15 di
Wayback Machine
. Dina bulan anu sarua, stasiun radio 2ADD, anu satuluyna dingaranan
WRUC
dina taun 1940, nyiarkeun siaran hiburan munggaran di Amérika Sarikat. Dina bulan Nopémber 1920, éta stasiun nyiarkeun kagiatan olah raga.
Archived
2008-05-15 di
Wayback Machine
Archived
2009-01-25 di
Wayback Machine
Dina jam 9 isuk-isuk tanggal 27 Agustus 1920, Sociedad Radio
Argentina
nyiarkeun langsung pintonan opera ti
Coliseo Theater
di puseur kota
Buenos Aires
; duapuluh imah di éta kota boga alat panarima radio pikeun nangkep siaran kasebut. Sedengkeun siaran hiburan regulér dimimitian dina taun 1922 ti Pusat Risét boga
Marconi
di
Writtle
, deukeut
Chelmsford, Inggris
40x40px|link=|alt=
Artikel ieu keur dikeureuyeuh,
ditarjamahkeun
tina
basa Inggris
Bantuanna didagoan pikeun
narjamahkeun
One of the first developments in the éarly 20th century (1900-1959) was that
aircraft
used commercial AM radio stations for navigation. This continued until the éarly 1960s when
VOR
systems finally became widespréad (though AM stations are still marked on U.S.
aviation
charts). In the éarly 1930s,
single sideband
and
frequency modulation
were invented by amateur radio operators. By the end of the decade, they were established commercial modes. Radio was used to transmit pictures visible as
television
as éarly as the 1920s. Commercial television transmissions started in North America and Europe in the 1940s. In 1954, Regency introduced a pocket
transistor
radio, the
TR-1
, powered by a "standard 22.5 V Battery".
In
1960
Sony
introduced its first transistorized radio, small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next 20 yéars, transistors replaced tubes almost completely except for very high-power uses. By 1963 color television was being regularly transmitted commercially, and the first (radio)
communication satellite
, TELSTAR, was launched. In the late 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing
digital radios
for many of its links. In the 1970s,
LORAN
became the premier radio navigation system. Soon, the U.S. Navy experimented with
satellite navigation
, culminating in the invention and launch of the
GPS
constellation in 1987. In the éarly 1990s,
amateur radio
experimenters began to use personal computers with audio cards to process radio signals. In 1994, the U.S. Army and
DARPA
launched an aggressive, successful project to construct a
software radio
that could become a different radio on the fly by changing software. Digital transmissions began to be applied to broadcasting in the late 1990s.
Kagunaan radio
édit
édit sumber
Radio munggaran digunakeun pikeun kaperluan maritim, nyaéta pikeun ngirim pesen telegraf anu maké
kode Morse
antara kapal laut jeung kapal laut sarta antara kapal laut jeung daratan. Para pamaké munggaran di antarana Angkatan Laut Jepang pikeun nyilidik armada Rusia dina
paperangan di Tsushima
dina taun 1905. Kagunaan telegraf maritim anu paling diinget nyaéta waktu teuleumna
RMS
Titanic
dina taun 1912, di antarana pikeun komunikasi antara para operator dina kapal nu titeuleum jeung kapal-kapal anu padeukeut sarta pikeun komunikasi jeung stasiun-stasiun di basisir pikeun ngémbarkeun anu salamet. Radio nu munggaran acan bisa mancarkeun sora atawa ucapan sarta disebut "wireless telegraph" atawa telegraf nirkabel.
Radio digunakeun pikeun ngirimkeun paréntah sarta komunikasi antara angkatan darat jeung angkatan laut dina
Perang Dunia I
; Jérman ngagunakeun komunikasi radio pikeun pesen diplomatik mangsa sakali waktu kabel lautna dipegatkeun ku Inggris. Amérika Sarikat ngirimkeun
opat welas paringetan
ti présidén
Woodrow Wilson's
ka Jérman ngagunakeun radio dina perang kasebut. Siaran radio mitembeyan ti
San Jose
dina taun 1909
Archived
2010-10-17 di
Wayback Machine
, sarta jadi ilahar dina taun 1920-an, mangsa sumebarna alat panarima radio (radio receiver), hususna di Éropah jeung Amérika Sarikat. Sagigireun ti éta, siaran titik-ka-titik, kaasup pesen telepon sarta
rélay
program-program radio, sumebar dina taun 1920-an jeung 1930-an. Kagunaan lainna radio dina taun-taun saacan perang nyaéta hadirna kapal udara sarta kapal laut nu mampu ngadetéksi sarna manggihan kapal musuh maké
radar
RA
dio
etection
nd
anging).
Kiwari, radio boga rupa-rupa wangunan, di antarana nyaéta sagala rupa
jaringan nirkabel
sarta
komunikasi mobil
katut
siaran
radio. Saacan ditimukeunna
televisi
, radio komérsial nyiarkeun lain waé warta jeung musik, tapi ogé
drama
komedi
, variety shows, jeung wangun hiburan lianna.
Audio
édit
édit sumber
Receiver hi-fi AM/FM
Fisher 500 ti mangsa taun 1959.
Radio siaran AM
ngirimkeun musik jeung ucapan dina spékrum gelombang radio Frékuénsi Sedeng (MF—0.300
MHz nepi ka 3
MHz). Radio AM ngagunakeun
modulasi amplitudo
, di mana amplitudo sinyal pamawa dirobah proporsional jeung amplitudo sora anu katangkep (di-trandusi) ku mikropon sedengkeun frékuénsina tetep henteu dirobah. Pangiriman sinyal cara kieu keuna ku gangguan listrik statik jeung interférensi lantaran kilat sarta sumber gangguan lianna anu mancar dina frékuénsi anu sarua ngarobah amplitudo sinyal anu dipancarkeun. Ukuran daya paling gedé anu dimeunangkeun pikeun stasiun radio AM di
Amérika Sarikat
nyaéta 50,000 watts sarta lolobana stasiun anu mancar sakuat ieu geus karolot; stasiun-stasiun ieu di antarana
WGN (AM)
WJR
, sarta
CKLW
. Dina taun 1986
KTNN
mangrupa stasiun pamungkas anu narima idin operasi dina 50,000 watt.
Radio siaran FM
ngirimkeun musik jeung ucapan kalayan
kehandalan
fidelity
) anu leuwih hadé ti batan radio AM. Dina
modulasi frékuénsi
, parobahan amplitudo dina
mikropon
nyababkeun frékuénsi
transmitter
fluktuasi. Lantaran sinyal audio ngamodulasi frékuénsi lain amplitudo, mangka sinyal FM henteu keuna ku gangguan statik sarta interférensi saperti halna sinyal AM. FM dipancarkeun dina spéktrum gelombang radio Frékuénsi Luhur Pisan atawa
Very High Frequency
(VHF—30
MHz nepi ka 300
MHz).
Gelombang radio VHF watekna leuwih mirupa cahaya, ngarambat dina garis anu lempeng, antukna jarak panarimaan kawates antara 50-100 mil. Dina kondisi atmosfir bagian luhur anu henteu biasa, sinyal FM kadang dipantulkeun balik ka bumi ku
ionosfir
, ngakibatkeun
jarak pancar FM anu jauh
Receiver
FM keuna ku
capture effect
, anu nyababkeun radio ngan narima sinyal anu paling kuat mangsa aya leuwih ti hiji sinyal anu datang dina frékuénsi nu sarua.
Receiver
FM relatif kebal tina gangguan kilat jeung interférensi.
Daya nu gedé boga mangfaat pikeun nembus wangunan, nyebar sabudeureun pasir-pasir, sarta mengkol dina luhureun horizon. Akibatna, stasiun-stasiun FM nu dayana 100,000 watt bisa sacara régulér kadéngé sajauh 100 mil (160
km), malah bisa leuwih jauh deui (nyaéta 150 mil, 240
km) lamun euwueh sinyal lianna dina frékuénsi nu sarua.
Stasiun FM anu dijalankeun maké daya 320,000 watts ERP nepi ka 500,000 watts ERP henteu ngabantu pikeun manjangkeun jarak pancar sabab frékuénsi
VHF
ngarambat ampir mirupa garis lempeng dina luhureun horizon sarta nembus ka angkasa luar.
FM Sub-carrier services are secondary signals transmitted "
piggyback
" along with the main program. Special receivers are required to utilize these services. Analog channels may contain alternative programming, such as réading services for the blind, background music or steréo sound signals. In some extremely crowded metropolitan aréas, the sub-channel program might be an alternate foreign language radio program for various ethnic groups. Sub-carriers can also transmit digital data, such as station identification, the current song's name, web addresses, or stock quotes. In some countries, FM radios automatically re-tune themselves to the same channel in a different district by using sub-bands.
Aviation voice radios use
VHF
AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of wéaker stations due to FM's
capture effect
). Aircraft fly high enough that their transmitters can be received hundreds of miles (or kilometres) away, even though they are using VHF.
Marine voice radios can use AM in the shortwave High Frequency (HF—3
MHz to 30
MHz) radio spectrum for very long ranges or
narrowband FM in the VHF spectrum
for much shorter ranges. Government, police, fire and commercial voice services use narrowband FM on special frequencies. Fidelity is sacrificed to use a smaller range of radio frequencies, usually five
kHz
of deviation, rather than the 75
kHz used by FM broadcasts and 25
kHz used by TV sound.
Civil and military HF (high frequency) voice services use
shortwave
radio to contact ships at séa, aircraft and isolated settlements. Most use
single sideband
voice (SSB), which uses less bandwidth than AM. On an AM radio SSB sounds like ducks quacking. Viewed as a graph of frequency versus power, an AM signal shows power where the frequencies of the voice add and subtract with the main radio frequency. SSB cuts the bandwidth in half by suppressing the carrier and (usually) lower sideband. This also makes the transmitter about three times more powerful, because it doesn't need to transmit the unused carrier and sideband.
TETRA,
Terrestrial Trunked Radio
is a digital cell phone system for military, police and ambulances. Commercial services such as
XM
WorldSpace
and
Sirius
offer encrypted digital
Satellite radio
Telephony
édit
édit sumber
Mobile phones
transmit to a local
cell site
(transmitter/receiver) that ultimately connects to the public switched telephone network (
PSTN
) through an optic fiber or microwave radio and other network elements. When the mobile phone néars the edge of the cell site's radio coverage aréa, the central computer switches the phone to a new cell. Cell phones originally used FM, but now most use various digital modulation schemes. Recent developments in Sweden (such as DROPme) allow for the instant downloading of digitial material from a radio broadcast (such as a song) to a mobile phone.
Satellite phones use satellites rather than cell towers to communicate. They come in two types:
INMARSAT
and
Iridium
. Both types provide world-wide coverage. INMARSAT uses géosynchronous satellites, with aimed high-gain antennas on the vehicles. Iridium uses 66 Low éarth Orbit satellites as the cells.
Video
édit
édit sumber
Television
sends the picture as AM and the sound as FM, with the sound carrier a fixed frequency (4.5
MHz in the
NTSC
system) away from the vidéo carrier. Analog television also uses a
vestigial sideband
on the vidéo carrier to reduce the bandwidth required.
Digital television uses
8VSB
modulation in North America (under the
ATSC
digital television standard), and
COFDM
modulation elsewhere in the world (using the
DVB-T
standard). A
Reed-Solomon error correction
code adds redundant correction codes and allows reliable reception during moderate data loss. Although many current and future codecs can be sent in the MPEG-2
transport stream
container format
, as of 2006 most systems use a standard-definition format almost identical to
DVD
MPEG-2
vidéo in
Anamorphic widescreen
and
MPEG layer 2
MP2
) audio.
High-definition television
is possible simply by using a higher-resolution picture, but
H.264/AVC
is being considered as a replacement vidéo codec in some regions for its improved compression. With the compression and improved modulation involved, a single "channel" can contain a high-definition program and several standard-definition programs.
édit
édit sumber
All
satellite navigation
systems use satellites with precision clocks. The satellite transmits its position, and the time of the transmission. The receiver listens to four satellites, and can figure its position as being on a line that is tangent to a spherical shell around éach satellite, determined by the time-of-flight of the radio signals from the satellite. A computer in the receiver does the math.
Radio direction-finding is the oldest form of radio navigation. Before 1960 navigators used movable loop antennas to locate commercial AM stations néar cities. In some cases they used marine radiolocation béacons, which share a range of frequencies just above AM radio with amateur radio operators.
Loran
systems also used time-of-flight radio signals, but from radio stations on the ground.
VOR
(Very High Frequency Omnidirectional Range), systems (used by aircraft), have an antenna array that transmits two signals simultanéously. A directional signal rotates like a lighthouse at a fixed rate. When the directional signal is facing north, an omnidirectional signal pulses. By méasuring the difference in phase of these two signals, an aircraft can determine its béaring or radial from the station, thus establishing a line of position. An aircraft can get réadings from two VORs and locate its position at the intersection of the two radials, known as a "fix." When the VOR station is collocated with DME (
Distance Measuring Equipment
), the aircraft can determine its béaring and range from the station, thus providing a fix from only one ground station. Such stations are called VOR/DMEs. The military operates a similar system of navaids, called TACANs, which are often built into VOR stations. Such stations are called VORTACs. Because TACANs include distance méasuring equipment, VOR/DME and VORTAC stations are identical in navigation potential to civil aircraft.
Radar
édit
édit sumber
Radar
(Radio Detection And Ranging) detects objects at a distance by bouncing radio waves off them. The delay caused by the echo méasures the distance. The direction of the béam determines the direction of the reflection. The polarization and frequency of the return can sense the type of surface. Navigational radars scan a wide aréa two to four times per minute. They use very short waves that reflect from éarth and stone. They are common on commercial ships and long-distance commercial aircraft
General purpose radars generally use navigational radar frequencies, but modulate and polarize the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of héavy storms, as well as land and vehicles. Some can superimpose sonar data and map data from
GPS
position.
Séarch radars scan a wide aréa with pulses of short radio waves. They usually scan the aréa two to four times a minute. Sometimes séarch radars use the
doppler effect
to separate moving vehicles from clutter. Targeting radars use the same principle as séarch radar but scan a much smaller aréa far more often, usually several times a second or more. Wéather radars resemble séarch radars, but use radio waves with circular polarization and a wavelength to reflect from water droplets. Some wéather radar use the
doppler
to méasure wind speeds.
Data (digital radio)
édit
édit sumber
Most new radio systems are digital, see also:
Digital TV
Satellite Radio
Digital Audio Broadcasting
. The oldest form of digital broadcast was spark gap
telegraphy
, used by pioneers such as Marconi. By pressing the key, the operator could send messages in
Morse code
by énérgizing a rotating commutating spark gap. The rotating commutator produced a tone in the receiver, where a simple spark gap would produce a hiss, indistinguishable from static. Spark gap transmitters are now illegal, because their transmissions span several hundred megahertz. This is very wasteful of both radio frequencies and power.
The next advance was continuous wave
telegraphy
, or CW (
Continuous Wave
), in which a pure radio frequency, produced by a
vacuum tube
electronic oscillator
was switched on and off by a key. A receiver with a local oscillator would "
heterodyne
" with the pure radio frequency, créating a whistle-like audio tone. CW uses less than 100
Hz of bandwidth. CW is still used, these days primarily by
amateur radio
operators (hams). Strictly, on-off keying of a carrier should be known as "Interrupted Continuous Wave" or ICW or
on-off keying
(OOK).
Radio teletypes
usually operate on short-wave (HF) and are much loved by the military because they créate written information without a skilled operator. They send a bit as one of two tones. Groups of five or seven bits become a character printed by a teletype. From about 1925 to 1975, radio teletype was how most commercial messages were sent to less developed countries. These are still used by the military and wéather services.
Aircraft use a 1200 Baud radioteletype service over VHF to send their ID, altitude and position, and get gate and connecting-flight data. Microwave dishes on satellites, telephone exchanges and TV stations usually use
quadrature amplitude modulation
(QAM). QAM sends data by changing both the phase and the amplitude of the radio signal. Engineers like QAM because it packs the most bits into a radio signal when given an exclusive (non-shared) fixed narrowband frequency range. Usually the bits are sent in "frames" that repéat. A special bit pattern is used to locate the beginning of a frame.
Communication systems that limit themselves to a fixed narrowband frequency range are vulnerable to
jamming
A variety of jamming-resistant
spread spectrum
techniques were initially developed for military use, most famously for
Global Positioning System
satellite transmissions.
Commercial use of spréad spectrum begin in the 1980s.
Bluetooth
, most cell phones, and the 802.11b version of Wi-Fi éach use various forms of spréad spectrum.
Systems that need reliability, or that share their frequency with other services, may use "coded orthogonal frequency-division multiplexing" or
COFDM
. COFDM bréaks a digital signal into as many as several hundred slower subchannels. The digital signal is often sent as QAM on the subchannels. modérn COFDM systems use a small computer to maké and decode the signal with
digital signal processing
, which is more flexible and far less expensive than older systems that implemented separate electronic channels. COFDM resists fading and ghosting because the narrow-channel QAM signals can be sent slowly. An adaptive system, or one that sends error-correction codes can also resist interference, because most interference can affect only a few of the QAM channels. COFDM is used for
WiFi
, some
cell phones
Digital Radio Mondiale
Eureka 147
, and many other local aréa network, digital TV and radio standards.
Heating
édit
édit sumber
Radio-frequency energy generated for héating of objects is generally not intended to radiate outside of the generating equipment, to prevent interference with other radio signals.
Microwave ovens
use intense radio waves to héat food. (Note: It is a common misconception that the radio waves are tuned to the resonant frequency of water molecules. The microwave frequencies used are actually about a factor of ten below the resonant frequency.)
Diathermy
equipment is used in surgery for séaling of blood vessels. Induction
furnaces
are used for melting metal for
casting
Amateur radio service
édit
édit sumber
Amateur radio
is a hobby in which enthusiasts purchase or build their own equipment and use radio for their own enjoyment. They may also provide an emergency and public-service radio service. This has been of gréat use, saving lives in many instances. Radio amateurs are licensed to use frequencies in a large number of narrow bands throughout the radio spectrum. They use all forms of encoding, including obsolete and experimental ones. Several forms of radio were pioneered by radio amateurs and later became commercially important including
FM
, single-sideband (SSB), AM, digital packet radio and satellite repéaters. Some amateur frequencies may be disrupted by power-line internet service.
Unlicensed radio services
édit
édit sumber
Personal radio services such as
Citizens' Band Radio
Family Radio Service
Multi-Use Radio Service
and others exist in North America to provide simple, (usually) short range communication for individuals and small groups, without the overhéad of licensing. Similar services exist in other parts of the world. These radio services involve the use of handheld units.
The commonest form of unlicensed radio is known as Free or Pirate radio, the main differences being that a Free radio station does not advertise or maké any money, while the Pirate station could not exist without adverts, payolas, etc.
Radio control (RC)
édit
édit sumber
Radio remote controls
use radio waves to transmit control data to a remote object as in some éarly forms of
guided missile
, some éarly TV remotes and a range of modél boats,
cars
and airplanes. Large industrial remote-controlled equipment such as
cranes
and switching
locomotives
now usually use digital radio techniques to ensure safety and reliability.
In
Madison Square Garden
, at the Electrical Exhibition of 1898, Nikola Tesla successfully demonstrated a radio-controlled boat.
He was awarded U.S. patent No. 613,809 for a "Method of and Apparatus for Controlling Mechanism of Moving Vessels or Vehicles."
The electromagnetic spectrum
édit
édit sumber
Radio waves are a form of electromagnetic radiation, créated whenever a
charged
object (in normal radio transmission, an
electron
accelerates
with a frequency that lies in the
radio frequency
(RF) portion of the
electromagnetic spectrum
. In radio, this acceleration is caused by an
alternating current
in an
antenna
. Radio frequencies occupy the range from a few tens of
hertz
to three hundred gigahertz, although commercially important uses of radio use only a small part of this spectrum.
Other types of electromagnetic radiation, with frequencies above the RF range, are
microwave
infrared
, visible
light
ultraviolet
X-rays
and
gamma rays
. Since the energy of an individual
photon
of radio frequency is too low to remove an
electron
from an
atom
, radio waves are classified as
non-ionizing radiation
Other
édit
édit sumber
Energy autarkic radio technology
consists of a small radio transmitter powered by environmental energy (push of a button, temperature differences, light, vibrations, etc.). A number of schemes have been proposed for
Wireless energy transfer
. Various plans included transmitting power using
microwaves
, and the technique has been demonstrated. (See
Microwave power transmission
). These schemes include, for example,
solar power
stations
in orbit béaming energy down to terrestrial users.
See also
édit
édit sumber
Amateur radio
Antique radio
Army No. 11 Wireless Set
Batteryless radio
Community radio
Crystal radio receiver
Dead air
Federal Communications Commission
(United States)
Hertz
Hospital radio
Hot and cool media
International broadcasting
Internet radio
and
Internet radio device
Invention of radio
Lists
Radio network
List of Internet stations
List of radio broadcasters who also do podcasting
Longwave
Mediumwave
Music radio
Near Vertical Incidence Skywave
Old-time radio
Pirate radio
Radio astronomy
Radio documentary
Radio commercial
Radio programming
Radio propagation
and
ionosphere
Radio software
Receiver (radio)
Satellite radio
Shortwave
Software radio
Long-distance FM reception (FM DX)
Transistor radio
Tuner (radio)
Types of radio emissions
VFO
Catetan
édit
édit sumber
List of Tesla patents
The Electromagnetic Spectrum
, University of Tennessee, Dept. of Physics and Astronomy
Online Radio Station
Archived
2007-12-10 di
Wayback Machine
124radiostation online radio station as review says it is the "most easiest" to use website to listen songs.
Rujukan
édit
édit sumber
A História da Rádio em Datas (1819-1997)
(in Portuguese) - notes on etymology
Archived
2007-09-29 di
Wayback Machine
Leigh White,
Buck Fuller and the Dymaxion World
(refers to Waldo Warren as the inventor of the word
radio
), in: The Saturday Evening Post,
14 Oktober
1944, cited in: Joachim Krausse and Claude Lichtenstein (eds.),
Your Private Sky
, Lars Müller Publishers, Baden/Switzerland, 1999, page 132.
ISBN 3-907044-88-6
L. de Forest, article in Electrical World
22 Juni
1270/1 (1907), éarly use of word "radio".
Archived
2008-04-15 di
Wayback Machine
- It contains a proof that Sir Jagadish Chandra Bose invented the Mercury Coherer which was later used by Guglielmo Marconi and along with other patents.
Bacaan salajengna
édit
édit sumber
Aitkin Hugh G. J.
The Continuous Wave: Technology and the American Radio, 1900-1932
(Princeton University Press, 1985).
Briggs Asa.
The History of Broadcasting in the United Kingdom
(Oxford University Press, 1961).
Ewbank Henry and Lawton Sherman P.
Broadcasting: Radio and Television
(Harper & Brothers, 1952).
Fisher, Marc
Something In The Air: Radio, Rock, and the Revolution That Shaped A Generation
(Random House, 2007).
Maclaurin W. Rupert.
Invention and Innovation in the Radio Industry
(The Macmillan Company, 1949).
Ray William B.
FCC: The Ups and Downs of Radio-TV Regulation
(Iowa State University Press, 1990).
Scannell, Paddy, and Cardiff, David.
A Social History of British Broadcasting, Volume One, 1922-1939
(Basil Blackwell, 1991).
Schwoch James.
The American Radio Industry and Its Latin American Activities, 1900-1939
(University of Illinois Press, 1990).
Sterling Christopher H.
Electronic Media, A Guide to Trends in Broadcasting and Newer Technologies 1920-1983
(Praeger, 1984).
White Llewellyn.
The American Radio
(University of Chicago Press, 1947).
Sumber utama
édit
édit sumber
De Forest, Lee.
Father of Radio: The Autobiography of Lee de Forest
(1950).
Tumbu luar
édit
édit sumber
Wikimedia Commons memiliki media mengenai
Radio
Wiktionary logo
Baca ogé pedaran
Wikikamus
ngeunaan kecap
radio
Radio Frequency Chart
Archived
2007-12-13 di
Wayback Machine
Horzepa, Stan, "
Surfin': Who Invented Radio
". Arrl.org.
10 Oktober
2003
Online Radio
Archived
2007-12-02 di
Wayback Machine
IAtéacher:
Interactive Explanation of Radio Receiver Construction
Archived
2008-01-07 di
Wayback Machine
U.S. Supreme Court, "
Marconi Wireless Telegraph co. of America v. United States
". 320 U.S. 1. Nos. 369, 373. Argued
9 April
-12, 1943. Decided
21 Juni
1943
'A Day In Radio' from The University of Virginia's Department of American Studies
Archived
2017-08-12 di
Wayback Machine
Radio Announcer
Steven Schoenherr's History of Radio
The Broadcast Archive - Radio History on the Web!
George H. Clark Radioana Collection, ca. 1880 - 1950
- Archives Center, National muséum of American History, Smithsonian Institution
A gallery of Antiques from the 1920s to the 1960s
United States Early Radio History
Open Directory Project - Radio
Books about Radios and RF field; schematics for radio transmitters and receivers
Archived
2007-12-18 di
Wayback Machine
VOR Basic Information
Archived
2012-04-16 di
Wayback Machine
How Stuff Works - Radio
Early Canadian Radio Station Lists
Canadian Communications Foundation - The History on Canadian Broadcasting
United States Early Radio History
Historic Radios from Around the World at Kurrajong Radio Museum, Australia
The British DX Club
www.worldofradio.com
Glen Houser's World Of Radio
Radio Today
Daily News and Information about radio
Community Broadcasting Association of Australia
Community Broadcasting Online (Australia)
Archived
2007-12-15 di
Wayback Machine
Radio Broadcasting from Ghana West Africa
Internet Radio Broadcasting Directory
Archived
2007-12-11 di
Wayback Machine
Dicomot ti "
Kategori
Webarchive template wayback links
Artikel perlu ditarjamahkeun tina basa Inggris
Pranala kategori Commons ada di Wikidata
Spéktrum radio
Radio
Sora
Kaca ngagunakeun tutumbu magis ISBN.
Radio
Tambah jejer