579:(SCA) services which used various subcarrier frequencies including 41 and 67 kHz. Many revenue-starved FM stations used SCAs for "storecasting" and other non-broadcast purposes. The Halstead system was rejected due to lack of high frequency stereo separation and reduction in the main channel signal-to-noise ratio. The GE and Zenith systems, so similar that they were considered theoretically identical, were formally approved by the FCC in April 1961 as the standard stereo FM broadcasting method in the United States and later adopted by most other countries. It is important that stereo broadcasts be compatible with mono receivers. For this reason, the left (L) and right (R) channels are algebraically encoded into sum (L+R) and difference (LâR) signals. A mono receiver will use just the L+R signal so the listener will hear both channels through the single loudspeaker. A stereo receiver will add the difference signal to the sum signal to recover the left channel, and subtract the difference signal from the sum to recover the right channel.
1374:' Format", but it was not until 1978 that listenership to FM stations exceeded that of AM stations in North America. In most of the 70s FM was seen as highbrow radio associated with educational programming and classical music, which changed during the 1980s and 1990s when Top 40 music stations and later even country music stations largely abandoned AM for FM. Today AM is mainly the preserve of talk radio, news, sports, religious programming, ethnic (minority language) broadcasting and some types of minority interest music. This shift has transformed AM into the "alternative band" that FM once was. (Some AM stations have begun to simulcast on, or switch to, FM signals to attract younger listeners and aid reception problems in buildings, during thunderstorms, and near high-voltage wires. Some of these stations now emphasize their presence on the FM band.)
1591:
broadcasting was reopened in 1975 using the VHF band, after the few encroaching TV stations had been moved. Subsequently, it developed steadily until in the 1980s many AM stations transferred to FM due to its superior sound quality and lower operating costs. Today, as elsewhere in the developed world, most urban
Australian broadcasting is on FM, although AM talk stations are still very popular. Regional broadcasters still commonly operate AM stations due to the additional range the broadcasting method offers. Some stations in major regional centres simulcast on AM and FM bands. Digital radio using the DAB+ standard has been rolled out to capital cities.
1119:. Transmitter powers should be carefully chosen so that the required area is covered without causing interference to other stations further away. Practical transmitter powers range from a few milliwatts to 80 kW. As transmitter powers increase above a few kilowatts, the operating costs become high and only viable for large stations. The efficiency of larger transmitters is now better than 70% (AC power in to RF power out) for FM-only transmission. This compares to 50% before high efficiency switch-mode power supplies and LDMOS amplifiers were used. Efficiency drops dramatically if any digital HD Radio service is added.
258:, multiples of 50 kHz are used. In most countries the maximum permitted frequency error of the unmodulated carrier is specified, which typically should be within 2 kHz of the assigned frequency. There are other unusual and obsolete FM broadcasting standards in some countries, with non-standard spacings of 1, 10, 30, 74, 500, and 300 kHz. To minimise inter-channel interference, stations operating from the same or nearby transmitter sites tend to keep to at least a 500 kHz frequency separation even when closer frequency spacing is technically permitted. The
995:, which became common and remain so, private data transmission services (for example sending stock market information to stockbrokers or stolen credit card number denial lists to stores,) subscription commercial-free background music services for shops, paging ("beeper") services, alternative-language programming, and providing a program feed for AM transmitters of AM/FM stations. SCA subcarriers are typically 67 kHz and 92 kHz. Initially the users of SCA services were private analog audio channels which could be used internally or leased, for example
1255:
84:
972:
272:
92:
1716:
1656:, FM broadcasting began in the late 1960s, carrying several shows from the One television network which was transferred from the AM frequency (also known as MW in Turkey). In subsequent years, more MW stations were slowly transferred to FM, and by the end of the 1970s, most radio stations that were previously on MW had been moved to FM, though many talk, news and sport, but mostly religious stations, still remain on MW.
381:
1665:
broadcasting than for national networks. In such countries, particularly where there are economic or infrastructural problems, "rolling out" a national FM broadcast network to reach the majority of the population can be a slow and expensive process. Despite this, mostly in east
European countries, national FM broadcast networks were established in the late 1960s and 1970s. In all Soviet-dependent countries except
1570:
No later than the end of 1977, the national public service broadcasting company EIRT (later also known as ERT) placed in service its first FM transmitter in the capital, Athens. By the end of the 1970s, most of Greek territory was covered by three
National FM programs, and every city had many FM "pirates" as well. The adaptation of the FM band for privately owned commercial radio stations came far later, in 1987.
5175:
5185:
1131:, so reception distances for FM stations are typically limited to 30â40 miles (50â60 km). They can also be blocked by hills and to a lesser extent by buildings. Individuals with more-sensitive receivers or specialized antenna systems, or who are located in areas with more favorable topography, may be able to receive useful FM broadcast signals at considerably greater distances.
5164:
5195:
1350:
1707:, the exception being some local stations remaining on FM until 2022, and might be extended to 2031. The switchover to DAB+ meant that especially rural areas obtained a far more diverse radio content compared to the FM-only period; several new radio stations had started transmissions on DAB+ in the years before the FM switch-off.
289:
1507:(previously the Radio Authority) in the UK issues on demand Restricted Service Licences on FM and also on AM (MW) for short-term local-coverage broadcasting which is open to anyone who does not carry a prohibition and can put up the appropriate licensing and royalty fees. In 2010 around 450 such licences were issued.
1851:
or so-called "bugs"); the advantage to using the FM broadcast band for such operations is that the receiving equipment would not be considered particularly suspect. Common practice is to tune the bug's transmitter off the ends of the broadcast band, into what in the United States would be TV channel
1745:
decks, which are no longer common on car radio designs) up to full-sized, near-professional-grade broadcasting systems that can be used to transmit audio throughout a property, including systems that synchronize holiday decorative lighting with music. Most such units transmit in full stereo, though
1599:
Like
Australia, New Zealand adopted the FM format relatively late. As was the case with privately owned AM radio in the late 1960s, it took a spate of 'pirate' broadcasters to persuade a control-oriented, technology-averse government to allow FM to be introduced after at least five years of consumer
1557:
adopted FM broadcast widely in the early 1970s, but first experiments made by RAI dated back to 1950, when the "movement for free radio", developed by so-called "pirates", forced the recognition of free speech rights also through the use of "free radio media such as
Broadcast transmitters", and took
1357:
On June 27, 1945 the FCC announced the reassignment of the FM band to 90 channels from 88â106 MHz (which was soon expanded to 100 channels from 88â108 MHz). This shift, which the AM-broadcaster RCA had pushed for, made all the
Armstrong-era FM receivers useless and delayed the expansion of
1054:
or "smart radio" system. In
Germany the analog ARI system was used prior to RDS to alert motorists that traffic announcements were broadcast (without disturbing other listeners). Plans to use ARI for other European countries led to the development of RDS as a more powerful system. RDS is designed to
829:
for the stereo subcarrier was proposed. It was theorized to be more spectrum-efficient and to produce a 4 dB s/n improvement at the receiver, and it was claimed that multipath distortion would be reduced as well. A handful of radio stations around the country broadcast stereo in this way, under
1569:
was another
European country where the FM radio spectrum was used at first by the so-called "pirates" (both in Athens and Thessaloniki, the two major Greek cities) in the mid-1970s, before any national stations had started broadcasting on it; there were many AM (MW) stations in use for the purpose.
1558:
the case to the
Constitutional Court of Italy. The court finally decided in favor of Free Radio. Just weeks after the court's final decision there was an "FM radio boom" involving small private radio stations across the country. By the mid-1970s, every city in Italy had a crowded FM radio spectrum.
1310:
stations W2XDA Schenectady and W2XOY New
Scotland, New Yorkâtwo experimental FM transmitters on 48.5 MHzâwhich signed on in 1939. The two began regular programming, as W2XOY, on November 20, 1940. Over the next few years this station operated under the call signs W57A, W87A and WGFM, and moved
1241:
in 1955, on the 102.1 MHz frequency, founded by businesswoman Anna Khoury. Due to the high import costs of FM radio receivers, transmissions were carried out in circuit closed to businesses and stores, which played ambient music offered by radio. Until 1976, RĂĄdio Imprensa was the only station
890:
There were several variations on this system submitted by GE, Zenith, RCA, and Denon for testing and consideration during the National Quadraphonic Radio Committee field trials for the FCC. The original Dorren Quadraplex System outperformed all the others and was chosen as the national standard for
543:
Two musical programs, consisting of both the Red and Blue Network program feeds of the NBC Radio Network, were simultaneously transmitted using the same system of subcarrier modulation as part of a studio-to-transmitter link system. In April 1935, the AM subcarriers were replaced by FM subcarriers,
364:
The maximum frequency deviation of the carrier is usually specified and regulated by the licensing authorities in each country. For a stereo broadcast, the maximum permitted carrier deviation is invariably ±75 kHz, although a little higher is permitted in the United States when SCA systems are
1590:
band: TV channel 5 (102.250 video carrier) if allocated would fall within the VHF FM band (98â108 MHz). The official policy on FM at the time was to eventually introduce it on another band, which would have required FM tuners custom-built for Australia. This policy was finally reversed and FM
547:
The first FM subcarrier transmissions emanating from Major Armstrong's experimental station KE2XCC at Alpine, New Jersey occurred in 1948. These transmissions consisted of two-channel audio programs, binaural audio programs and a fax program. The original subcarrier frequency used at KE2XCC was
821:
for the stereo signal will be worse than for the mono receiver. For this reason many stereo FM receivers include a stereo/mono switch to allow listening in mono when reception conditions are less than ideal, and most car radios are arranged to reduce the separation as the signal-to-noise ratio
1664:
Most other countries implemented FM broadcasting through the 1960s and expanded their use of FM through the 1990s. Because it takes a large number of FM transmitting stations to cover a geographically large country, particularly where there are terrain difficulties, FM is more suited to local
1627:
Like many other countries in Africa and Asia that drive on the left, New Zealand imports vehicles from Japan. The standard radios in these vehicles operate on 76-to-90 MHz, which is not compatible with the 88-to-108 MHz range. Imported cars with Japanese radios can have FM expanders
1502:
However, only when commercial broadcasting was introduced to the UK in 1973 did the use of FM pick up in Britain. With the gradual clearance of other users (notably Public Services such as police, fire and ambulance) and the extension of the FM band to 108.0 MHz between 1980 and 1995, FM
809:
Another way to look at the resulting signal is that it alternates between left and right at 38 kHz, with the phase determined by the 19 kHz pilot signal. Most stereo encoders use this switching technique to generate the 38 kHz subcarrier, but practical encoder designs need to
520:
Long before FM stereo transmission was considered, FM multiplexing of other types of audio-level information was experimented with. Edwin Armstrong, who invented FM, was the first to experiment with multiplexing, at his experimental 41 MHz station W2XDG located on the 85th floor of the
283:
at its New York lab in 1940. The radio had both AM and FM receivers. With a million-volt arc as a source of interference behind it, the AM receiver produced a roar of static, while the FM receiver clearly reproduced a music program from Armstrong's experimental FM transmitter in New
1189:. Interference from other stations is also a factor in some places. In the U.S, the FCC publishes curves that aid in calculation of this maximum distance as a function of signal strength at the receiving location. Computer modelling is more commonly used for this around the world.
1542:, a frequency range of 97.6-99.8 MHz was allocated once police mobile radio transmitters were moved from band II, starting in London before being nationally completed by 1989. Radio 1 in London moved from its previous frequency to 98.8 MHz transmitted from the BBC's
1011:
around 19 kHz (±4 kHz) must still be maintained, so as not to trigger stereo decoders on receivers. If there is stereo, there will typically be a guard band between the upper limit of the DSBSC stereo signal (53 kHz) and the lower limit of any other subcarrier.
495:
The use of pre-emphasis becomes a problem because many forms of contemporary music contain more high-frequency energy than the musical styles which prevailed at the birth of FM broadcasting. Pre-emphasizing these high-frequency sounds would cause excessive deviation of the FM
810:
incorporate circuitry to deal with the switching harmonics. Converting the multiplex signal back into left and right audio signals is performed by a decoder, built into stereo receivers. Again, the decoder can use a switching technique to recover the left and right channels.
883:. Following this experiment, a long-term test period was proposed that would permit one FM station in each of the top 25 U.S. radio markets to transmit in Quadraplex. The test results hopefully would prove to the FCC that the system was compatible with existing two-channel
822:
worsens, eventually going to mono while still indicating a stereo signal is received. As with monaural transmission, it is normal practice to apply pre-emphasis to the left and right channels before encoding and to apply de-emphasis at the receiver after decoding.
1672:
The use of FM for domestic radio encouraged listeners to acquire cheap FM-only receivers and so reduced the number able to listen to longer-range AM foreign broadcasters. Similar considerations led to domestic radio in South Africa switching to FM in the 1960s.
262:
publishes Protection Ratio graphs, which give the minimum spacing between frequencies based on their relative strengths. Only broadcast stations with large enough geographic separations between their coverage areas can operate on the same or close frequencies.
842:
invented the Quadraplex system of single station, discrete, compatible four-channel FM broadcasting. There are two additional subcarriers in the Quadraplex system, supplementing the single one used in standard stereo FM. The baseband layout is as follows:
1353:
announced on October 31, 1940. These stations primarily simulcast their AM sister stations, in addition to broadcasting lush orchestral music for stores and offices, classical music to an upmarket listenership in urban areas, and educational programming.
1855:
Constructing a "bug" is a common early project for electronics hobbyists, and project kits to do so are available from a wide variety of sources. The devices constructed, however, are often too large and poorly shielded for use in clandestine activity.
1196:/processing to keep essential sound above the background noise for listeners, often at the expense of overall perceived sound quality. In such instances, however, this technique is often surprisingly effective in increasing the station's useful range.
548:
27.5 kHz. The IF bandwidth was ±5 kHz, as the only goal at the time was to relay AM radio-quality audio. This transmission system used 75 Όs audio pre-emphasis like the main monaural audio and subsequently the multiplexed stereo audio.
987:(SCA) services capability since its inception, as it was seen as another service which licensees could use to create additional income. Use of SCAs was particularly popular in the US, but much less so elsewhere. Uses for such subcarriers include
1852:
6 (<87.9 MHz) or aviation navigation frequencies (>107.9 MHz); most FM radios with analog tuners have sufficient overcoverage to pick up these slightly-beyond-outermost frequencies, although many digitally tuned radios have not.
1158:
can occasionally allow distant stations to be intermittently received over very large distances (hundreds of miles), but cannot be relied on for commercial broadcast purposes. Good reception across the country is one of the main advantages over
858:
61 to 91 kHz (sine quadrature 76 kHz subcarrier) (LF+RF) â (LR+RR) Front-back difference. This signal's modulation in algebraic sum and difference with the main channel and all the other subcarriers is also used for the Quadraphonic
602:
with the correct phase. The composite stereo multiplex signal contains the Main Channel (L+R), the pilot tone, and the (LâR) difference signal. This composite signal, along with any other sub-carriers, modulates the FM transmitter. The terms
854:
23 to 53 kHz (cosine quadrature 38 kHz subcarrier) (LF+RR) â (LR+RF) Diagonal difference. This signal's modulation in algebraic sum and difference with the main channel and all the other subcarriers is used for the Quadraphonic
1685:. The milestone of those conferences is the Stockholm agreement of 1961 among 38 countries. A 1984 conference in Geneva made some modifications to the original Stockholm agreement particularly in the frequency range above 100 MHz.
31:
1530:, the new station was the only one of the main four to not have an FM frequency allocated, which was the case for 21 years. Instead, Radio 1 shared airtime with Radio 2 FM, on Saturday afternoons, Sunday evenings, weekday evenings (10
452:
and reducing them by a corresponding amount in the receiver. Reducing the high audio frequencies in the receiver also reduces the high-frequency noise. These processes of boosting and then reducing certain frequencies are known as
866:
The normal stereo signal can be considered as switching between left and right channels at 38 kHz, appropriately band-limited. The quadraphonic signal can be considered as cycling through LF, LR, RF, RR, at 76 kHz.
830:
FCC experimental authority. It may not be compatible with very old receivers, but it is claimed that no difference can be heard with most newer receivers. At present, the FCC rules do not allow this mode of stereo operation.
850:
23 to 53 kHz (sine quadrature subcarrier) (LF+LR) â (RF+RR) left minus right difference signal. This signal's modulation in algebraic sum and difference with the main channel is used for 2 channel stereo listener
388:
in the FM broadcast band showing three strong local stations; speech and music show different patterns of frequency vs. time. When the transmitted audio is quiet, the 19 kHz stereo pilot tones can be resolved in the
1390:
band because most stations using it employ amplitude modulation) was overcrowded in western Europe, leading to interference problems and, as a result, many MW frequencies are suitable only for speech broadcasting.
774:
1245:
In 2021, the Brazilian Ministry of Communications expanded the FM radio band from 87.5-108.0 MHz to 76.1-108.0 MHz to enable the migration of AM radio stations in Brazilian capitals and large cities.
238:, only odd multiples are used. Some other countries follow this plan because of the import of vehicles, principally from the United States, with radios that can only tune to these frequencies. In some parts of
870:
Early efforts to transmit discrete four-channel quadraphonic music required the use of two FM stations; one transmitting the front audio channels, the other the rear channels. A breakthrough came in 1970 when
1114:
The output power of an FM broadcasting transmitter is one of the parameters that governs how far a transmission will cover. The other important parameters are the height of the transmitting antenna and the
336:
at any instant is directly proportional to the amplitude of the (audio) input signal, determining the instantaneous frequency of the transmitted signal. Because transmitted FM signals use significantly more
511:
Pre-emphasis and de-emphasis was used in the earliest days of FM broadcasting. According to a BBC report from 1946, 100 ÎŒs was originally considered in the US, but 75 ÎŒs subsequently adopted.
2843:
1417:
band in Western Europe became overcrowded after World War II, mainly due to the best available medium wave frequencies used at high power levels by the Allied Occupation Forces, both for broadcasting
3067:
1503:
expanded rapidly throughout the British Isles and effectively took over from LW and MW as the delivery platform of choice for fixed and portable domestic and vehicle-based receivers. In addition,
365:
used. For a monophonic broadcast, again the most common permitted maximum deviation is ±75 kHz. However, some countries specify a lower value for monophonic broadcasts, such as ±50 kHz.
3378:
1741:
or similar) to a standard FM radio receiver; such devices range from small units built to carry audio to a car radio with no audio-in capability (often formerly provided by special adapters for
582:
The (L+R) signal is limited to 30 Hz to 15 kHz to protect a 19 kHz pilot signal. The (LâR) signal, which is also limited to 15 kHz, is amplitude modulated onto a 38 kHz
1669:, the OIRT band was used. First restricted to 68â73 MHz with 100 kHz channel spacing, then in the 1970s eventually expanded to 65.84â74.00 MHz with 30 kHz channel spacing.
3294:
1780:
or similar purposes, allowing the user to use an FM radio as an output rather than a dedicated amplifier and speaker. Professional-grade wireless microphones generally use bands in the
3235:
1174:, so AM radio stations can be received at hundreds (sometimes thousands) of miles. This is a property of the carrier wave's typical frequency (and power), not its mode of modulation.
376:, New York City, which he used for secret tests of his system between 1934 and 1935. Licensed as experimental station W2XDG, it transmitted on 41 MHz at a power of 2 kW.
2769:
1138:
can permit reception where there is no direct line of sight between broadcaster and receiver. The reception can vary considerably depending on the position. One example is the
934:
arrangement to reduce noise. The pre-emphasis change compensates for the excess treble response that otherwise would make listening difficult for those without Dolby decoders.
2573:
2367:
500:. Modulation control (limiter) devices are used to prevent this. Systems more modern than FM broadcasting tend to use either programme-dependent variable pre-emphasis; e.g.,
1811:
are based on FM radio, mostly using the 72.1 to 75.8 MHz band. Aside from the assisted listening receivers, only certain kinds of FM receivers can tune to this band.
1242:
operating in FM in Brazil. From the second half of the 1970s onwards, FM radio stations began to become popular in Brazil, causing AM radio to gradually lose popularity.
2713:
806:=19 kHz is the frequency of the pilot tone. Slight variations in the peak deviation may occur in the presence of other subcarriers or because of local regulations.
193:
1819:
Low-power transmitters such as those mentioned above are also sometimes used for neighborhood or campus radio stations, though campus radio stations are often run over
142:, having less static and popping sounds than are often heard on AM. Therefore, FM is used for most broadcasts of music and general audio (in the audio spectrum). FM
2790:
879:) in San Francisco successfully transmitted true quadraphonic sound from a single FM station using the Quadraplex system under Special Temporary Authority from the
804:
3264:
2931:
1586:
feed, consisting largely of classical music and Parliament, as a programme source. It had a very small audience and was shut down in 1961 ostensibly to clear the
3353:
2883:
369:
3324:
2835:
1990:
5147:
5119:
5114:
4139:
3555:
3857:
2165:
2094:
3498:
3051:
3607:
2293:
594:
frequency and with a precise phase relationship to it, as defined by the formula below, is also generated. The pilot is transmitted at 8â10% of overall
3374:
188:
countries, the older 65.8â74 MHz band is also used. Assigned frequencies are at intervals of 30 kHz. This band, sometimes referred to as the
2509:
2058:
3286:
1932:
1499:. These three networks used the sub-band 88.0â94.6 MHz. The sub-band 94.6â97.6 MHz was later used for BBC and local commercial services.
984:
576:
2251:
222:
The frequency of an FM broadcast station (more strictly its assigned nominal center frequency) is usually a multiple of 100 kHz. In most of
5141:
3896:
1927:
3409:
1791:
transmit in the FM broadcast band, with the headphones tunable to only a subset of the broadcast band. Higher-quality wireless headphones use
624:
134:. FM broadcasting offers higher fidelityâmore accurate reproduction of the original program soundâthan other broadcasting techniques, such as
5136:
5126:
5106:
4908:
3867:
3227:
3107:
3004:
2422:
1965:
1863:
activity is broadcast in the FM range, because of the band's greater clarity and listenership, the smaller size and lower cost of equipment.
259:
3434:
1912:
1312:
2813:
5131:
4977:
4092:
3916:
2026:
1334:, with studios in Boston and later Portland, Maine, but whose transmitter was atop the highest mountain in the northeast United States,
2197:
4903:
3523:
3125:
583:
181:
4997:
3061:
2562:
2356:
2287:
2229:
1754:
1609:
1534:
pm to midnight) and Bank Holidays, eventually having its own FM frequency starting in London in October 1987 on 104.8 MHz from
880:
556:
449:
2761:
4782:
4330:
4132:
3548:
3154:
1937:
891:
Quadraphonic FM broadcasting in the United States. The first commercial FM station to broadcast quadraphonic program content was
2538:
2473:
563:), Zenith, and General Electric. The individual systems were evaluated for their strengths and weaknesses during field tests in
4893:
2670:
2655:
1969:
1335:
942:
618:
The instantaneous deviation of the transmitter carrier frequency due to the stereo audio and pilot tone (at 10% modulation) is
2705:
1827:. As a general rule, enforcement towards low-power FM stations is stricter than with AM stations, due to problems such as the
1432:
After World War II, broadcasting frequencies were reorganized and reallocated by delegates of the victorious countries in the
1274:
FM broadcasting began in the late 1930s, when it was initiated by a handful of early pioneer experimental stations, including
402:
which is the sum of twice the maximum deviation and twice the maximum modulating frequency. For a transmission that includes
5224:
4888:
4439:
4029:
3180:
1897:
3020:
1315:
to the 88â108 MHz portion of the radio spectrum. General Electric sold the station in the 1980s. Today this station is
2669:"PrĂŒfung eines modifizierten HIGH COM-Kompanders fĂŒr den Einsatz bei der RF-Ăbertragung im UKW-Hörfunk" (in German).
5219:
4913:
3877:
862:
105 kHz SCA subcarrier, phase-locked to 19 kHz pilot, for reading services for the blind, background music, etc.
505:
338:
5198:
2606:
2129:
847:
50 Hz to 15 kHz main channel (sum of all 4 channels) (LF+LR+RF+RR) signal, for mono FM listening compatibility.
5188:
4949:
4846:
4389:
4156:
3804:
2451:
1872:
1628:
installed which down-convert the higher frequencies above 90 MHz. New Zealand has no indigenous car manufacturers.
1543:
1254:
1007:
sound. If a station does not broadcast in stereo, everything from 23 kHz on up can be used for other services. The
276:
139:
3256:
2921:
1306:, Alpine, New Jersey (owned by Edwin Armstrong himself, closed down upon Armstrong's death in 1954). Also of note were
1142:
mountain range, which makes constant reception of Italian signals from Veneto and Marche possible in a good portion of
5178:
4685:
4125:
4102:
3541:
3345:
2880:
1902:
1370:) were reported as the first stereo stations. By the late 1960s, FM had been adopted for broadcast of stereo "A.O.R.â'
3316:
532:
These FM multiplex transmissions started in November 1934 and consisted of the main channel audio program and three
5037:
4959:
4898:
4605:
4075:
4044:
3789:
3699:
1808:
1704:
1694:
1613:
1436:. German broadcasters were left with only two remaining AM frequencies and were forced to look to FM for expansion.
1232:
1071:
826:
3506:
2738:
288:
192:
band, is slowly being phased out. Where the OIRT band is used, the 87.5â108.0 MHz band is referred to as the
4809:
4770:
4615:
4515:
4444:
4377:
4204:
2154:
2083:
1907:
1877:
1433:
1303:
1270:, USA. The insets show a part of the transmitter, and a map of FM stations in 1940. The tower still stands today.
1193:
1349:
A commercial FM broadcasting band was formally established in the United States as of January 1, 1941, with the
271:
5168:
4410:
4345:
4298:
4184:
1892:
1887:
1882:
1737:
in United States terms) transmitters are available that can transmit a signal from an audio device (usually an
1287:
1087:
922:
A commercially unsuccessful noise reduction system used with FM radio in some countries during the late 1970s,
559:. Included were systems from 14 proponents including Crosby, Halstead, Electrical and Musical Industries, Ltd (
358:
2314:
van Duyne, John P. (Fall 1961). "The Notebook:A Modulator for the New FM Stereo System". Boontown Radio Corp.
368:
210:, until the late 2010s, FM broadcast stations only used the 88â108 MHz band, but with the phasing out of
3206:
2277:
5007:
4992:
4836:
4787:
4710:
4610:
4288:
4174:
4169:
4054:
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3906:
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2646:
Mielke, E.-JĂŒrgen (1977). "EinfluĂ des Dolby-B-Verfahrens auf die ĂbertragungsqualitĂ€t im UKW-Hörrundfunk".
1848:
1616:
began full-time FM transmissions. Commercial FM licences were finally approved in 1983, with Auckland-based
1418:
1209:
1166:
This is still less than the range of AM radio waves, which because of their lower frequencies can travel as
564:
3453:
2501:
1327:
4929:
4715:
4530:
4475:
4470:
4283:
4248:
3948:
3862:
3704:
3494:
Stereo Multiplexing for Dummies Graphs that show waveforms at different points in the FM Multiplex process
2315:
2051:
1535:
1331:
83:
1102:, is authorized for "hybrid" mode operation, wherein both the conventional analog FM carrier and digital
4831:
4635:
4600:
4520:
4500:
4422:
4310:
4231:
4049:
3872:
3852:
2678:
2329:
1601:
1539:
1523:
1487:
conducted tests during the 1940s, then began FM broadcasting in 1955, with three national networks: the
1367:
1283:
1031:
988:
916:
814:
522:
501:
399:
373:
305:
2255:
4745:
4705:
4675:
4432:
4367:
4258:
3677:
3617:
3602:
3597:
3488:
1781:
1275:
1237:
The first radio station to broadcast in FM in Brazil was RĂĄdio Imprensa, which began broadcasting in
1151:
1043:
325:
317:
115:
95:
A commercial 35 kW FM radio transmitter built in the late 1980s. It belongs to FM radio station
39:
35:
2968:
2952:
2903:
2864:
2320:
1799:
such as 315 MHz, 863 MHz, 915 MHz, or 2.4 GHz instead of the FM broadcast band.
214:, the 76-88 MHz band (old band channels 5 and 6 in VHF television) are allocated for old local
4755:
4695:
4454:
4416:
4273:
4214:
4199:
3784:
3655:
3401:
2805:
2633:
1917:
1734:
1546:
site in Kent. Following this the BBC Radio 1 FM frequencies were rolled out to the rest of the UK.
1492:
1488:
1441:
1409:
were among the first countries to adopt FM on a widespread scale. Among the reasons for this were:
1371:
598:
level and used by the receiver to identify a stereo transmission and to regenerate the 38 kHz
329:
147:
91:
2411:
1746:
some models designed for beginner hobbyists might not. Similar transmitters are often included in
971:
440:
distribution in an FM system, with the effect that noise occurs predominantly at the higher audio
4982:
4939:
4870:
4740:
4670:
4645:
4580:
4427:
4148:
3921:
3520:
2926:
1267:
1079:
960:
884:
485:
437:
111:
2119:"Digital Audio BroadcastingSupplementary Analog SCA Compatibility TestsTest Plan and Procedures"
1831:, and as a result, FM microbroadcasters generally do not reach as far as their AM competitors.
5022:
4944:
4858:
4841:
4804:
4690:
4650:
4480:
4449:
4315:
4209:
4034:
3911:
3103:
3057:
3000:
2784:
2283:
1922:
1824:
1715:
1641:
1147:
1135:
1051:
1047:
1027:
1019:
403:
354:
333:
211:
163:
100:
2015:
1600:
campaigning starting in the mid-1970s, particularly in Auckland. An experimental FM station,
5027:
4987:
4967:
4934:
4863:
4821:
4735:
4590:
4575:
4550:
4525:
4485:
4335:
4194:
4189:
4179:
4070:
4014:
3828:
3639:
3564:
3095:
2992:
2189:
1761:
allow them. Starting on 1 October 2006, these devices became legal in most countries in the
1496:
1307:
1205:
904:
280:
3122:
782:
328:
or AM varies the amplitude of the carrier, with its frequency remaining constant. With FM,
4655:
4510:
4278:
4241:
4009:
3645:
3527:
3510:
3129:
2887:
2691:
2342:
1820:
1758:
1747:
1621:
1259:
1216:
1039:
151:
135:
123:
4253:
2221:
488:
transmissions. For stereo, pre-emphasis is applied to the left and right channels before
75:
the original program sound from the modulated radio signal and reproduces the sound in a
3533:
2118:
4853:
4725:
4700:
4660:
4630:
4505:
4340:
4226:
3649:
2628:
1828:
1766:
1762:
1742:
1583:
1480:
1238:
1186:
385:
380:
251:
173:
69:
64:
of the carrier wave is modulated to encode the original sound. In FM broadcasting, the
3448:
3146:
2477:
952:
broadband compander system, but was never introduced commercially in FM broadcasting.
586:(DSB-SC) signal, thus occupying 23 kHz to 53 kHz. A 19 kHz ± 2 Hz
320:
or FM is a form of modulation which conveys information by varying the frequency of a
176:. Usually 87.5 to 108.0 MHz is used, or some portion of it, with few exceptions:
5213:
5002:
4775:
4765:
4680:
4570:
4565:
4555:
4540:
4362:
4221:
4024:
3749:
3629:
3568:
3089:
2531:
1445:
1339:
1083:
1067:
1059:
996:
572:
526:
465:
143:
127:
17:
1957:
930:
but used a modified 25 ÎŒs pre-emphasis time constant and a frequency selective
4880:
4720:
4665:
4595:
4560:
4495:
4394:
4384:
4236:
4096:
3571:
1860:
1844:
1460:
1426:
1182:
1116:
1015:
1004:
963:
implemented in some radio broadcasting stations in the United States in the 1980s.
839:
497:
489:
448:. This can be offset, to a limited extent, by boosting the high frequencies before
321:
227:
185:
72:
55:
51:
47:
3176:
3375:"Change to the law to allow the use of low power FM transmitters for MP3 players"
3028:
5080:
4730:
4640:
4625:
4585:
4545:
4404:
4019:
3844:
3635:
1792:
1527:
1519:
1515:
1511:
1414:
1398:
1383:
1192:
Many FM stations, especially those located in severe multipath areas, use extra
1178:
1167:
1055:
be capable of use alongside ARI despite using identical subcarrier frequencies.
938:
599:
591:
533:
477:
473:
454:
231:
223:
215:
76:
2922:"MUSIC FOR BUSES URGED / F. C. C. Proposes Wide Field Also for FM News Reports"
2052:"Ofcom Site Engineering Code for Analogue Radio Broadcast Transmission Systems"
1993:[MCom awards certificate to stations that debut the extended FM band].
1839:
FM transmitters have been used to construct miniature wireless microphones for
1681:
The frequencies available for FM were decided by some important conferences of
5085:
4792:
4490:
4399:
4355:
4325:
4303:
4293:
4268:
3901:
3887:
3589:
3476:
3469:
3099:
2598:
2447:
1784:
region so they can run on dedicated equipment without broadcast interference.
1773:
1738:
1617:
1587:
1171:
1155:
1035:
1034:(AF), traffic data for satellite navigation systems and radio text (RT). This
1008:
1000:
976:
956:
946:
931:
818:
595:
587:
469:
458:
43:
2996:
122:) of the radio broadcast carrier wave. Invented in 1933 by American engineer
5070:
4535:
4350:
3993:
3988:
3983:
3973:
3964:
3823:
3493:
2836:"MCom entrega certificado Ă s emissoras que estreiam a faixa estendida da FM"
1991:"MCom entrega certificado Ă s emissoras que estreiam a faixa estendida da FM"
1840:
1788:
1765:. Devices made to the harmonized European specification became legal in the
1637:
1624:
being the first to take up the offer. Broadcasting was deregulated in 1989.
1605:
1579:
1468:
1160:
992:
900:
536:: a fax program, a synchronizing signal for the fax program and a telegraph
441:
293:
243:
235:
65:
61:
540:
channel. These original FM multiplex subcarriers were amplitude modulated.
341:
than AM signals, this form of modulation is commonly used with the higher (
1636:
Trinidad and Tobago's first FM Radio station was 95.1FM, now rebranded as
1146:, Croatia, despite the distance being over 200 km (125 miles). Other
5065:
5055:
4972:
4797:
4620:
3714:
3667:
3625:
1796:
1422:
1103:
1099:
1091:
1023:
949:
923:
481:
445:
1444:
and Australia were far slower at adopting FM radio than those in either
769:{\displaystyle \left+0.1\sin 2\pi f_{p}t\right]\times 75~\mathrm {kHz} }
30:
5060:
5045:
3754:
3709:
3663:
3503:
3483:
2734:
1777:
1406:
1402:
1394:
1343:
1323:
1139:
1128:
927:
896:
892:
2412:"Subsidiary communications multiplex operation: engineering standards"
779:
where A and B are the pre-emphasized left and right audio signals and
5090:
5050:
4372:
4164:
4117:
3978:
3794:
3768:
3763:
3722:
3673:
3659:
3346:"Switching off FM in Norway and, soon, Switzerland | News | WorldDAB"
3287:"Norway becomes first country to end national radio broadcasts on FM"
2392:"Stereophonic Broadcasting: Technical Details of Pilot-tone System",
1719:
1700:
1653:
1566:
1449:
1299:
1143:
1063:
552:
372:
Armstrong's first prototype FM broadcast transmitter, located in the
247:
239:
207:
3053:
Early FM Radio: Incremental Technology in Twentieth-Century America
1026:
of the stereo pilot tone) is used to carry a low-bandwidth digital
5075:
5012:
4320:
3799:
3694:
3586:
3202:
1714:
1554:
1504:
1295:
1263:
1253:
1095:
970:
575:
was rejected by the FCC because it was incompatible with existing
464:
The amount of pre-emphasis and de-emphasis used is defined by the
430:
379:
367:
287:
270:
255:
200:
131:
90:
82:
29:
2084:"Planning standards for terrestrial FM sound broadcasting at VHF"
5017:
1772:
The FM broadcast band is also used by some inexpensive wireless
1471:
from 1919 to 1924, which employed narrow-band FM transmissions.
1464:
1363:
1359:
1316:
1291:
1279:
1075:
872:
568:
189:
96:
4121:
3934:
3537:
4263:
3402:"Inexpensive Options for Assistive Listening Device Receivers"
2397:
1682:
1666:
1484:
560:
346:
342:
169:
2985:
Lemstra, Wolter; Hayes, Vic; Groenewegen, John (2010-11-18).
941:
was tested in Germany between July 1979 and December 1981 by
168:
Throughout the world, the FM broadcast band falls within the
1582:
capital cities in 1947 on an "experimental" basis, using an
1127:
VHF radio waves usually do not travel far beyond the visual
919:
to FM broadcasting were carried out in the 1970s and 1980s:
2988:
The Innovation Journey of Wi-Fi: The Road to Global Success
2279:
Living Stereo: Histories and Cultures of Multichannel Sound
1070:
services are deployed within the FM band rather than using
350:
46:. The sound of the program material, usually coming from a
2276:
Théberge, Paul; Devine, Kyle; Everrett, Tom (2015-01-29).
1046:
systems are used for private communications. A variant of
907:
under the guidance of Chief Engineer Brian Jeffrey Brown.
1958:"Transmission standards for FM sound broadcasting at VHF"
975:
Typical spectrum of composite baseband signal, including
279:) than AM. This was shown in a dramatic demonstration by
218:
stations which have moved to FM in agreement with ANATEL.
1703:
became the first country so far to completely switch to
68:
of the carrier wave is modulated to encode the sound. A
1030:
signal, providing extra features such as station name,
1018:
services are also available. A 57 kHz subcarrier (
813:
In addition, for a given RF level at the receiver, the
887:
and that it did not interfere with adjacent stations.
3515:
3257:"Norway becomes first country to switch off FM radio"
785:
627:
398:
The bandwidth of an FM transmission is given by the
87:
Position of FM radio in the electromagnetic spectrum
5099:
5036:
4958:
4922:
4879:
4820:
4754:
4463:
4155:
4063:
4002:
3962:
3941:
3886:
3843:
3813:
3777:
3742:
3735:
3687:
3616:
3585:
3578:
2762:"Live traffic information services for GPS systems"
27:
Radio transmission of audio by frequency modulation
2491:Includes tips for multipath & fringe problems.
2016:"FM BROADCAST STATION SELF - INSPECTION CHECKLIST"
798:
768:
615:are used interchangeably to describe this signal.
1753:Legality of these devices varies by country. The
2806:"O sonho dourado: 45 anos de RĂĄdio FM no Brasil"
2706:"Full text of "Radio Electronics (August 1987)""
304:transmitter on Lake Mountain, Utah. It radiates
3521:FM Broadcast and TV Broadcast Aural Subcarriers
1177:The range of FM transmission is related to the
571:in Pittsburgh as the originating station. The
4133:
3549:
1346:Milwaukee, Wisconsin (went off air in 1950).
126:, wide-band FM is used worldwide to transmit
8:
3285:Oslo, Agence France-Presse in (2017-12-13).
3136:(Netherlands Institute for Sound and Vision)
3021:""Stereophonic FM Broadcast Begun by WEFM",
5148:Global telecommunications regulation bodies
2789:: CS1 maint: numeric names: authors list (
1510:When the BBC's radio networks were renamed
1330:Nashville, Tennessee (signed off in 1951);
480:, 75 ÎŒs is used. This applies to both
476:time constant is used. In the Americas and
34:AM and FM modulated signals for radio. AM (
5184:
4140:
4126:
4118:
3931:
3739:
3582:
3556:
3542:
3534:
3504:Invention History – The Father of FM
2991:(1 ed.). Cambridge University Press.
2673:(IRT). 1981-12-30. Technical Report 55/81.
2400:Engineering Information Service, June 1970
2282:. Bloomsbury Publishing USA. p. 189.
1640:, which was launched in March 1976 by the
551:In the late 1950s, several systems to add
3134:Nederlands Instituut voor Beeld en Geluid
2319:
2216:
2214:
2128:. Advanced Television Technology Center.
1823:. This is generally considered a form of
790:
784:
755:
732:
696:
662:
641:
626:
3317:"Norway's FM Shutdown, Six Months Later"
2760:comments, Crutchfield's Matt Freeman 9.
2421:. US Federal Communications Commission.
1933:Lists of radio stations in North America
1711:Small-scale use of the FM broadcast band
1204:For broader coverage of this topic, see
1042:, thus is only suitable for text. A few
472:circuit. In most of the world a 50
292:Crossed-dipole antenna array of station
2842:(in Brazilian Portuguese). 7 May 2021.
2512:from the original on September 13, 2018
2222:"Report 1946-04 â Frequency Modulation"
2190:"The 75 Microsecond Pre-Emphasis Curve"
1949:
985:subsidiary communications authorization
577:subsidiary communications authorization
250:, only even multiples are used. In the
3412:from the original on 27 September 2019
3381:from the original on 12 September 2015
3088:Lewis, Peter M.; Booth, Jerry (1989).
2782:
2741:from the original on November 29, 2019
2687:
2676:
2338:
2327:
1928:List of FM radio stations in Bangalore
1755:U.S. Federal Communications Commission
1311:to 99.5 MHz when the FM band was
2816:from the original on 27 November 2021
2135:from the original on 18 November 2019
2091:International Telecommunication Union
2032:from the original on 16 February 2017
1966:International Telecommunication Union
7:
5194:
3123:Idzerda, the first radio broadcaster
2953:"FCC Allocates 88-106 mc Band to FM"
2846:from the original on 7 November 2021
2840:Ministry of Communications of Brazil
2609:from the original on 2 February 2017
2474:"FM Reception Guide: FM Propagation"
2428:from the original on 3 February 2017
2373:from the original on 22 January 2019
1913:FM broadcasting in the United States
1258:One of the first FM radio stations,
3499:Factbook list of stations worldwide
2599:"Compatible four channel FM system"
555:to FM radio were considered by the
275:FM has better rejection of static (
3489:Frequency Modulation (FM) Tutorial
3094:. London: Macmillan Education UK.
2934:from the original on March 8, 2021
2064:from the original on July 22, 2019
1835:Clandestine use of FM transmitters
1351:first fifteen construction permits
1292:W1XSL/W1XPW/W65H/WDRC-FM/WFMQ/WHCN
1086:techniques, makes use of advanced
762:
759:
756:
590:, at exactly half the 38 kHz
584:double-sideband suppressed-carrier
203:, the band 76â95 MHz is used.
25:
3480:Compatible Four Channel FM System
3183:from the original on 5 March 2016
3177:"[IT] Radio FM in Italia"
3157:from the original on 27 June 2013
2579:from the original on 31 July 2020
2454:from the original on 24 June 2017
1610:Victoria University of Wellington
1463:operated a broadcasting station,
885:stereo transmission and reception
508:TV sound system, or none at all.
254:, both odd and even are used. In
138:. It is also less susceptible to
5193:
5183:
5174:
5173:
5162:
4783:Free-space optical communication
4090:
3147:"Radio 1 History - Transmitters"
2502:"SSBSC: A Win-Win for FM Radio?"
2448:"FM Stereo demodulation circuit"
1938:Lists of radio stations in Ghana
1918:Ripping music from FM broadcasts
1733:In some countries, small-scale (
1608:in early 1982. Later that year,
3356:from the original on 2023-01-31
3327:from the original on 2023-01-31
3297:from the original on 2023-02-05
3267:from the original on 2017-12-16
3238:from the original on 2007-06-26
3209:from the original on 2016-06-04
3070:from the original on 2023-07-01
2772:from the original on 2023-07-01
2716:from the original on 2016-04-02
2648:Rundfunktechnische Mitteilungen
2544:from the original on 2018-09-13
2296:from the original on 2023-07-01
2232:from the original on 2020-01-03
2200:from the original on 2019-10-30
2171:from the original on 2022-05-29
2155:"Recommendation ITU-R SM.853-1"
2100:from the original on 2018-08-20
1972:from the original on 2012-11-06
1729:Consumer use of FM transmitters
1723:TuneCast II FM microtransmitter
1526:to coincide with the launch of
1440:Public service broadcasters in
979:and a subcarrier on 92 kHz
915:Various attempts to add analog
825:In the U.S. around 2010, using
50:, is used to modulate (vary) a
4030:Error detection and correction
3315:Careless, James (2018-06-06).
2904:"New FM Call Letters Proposed"
2226:BBC Research & Development
1898:FM broadcasting in New Zealand
1278:(shut down in 1953) and W1XTG/
1217:AM broadcasting § History
959:-based noise reduction system
54:of a specific frequency, then
1:
3050:Frost, Gary L. (April 2010).
2920:no byline (January 1, 1954).
2910:, November 15, 1940, page 77.
1419:entertainment to their troops
1106:subcarriers are transmitted.
983:FM broadcasting has included
417:. This is also known as the
103:, and broadcasts at 95.5 MHz.
5169:Telecommunication portal
4950:Telecommunications equipment
3454:Resources in other libraries
2975:, July 2, 1945, pages 64-68.
2969:"FCC Allocations Order Text"
2959:, July 2, 1945, pages 13-14.
2871:, December 1, 1940, page 76.
2671:Institut fĂŒr Rundfunktechnik
2656:Institut fĂŒr Rundfunktechnik
2252:"How FM Stereo Came to Life"
1873:FM broadcasting in Australia
1294:, Meriden, Connecticut; and
1038:signal runs at only 1,187.5
544:with much improved results.
425:Pre-emphasis and de-emphasis
140:common forms of interference
4686:Alexander Stepanovich Popov
4103:Comparison of radio systems
3377:. Ofcom. 23 November 2006.
2812:(in Brazilian Portuguese).
2194:Cornelius' home on the web!
1995:Ministério das ComunicaçÔes
1903:FM broadcasting in Pakistan
1809:assistive listening devices
1578:FM broadcasting started in
999:-type services. There were
955:Yet another system was the
384:Instantaneous spectrum and
5241:
4390:Telecommunications history
4076:International broadcasting
4045:FM extended band in Brazil
2894:, May 25, 1940, page 2011.
1705:Digital audio broadcasting
1695:Digital audio broadcasting
1692:
1689:FM broadcasting switch-off
1362:(in the Chicago area) and
1233:FM extended band in Brazil
1230:
1214:
1203:
827:single-sideband modulation
161:
5157:
4998:Public Switched Telephone
4810:telecommunication circuit
4771:Fiber-optic communication
4516:Francis Blake (telephone)
4311:Optical telecommunication
4084:
3930:
3516:Audio Engineering Society
3463:Related technical content
3449:Resources in your library
3400:Clem, Richard P. (2014).
3100:10.1007/978-1-349-19984-6
2394:Information Sheet 1604(4)
1997:(in Brazilian Portuguese)
1908:FM broadcasting in the UK
1878:FM broadcasting in Canada
1750:receivers and some toys.
1434:Copenhagen Frequency Plan
1342:(shut down in 1948); and
1282:, both transmitting from
1074:or the Japanese standard
967:Other subcarrier services
359:land mobile radio systems
4909:Orbital angular-momentum
4346:Satellite communications
4185:Communications satellite
3025:, June 2, 1961, p. B-10"
2997:10.1017/cbo9780511666995
2563:"FCC CFR 47 Part 73.322"
1893:FM broadcasting in Japan
1888:FM broadcasting in India
1883:FM broadcasting in Egypt
1849:covert listening devices
1677:ITU Conferences about FM
1324:W2XQR/W59NY/WQXQ/WQXR-FM
1322:Other pioneers included
1288:Worcester, Massachusetts
1262:'s experimental station
60:In AM broadcasting, the
4788:Molecular communication
4611:Gardiner Greene Hubbard
4440:Undersea telegraph line
4175:Cable protection system
4055:Shortwave relay station
3954:Audio signal processing
1923:RDS (Radio Data System)
1210:History of broadcasting
937:A similar system named
565:Uniontown, Pennsylvania
182:former Soviet republics
4930:Communication protocol
4716:Charles Sumner Tainter
4531:Walter Houser Brattain
4476:Edwin Howard Armstrong
4284:Information revolution
3949:Audio data compression
3530:â Clifton Laboratories
3484:Introduction to FM MPX
2686:Cite journal requires
2476:. WGBH. Archived from
2337:Cite journal requires
1725:
1425:propaganda across the
1271:
1050:is the North American
989:radio reading services
980:
945:. It was based on the
939:High Com FM
800:
770:
390:
377:
349:) frequencies used by
309:
285:
104:
88:
80:
5225:Broadcast engineering
4904:Polarization-division
4636:Narinder Singh Kapany
4601:Erna Schneider Hoover
4521:Jagadish Chandra Bose
4501:Alexander Graham Bell
4232:online video platform
4050:Multipath propagation
3873:MPEG-1 Audio Layer II
3743:Frequency allocations
3618:Frequency allocations
3477:U.S. patent 3,708,623
3470:U.S. patent 1,941,066
2865:"Carnival Atmosphere"
1793:infrared transmission
1718:
1421:and for broadcasting
1368:Schenectady, New York
1284:Paxton, Massachusetts
1257:
1032:alternative frequency
974:
815:signal-to-noise ratio
801:
799:{\displaystyle f_{p}}
771:
523:Empire State Building
400:Carson bandwidth rule
383:
374:Empire State Building
371:
291:
274:
130:sound over broadcast
94:
86:
33:
18:FM radio broadcasting
5220:Radio communications
4746:Vladimir K. Zworykin
4706:Almon Brown Strowger
4676:Charles Grafton Page
4331:Prepaid mobile phone
4259:Electrical telegraph
4003:Technical (emission)
3091:The Invisible Medium
1769:on 8 December 2006.
1584:ABC national network
1152:tropospheric ducting
1082:approach, as do all
783:
625:
326:amplitude modulation
318:Frequency modulation
306:circularly polarized
116:frequency modulation
40:frequency modulation
36:amplitude modulation
4696:Johann Philipp Reis
4455:Wireless revolution
4417:The Telephone Cases
4274:Hydraulic telegraph
3031:on October 20, 2000
2634:Ann Arbor, Michigan
2025:. FCC. p. 18.
1803:Assistive listening
1632:Trinidad and Tobago
1604:, was broadcast in
1386:band (known as the
1372:Album Oriented Rock
1170:or reflect off the
419:necessary bandwidth
330:frequency deviation
148:very high frequency
4894:Frequency-division
4871:Telephone exchange
4741:Charles Wheatstone
4671:Jun-ichi Nishizawa
4646:Innocenzo Manzetti
4581:Reginald Fessenden
4316:Optical telegraphy
4149:Telecommunications
3526:2011-12-23 at the
3509:2017-06-22 at the
3228:"ITU Publications"
3128:2021-02-06 at the
2927:The New York Times
2886:2022-01-15 at the
2881:"FCC Order No. 67"
2804:Pacelli, Edoardo.
2532:"Radio Tech Check"
2023:transition.fcc.gov
1859:In addition, much
1726:
1344:W9XAO/W55M/WTMJ-FM
1272:
1268:Alpine, New Jersey
1123:Reception distance
1110:Transmission power
1090:. The proprietary
1080:in-band on-channel
981:
796:
766:
391:
378:
332:from the assigned
310:
286:
184:, and some former
112:radio broadcasting
105:
89:
81:
5207:
5206:
4945:Store and forward
4940:Data transmission
4854:Network switching
4805:Transmission line
4651:Guglielmo Marconi
4616:Internet pioneers
4481:Mohamed M. Atalla
4450:Whistled language
4115:
4114:
4111:
4110:
4035:FM broadcast band
3942:Technical (audio)
3839:
3838:
3731:
3730:
3435:Library resources
3109:978-0-333-42366-0
3006:978-0-511-66699-5
2636:, January 3, 1973
2508:. April 2, 2012.
1825:microbroadcasting
1815:Microbroadcasting
1776:sold as toys for
1642:TBC Radio Network
1405:and particularly
1194:audio compression
1181:'s RF power, the
1148:radio propagation
1136:knife edge effect
1028:Radio Data System
754:
678:
657:
355:FM broadcast band
334:carrier frequency
212:analog television
164:FM broadcast band
152:radio frequencies
101:Henderson, Nevada
16:(Redirected from
5232:
5197:
5196:
5187:
5186:
5177:
5176:
5167:
5166:
5165:
5038:Notable networks
5028:Wireless network
4968:Cellular network
4960:Types of network
4935:Computer network
4822:Network topology
4736:Thomas A. Watson
4591:Oliver Heaviside
4576:Philo Farnsworth
4551:Daniel Davis Jr.
4526:Charles Bourseul
4486:John Logie Baird
4195:Data compression
4190:Computer network
4142:
4135:
4128:
4119:
4097:Radio portal
4095:
4094:
4093:
4071:History of radio
4015:AM expanded band
3932:
3815:Commercial radio
3740:
3583:
3558:
3551:
3544:
3535:
3479:
3472:
3422:
3421:
3419:
3417:
3397:
3391:
3390:
3388:
3386:
3371:
3365:
3364:
3362:
3361:
3350:www.worlddab.org
3342:
3336:
3335:
3333:
3332:
3312:
3306:
3305:
3303:
3302:
3282:
3276:
3275:
3273:
3272:
3261:The Local Norway
3253:
3247:
3246:
3244:
3243:
3224:
3218:
3217:
3215:
3214:
3199:
3193:
3192:
3190:
3188:
3173:
3167:
3166:
3164:
3162:
3143:
3137:
3120:
3114:
3113:
3085:
3079:
3078:
3076:
3075:
3047:
3041:
3040:
3038:
3036:
3027:. Archived from
3017:
3011:
3010:
2982:
2976:
2966:
2960:
2955:by Bill Bailey,
2950:
2944:
2943:
2941:
2939:
2917:
2911:
2901:
2895:
2892:Federal Register
2878:
2872:
2862:
2856:
2855:
2853:
2851:
2832:
2826:
2825:
2823:
2821:
2801:
2795:
2794:
2788:
2780:
2778:
2777:
2757:
2751:
2750:
2748:
2746:
2731:
2725:
2724:
2722:
2721:
2702:
2696:
2695:
2689:
2684:
2682:
2674:
2666:
2660:
2659:
2643:
2637:
2625:
2619:
2618:
2616:
2614:
2603:pdfpiw.uspto.gov
2595:
2589:
2588:
2586:
2584:
2578:
2567:
2559:
2553:
2552:
2550:
2549:
2543:
2536:
2528:
2522:
2521:
2519:
2517:
2498:
2492:
2489:
2487:
2485:
2470:
2464:
2463:
2461:
2459:
2444:
2438:
2437:
2435:
2433:
2427:
2416:
2408:
2402:
2401:
2389:
2383:
2382:
2380:
2378:
2372:
2361:
2353:
2347:
2346:
2340:
2335:
2333:
2325:
2323:
2311:
2305:
2304:
2302:
2301:
2273:
2267:
2266:
2264:
2263:
2254:. Archived from
2247:
2241:
2240:
2238:
2237:
2228:. January 1946.
2218:
2209:
2208:
2206:
2205:
2186:
2180:
2179:
2177:
2176:
2170:
2159:
2151:
2145:
2144:
2142:
2140:
2134:
2123:
2115:
2109:
2108:
2106:
2105:
2099:
2088:
2080:
2074:
2073:
2071:
2069:
2063:
2056:
2048:
2042:
2041:
2039:
2037:
2031:
2020:
2012:
2006:
2005:
2003:
2002:
1987:
1981:
1980:
1978:
1977:
1968:. pp. 4â5.
1954:
1538:. Eventually in
1533:
1522:respectively in
1336:Mount Washington
1308:General Electric
1206:History of radio
1150:effects such as
1088:compressed audio
905:Saline, Michigan
805:
803:
802:
797:
795:
794:
775:
773:
772:
767:
765:
752:
745:
741:
737:
736:
709:
705:
701:
700:
679:
674:
663:
658:
653:
642:
461:, respectively.
416:
412:
409:
303:
299:
281:General Electric
21:
5240:
5239:
5235:
5234:
5233:
5231:
5230:
5229:
5210:
5209:
5208:
5203:
5163:
5161:
5153:
5095:
5032:
4954:
4918:
4875:
4824:
4816:
4757:
4750:
4656:Robert Metcalfe
4511:Tim Berners-Lee
4459:
4279:Information Age
4151:
4146:
4116:
4107:
4091:
4089:
4080:
4059:
4040:FM broadcasting
4010:AM broadcasting
3998:
3958:
3937:
3926:
3882:
3835:
3809:
3778:Digital systems
3773:
3758:
3727:
3688:Digital systems
3683:
3612:
3574:
3562:
3528:Wayback Machine
3511:Wayback Machine
3475:
3468:
3460:
3459:
3458:
3443:
3442:
3440:FM broadcasting
3438:
3431:
3426:
3425:
3415:
3413:
3399:
3398:
3394:
3384:
3382:
3373:
3372:
3368:
3359:
3357:
3344:
3343:
3339:
3330:
3328:
3314:
3313:
3309:
3300:
3298:
3284:
3283:
3279:
3270:
3268:
3255:
3254:
3250:
3241:
3239:
3226:
3225:
3221:
3212:
3210:
3201:
3200:
3196:
3186:
3184:
3175:
3174:
3170:
3160:
3158:
3145:
3144:
3140:
3130:Wayback Machine
3121:
3117:
3110:
3087:
3086:
3082:
3073:
3071:
3064:
3049:
3048:
3044:
3034:
3032:
3023:Chicago Tribune
3019:
3018:
3014:
3007:
2984:
2983:
2979:
2967:
2963:
2951:
2947:
2937:
2935:
2919:
2918:
2914:
2902:
2898:
2888:Wayback Machine
2879:
2875:
2863:
2859:
2849:
2847:
2834:
2833:
2829:
2819:
2817:
2803:
2802:
2798:
2781:
2775:
2773:
2759:
2758:
2754:
2744:
2742:
2733:
2732:
2728:
2719:
2717:
2712:. August 1987.
2704:
2703:
2699:
2685:
2675:
2668:
2667:
2663:
2658:(IRT): 222â228.
2645:
2644:
2640:
2626:
2622:
2612:
2610:
2597:
2596:
2592:
2582:
2580:
2576:
2565:
2561:
2560:
2556:
2547:
2545:
2541:
2534:
2530:
2529:
2525:
2515:
2513:
2500:
2499:
2495:
2490:
2483:
2481:
2472:
2471:
2467:
2457:
2455:
2446:
2445:
2441:
2431:
2429:
2425:
2414:
2410:
2409:
2405:
2391:
2390:
2386:
2376:
2374:
2370:
2364:www.govinfo.gov
2359:
2355:
2354:
2350:
2336:
2326:
2321:10.1.1.309.3861
2313:
2312:
2308:
2299:
2297:
2290:
2275:
2274:
2270:
2261:
2259:
2249:
2248:
2244:
2235:
2233:
2220:
2219:
2212:
2203:
2201:
2188:
2187:
2183:
2174:
2172:
2168:
2157:
2153:
2152:
2148:
2138:
2136:
2132:
2126:ecfsapi.fcc.gov
2121:
2117:
2116:
2112:
2103:
2101:
2097:
2086:
2082:
2081:
2077:
2067:
2065:
2061:
2054:
2050:
2049:
2045:
2035:
2033:
2029:
2018:
2014:
2013:
2009:
2000:
1998:
1989:
1988:
1984:
1975:
1973:
1962:ITU Rec. BS.450
1956:
1955:
1951:
1946:
1869:
1837:
1821:carrier current
1817:
1805:
1759:Industry Canada
1748:satellite radio
1731:
1713:
1697:
1691:
1679:
1662:
1660:Other countries
1650:
1634:
1597:
1576:
1564:
1552:
1531:
1493:Third Programme
1489:Light Programme
1477:
1458:
1448:or continental
1380:
1332:W1XER/W39B/WMNE
1286:(now listed as
1276:W1XOJ/W43B/WGTR
1260:Edwin Armstrong
1252:
1235:
1229:
1224:
1219:
1213:
1202:
1125:
1112:
1040:bits per second
969:
926:was similar to
917:noise reduction
913:
911:Noise reduction
836:
834:Quadraphonic FM
786:
781:
780:
728:
692:
664:
643:
640:
636:
632:
628:
623:
622:
518:
427:
414:
410:
407:
396:
315:
301:
297:
269:
166:
160:
158:Broadcast bands
136:AM broadcasting
124:Edwin Armstrong
110:is a method of
108:FM broadcasting
59:
42:) are types of
28:
23:
22:
15:
12:
11:
5:
5238:
5236:
5228:
5227:
5222:
5212:
5211:
5205:
5204:
5202:
5201:
5191:
5181:
5171:
5158:
5155:
5154:
5152:
5151:
5144:
5139:
5134:
5129:
5124:
5123:
5122:
5117:
5109:
5103:
5101:
5097:
5096:
5094:
5093:
5088:
5083:
5078:
5073:
5068:
5063:
5058:
5053:
5048:
5042:
5040:
5034:
5033:
5031:
5030:
5025:
5020:
5015:
5010:
5005:
5000:
4995:
4990:
4985:
4980:
4975:
4970:
4964:
4962:
4956:
4955:
4953:
4952:
4947:
4942:
4937:
4932:
4926:
4924:
4920:
4919:
4917:
4916:
4911:
4906:
4901:
4896:
4891:
4889:Space-division
4885:
4883:
4877:
4876:
4874:
4873:
4868:
4867:
4866:
4861:
4851:
4850:
4849:
4839:
4834:
4828:
4826:
4818:
4817:
4815:
4814:
4813:
4812:
4802:
4801:
4800:
4790:
4785:
4780:
4779:
4778:
4768:
4762:
4760:
4752:
4751:
4749:
4748:
4743:
4738:
4733:
4728:
4726:Camille Tissot
4723:
4718:
4713:
4708:
4703:
4701:Claude Shannon
4698:
4693:
4691:Tivadar PuskĂĄs
4688:
4683:
4678:
4673:
4668:
4663:
4661:Antonio Meucci
4658:
4653:
4648:
4643:
4638:
4633:
4631:Charles K. Kao
4628:
4623:
4618:
4613:
4608:
4606:Harold Hopkins
4603:
4598:
4593:
4588:
4583:
4578:
4573:
4568:
4563:
4558:
4553:
4548:
4543:
4538:
4533:
4528:
4523:
4518:
4513:
4508:
4506:Emile Berliner
4503:
4498:
4493:
4488:
4483:
4478:
4473:
4467:
4465:
4461:
4460:
4458:
4457:
4452:
4447:
4445:Videotelephony
4442:
4437:
4436:
4435:
4430:
4420:
4413:
4408:
4402:
4397:
4392:
4387:
4382:
4381:
4380:
4375:
4370:
4360:
4359:
4358:
4348:
4343:
4341:Radiotelephone
4338:
4333:
4328:
4323:
4318:
4313:
4308:
4307:
4306:
4296:
4291:
4286:
4281:
4276:
4271:
4266:
4261:
4256:
4251:
4246:
4245:
4244:
4239:
4234:
4229:
4227:Internet video
4219:
4218:
4217:
4212:
4207:
4202:
4192:
4187:
4182:
4177:
4172:
4167:
4161:
4159:
4153:
4152:
4147:
4145:
4144:
4137:
4130:
4122:
4113:
4112:
4109:
4108:
4106:
4105:
4100:
4085:
4082:
4081:
4079:
4078:
4073:
4067:
4065:
4061:
4060:
4058:
4057:
4052:
4047:
4042:
4037:
4032:
4027:
4022:
4017:
4012:
4006:
4004:
4000:
3999:
3997:
3996:
3991:
3989:Kahn-Hazeltine
3986:
3981:
3976:
3970:
3968:
3960:
3959:
3957:
3956:
3951:
3945:
3943:
3939:
3938:
3936:Related topics
3935:
3928:
3927:
3925:
3924:
3919:
3914:
3909:
3904:
3899:
3893:
3891:
3884:
3883:
3881:
3880:
3875:
3870:
3865:
3860:
3855:
3849:
3847:
3841:
3840:
3837:
3836:
3834:
3833:
3832:
3831:
3820:
3818:
3811:
3810:
3808:
3807:
3802:
3797:
3792:
3787:
3781:
3779:
3775:
3774:
3772:
3771:
3766:
3761:
3756:
3752:
3746:
3744:
3737:
3733:
3732:
3729:
3728:
3726:
3725:
3720:
3717:
3712:
3707:
3702:
3697:
3691:
3689:
3685:
3684:
3682:
3681:
3671:
3653:
3643:
3633:
3622:
3620:
3614:
3613:
3611:
3610:
3605:
3600:
3594:
3592:
3580:
3576:
3575:
3563:
3561:
3560:
3553:
3546:
3538:
3532:
3531:
3518:
3513:
3501:
3496:
3491:
3486:
3481:
3473:
3465:
3464:
3457:
3456:
3451:
3445:
3444:
3433:
3432:
3430:
3429:External links
3427:
3424:
3423:
3392:
3366:
3337:
3307:
3277:
3263:. 2017-12-13.
3248:
3219:
3194:
3168:
3138:
3115:
3108:
3080:
3062:
3042:
3012:
3005:
2977:
2961:
2945:
2912:
2896:
2873:
2857:
2827:
2796:
2752:
2726:
2697:
2688:|journal=
2661:
2638:
2629:Ann Arbor News
2620:
2590:
2554:
2523:
2493:
2480:on 8 July 2007
2465:
2439:
2403:
2384:
2348:
2339:|journal=
2306:
2288:
2268:
2242:
2210:
2196:. 2013-10-10.
2181:
2146:
2110:
2075:
2043:
2007:
1982:
1948:
1947:
1945:
1942:
1941:
1940:
1935:
1930:
1925:
1920:
1915:
1910:
1905:
1900:
1895:
1890:
1885:
1880:
1875:
1868:
1865:
1836:
1833:
1829:capture effect
1816:
1813:
1804:
1801:
1787:Some wireless
1763:European Union
1743:audio cassette
1730:
1727:
1712:
1709:
1690:
1687:
1678:
1675:
1661:
1658:
1649:
1646:
1633:
1630:
1596:
1593:
1575:
1572:
1563:
1560:
1551:
1548:
1536:Crystal Palace
1481:United Kingdom
1476:
1475:United Kingdom
1473:
1457:
1454:
1438:
1437:
1430:
1379:
1376:
1251:
1248:
1239:Rio de Janeiro
1228:
1225:
1223:
1220:
1201:
1198:
1187:antenna height
1124:
1121:
1111:
1108:
968:
965:
950:High Com
912:
909:
864:
863:
860:
856:
852:
851:compatibility.
848:
835:
832:
817:and multipath
793:
789:
777:
776:
764:
761:
758:
751:
748:
744:
740:
735:
731:
727:
724:
721:
718:
715:
712:
708:
704:
699:
695:
691:
688:
685:
682:
677:
673:
670:
667:
661:
656:
652:
649:
646:
639:
635:
631:
517:
514:
426:
423:
406:this would be
395:
392:
386:waterfall plot
314:
311:
268:
265:
252:United Kingdom
220:
219:
204:
197:
174:radio spectrum
162:Main article:
159:
156:
144:radio stations
70:radio receiver
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
5237:
5226:
5223:
5221:
5218:
5217:
5215:
5200:
5192:
5190:
5182:
5180:
5172:
5170:
5160:
5159:
5156:
5149:
5145:
5143:
5140:
5138:
5135:
5133:
5130:
5128:
5125:
5121:
5118:
5116:
5113:
5112:
5110:
5108:
5105:
5104:
5102:
5098:
5092:
5089:
5087:
5084:
5082:
5079:
5077:
5074:
5072:
5069:
5067:
5064:
5062:
5059:
5057:
5054:
5052:
5049:
5047:
5044:
5043:
5041:
5039:
5035:
5029:
5026:
5024:
5021:
5019:
5016:
5014:
5011:
5009:
5006:
5004:
5001:
4999:
4996:
4994:
4991:
4989:
4986:
4984:
4981:
4979:
4976:
4974:
4971:
4969:
4966:
4965:
4963:
4961:
4957:
4951:
4948:
4946:
4943:
4941:
4938:
4936:
4933:
4931:
4928:
4927:
4925:
4921:
4915:
4914:Code-division
4912:
4910:
4907:
4905:
4902:
4900:
4899:Time-division
4897:
4895:
4892:
4890:
4887:
4886:
4884:
4882:
4878:
4872:
4869:
4865:
4862:
4860:
4857:
4856:
4855:
4852:
4848:
4845:
4844:
4843:
4840:
4838:
4835:
4833:
4830:
4829:
4827:
4825:and switching
4823:
4819:
4811:
4808:
4807:
4806:
4803:
4799:
4796:
4795:
4794:
4791:
4789:
4786:
4784:
4781:
4777:
4776:optical fiber
4774:
4773:
4772:
4769:
4767:
4766:Coaxial cable
4764:
4763:
4761:
4759:
4753:
4747:
4744:
4742:
4739:
4737:
4734:
4732:
4729:
4727:
4724:
4722:
4719:
4717:
4714:
4712:
4709:
4707:
4704:
4702:
4699:
4697:
4694:
4692:
4689:
4687:
4684:
4682:
4681:Radia Perlman
4679:
4677:
4674:
4672:
4669:
4667:
4664:
4662:
4659:
4657:
4654:
4652:
4649:
4647:
4644:
4642:
4639:
4637:
4634:
4632:
4629:
4627:
4624:
4622:
4619:
4617:
4614:
4612:
4609:
4607:
4604:
4602:
4599:
4597:
4594:
4592:
4589:
4587:
4584:
4582:
4579:
4577:
4574:
4572:
4571:Lee de Forest
4569:
4567:
4566:Thomas Edison
4564:
4562:
4559:
4557:
4556:Donald Davies
4554:
4552:
4549:
4547:
4544:
4542:
4541:Claude Chappe
4539:
4537:
4534:
4532:
4529:
4527:
4524:
4522:
4519:
4517:
4514:
4512:
4509:
4507:
4504:
4502:
4499:
4497:
4494:
4492:
4489:
4487:
4484:
4482:
4479:
4477:
4474:
4472:
4469:
4468:
4466:
4462:
4456:
4453:
4451:
4448:
4446:
4443:
4441:
4438:
4434:
4431:
4429:
4426:
4425:
4424:
4421:
4419:
4418:
4414:
4412:
4409:
4406:
4403:
4401:
4398:
4396:
4393:
4391:
4388:
4386:
4385:Smoke signals
4383:
4379:
4376:
4374:
4371:
4369:
4366:
4365:
4364:
4363:Semiconductor
4361:
4357:
4354:
4353:
4352:
4349:
4347:
4344:
4342:
4339:
4337:
4334:
4332:
4329:
4327:
4324:
4322:
4319:
4317:
4314:
4312:
4309:
4305:
4302:
4301:
4300:
4297:
4295:
4292:
4290:
4287:
4285:
4282:
4280:
4277:
4275:
4272:
4270:
4267:
4265:
4262:
4260:
4257:
4255:
4252:
4250:
4247:
4243:
4240:
4238:
4235:
4233:
4230:
4228:
4225:
4224:
4223:
4222:Digital media
4220:
4216:
4213:
4211:
4208:
4206:
4203:
4201:
4198:
4197:
4196:
4193:
4191:
4188:
4186:
4183:
4181:
4178:
4176:
4173:
4171:
4168:
4166:
4163:
4162:
4160:
4158:
4154:
4150:
4143:
4138:
4136:
4131:
4129:
4124:
4123:
4120:
4104:
4101:
4099:
4098:
4087:
4086:
4083:
4077:
4074:
4072:
4069:
4068:
4066:
4062:
4056:
4053:
4051:
4048:
4046:
4043:
4041:
4038:
4036:
4033:
4031:
4028:
4026:
4025:Digital radio
4023:
4021:
4018:
4016:
4013:
4011:
4008:
4007:
4005:
4001:
3995:
3992:
3990:
3987:
3985:
3982:
3980:
3977:
3975:
3972:
3971:
3969:
3966:
3961:
3955:
3952:
3950:
3947:
3946:
3944:
3940:
3933:
3929:
3923:
3920:
3918:
3915:
3913:
3910:
3908:
3905:
3903:
3900:
3898:
3895:
3894:
3892:
3889:
3885:
3879:
3876:
3874:
3871:
3869:
3866:
3864:
3861:
3859:
3856:
3854:
3851:
3850:
3848:
3846:
3842:
3830:
3827:
3826:
3825:
3822:
3821:
3819:
3816:
3812:
3806:
3803:
3801:
3798:
3796:
3793:
3791:
3788:
3786:
3783:
3782:
3780:
3776:
3770:
3767:
3765:
3762:
3760:
3753:
3751:
3748:
3747:
3745:
3741:
3738:
3734:
3724:
3721:
3718:
3716:
3713:
3711:
3708:
3706:
3703:
3701:
3698:
3696:
3693:
3692:
3690:
3686:
3679:
3675:
3672:
3669:
3665:
3661:
3657:
3654:
3651:
3647:
3644:
3641:
3637:
3634:
3631:
3627:
3624:
3623:
3621:
3619:
3615:
3609:
3606:
3604:
3601:
3599:
3596:
3595:
3593:
3591:
3588:
3584:
3581:
3577:
3573:
3570:
3569:digital audio
3566:
3559:
3554:
3552:
3547:
3545:
3540:
3539:
3536:
3529:
3525:
3522:
3519:
3517:
3514:
3512:
3508:
3505:
3502:
3500:
3497:
3495:
3492:
3490:
3487:
3485:
3482:
3478:
3474:
3471:
3467:
3466:
3462:
3461:
3455:
3452:
3450:
3447:
3446:
3441:
3436:
3428:
3411:
3407:
3403:
3396:
3393:
3380:
3376:
3370:
3367:
3355:
3351:
3347:
3341:
3338:
3326:
3322:
3318:
3311:
3308:
3296:
3292:
3288:
3281:
3278:
3266:
3262:
3258:
3252:
3249:
3237:
3233:
3229:
3223:
3220:
3208:
3204:
3198:
3195:
3182:
3178:
3172:
3169:
3156:
3152:
3148:
3142:
3139:
3135:
3131:
3127:
3124:
3119:
3116:
3111:
3105:
3101:
3097:
3093:
3092:
3084:
3081:
3069:
3065:
3063:9780801899133
3059:
3056:. JHU Press.
3055:
3054:
3046:
3043:
3030:
3026:
3024:
3016:
3013:
3008:
3002:
2998:
2994:
2990:
2989:
2981:
2978:
2974:
2970:
2965:
2962:
2958:
2954:
2949:
2946:
2933:
2929:
2928:
2923:
2916:
2913:
2909:
2905:
2900:
2897:
2893:
2889:
2885:
2882:
2877:
2874:
2870:
2866:
2861:
2858:
2845:
2841:
2837:
2831:
2828:
2815:
2811:
2807:
2800:
2797:
2792:
2786:
2771:
2767:
2763:
2756:
2753:
2740:
2736:
2730:
2727:
2715:
2711:
2707:
2701:
2698:
2693:
2680:
2672:
2665:
2662:
2657:
2653:
2650:(in German).
2649:
2642:
2639:
2635:
2631:
2630:
2624:
2621:
2608:
2604:
2600:
2594:
2591:
2575:
2571:
2564:
2558:
2555:
2540:
2533:
2527:
2524:
2511:
2507:
2503:
2497:
2494:
2479:
2475:
2469:
2466:
2453:
2449:
2443:
2440:
2424:
2420:
2413:
2407:
2404:
2399:
2395:
2388:
2385:
2369:
2365:
2358:
2352:
2349:
2344:
2331:
2322:
2317:
2310:
2307:
2295:
2291:
2289:9781623566876
2285:
2281:
2280:
2272:
2269:
2258:on 2016-10-18
2257:
2253:
2246:
2243:
2231:
2227:
2223:
2217:
2215:
2211:
2199:
2195:
2191:
2185:
2182:
2167:
2163:
2156:
2150:
2147:
2131:
2127:
2120:
2114:
2111:
2096:
2092:
2085:
2079:
2076:
2060:
2053:
2047:
2044:
2028:
2024:
2017:
2011:
2008:
1996:
1992:
1986:
1983:
1971:
1967:
1963:
1959:
1953:
1950:
1943:
1939:
1936:
1934:
1931:
1929:
1926:
1924:
1921:
1919:
1916:
1914:
1911:
1909:
1906:
1904:
1901:
1899:
1896:
1894:
1891:
1889:
1886:
1884:
1881:
1879:
1876:
1874:
1871:
1870:
1866:
1864:
1862:
1857:
1853:
1850:
1846:
1842:
1834:
1832:
1830:
1826:
1822:
1814:
1812:
1810:
1802:
1800:
1798:
1794:
1790:
1785:
1783:
1779:
1775:
1770:
1768:
1764:
1760:
1756:
1751:
1749:
1744:
1740:
1736:
1728:
1724:
1721:
1717:
1710:
1708:
1706:
1702:
1696:
1688:
1686:
1684:
1676:
1674:
1670:
1668:
1659:
1657:
1655:
1647:
1645:
1643:
1639:
1631:
1629:
1625:
1623:
1619:
1615:
1611:
1607:
1603:
1594:
1592:
1589:
1585:
1581:
1573:
1571:
1568:
1561:
1559:
1556:
1549:
1547:
1545:
1541:
1537:
1529:
1525:
1521:
1517:
1513:
1508:
1506:
1500:
1498:
1494:
1490:
1486:
1482:
1474:
1472:
1470:
1466:
1462:
1455:
1453:
1451:
1447:
1446:North America
1443:
1435:
1431:
1428:
1424:
1420:
1416:
1412:
1411:
1410:
1408:
1404:
1400:
1396:
1392:
1389:
1385:
1377:
1375:
1373:
1369:
1365:
1361:
1355:
1352:
1347:
1345:
1341:
1340:New Hampshire
1337:
1333:
1329:
1325:
1320:
1318:
1314:
1309:
1305:
1301:
1297:
1293:
1289:
1285:
1281:
1277:
1269:
1265:
1261:
1256:
1250:United States
1249:
1247:
1243:
1240:
1234:
1226:
1221:
1218:
1211:
1207:
1199:
1197:
1195:
1190:
1188:
1184:
1180:
1175:
1173:
1169:
1164:
1162:
1157:
1153:
1149:
1145:
1141:
1137:
1132:
1130:
1122:
1120:
1118:
1109:
1107:
1105:
1101:
1097:
1093:
1089:
1085:
1084:digital radio
1081:
1077:
1073:
1069:
1068:digital radio
1065:
1061:
1060:United States
1056:
1053:
1049:
1045:
1041:
1037:
1033:
1029:
1025:
1022:to the third
1021:
1017:
1013:
1010:
1006:
1002:
998:
994:
990:
986:
978:
973:
966:
964:
962:
958:
953:
951:
948:
944:
940:
935:
933:
929:
925:
920:
918:
910:
908:
906:
902:
898:
894:
888:
886:
882:
878:
874:
868:
861:
857:
853:
849:
846:
845:
844:
841:
833:
831:
828:
823:
820:
816:
811:
807:
791:
787:
749:
746:
742:
738:
733:
729:
725:
722:
719:
716:
713:
710:
706:
702:
697:
693:
689:
686:
683:
680:
675:
671:
668:
665:
659:
654:
650:
647:
644:
637:
633:
629:
621:
620:
619:
616:
614:
610:
606:
601:
597:
593:
589:
585:
580:
578:
574:
573:Crosby system
570:
566:
562:
558:
554:
549:
545:
541:
539:
535:
530:
528:
527:New York City
524:
515:
513:
509:
507:
503:
499:
493:
491:
487:
483:
479:
475:
471:
467:
466:time constant
462:
460:
456:
451:
447:
443:
439:
436:
432:
424:
422:
420:
405:
401:
393:
387:
382:
375:
370:
366:
362:
360:
356:
352:
348:
344:
340:
335:
331:
327:
323:
319:
312:
307:
295:
290:
282:
278:
273:
266:
264:
261:
257:
253:
249:
245:
241:
237:
233:
229:
225:
217:
213:
209:
205:
202:
198:
195:
191:
187:
183:
179:
178:
177:
175:
171:
165:
157:
155:
153:
149:
145:
141:
137:
133:
129:
128:high-fidelity
125:
121:
117:
113:
109:
102:
98:
93:
85:
78:
74:
71:
67:
63:
57:
53:
49:
45:
41:
37:
32:
19:
4881:Multiplexing
4756:Transmission
4721:Nikola Tesla
4711:Henry Sutton
4666:Samuel Morse
4596:Robert Hooke
4561:Amos Dolbear
4496:John Bardeen
4415:
4395:Telautograph
4299:Mobile phone
4254:Edholm's law
4237:social media
4170:Broadcasting
4088:
4039:
3572:broadcasting
3439:
3414:. Retrieved
3405:
3395:
3383:. Retrieved
3369:
3358:. Retrieved
3349:
3340:
3329:. Retrieved
3320:
3310:
3299:. Retrieved
3291:the Guardian
3290:
3280:
3269:. Retrieved
3260:
3251:
3240:. Retrieved
3231:
3222:
3211:. Retrieved
3203:"OIRT Tuner"
3197:
3187:22 September
3185:. Retrieved
3171:
3159:. Retrieved
3151:Radio Rewind
3150:
3141:
3133:
3118:
3090:
3083:
3072:. Retrieved
3052:
3045:
3033:. Retrieved
3029:the original
3022:
3015:
2987:
2980:
2973:Broadcasting
2972:
2964:
2957:Broadcasting
2956:
2948:
2938:February 19,
2936:. Retrieved
2925:
2915:
2908:Broadcasting
2907:
2899:
2891:
2876:
2869:Broadcasting
2868:
2860:
2848:. Retrieved
2839:
2830:
2818:. Retrieved
2809:
2799:
2774:. Retrieved
2765:
2755:
2743:. Retrieved
2735:"CRIS Radio"
2729:
2718:. Retrieved
2709:
2700:
2679:cite journal
2664:
2651:
2647:
2641:
2627:
2623:
2611:. Retrieved
2602:
2593:
2581:. Retrieved
2569:
2557:
2546:. Retrieved
2526:
2514:. Retrieved
2505:
2496:
2482:. Retrieved
2478:the original
2468:
2456:. Retrieved
2442:
2430:. Retrieved
2418:
2406:
2393:
2387:
2375:. Retrieved
2363:
2351:
2330:cite journal
2309:
2298:. Retrieved
2278:
2271:
2260:. Retrieved
2256:the original
2245:
2234:. Retrieved
2225:
2202:. Retrieved
2193:
2184:
2173:. Retrieved
2161:
2149:
2137:. Retrieved
2125:
2113:
2102:. Retrieved
2090:
2078:
2066:. Retrieved
2046:
2034:. Retrieved
2022:
2010:
1999:. Retrieved
1994:
1985:
1974:. Retrieved
1961:
1952:
1861:pirate radio
1858:
1854:
1845:surveillance
1838:
1818:
1806:
1786:
1771:
1752:
1732:
1722:
1698:
1680:
1671:
1663:
1651:
1635:
1626:
1614:Radio Active
1598:
1577:
1565:
1553:
1509:
1501:
1497:Home Service
1478:
1461:Hans Idzerda
1459:
1439:
1427:Iron Curtain
1393:
1387:
1381:
1358:FM. In 1961
1356:
1348:
1328:W47NV/WSM-FM
1326:, New York;
1321:
1273:
1244:
1236:
1191:
1183:antenna gain
1176:
1168:ground waves
1165:
1133:
1126:
1117:antenna gain
1113:
1057:
1020:phase locked
1016:Digital data
1014:
1005:quadraphonic
982:
954:
936:
921:
914:
895:(now called
889:
876:
869:
865:
840:Louis Dorren
837:
824:
812:
808:
778:
617:
612:
608:
604:
581:
550:
546:
542:
537:
531:
519:
510:
494:
490:multiplexing
468:of a simple
463:
455:pre-emphasis
450:transmission
434:
428:
418:
408:2 Ă 75 kHz +
397:
363:
324:; the older
322:carrier wave
316:
308:radio waves.
228:the Americas
221:
186:Eastern Bloc
172:part of the
167:
119:
107:
106:
52:carrier wave
48:radio studio
5081:NPL network
4793:Radio waves
4731:Alfred Vail
4641:Hedy Lamarr
4626:Dawon Kahng
4586:Elisha Gray
4546:Yogen Dalal
4471:Nasir Ahmed
4405:Teleprinter
4269:Heliographs
4020:Cable radio
3963:Technical (
3723:DVB-T2 Lite
3579:Terrestrial
3321:Radio World
2766:Crutchfield
2710:archive.org
2506:Radio World
2419:www.fcc.gov
1774:microphones
1595:New Zealand
1456:Netherlands
1415:medium wave
1399:Netherlands
1384:medium wave
1179:transmitter
1161:DAB/+ radio
1044:proprietary
1001:experiments
600:sub-carrier
592:sub-carrier
534:subcarriers
478:South Korea
459:de-emphasis
444:within the
442:frequencies
232:Philippines
224:South Korea
77:loudspeaker
5214:Categories
5127:Antarctica
5086:Toasternet
5008:Television
4491:Paul Baran
4423:Television
4407:(teletype)
4400:Telegraphy
4378:transistor
4356:Phryctoria
4326:Photophone
4304:Smartphone
4294:Mass media
3902:DirectBand
3888:Subcarrier
3590:modulation
3360:2023-01-31
3331:2023-01-31
3301:2023-01-31
3271:2023-01-31
3242:2007-03-26
3213:2016-10-25
3074:2023-03-13
2850:7 November
2820:7 November
2810:Italiamiga
2776:2019-06-14
2720:2015-04-10
2613:19 October
2548:2018-05-30
2458:6 December
2432:12 January
2300:2020-10-25
2262:2016-03-06
2236:2020-01-03
2204:2019-10-30
2175:2022-05-29
2139:30 October
2104:2019-08-02
2001:2023-07-11
1976:2011-01-08
1944:References
1847:purposes (
1789:headphones
1739:MP3 player
1693:See also:
1588:television
1580:Australian
1231:See also:
1215:See also:
1172:ionosphere
1156:Sporadic E
1072:Eureka 147
1036:narrowband
1009:guard band
977:DirectBand
947:Telefunken
932:companding
819:distortion
596:modulation
588:pilot tone
435:triangular
411:2 Ă 60 kHz
313:Modulation
267:Technology
234:, and the
114:that uses
44:modulation
38:) and FM (
5111:Americas
5100:Locations
5071:Internet2
4832:Bandwidth
4536:Vint Cerf
4433:streaming
4411:Telephone
4351:Semaphore
4242:streaming
3965:AM stereo
3824:Sirius XM
3817:providers
3736:Satellite
3161:11 August
2605:. USPTO.
2570:FCC Rules
2450:. USPTO.
2316:CiteSeerX
1841:espionage
1797:ISM bands
1699:In 2017,
1638:951 Remix
1606:Whakatane
1574:Australia
1469:The Hague
1313:relocated
901:Ann Arbor
859:listener.
855:listener.
838:In 1969,
747:×
726:π
720:
690:π
684:
669:−
611:and even
609:multiplex
605:composite
516:Stereo FM
470:RC filter
394:Bandwidth
389:spectrum.
339:bandwidth
244:Greenland
236:Caribbean
150:range of
66:frequency
62:amplitude
56:broadcast
5179:Category
5066:Internet
5056:CYCLADES
4973:Ethernet
4923:Concepts
4847:terminal
4798:wireless
4621:Bob Kahn
4464:Pioneers
4289:Internet
4180:Cable TV
4064:Cultural
3994:Magnavox
3967:formats)
3917:SCA/SCMO
3912:RDS/RBDS
3715:HD Radio
3705:DRM/DRM+
3700:DAB/DAB+
3524:Archived
3507:Archived
3410:Archived
3406:W0IS.com
3385:8 August
3379:Archived
3354:Archived
3325:Archived
3295:Archived
3265:Archived
3236:Archived
3207:Archived
3181:Archived
3155:Archived
3126:Archived
3068:Archived
2932:Archived
2884:Archived
2844:Archived
2814:Archived
2785:cite web
2770:Archived
2745:April 8,
2739:Archived
2714:Archived
2607:Archived
2574:Archived
2539:Archived
2510:Archived
2452:Archived
2423:Archived
2377:11 April
2368:Archived
2357:"73-319"
2294:Archived
2230:Archived
2198:Archived
2166:Archived
2130:Archived
2095:Archived
2068:April 8,
2059:Archived
2027:Archived
1970:Archived
1867:See also
1423:Cold War
1222:Americas
1104:sideband
1100:HD Radio
1094:system,
1092:iBiquity
1024:harmonic
991:for the
924:Dolby FM
567:, using
446:baseband
438:spectral
413: =
298:94.9 MHz
146:use the
73:extracts
5199:Commons
5189:Outline
5142:Oceania
5061:FidoNet
5046:ARPANET
4859:circuit
4428:digital
4157:History
3890:signals
3858:AMR-WB+
3710:FMeXtra
3416:13 July
2516:May 30,
2366:. FCC.
1795:or UHF
1778:karaoke
1735:Part 15
1602:FM 90.7
1544:Wrotham
1528:Radio 1
1520:Radio 4
1516:Radio 3
1512:Radio 2
1479:In the
1442:Ireland
1407:Germany
1403:Denmark
1395:Belgium
1200:History
1129:horizon
1096:branded
1078:. This
1058:In the
928:Dolby B
897:WWWW-FM
569:KDKA-FM
504:in the
498:carrier
429:Random
415:270 kHz
284:Jersey.
180:In the
5137:Europe
5107:Africa
5091:Usenet
5051:BITNET
4988:Mobile
4864:packet
4373:MOSFET
4368:device
4165:Beacon
3984:Harris
3979:C-QUAM
3868:HE-AAC
3845:Codecs
3829:Canada
3795:DVB-SH
3769:S band
3764:L band
3750:C band
3674:L band
3565:Analog
3437:about
3106:
3060:
3035:Apr 8,
3003:
2583:23 May
2318:
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2036:8 June
1720:Belkin
1701:Norway
1654:Turkey
1648:Turkey
1567:Greece
1562:Greece
1532:
1450:Europe
1397:, the
1378:Europe
1302:, and
1300:KE2XCC
1227:Brazil
1185:, and
1144:Rijeka
1064:Canada
753:
553:stereo
486:stereo
433:has a
357:, and
353:, the
248:Africa
246:, and
240:Europe
230:, the
208:Brazil
5120:South
5115:North
5076:JANET
5013:Telex
5003:Radio
4842:Nodes
4837:Links
4758:media
4336:Radio
4321:Pager
4249:Drums
4215:video
4210:image
4200:audio
3974:Belar
3800:S-DMB
3790:DAB-S
3695:CAM-D
3608:COFDM
3587:Radio
2577:(PDF)
2566:(PDF)
2542:(PDF)
2535:(PDF)
2484:9 May
2426:(PDF)
2415:(PDF)
2371:(PDF)
2360:(PDF)
2250:RWO.
2169:(PDF)
2158:(PDF)
2133:(PDF)
2122:(PDF)
2098:(PDF)
2087:(PDF)
2062:(PDF)
2055:(PDF)
2030:(PDF)
2019:(PDF)
1807:Some
1555:Italy
1550:Italy
1505:Ofcom
1467:, at
1296:W2XMN
1264:W2XMN
1003:with
997:Muzak
993:blind
899:) in
877:K-101
538:order
431:noise
302:48 kW
256:Italy
201:Japan
196:band.
132:radio
99:, in
5132:Asia
5018:UUCP
4978:ISDN
3922:DARC
3897:AMSS
3878:DRA+
3759:band
3668:high
3567:and
3418:2019
3387:2015
3189:2015
3163:2013
3104:ISBN
3058:ISBN
3037:2020
3001:ISBN
2940:2019
2852:2021
2822:2021
2791:link
2747:2020
2692:help
2615:2016
2585:2020
2518:2018
2486:2010
2460:2015
2434:2017
2379:2021
2343:help
2284:ISBN
2141:2019
2070:2020
2038:2018
1843:and
1757:and
1622:89FM
1620:and
1618:91FM
1540:1987
1524:1967
1518:and
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1366:(in
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1360:WEFM
1317:WRVE
1304:WFMN
1280:WSRS
1208:and
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1134:The
1076:ISDB
1062:and
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506:BTSC
484:and
482:mono
457:and
294:KENZ
194:CCIR
190:OIRT
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5023:WAN
4993:NGN
4983:LAN
4264:Fax
4205:DCT
3907:PAD
3863:HDC
3853:AAC
3805:SDR
3785:ADR
3719:CDR
3678:UHF
3664:mid
3660:low
3656:VHF
3232:ITU
3096:doi
2993:doi
2398:BBC
2162:ITU
1782:UHF
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1667:GDR
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1290:);
1266:in
1098:as
1048:RDS
961:FMX
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881:FCC
717:sin
714:0.1
681:sin
634:0.9
613:MPX
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557:FCC
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