FM broadcast band

The FM broadcast band, used for FM broadcast radio by radio stations, differs between different parts of the world. In Europe, Australia[1] and Africa ((defined as International Telecommunication Union (ITU) region 1)), it spans from 87.5 to 108 megahertz (MHz) - also known as VHF Band II - while in the Americas (ITU region 2) it ranges from 88 to 108 MHz. The FM broadcast band in Japan uses 76 to 95 MHz. The International Radio and Television Organisation (OIRT) band in Eastern Europe is from 65.8 to 74.0 MHz, although these countries now primarily use the 87.5 to 108 MHz band, as in the case of Russia. Some other countries have already discontinued the OIRT band and have changed to the 87.5 to 108 MHz band.

Frequency modulation radio originated in the United States during the 1930s; the system was developed by the American electrical engineer Edwin Howard Armstrong. However, FM broadcasting did not become widespread, even in North America, until the 1960s.

Frequency-modulated radio waves can be generated at any frequency. All the bands mentioned in this article are in the very high frequency (VHF) range, which extends from 30 to 300 MHz.

CCIR bandplan

Center frequencies

While all countries use FM channel center frequencies ending in 0.1, 0.3, 0.5, 0.7, and 0.9 MHz, some countries also use center frequencies ending in 0.0, 0.2, 0.4, 0.6, and 0.8 MHz. A few others also use 0.05, 0.15, 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, 0.85, and 0.95 MHz.

An ITU conference in Geneva, Switzerland, on December 7, 1984, resolved to discontinue the use of 50 kHz channel spacings throughout Europe.[2]

  • Most countries have used 100 kHz or 200 kHz channel spacings for FM broadcasting since this ITU conference in 1984.
  • Some digitally-tuned FM radios are unable to tune using 50 kHz or even 100 kHz increments. Therefore, when traveling abroad, stations that broadcast on certain frequencies using such increments may not be heard clearly. This problem will not affect reception on an analog-tuned radio.
  • A few countries, such as Italy, which have heavily congested FM bands, still allow a station on any multiple of 50 kHz wherever one can be squeezed in.
  • The 50 kHz channel spacings help prevent co-channel interference, and these take advantage of FM's capture effect and receiver selectivity.

ITU Region 2 bandplan and channel numbering

The original frequency allocation in North America used by Edwin Armstrong used the frequency band from 42 through 50 MHz, but this allocation was changed to a higher band beginning in 1945. In Canada, the United States, Mexico, the Bahamas, etc., there are 101 FM channels numbered from 200 (center frequency 87.9 MHz) to 300 (center frequency 107.9 MHz), though these numbers are rarely used outside the fields of radio engineering and government.

The center frequencies of the FM channels are spaced in increments of 200 kHz. The frequency of 87.9 MHz, while technically part of TV channel 6 (82 to 88 MHz), is used by just two FM class-D stations in the United States. Portable radio tuners often tune down to 87.5 MHz, so that the same radios can be made and sold worldwide. Automobiles usually have FM radios that can tune down to 87.7 MHz, so that TV channel 6's audio at 87.75 MHz (±10 kHz) could be received, such as in Birmingham, Alabama, and Denver, Colorado. With the advent of digital television in the United States, this ability will soon be irrelevant when the remaining analog LPTV stations are required by the FCC to shut down or convert to digital by September 2015[3]—but there are still analog television stations in the sparsely-populated regions of northern Canada. There are also analog TV stations on the other continents and on scores of different islands.

In the United States, the twenty-one channels with center frequencies of 87.9–91.9 MHz (channels 200 through 220) constitute the reserved band, exclusively for non-commercial educational (NCE) stations. The other channels (92.1 MHz through 107.9 MHz (Channels 221–300) may be used by both commercial and non-commercial stations.[4] (Note that in Canada and in Mexico this reservation does not apply.)

Originally, the American Federal Communications Commission (FCC) devised a bandplan in which FM radio stations would be assigned at intervals of four channels (800 kHz separation) for any one geographic area. Thus, in one area, stations might be at 88.1, 88.9, 89.7, etc., while in an adjacent area, stations might be at 88.3, 89.1, 89.9, 90.7 etc. Certain frequencies were designated for Class A only (see FM broadcasting), which had a limit of three kilowatts of effective radiated power (ERP) and an antenna height limit for the center of radiation of 300 feet (91.4 m) height above average terrain (HAAT). These frequencies were 92.1, 92.7, 93.5, 94.3, 95.3, 95.9, 96.7, 97.7, 98.3, 99.3, 100.1, 100.9, 101.7, 102.3, 103.1, 103.9, 104.9, 105.5, 106.3 and 107.1. On other frequencies, a station could be Class B (50 kW, 500 feet) or Class C (100 kW, 2000 feet), depending on which zone it was in.

In the late 1980s, the FCC switched to a bandplan based on a distance separation table using currently operating stations, and subdivided the class table to create extra classes and change antenna height limits to meters. Class A power was doubled to six kilowatts, and the frequency restrictions noted above were removed. As of late 2004, a station can be "squeezed in" anywhere as long as the location and class conform to the rules in the FCC separation table.[5] The rules for second-adjacent-channel spacing do not apply for stations licensed before 1964.

Deviation and bandpass

Normally each channel is 200 kHz (0.2 MHz) wide, and can pass audio and subcarrier frequencies up to 100 kHz. Deviation is typically limited to 150 kHz total (±75 kHz) in order to prevent adjacent channel interference on the band. Stations in the U.S. may go up to 10% over this limit if they use non-stereo subcarriers, increasing total modulation by 0.5% for each 1% used by the subcarriers.

OIRT bandplan

The OIRT FM broadcast band covers 65.9 to 74 MHz. It was used in the Union of Soviet Socialist Republics and most of the other Warsaw Pact member countries of the International Radio and Television Organisation in Eastern Europe (OIRT), with the exception of East Germany, which always used the 87.5 to 100 (later 104) MHz broadcast band—in line with Western Europe.

The lower portion of the VHF band behaves a bit like shortwave radio in that it has a longer reach than the upper portion of the VHF band. It was ideally suited for reaching vast and remote areas that would otherwise lack FM radio reception. In a way, FM suited this band because the capture effect of FM could mitigate interference from skywaves.

Transition to the 87.5 to 108 MHz band started as early as in eighties in some East European countries. Following the collapse of the communist governments, that transition was remarkably accelerated as private stations have been established. This was also prompted by the lack of equipment for the OIRT band and the modernisation of existing transmission networks.

Many countries have completely ceased broadcasting on the OIRT FM band, although use continues in others, mainly the former republics of the USSR. The future of broadcasting on the OIRT FM band is limited, due to the lack of new consumer receivers for this band outside of Russia.

Countries which still use the OIRT band are Russia (including Kaliningrad), Belarus,[6] Moldova,[7] Ukraine[8] and Turkmenistan.[9]

In Czechoslovakia, the decision to use the 87.5 to 108 MHz band instead of 65.9 to 74 MHz band was made in the begin of eighties. The frequency plan was created, which was internationally coordinated at Regional Administrative Conference for FM Sound Broadcasting in the VHF band in Geneva, 1984 [10]. Allocated frequencies are still valid and are used in the Czech Republic and Slovakia. The first transmitter was put into operation at 102.5 MHz near Prague in November 1984, and nine primary transmitters were built during next three years along country; 270 transmitters from 45 locations should be the final number [11]. The transition was finished in 1993.

Hungary closed down its remaining broadcast transmitters in 2007, and for thirty days in July of that year, several Hungarian amateur radio operators received a temporary experimental permit to perform propagation and interference experiments in the 70–70.5 MHz band.

In Belarus, only government-run public radio stations are still active on OIRT. All stations on OIRT in Belarus are a mirror of normal FM broadcasts. The main purpose of those stations is compatibility with older equipment.

In 2014, Russia began replacing OIRT-banded transmitter with CCIR-banded (the "western") FM transmitters. The main reason for the change to CCIR FM is to reach more listeners.

Unlike Western practice, OIRT FM frequencies are based on 30 kHz rather than 50, 100 or 200 kHz multiples. This may have been to reduce co-channel interference caused by Sporadic E propagation and other atmospheric effects, which occur more often at these frequencies. However, multipath distortion effects are less annoying than on the CCIR band.

Stereo is generally achieved by sending the stereo difference signal, using a process called polar modulation. Polar modulation uses a reduced subcarrier on 31.25 kHz with the audio on both side-bands. This gives the following signal structure: L + R --> 31.25 kHz reduced subcarrier L - R.

The 4-meter band (70–70.5 MHz) amateur radio allocation used in many European countries is entirely within the OIRT FM band. Operators on this band and the 6-meter band (50–54 MHz) use the presence of broadcast stations as an indication that there is an "opening" into Eastern Europe or Russia. This can be a mixed blessing because the 4 meter amateur allocation is only 0.5 MHz or less, and a single broadcast station causes considerable interference to a large part of the band.

The System D television channels R4 and R5 lie wholly or partly within the 87.5–108 MHz FM audio broadcast band. Countries which still use System D therefore have to consider the re-organisation of TV broadcasting in order to make full use of this band for audio broadcasting.

Japanese bandplan

The FM band in Japan is 76–95 MHz (previously 76–90). The 90–108 MHz section was used for analog VHF TV Channels 1, 2 and 3 (each NTSC television channel was 6 MHz wide). The narrowness of the Japanese band (19 MHz compared to slightly more than 20 MHz for the CCIR band) limits the number of FM stations that can be accommodated on the dial with the result that many commercial radio stations are forced to use AM.

Many Japanese radios are capable of receiving both the Japanese FM band and the CCIR FM band, so that the same model can be sold within Japan or exported. The radio may cover 76 to 108 MHz, the frequency coverage may be selectable by the user, or during assembly the radio may be set to operate on one band by means of a specially placed diode or other internal component.

Conventional analog-tuned (dial & pointer) radios were formerly marked with "TV Sound" in the 76–88 section. If these radios were sold in the US, for example, the 76–88 section would be marked TV sound for VHF channels 5 and 6 (as two 6 MHz-wide NTSC TV channels), with the 88–108 section band as normal FM. The compatibility of "TV sound" with conventional FM radio ended with the U.S. digital TV transition in 2009, with the exception of the limited number of low-power stations on channel 6 that still use analog; these low-power stations will switch to digital in 2021.

Second-hand automobiles imported from Japan contain a radio designed for the Japanese FM band, and importers often fit a "converter" to down-convert the 87.5 to 107.9 MHz band to the frequencies that the radio can accept. In addition to showing an incorrect frequency, there are two other disadvantages that can result in undesired performance; the converter cannot down-convert in full the regular international FM band (up to 20.5 MHz wide) to the only 14 MHz-wide Japanese band (unless the converter incorporates two user-switchable down-convert modes), and the car's antenna may perform poorly on the higher FM band. Some converters simply down-convert the FM band by 12 MHz, leading to logical frequencies (e.g. 78.9 for 90.9, 82.3 for 94.3, etc.), but leaving off the 102–108 MHz band. Also, RDS is not used in Japan, whereas most modern car radios available in Europe have this system. Also the converter may not allow pass-through of the MW band, which is used for AM broadcasting. A better solution is to replace the radio and antenna with ones designed for the country where the car will be used.

Australia had a similar situation with Australian TV channels 3, 4 and 5 that are between 88 and 108 MHz, and was intending to follow Japan, but in the end opted for the western bandplan, due to CCIR radios that entered the country. There were some radios sold in Australia for 76 to 90 MHz.[12]

Historic U.S. bandplan

Early FM broadcasting in North America originally used the 42–50 MHz band[13] (this range was also used by a class of experimental wideband AM stations known as apex broadcasters). In 1941, the Yankee Network, which was already using FM for AM station feeds, started operating a station, W39B, in this band from a transmitter atop Mount Washington, New Hampshire, the highest point in the northeast United States.[14] (Studios were in Boston.) In 1945 the United States FCC decided to move FM broadcasters to the 88–106 MHz band (later extended to 108 MHz); this made all the existing FM radios useless, although converters could be purchased. It was even more expensive for broadcasters to rebuild their transmitters to work on the new band. Altogether, the change set FM radio back ten years.

The "devastating" change was successfully lobbied for (with the FCC) by RCA, which did not want FM radio to become dominant, although the higher frequencies had fewer interference problems. RCA conducted "an organized campaign of misinformation". This protected RCA's and other networks' investments in AM radio, and avoided competition with television, which RCA wanted to focus on.[15]

In March 2008, the FCC requested public comment on turning the bandwidth currently occupied by analog television channels 5 and 6 (76–88 MHz) over to extending the FM broadcast band when the digital television transition was to be completed in February 2009 (ultimately delayed to June 2009).[16] This proposed allocation would effectively assign frequencies corresponding to the existing Japanese FM radio service (which begins at 76 MHz) for use as an extension to the existing North American FM broadcast band.[17]

FM radio switch-off

With the invention of DAB+ radio, some countries have planned and started a FM radio switch-off. Norway, in January 2018, was the first country to discontinue FM as a result.

See also

References

  1. ^ http://www.acma.gov.au/webwr/_assets/main/lib550024/attach_a1-chptr_1-general_information-26sept2012.docx.
  2. ^ "UK Radio Frequency Bands". ukspec.tripod.com. Retrieved 19 March 2018.
  3. ^ "DTV Transition and LPTV - Class A - Translator Stations". fcc.gov. 24 May 2011. Retrieved 19 March 2018.
  4. ^ http://www.fcc.gov/topic/fm-radio
  5. ^ "separation table". fcc.gov. Retrieved 19 March 2018.
  6. ^ "1 канал. Первый национальный канал Белорусского радио". www.tvr.by. Retrieved 19 March 2018.
  7. ^ http://www.egocities.com
  8. ^ "FM,УКВ-радиостанции в Украине". www.radiofm.narod.ru. Retrieved 19 March 2018.
  9. ^ "OIRT Tuner". ukradio.info. Retrieved 19 March 2018.
  10. ^ Regional Administrative Conference for FM Sound Broadcasting in the VHF band (Region 1 and certain countries concerned in Region 3) (2nd session) (Geneva, 1984), Accessed 2019-03-05
  11. ^ (Czechoslovak DX Club, in Czech) Accessed 2019-03-05
  12. ^ This was taught at the TAFE college Audio course of the electronic servicing certificate, and it is also part of the long story of the introduction of FM radio in Australia, which can be found in older Australian electronics magazines.
  13. ^ Regarding the 42—50 MHz FM band and the switchover Accessed 2010-08-28
  14. ^ http://www.mountwashington.org/about/visitor/history/, retrieved 10-08-2014.
  15. ^ Edwin Howard Armstrong#FM radio, FM broadcasting in the United States, Yankee Network.
  16. ^ Federal Communications Commission (2008-05-16). "In the Matter of Promoting Diversification of Ownership in the Broadcasting Services". Retrieved 2008-08-26. Certain commenters have urged the Commission to give a "hard look" to a proposal that the Commission re-allocate TV Channels 5 and 6 for FM broadcasting 73 FR 28400, 28403
  17. ^ Could EXB Band Be Your New Home?RadioWorld September 10, 2008
Ark Two Shelter

The Ark Two Shelter is a nuclear fallout shelter built by Bruce Beach in the village of Horning's Mills (north of Toronto, Ontario). The shelter first became habitable in 1980 and has been continuously expanded and improved since then. The 10,000-square-foot shelter is composed of 42 school buses, which were buried underground as patterns for concrete that was then poured over to provide the main structure, onto which up to fourteen feet of earth were piled to provide fallout protection.With construction beginning in the early 1980s (during the height of the cold war), the shelter was designed to accommodate as many as five hundred people for the length of time required to allow the widespread nuclear fallout to decay to a level allowing a safe return to the surface after a cataclysmic nuclear event.

Powered by redundant diesel generators, the heavily fortified ("virtually impenetrable to anything short of a direct nuclear strike") shelter includes two commercial kitchens, full plumbing (including a private well for potable water and a motel-sized septic tank), three months' worth of diesel, a radio based communications center, a chapel, and a decontamination room.Ark Two is equipped with a communications room capable of broadcasting locally on the FM broadcast band, and throughout Canada and the United States on the AM and Shortwave Bands. A particularly novel feature is a collapsible, weather balloon deployed antenna, capable of being launched from within the shelter. All Ark Two communication equipment is EMP hardened and generator powered so as to be able to transmit survival information to the general public in the event of nuclear war.

Beach does not charge money for admission to the shelter, instead guaranteeing individuals admission in return for sweat equity and active involvement in the Ark Two communities' various activities. In addition, "Everyone is welcome here, regardless of religion, race, nationality, political views...". In return for the promise of safe haven in times of nuclear attack, a person residing in nearby areas might be expected to, for example, work at the shelter several weekends each year, assisting in the routine maintenance or continuing renovations of the facility. A large percentage of the shelter population is expected to be children, as the primary purpose of the shelter is to serve as an "underground orphanage, a place where a new generation could be saved from nuclear apocalypse", which, according to Beach, would otherwise wipe out over 80% of the world's population. "We're going to say to people: 'Well, we have room for your children, but we don't have room for you.' That's the nature of life... this is the lifeboat."Beach believes that the majority of preppers are too concerned with personal survival, when they should be focused on reconstructing the world after a cataclysmic disaster. He runs an online "reconstruction network" (the "SAFE" community) through which he shares information about Ark Two and his evacuation plans.Ark Two was featured in Beach's interview for National Geographic's Doomsday Preppers, episode 8: "It's Gonna Get Worse". It was also featured on the Global Television Network series 16:9 (original air date: February 25, 2012), and on the Showtime series Penn & Teller: Bullshit! season one episode four: "End of the World".

Beach has authored two related books: Society After Doomsday (ISBN 978-0-919553-20-0) and TRIAD Individual Networking: Preparedness For Disastrous Times (ISBN 978-0-919553-50-7)

Channel 1 (North American TV)

In North American broadcast television frequencies, channel 1 is a former broadcast (over-the-air) television channel. During the experimental era of TV operation, Channel 1 was moved around the lower VHF spectrum repeatedly, with the entire band displaced upward at one point due to an early 40 MHz allocation for the FM broadcast band.

FM was moved to its current frequencies in 1946. TV Channel 1's last location was 44 to 50 MHz.

Land Mobile Radio and television broadcasters shared the same frequencies until 1948. This shared allocation was eventually found to be unworkable, so the FCC reallocated the Channel 1 frequencies for public safety and land mobile use and assigned TV channels 2–13 exclusively to broadcasters. Aside from the shared frequency issue, this part of the VHF band was (and to some extent still is) prone to higher levels of radio-frequency interference (RFI) than even VHF 2 (System M).

Neither Canada nor Mexico allocated television frequencies until 1946, so the historical Channel 1 (System M) is exclusively a US allocation artifact.

FM broadcasting

FM broadcasting is a method of radio broadcasting using frequency modulation (FM) technology. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high-fidelity sound over broadcast radio. FM broadcasting is capable of better sound quality than AM broadcasting (under normal listening conditions), the chief competing radio broadcasting technology, so it is used for most music broadcasts. Theoretically wideband AM can offer equally good sound quality, provided the reception conditions are ideal. FM radio stations use the VHF frequencies. The term "FM band" describes the frequency band in a given country which is dedicated to FM broadcasting.

FM transmitter (personal device)

A personal FM transmitter is a low-power FM radio transmitter that broadcasts a signal from a portable audio device (such as an MP3 player) to a standard FM radio. Most of these transmitters plug into the device's headphone jack and then broadcast the signal over an FM broadcast band frequency, so that it can be picked up by any nearby radio. This allows portable audio devices to make use of the louder or better sound quality of a home audio system or car stereo without requiring a wired connection. They are often used in cars but may also be in fixed locations such as broadcasting from a computer sound card throughout a building.Being low-powered, most transmitters typically have a short range of 100–300 feet (30–100 metres), depending on the quality of the receiver, obstructions and elevation. Typically they broadcast on any FM frequency from 87.5 to 108.0 MHz in most of the world, 76.0 - 95.0 MHz for Japan, 65.0 - 74.2 MHz for Russia (or 88.1 to 107.9 MHz in the US and Canada).

FunX

FunX is a Dutch public radio station which has been on air since 3 August 2002. The station runs mainly urban music.

The station is aimed at an audience of young people between 15 and 34 years and is designed specifically to immigrant to reach young people and mainly concentrates on such music styles as R&B, Hip hop, Latin, Reggae, Dancehall, Oriental, Arabpop, Turkpop, Farsipop, Banghra, Rai, French-African hip hop, Mandopop, and various crossover styles. The station aims to give "street" opinions airtime and follows the latest trends.

There are four local city editions of FunX: Amsterdam, Rotterdam, Utrecht and The Hague, and since 6 September 2005 a national edition. The local broadcasts consist of a joint framework program, some hours are split into different (local) editions. These city editions air on FM broadcast band near the mentioned cities. A national version is also available via DVB-T, DAB+, cable, satellite and the Internet but not via FM.

Via the Internet are also to listen to special editions, each with its own musical style: FunX Arab, FunX Dance, FunX Hip Hop, FunX Latin, FunX Reggae and FunX Slow Jamz.

Gail Scott (journalist)

Gail M. Scott (born 25 June 1943) is a Canadian television personality. She is a former co-host of Canada AM and was inducted into the Canadian Broadcast Hall of Fame in 2005.Scott graduated from Carleton University with a bachelor of journalism in 1966 and began her television career with the Canadian Broadcasting Corporation (CBC) at CBOT-TV in Ottawa. In 1971, she became the CBC's parliamentary correspondent. In 1972, she became the parliamentary correspondent for CTV Television Network. In 1976, Scott was the field producer and host of W5. She was co-host of Canada AM from 1978 to 1981 with Norm Perry.Born in Ottawa, Scott became a part-time member of the CRTC in 1987 and was named commissioner in 1993. As commissioner, Scott and fellow CRTC member William Callahan opposed CRTC's 29 July 1997 granting of the last FM broadcast band in Toronto to CBC because "an Afro-Canadian music station would better serve the public interest in Canada's largest city, which has a 200,000-strong Caribbean community".Scott was a professor at Ryerson University's School of Journalism in 1989. She was part of the board of directors of the Michener Awards Foundation from 1986 to 1994, serving as its president from 1991 to 1993. On leaving the CRTC in 1998, Scott became a Member of the Ontario Criminal Injuries Compensation Board where she served until 2008. In 2006, she served as an independent board member of the Canadian Television Fund. In 2017, Scott was granted a Masters Degree in Theological Studies at Trinity College, University of Toronto.

HD Radio

HD Radio is a trademarked term for Xperi's in-band on-channel (IBOC) digital radio technology used by AM and FM radio stations to transmit audio and data by using a digital signal embedded "on-frequency" immediately above and below a station's standard analog signal, providing the means to listen to the same program in either HD (digital radio with less noise) or as a standard broadcast (analog radio with standard sound quality). The HD format also provides the means for a single radio station to simultaneously broadcast one or more different programs in addition to the program being transmitted on the radio station's analog channel. It was originally developed by iBiquity. In September 2015 iBiquity was acquired by DTS bringing the HD Radio technology under the same banner as DTS' eponymous theater surround sound systems.. It was later acquired by Xperi in 2016.

It was selected by the U.S. Federal Communications Commission (FCC) in 2002 as a digital audio broadcasting method for the United States, and is the only digital system approved by the FCC for digital AM/FM broadcasts in the United States. It is officially known as NRSC-5, with the latest version being NRSC-5-D. Other digital radio systems include FMeXtra, Digital Audio Broadcasting (DAB) (Eureka 147), Digital Radio Mondiale (DRM30 and DRM+ configurations), and Compatible AM-Digital (CAM-D).

While HD Radio does allow for an all-digital mode, this system currently is used by some AM and FM radio stations to simulcast both digital and analog audio within the same channel (a hybridized digital-analog signal) as well as to add new FM channels and text information. Although HD Radio broadcasting's content is currently free-to-air, listeners must purchase new receivers in order to receive the digital portion of the signal.

By May 2018, HD Radio technology was claimed to be used by more than 3500 individual services, mostly in the United States. This compares with more than 2200 services operating with the DAB system.

HD Radio increases the bandwidth required in the FM band to 400 kHz for the analog/digital hybrid version. This makes adoption outside the United States problematic. In the United States the FM broadcast band channels have a spacing of 200 kHz, as opposed to the 100 kHz that is normal elsewhere. The 200 kHz spacing means that in practice, stations having concurrent or adjacent coverage areas will not be spaced at less than 400 kHz in order to respect protection ratios which would not be met with 200 kHz spacing. This also leaves space for the digital sidebands. Outside the US, spacing can be 300 kHz, which causes problems with the digital sidebands.

The FCC has not indicated any intent to force off analog radio broadcasts as it has with analog television broadcasts, as it would not result in the recovery of any radio spectrum rights which could be sold. Thus, there is no deadline by which consumers must buy an HD Radio receiver. In addition, there are many more analog AM/FM radio receivers than there were analog televisions, and many of these are car stereos or portable units that cannot be upgraded.

In-band on-channel

In-band on-channel (IBOC) is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency.

By utilizing additional digital subcarriers or sidebands, digital information is "multiplexed" on an AM or FM analog signal, thus avoiding re-allocation of the broadcast bands. However, by putting RF energy outside of the normally-defined channel, interference to adjacent channel stations is increased when using digital sidebands. The addition of the digital sidebands works better in the United States, where the FM broadcast band channels have a spacing of 200 kHz, as opposed to the 100 kHz that is normal elsewhere. The 200 kHz spacing means that in practice, stations having concurrent or adjacent coverage areas will not be spaced at less than 400 kHz. Outside of the US, spacing can be 300 kHz, which causes problems with the IBOC digital sidebands.

IBOC does allow for multiple program channels, though this can entail taking some existing subcarriers off the air to make additional bandwidth available in the modulation baseband. On FM, this could eventually mean removing stereo. On AM, IBOC is incompatible with analog stereo, and any additional channels are limited to highly compressed voice, such as traffic and weather. Eventually, stations can go from hybrid mode (both analog and digital) to all-digital, by eliminating the baseband monophonic audio.

KLOA-LP

KLOA-LP is a low power television station broadcasting on VHF channel 6 and serving the Antelope Valley area in California. Because the allocation of channel 6 in NTSC System M falls approximately within the lower fringes of the FM broadcast band, KLOA-LP takes advantage of the station's audio carrier, broadcasting on 87.75 MHz, and markets itself as a radio station. It airs a Country format under the moniker "Kickin' Country 87.7". According to the Federal Communications Commission, television stations must operate both the audio and video carriers; however, the carriers are not required to "accompany" each other, meaning that the audio and video can operate independently of one another. This means that KLOA-LP need not broadcast any particular image, as long as they broadcast a video signal. It is currently unknown what video signal the station broadcasts.

Kalanjiam Community Radio

Kalanjiam Community Radio (Tamil: களஞ்சியம் சமூக வானொலி) is a radio broadcasting service in Tamil, operating from Vizhunthamavadi, a tiny village in the coastal area of Tamil Nadu, India. It broadcasts in the FM broadcast band on 90.8 MHz from local time (GMT+5½) 9.00 a.m. till 5.00 p.m.

List of channel numbers assigned to FM frequencies in North America

In the Americas (defined as International Telecommunication Union (ITU) region 2), the FM broadcast band consists of 101 channels, each 200 kHz wide, in the frequency range from 87.8 to 108.0 MHz, with "center frequencies" running from 87.9 Mhz to 107.9 MHz. For most purposes an FM station is associated with its center frequency. However, each FM frequency has also been assigned a channel number, which ranges from 200 to 300.FM channel numbers are most commonly used for internal regulatory purposes. The range originally began with channel 201 (88.1 MHz), or a value high enough to avoid confusion with television channel numbers, which over the years have had values ranging from 1 to 83. Having a gap between the highest TV channel number and the lowest FM channel number allowed for expansion, which occurred in the 1980s when FM channel 200 (87.9 MHz) was added.

FM channel numbers are commonly used for listing FM Station Allotments, which are the FM station assignments designated for individual communities. In the United States they are also used in the callsigns of low-powered FM translators relaying AM or FM station signals. For example, the "237" in the callsign for translator K237FR in Tumwater, Washington indicates that the station is transmitting on channel 237, which corresponds to 95.3 MHz.

Local Community Radio Act

The Local Community Radio Act is an act of broadcast law in the United States, explicitly authorizing the Federal Communications Commission (FCC) to license local low-power broadcasting in the FM broadcast band (LPFM). After five years and four versions, it passed the U.S. Congress in 2010, granting equal protection to community radio stations with regard to translator and booster stations. All three types of stations remain secondary to full-power radio stations, which are typically owned by major corporations and nonprofits. (Previously, this second-class status was only a part of FCC regulation, rather than law.) The act negates the Radio Broadcasting Preservation Act of 2000, which enacted prevented community LPFM stations on the basis of RF interference.

Popular Communications

Popular Communications was a magazine with content relating to the radio hobby, including scanners, shortwave radio, CB, amateur radio, AM and FM broadcast band listening, radio history, and vintage radio restoration. The magazine existed between 1982 and 2013. It was based in Hicksville, New York.

Road and Street Traffic Awareness

Road and Street Traffic Awareness (RASTA 88.6 FM) is a radio station in Lahore, Pakistan that broadcasts traffic information 24 hours a day on 88.6 MHz on the FM broadcast band. It is the first 24-hour traffic program in Pakistan. The station was funded and constructed by United Team Network Technologies (UTNT), a Pakistan-based system design and integration firm. It is manned by members of the Lahore Traffic Police. RASTA facilities include

Integrated control room

24/7 traffic helpline

Website showing live traffic conditions in map and in tabular form

Commercial free FM 88.6 traffic radio

Traffic cameras connected with control room

Variable messaging systems (VMS)

Traffic messaging

Automated phone service for traffic update

Educational resources regarding Pakistan driving lawsA second phase is planned that will include cable and satellite television channels.

Sporadic E propagation

Sporadic E or Es is an unusual form of radio propagation using characteristics of the Earth's ionosphere. Whereas most forms of skywave propagation use the normal and cyclic ionization properties of the ionosphere's F region to refract (or "bend") radio signals back toward the Earth's surface, sporadic E propagation bounces signals off smaller "clouds" of unusually ionized atmospheric gas in the lower E region (located at altitudes of approx. 90 to 160 km). This occasionally allows for long-distance communication at VHF frequencies not usually well-suited to such communication.Communication distances of 800–2200 km can occur using a single Es cloud. This variability in distance depends on a number of factors, including cloud height and density. MUF also varies widely, but most commonly falls in the 25 – 150 MHz range, which includes the FM broadcast band (87.5–108 MHz), Band I VHF television (American channels 2-6, Russian channels 1-3, and European channels 2-4, the latter no longer used in Western Europe), CB radio (27 MHz) and the amateur radio 2-meter, 4-meter, 6-meter, and 10-meter bands. Strong events have allowed propagation at frequencies as high as 250 MHz.As its name suggests, sporadic E is an abnormal event, but can happen at almost any time; it does, however, display seasonal patterns. Sporadic E activity peaks predictably in the summertime in both hemispheres. In North America, the peak is most noticeable in mid-to-late June, trailing off through July and into August. A much smaller peak is seen around the winter solstice. Activity usually begins in mid-December in the southern hemisphere, with the days immediately after Christmas being the most active period.On June 12, 2009, sporadic E allowed some television viewers in the eastern United States to see VHF analog TV stations from other states at great distances, in places and on TV channels where local stations had already done their permanent analog shutdown on the final day of the DTV transition in the United States. This was possible because VHF has been mostly avoided by digital TV stations, leaving the analog stations the last ones on the band. It is still possible (as of April, 2010) for many Americans to see Canadian and Mexican analog stations in this manner when sporadic-E occurs, until those countries do their own analog shutdowns over the following few years.

In some cases it is even possible to get DTV Es receptions from well over 1000 miles (1600 km), since some US stations still use Band 1 even for DTV; these signals are characterized for being either extremely clear or extremely blocky. They are also much easier to identify.

On November 24, 2016, many radio listeners from Australia and New Zealand were able to listen to radio stations from other states of Australia, overlapping many radio signals. Many people complained about this, saying that many of their favourite radio stations got replaced by other radio stations from other states. Later, the ACMA confirmed that this was caused by Sporadic E.

Very high frequency

Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter.

Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

Common uses for radio waves in the VHF band are FM radio broadcasting, television broadcasting, two way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometers with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR & ILS) work at distances of 100 kilometres (62 mi) or more to aircraft at cruising altitude.

In the Americas and many other parts of the world, VHF Band I was used for the transmission of analog television. As part of the worldwide transition to digital terrestrial television most countries require broadcasters to air television in the VHF range using digital rather than analog format.

WA2XMN

WA2XMN is an experimental FM radio station which broadcasts sporadically from the Armstrong Tower in Alpine, New Jersey. The station commemorates the pioneering broadcasts of the world's first FM radio station, W2XMN, built by Edwin Howard Armstrong, which began experimental broadcasts from this tower in June 1938 followed by full power broadcasting beginning on July 18, 1939. Armstrong's station signed off as KE2XCC on March 4, 1954.WA2XMN broadcasts at 42.8 MHz, one of the frequencies used by Armstrong's station on the original 42-50 MHz FM broadcast band. Transmitting from near the top of the 425-foot tall Armstrong Tower, which sits on top of the 500-foot-tall Pallisades (for a total height of over 900 feet above mean sea level), WA2XMN has a listening range of roughly 60-100 miles. The building at the base of the tower still has the W2XMN call sign engraved above the entrance.The station signed on using a restored Phasitron transmitter built by Steve Hemphill, with technical assistance from WFDU 89.1, which has broadcast from the tower since its first sign on in 1971. The WA2XMN broadcasts have been simulcast on WFDU's FM signal and internet stream, allowing listeners who lack a VHF receiver that can tune to 42.8 MHz to listen to the broadcasts.

WKSB

WKSB (102.7 FM, "Kiss 102.7") is a commercial FM radio station licensed to serve Williamsport, Pennsylvania. The station is owned by iHeartMedia, Inc., through licensee Clear Channel Broadcasting Licenses, Inc., and broadcasts a Hot Adult Contemporary format. Its broadcast tower is located on Bald Eagle Mountain south of Williamsport at (41°11′24.7″N 76°58′46.2″W).WKSB is a grandfathered “superpower” station. The station’s effective radiated power (ERP) exceeds the maximum limit allowed for a Class B FM station, and is also far above the maximum allowable ERP for its antenna height above average terrain (HAAT) according to current FCC rules.

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