Editing TV and FM DX

{{Short description|Long-distance reception of signals on the VHF frequency band}}{{More citations needed|date=May 2025}}[[File:Antenna-178969.jpg|right|thumb|amateur HF/UHF radio antenna]]
[[File:Antennes uhf.JPG|right|thumb|amateur UHF radio antenna]]
'''TV DX''' and '''FM DX''' refer to the active search for distant [[radio station|radio]] or [[television station]]s received during unusual atmospheric conditions. The term [[DXing|DX]] is an old [[telegraphy|telegraphic]] term meaning "long distance."

[[very high frequency|VHF]]/[[ultra high frequency|UHF]] television and radio signals are normally limited to a maximum "deep fringe" reception service area of approximately {{convert|40|-|100|mi|km|lk=on}} in areas where the broadcast spectrum is congested, and about 50 percent farther in the absence of interference. However, providing [[anomalous propagation|favourable atmospheric conditions]] are present, television and radio signals sometimes can be received hundreds or even thousands of miles outside their intended coverage area. These signals are often received using a large outdoor [[antenna (radio)|antenna]] system connected to a sensitive TV or FM receiver, although this may not always be the case. smaller antennas and receivers, such as those in vehicles, will receive stations from farther away than usual depending on how favourable conditions are.

While only a limited number of local stations can normally be received at satisfactory signal strengths in any given area, tuning into other channels may reveal weaker signals from adjacent areas. More consistently strong signals, especially those accentuated by unusual atmospheric conditions, can be achieved by improving the [[television antenna|antenna system]]. The development of interest in TV-FM DX as a [[hobby]] has grown over time, with enthusiasts installing and upgrading HF/UHF antennae for the purpose of gaining a higher range. The TV-FM DX hobby is similar to other radio/electronic related hobbies such as [[amateur radio]], [[MW DX|Medium Wave DX]], or [[short-wave radio]]; and organisations such as the Worldwide TV-FM DX Association have developed to coordinate and foster the further study and enjoyment of VHF/UHF television and FM broadcast DX.<ref>[http://anarc.org/wtfda Official WTFDA Club Website] {{Webarchive|url=https://web.archive.org/web/20030621134535/http://www.anarc.org/wtfda/ |date=2003-06-21 }}</ref>

==History==
After the [[Alexandra Palace]], [[London]] [[405-line]] [[BBC]] channel B1 [[BBC One|TV service]] was introduced in 1936, it soon became apparent that television could be received well outside the original intended service area.

For example, in November 1938, engineers at the [[RCA]] Research Station, [[Riverhead, Long Island]], accidentally received a 3,000-mile (4,800&nbsp;km) [[Atlantic Ocean|transatlantic]] [[Ionosphere#F layer|F2]] broadcast of the London 45.0 [[Megahertz|MHz]], 405-line  BBC Television service.

The flickering black-and-white footage (characteristic of F2 propagation) included [[Jasmine Bligh]], one of the original BBC announcers, and a brief shot of [[Elizabeth Cowell]], who also shared announcing duties with Jasmine, an excerpt from an unknown period costume drama and the BBC's station identification [[logo]] transmitted at the beginning and end of the day's [[Television programming|programmes]].

This reception was [[kinescope|recorded]] on 16 mm [[film|movie]] [[photographic film|film]], and is now considered to be the only surviving example of pre-war, live British television.<ref>{{cite web | title=First Live BBC Recording | work=Alexandra Palace Television Society | url=http://www.apts.org.uk/recording.htm | access-date=April 26, 2005}}</ref>

The BBC temporarily ceased transmissions on September 1, 1939 as [[World War II]] began. After the BBC Television Service  recommenced in 1946, distant reception reports were received from various parts of the world, including [[Italy]], [[South Africa]], [[India]], the [[Middle East]], [[North America]] and the [[Caribbean]].

In May 1940, the [[Federal Communications Commission]] (FCC), a U.S. government agency, formally allocated the 42 – 50 MHz band for FM radio broadcasting. It was soon apparent that distant FM signals from up to {{convert|1400|mi|km}} distance would often interfere with local stations during the summer months.

Because the 42 – 50 MHz FM signals were originally intended to only cover a relatively confined service area, the sporadic long-distance signal propagation was seen as a nuisance, especially by station management.

In February 1942, the first known published long-distance FM broadcast station reception report was reported by ''FM magazine''. The report provided details of 45.1MHz W51C [[Chicago, Illinois]], received in [[Monterrey]], [[Mexico]]: "Zenith Radio Corporation, operating W51C, has received a letter from a listener in [[Monterrey, Mexico]], telling of daily reception of this station between 3:00 P.M. and 6:00 P.M. This is the greatest distance, 1,100 miles, from which consistent reception of the 50 [kW] transmitter has been reported."<ref>{{cite web | title=FM Broadcasting Chronology | work=History of American Broadcasting | url=http://members.aol.com/jeff560/chronofm.html | access-date=May 22, 2005}}</ref>

In June 1945, the FCC decided that FM would have to move from the established 42 – 50 MHz pre-war band to a new band at 88 – 108 MHz. According to 1945 and 1946 FCC documents, the three major factors which the commission considered in its decision to place FM in the 88 – 108 MHz band were sporadic E co-channel interference, F2 layer interference, and extent of coverage.<ref>{{cite web | title=FM Radio Finds its Niche | work=R. J. Reiman | url=http://ieee.cincinnati.fuse.net/reiman/09_1994.html | access-date=May 22, 2005 | url-status=dead | archive-url=https://web.archive.org/web/20050410235932/http://ieee.cincinnati.fuse.net/reiman/09_1994.html | archive-date=April 10, 2005 }}</ref>

During the 1950s to early 1960s, long-distance television reports started to circulate via popular U.S. electronics hobbyist [[magazine|periodical]]s such as ''DXing Horizons'', ''[[Popular Electronics]]'', ''Television Horizons'', ''Radio Horizons'', and ''[[Radio-Electronics]]''. In January 1960, the TV DX interest was further promoted via Robert B. Cooper's regular ''DXing Horizons'' column.

In 1957, the world record for TV DX was extended to {{convert|10800|mi|km}} with the reception of Britain's channel BBC TV in various parts of [[Australia]]. Most notably, George Palmer in [[Melbourne, Australia|Melbourne, Victoria]], received viewable pictures and audio of a news program from the BBC TV London station. This BBC F2 reception was recorded on movie film.<ref>{{cite web | title=George Palmer – Australian TV DX Pioneer | work=Todd Emslie's TV DX Page | url=http://home.iprimus.com.au/toddemslie/George_Palmer_TVDX.html | archive-url=https://web.archive.org/web/20220518052319/http://home.iprimus.com.au/toddemslie/George_Palmer_TVDX.html | access-date=May 16, 2024| archive-date=2022-05-18 }}</ref>

During the early 1960s, the [[United Kingdom|U.K.]] magazine ''[[Practical Television]]'' first published a regular TV DX column edited by Charles Rafarel. By 1970, Rafarel's column had attracted considerable interest from TV DXers worldwide. After Rafarel's death in 1971, UK TV DXer Roger Bunney continued the monthly column, which continued to be published by ''Television Magazine''. With the demise of ''Television Magazine'' in June 2008, Bunney's column finished after 36 years of publication. In addition to the monthly TV DX column, Bunney has also published several TV DX books, including ''Long Distance Television Reception (TV-DX) for the Enthusiast'' 1981 {{ISBN|0-900162-71-6}}, and ''A TV DXer's Handbook'' 1986 {{ISBN|0-85934-150-X}}.

==Tropospheric propagation==
[[File:Atmosphere structure numbered.svg|right|thumb|Diagram of the different layers of the [[atmosphere]].]]
{{Main|Tropospheric propagation}}

[[Tropospheric propagation]] refers to the way radio signals travel through the lowest layer of the Earth's atmosphere, the [[troposphere]], at altitudes up to about to 17 km (11 miles). Weather conditions in the lower atmosphere can produce radio propagation over greater ranges than normal. If a [[temperature inversion]] occurs, with upper air warmer than lower air, VHF and UHF radio waves can be refracted over the Earth's surface instead of following a straight-line path into space or into the ground. Such "tropospheric ducting" can carry signals for 800 km (500 miles) or more, far beyond usual range.

==F2 propagation ==
{{Main|F2 propagation}}

The F2 layer is found about 200 miles (320 km) above the Earth's surface and can reflect radio waves back toward the Earth. When the layer is particularly strong during periods of high [[sunspot]] activity, FM and TV reception can take place over 2000 miles (3000 km) or more, as the signal effectively "bounces" off the high atmospheric layer.

==Sporadic E propagation (E-skip)==
[[File:SporadicE-NPS.gif|thumb|Ray diagram of sporadic E event]]
[[File:LUXMAN L-235 & TUNER T-230L.jpg|thumb|upright=0.9|right|Luxman T-240L stereo FM tuner (top) and L-235 amplifier (bottom)]]
{{main|Sporadic E propagation}}

Sporadic E, also called E-skip, is the phenomenon of irregularly scattered patches of relatively dense [[ionization]] that develop seasonally within the [[E region]] of the [[ionosphere]] and reflect TV and FM frequencies, generally up to about 150 MHz. When frequencies reflect off multiple patches, it is referred to as multi-hop skip. E-skip allows [[radio wave]]s to travel a thousand miles or even more beyond their intended area of reception. E-skip is unrelated to tropospheric ducting.

Television and FM signals received via Sporadic E can be extremely strong and range in strength over a short period from just detectable to overloading. Although [[Polarization (waves)|polarisation]] shift can occur, single-hop Sporadic E signals tend to remain in the original transmitted polarisation. Long single-hop ({{convert|900|-|1500|mi|km|disp=or}}) Sporadic E television signals tend to be more stable and relatively free of multipath images. Shorter-skip ({{convert|400|-|800|mi|km|disp=or}}) signals tend to be reflected from more than one part of the Sporadic E layer, resulting in multiple images and ghosting, with [[Phase (waves)|phase reversal]] at times. Picture degradation and signal-strength attenuation increases with each subsequent Sporadic E hop.

Sporadic E usually affects the lower [[very high frequency|VHF]] band I (TV channels 2 – 6) and band II (88 – 108 MHz FM broadcast band). The typical expected distances are about {{convert|600|to|1400|mi|km}}. However, under exceptional circumstances, a highly ionized Es cloud can propagate band I VHF signals down to approximately {{convert|350|mi|km}}. When short-skip Es reception occurs, i.e., under {{convert|500|mi|km}} in band I, there is a greater possibility that the ionized Es cloud will be capable of reflecting a signal at a much higher frequency – i.e., a VHF band 3 channel – since a sharp reflection angle (short skip) favours low frequencies, a shallower reflection angle from the same ionized cloud will favour a higher frequency.

At polar latitudes, Sporadic E can accompany auroras and associated disturbed magnetic conditions and is called Auroral-E.

No conclusive theory has yet been formulated as to the origin of Sporadic E. Attempts to connect the incidence of Sporadic E with the eleven-year [[Sunspot cycle]] have provided tentative correlations. There seems to be a positive correlation between sunspot maximum and Es activity in Europe. Conversely, there seems to be a negative correlation between maximum sunspot activity and Es activity in [[Australasia]].

==Transequatorial propagation (TEP)==
Discovered in 1947, transequatorial spread-F (TE) propagation makes it possible for reception of television and radio stations between {{convert|3000|-|5000|mi|km}} across the [[equator]] on frequencies as high as 432 MHz. Reception of lower frequencies in the 30 – 70 MHz range are most common. If sunspot activity is sufficiently high, signals up to 108 MHz are also possible. Reception of TEP signals above 220 MHz is extremely rare. Transmitting and receiving stations should be nearly equidistant from the [[geomagnetic]] [[L-shell|equator]].

The first large-scale VHF TEP communications occurred around 1957 – 58 during the peak of solar cycle 19. Around 1970, the peak of cycle 20, many TEP contacts were made between Australian and Japanese radio amateurs. With the rise of cycle 21 starting around 1977, amateur contacts were made between [[Greece]]/[[Italy]] and Southern Africa (both South Africa and [[Rhodesia]]/[[Zimbabwe]]), and between Central and South America by TEP.

"Afternoon" and "evening" are two distinctly different types of trans-equatorial propagation.

===Afternoon TEP===
Afternoon TEP peaks during the mid-afternoon and early evening hours and is generally limited to distances of {{convert|4000|-|5000|mi|km}}. Signals propagated by this mode are limited to approximately 60 MHz. Afternoon TEP signals tend to have high signal strength and suffer moderate distortion due to multipath reflections.

===Evening TEP===
The second type of TEP peaks in the evening around 1900 to 2300 hours local time. Signals are possible up to 220 MHz, and even very rarely on 432 MHz. Evening TEP is quenched by moderate to severe geomagnetic disturbances. The occurrence of evening TEP is more heavily dependent on high solar activity than is the afternoon type.

During late September 2001, from 2000 to 2400 local time, VHF television and radio signals from [[Japan]] and [[Korea]] up to 220 MHz were received via evening transequatorial propagation near [[Darwin, Northern Territory]].<ref name="darwin_DX">{{cite web |last1=Mann |first1=Tony |last2=Emslie |first2=Todd |title=Darwin, Australia VHF DXpedition |url=http://home.iprimus.com.au/toddemslie/darwin-dxpedition.html |url-status=dead |archive-url=https://web.archive.org/web/20220518052319/http://home.iprimus.com.au/toddemslie/darwin-dxpedition.html |archive-date= May 18, 2022 |access-date=May 16, 2024 |work=Todd Emslie's TV DX Page}}</ref>

==Earth – Moon – Earth (EME) propagation (Moonbounce)==
Since 1953, radio amateurs have been experimenting with lunar communications by reflecting VHF and UHF signals off the [[Moon]]. [[EME (communications)|Moonbounce]] allows communication on Earth between any two points that can observe the Moon at a common time.<ref>{{cite web | title=''Space&Beyond'': Moonbounce Advances the State of the Radio Art | work=ARRL, the national association for Amateur Radio | url=http://www.arrl.org/news/features/2002/01/21/1/ | access-date=May 5, 2005 |archive-url = https://web.archive.org/web/20050414115309/http://www.arrl.org/news/features/2002/01/21/1/ |archive-date = April 14, 2005}}</ref>

Since [[the Moon]]'s mean distance from Earth is {{convert|239000|mi|km}}, path losses are very high. It follows that a typical 240 [[decibel|dB]] total path loss places great demand on high-gain receiving antennas, high-power transmissions, and sensitive receiving systems. Even when all these factors are observed, the resulting signal level is often just above the noise.

Because of the low [[signal-to-noise ratio]], as with amateur-radio practice, EME signals can generally only be detected using narrow-band receiving systems. This means that the only aspect of the TV signal that could be detected is the field scan modulation (AM vision carrier). FM broadcast signals also feature wide frequency modulation, hence EME reception is generally not possible. There are no published records of VHF/UHF EME amateur radio contacts using FM.

===Notable Earth-Moon-Earth (EME) DX receptions===
During the mid-1970s, John Yurek, K3PGP,<ref>{{cite web|url=http://www.k3pgp.org/uhftveme.htm|title=K3PGP – Experimenters Corner – K3PGP UHF TV reception via EME (1970)|website=www.k3pgp.org}}</ref> using a home-constructed, 24-foot (7.3 m), 0.6-focal-diameter [[Parabolic reflector|parabolic]] dish and UHF TV dipole feed-point tuned to channel 68, received KVST-68 [[Los Angeles]] (1200 kW ERP) and WBTB-68 [[Newark, New Jersey]] via moonbounce.  At the time of the experiment there were only two known transmitters operating in the United States on UHF television channel 68, the main reason why this channel was selected for EME experiments.

For three nights in December 1978, [[astronomer]] Dr. [[Woodruff T. Sullivan III]] used the 305-metre [[Arecibo Observatory|Arecibo radio telescope]] to observe the Moon at a variety of frequencies. This experiment demonstrated that the lunar surface is capable of reflecting [[Terrestrial television|terrestrial]] band III (175 – 230 MHz) television signals back to Earth.<ref>{{cite web | title=Eavesdropping Mode and Radio Leakage from Earth | work=NASA CP-2156 Life In The Universe | url=https://history.nasa.gov/CP-2156/ch5.4.htm | access-date=April 26, 2005}}</ref> While not yet confirmed, FM broadcast EME reception may also be possible using the Arecibo dish antenna.

In 2002, [[physicist]] Dr. Tony Mann demonstrated that a single high-gain UHF [[yagi antenna]], low noise masthead preamplifier, VHF/UHF synthesised communications receiver, and personal computer with [[Fast Fourier transform|FFT]] [[Spectrum analyzer|spectrum analyser]] software could be used to successfully detect extremely weak UHF television carriers via EME.<ref>{{cite web|url=http://internal.physics.uwa.edu.au/~agm/eme.html|title=UHF TV carrier detection by moonbounce (EME)|website=internal.physics.uwa.edu.au}}</ref>

==Auroral propagation==
An [[aurora (astronomy)|aurora]] is most likely to occur during periods of high solar activity when there is a high probability of a large [[solar flare]]. When such an eruption occurs, charged particles from the flare may spiral towards Earth arriving about a day later. This may or may not cause an aurora: if the interstellar magnetic field has same polarity, the particles do not get coupled to the [[geomagnetic field]] efficiently. Besides sunspot-related active solar surface areas, other solar phenomena that produce particles causing auroras, such as re-occurring coronal holes spraying out intense [[solar wind]]. These charged particles are affected and captured by the geomagnetic field and the various [[Van Allen radiation belt|radiation belts]] surrounding earth. The aurora-producing relativistic electrons eventually precipitate towards Earth's magnetic poles, resulting in an aurora which disrupts short-wave communications (SID) due to ionospheric/magnetic storms in the D, E, and F layers. Various visual effects are also seen in the sky towards the north – aptly called the [[Aurora (astronomy)|Northern Lights]]. The same effect occurs in the Southern Hemisphere, but the visual effects are towards the south. The auroral event starts by onset of [[geomagnetic storm]], followed by number of sub-storms over the next day or so.

The aurora produces a reflecting sheet (or metric sized columns) which tends to lie in a vertical plane. The result of this vertical ionospheric "curtain" is reflection of signals well into the upper VHF band. The reflection is very aspect sensitive. Since the reflecting sheet lies towards the poles, it follows that reflected signals will arrive from that general direction. An active region or coronal hole may persist for some 27 days resulting in a second aurora when the Sun has rotated. There is a tendency for auroras to occur around the March/April, September/October [[equinox]] periods, when the geomagnetic field is at right angle to Sun for efficient charged particle coupling. Signals propagated by aurora have a characteristic hum effect, which makes video and audio reception difficult. Video carriers, as heard on a communications receiver, no longer can be heard as a pure tone.

A typical radio aurora occurs in the afternoon, which produces strong and distorted signals for few hours. The local midnight sub-storming usually produces weaker signals, but with less distortion by Doppler from gyrating electrons.

Frequencies up to 200 MHz can be affected by auroral propagation.

==Meteor scatter propagation==
[[Meteor]] scatter occurs when a signal bounces off a meteor's ionized trail.

When a meteor strikes earth's atmosphere, a cylindrical region of free [[electron]]s is formed at the height of the E layer. This slender, ionized column is relatively long, and when first formed is sufficiently dense to reflect and scatter television and radio signals, generally observable from 25&nbsp;MHz upwards through UHF TV, back to earth. Consequently, an incident television or radio signal is capable of being reflected up to distances approaching that of conventional Sporadic E propagation, typically about 1500 km (1000 miles). A signal reflected by such meteor ionisation can vary in duration from fractions of a second up to several minutes for intensely ionized trails. The events are classified as overdense and underdense, depending on the electron line-density (related to used frequency) of the trail plasma. The signal from overdense trail has a longer signal decay associated with fading and is physically a reflection from the ionized cylinder surface, while an underdense trail gives a signal of short duration, which rises fast and decays exponentially and is scattered from individual electrons inside the trail.

Frequencies in the range of 50 to 80&nbsp;MHz have been found to be optimum for meteor scatter propagation. The 88 – 108 MHz FM broadcast band is also highly suited for meteor scatter experiments. During the major meteor showers, with extremely intense trails, band III 175 – 220 MHz signal reception can occur.

Ionized trails generally reflect lower frequencies for longer periods (and produce stronger signals) compared to higher frequencies. For example, an 8-second burst on 45.25 MHz may only cause a 4-second burst at 90.5 MHz.

The effect of a typical visually seen single meteor (of size 0.5 mm) shows up as a sudden "burst" of signal of short duration at a point not normally reached by the transmitter. The combined effect of several meteors impinging on earth's atmosphere, while perhaps too weak to provide long-term ionisation, is thought to contribute to the existence of the night-time E layer.

The optimum time for receiving RF reflections off sporadic meteors is the early morning period, when the [[velocity]] of earth relative to the velocity of the particles is greatest which also increases the number of meteors occurring on the morning-side of the earth, but some sporadic meteor reflections can be received at any time of the day, least in the early evening.

The annual major meteor showers are detailed below:

* January 3 – 4: [[Quadrantids]]
* April 22 – 23: [[Lyrids]]
* May 5 – 6: [[Eta Aquariids]]
* June 9 – 10: [[Arietids]] & [[Zeta Perseids|zeta-Perseids]]
* August 12 – 13: [[Perseids]]
* October 21 – 22: [[Orionids]]
* November 3 – 5: [[Taurids]]
* November 16 – 18: [[Leonids]] (Note: activity varies, outburst only at about 33 year interval)
* December 13 – 14: [[Geminids]]
* December 22 – 23: [[Ursids]]

For observing meteor shower-related radio signals, the shower's radiant must be above the (propagation mid path) horizon. Otherwise no meteor of the shower can hit the atmosphere along the propagation path and no reflections from the shower's meteor trails can be observed.

== Satellite UHF TVRO DX ==
Although not by strict definition terrestrial TV DX, [[satellite]] UHF [[TVRO]] reception is related in certain aspects. For example, reception of satellite signals requires sensitive receiving systems and large outdoor antenna systems. However, unlike terrestrial TV DX, satellite UHF TV reception is far easier to predict. The [[geosynchronous]] satellite at {{convert|22375|mi|km}} height is a line of sight reception source. If the satellite is above the horizon, it can be generally received, if it is below the horizon, reception is not possible.

=== Notable Satellite UHF TVRO DX receptions ===
* In December 1975, Stephen Birkill, [[Sheffield, England]], was the first DXer to receive viewable pictures from the 860 MHz Indian [[ATS-6]] [[satellite]], which was in [[synchronous orbit]] over [[Central Africa]], for the purpose of providing [[education]]al [[television program]]s to the [[Indian subcontinent]].<ref>{{cite web | title=RWT and the History of TVRO | work=Real-World Technology Ltd | url=http://www.rwt.co.uk/rwthist.htm | access-date=April 26, 2005 |archive-url = https://web.archive.org/web/20050416035812/http://www.rwt.co.uk/rwthist.htm |archive-date = April 16, 2005}}</ref>
* In 1978, Ian Roberts, [[South Africa]], received 714 MHz television pictures from the [[Soviet Union|Soviet]] UHF [[Ekran]]-class Statsionar-T satellite.<ref>{{cite web | title=Amateur radio page of Ian Roberts, ZS6BTE | work=QSL.net | url=http://www.qsl.net/zs6bte/ | access-date=April 26, 2005}}</ref>
* In 2022, amateur radio operator Derek OK9SGC, [[Czech Republic]], received one of the few remaining analog terrestrial transmissions from [[Turkmenistan]], which is being periodically picked up and relayed by newer [[Russia|Russian]] [[Meridian (satellite)|Meridian]] satellites.<ref>{{cite web | title=Amateur radio page of Derek OK9SGC | url=https://sgcderek.github.io/blog/meridian-tv.html | access-date=March 30, 2023}}</ref>

==Digital modes==
[[Digital radio]] and [[digital television]] can also be received; however, there is much greater difficulty with reception of weak signals due to the [[cliff effect]], particularly with the [[ATSC]] TV standard mandated in the U.S. However, when the signal is strong enough to be decoded identification is much easier than with analog TV as the picture is guaranteed to be noise-free when present.  For [[DVB-T]], [[hierarchical modulation]] may allow a lower-definition signal to be received even if the details of the full signal cannot be decoded. In reality, though, it's actually much more difficult to get DVB-T E-skip reception as the lowest channel DVB-T transmissions operate on is channel E5 which is 178 MHz. A unique issue observed on [[analog TV]] at the end of the [[DTV transition in the United States]] was that very distant analog stations were viewable in the hours after the permanent shutdown of local analog transmitters in June 2009.  This was particularly pronounced because June is one of the strongest months for DX reception on VHF, and most digital stations were assigned to UHF.

==DXing Software==
With the growth of the hobby, DXing software has been made available through various vendors to enthusiasts wanting to experience the hobby through their computer. Examples include XDR-GTK, FM-DX Webserver, SDRSharp, and SDR++.

==See also==
* [[Federal Standard 1037C]]
* [[MW DX]]
* [[Skywave]]
* [[Radio propagation]]
* [[Thermal fade]]
* [[Clear-channel station]]
* [[In Channel Select]] (ICS)
* [[DYNAS]]

==References==
<references/>
* {{cite web | title=DXing FAQ | work=Worldwide TV-FM DX Association| url=http://anarc.org/wtfda/dx_faq.htm | access-date=April 25, 2005}}
* {{cite web | title=William Hepburn's VHF / UHF Tropospheric Ducting Forecast | work= William Hepburn's TV & Radio DX Information Centre | url=http://www.dxinfocentre.com/tropo.html | access-date=June 12, 2006}}
* {{cite web | title=Bellevue, NE DX Photos | work=Matthew C. Sittel's DX Page | url=http://www.mcsittel.com/html/channels_2-6.html | access-date=April 26, 2005 | url-status=usurped | archive-url=https://web.archive.org/web/20070927182511/http://www.mcsittel.com/html/channels_2-6.html | archive-date=September 27, 2007 }}
* {{cite web | title=Optical Echoes from the Moon | work=K3PGP.Experimenter's. Corner | url=http://www.k3pgp.org/lasereme.htm | access-date=April 26, 2005}}

== External links ==
* [http://francoisf.wix.com/dxtv european DXTV reception in the 60's]
* [https://web.archive.org/web/20080323115406/http://www.digitalstar.com/antenna/ TV/FM Antenna Locator]
* [http://www.wtfda.org Worldwide TV/FM DX Association]
* [http://forums.wtfda.org Worldwide TV/FM DX Association Forums]
* [https://web.archive.org/web/20090412030636/http://dxfm.com/ Girard Westerberg's page, including a live DX webcam]
* [http://fmdx.usclargo.com Mike's TV and FM DX]
* [https://sites.google.com/view/todd-emslie-dx-page Todd Emslie's TV FM DX Site]
* [https://web.archive.org/web/20020829140755/http://www.oldtvguides.com/K1MOD/ Jeff Kadet's TV DX Page]
* {{usurped|1=[https://web.archive.org/web/20050506131940/http://www.mcsittel.com/html/dx.html Matt Sittel's DX Page]}}
* [http://www.siciliamedia.it/ Siciliamedia] Home of FM & TV DX in Sicily
* [http://www.fmlist.org/ FMLIST] is a non-commercial worldwide database of FM stations, including a bandscan and logbook tool (FMINFO/myFM)
* [http://www.mixture.fr/ Mixture.fr] AM/FM/DAB database for France
* [https://web.archive.org/web/20060317193121/http://www.meteorcomm.com/technologies/tech_burst_tech.aspx MeteorComm] Meteor Burst Technology used for Data Communication
* [http://www.fmscan.de/ FMSCAN] reception prediction of FM, TV, MW, SW stations (also use the expert options for better results)
* [https://web.archive.org/web/20070929083127/http://home.scarlet.be/rdsdx/ Herman Wijnants' FMDX pages]
* [http://dxworld.com/tvfmlog.html TV/FM Skip Log]
* [http://mailman.qth.net/mailman/listinfo qth.net] Mailing Lists for Radio, Television, Amateur and other related information for Enthusiasts.
* [https://web.archive.org/web/20101011125305/http://www.wtfda.org/kw4rz/ VHF DXing] – From Fort Walton Beach, Florida
* [https://web.archive.org/web/20060521034844/http://www.radio-info.com/smf/index.php/?board=301.0 Radio-info.com] DX and Reception
* [https://web.archive.org/web/20020917043349/http://www.apritch.myby.co.uk/radioprop.htm FM DX RDS LogBook Software]
* [http://www.vhfdx.org VHF-DX network in South America and The Caribbean]
* [http://www.amro-net.jp/radio.htm The International Project for Radio Meteor Observation] researching meteor showers with Radio Meteor Observation
* [https://list.fmdx.pl/ FM-DX Webserver List] Online list of currently active servers, which users can DX from.
* [https://fmdx.pl FMDX.pl] Polish blog about DXing (with English articles), also containing tutorials on building FM yagis.

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