Author Archives: DK8OK

Sporadic-E Reception: Some Notes

Running from top to bottom: that’s DX! The spectrogram runs from 87.5 MHz to 94.5 MHz. The lower part shows Sporadic-E conditions around 18:00 UTC, the upper part was switched to 19:37 UTC when Sporadic-E had largely disappeared. 29May2020.

When HF collects new power for the autumn season, it’s time to thrown an ear onto VHF. I did so in May 2020, and the spectrogram at the top should give you an impression of the power and glory with with Sporadic-E fills the ORT band and the FM broadcast band. Having published some audio examples from both bands in the two recent posts, I now want to make some comments on this exciting propagation mode.

One signature of Sporadic-E is a highly selective propagation in respect to geographical regions – resembling a laser pointer. Please find below an example of just 90 seconds on 93.9 MHz on 29May2020, around 18:00 UTC (the vertical interruption at the last quarter of the audio spectrogram. It starts with a powerful-modulated, yet unidentified, Italien station with pop music. Then, Radio Constanine from Kef El Akhal (per RDS 2425) takes over with a distinctive (lower) sound, gevoerning the channel for a time, until the Italian comes through again. If play the audio clip and following its spectrogram in parallel, you surely will see what I mean.

93.9 MHz: Two stations on one channel, see text. The vertical frequency is in the logarithmic style to enhance the visibility of the most important speech formants. Listen to audio clip below.
Here you can listen to what is shown in the spectrogram above: two different stations fighting on 93.9 MHz.

Parallel listening on two channels is an essential tool to identify the same station on different channels. Place one (e.g. the left) audio channel on one frequency, and the other audio channel with a 2nd RX on the other (in this case: right channel). This can be done easily with SDRC V3 software. There will always be a time lag between both channels for at least two reasons: the main reason is that two frequencies are usually coming from two different locations, fed over different lines from the studio which causes a slight time difference. The other reason: different RXs in SDRC V3 software ore not phase-synchronized, so there is a small difference. Another difference might occur from different propagation time from two locations (300 km = 1ms!).

The screenshot below shows a typical setup: on 87.7 MHz a station in Arabic was heard. It was set onto RX1/left audio channel. To identify this station, RX2 was set to the right audio channel. Leaving RX1 on its frequency as the reference channel, RX2 was tuned to other channels with Arabic programme. The first hit was made on 87,6 MHz, second on 90,8 MHz, third on 92.5 MHz – all carrying the same programme. Hence, it was very likely SNRT Al Idaa Al-Watania from Morocco from four different locations at distances from 2312 to 2613 km.

Searching parallel programs: right (as basic) audio channel on 87.7 MHz, left audio channel on 90,9 MHz showed programmmes being (largely) in parallel – see the spectrum, and listen to the audio, both below.
Spectrogram of both channels of the audio clip below: left audio = top, right audio = bottom In the first few seconds, including the time-beeps, 87.7 MHz produces “Radio Chlef” from Bou Kadir/Algeria (1963 km), according RDS. Then SNRT Al Idaa-Watani from Midell (2498 km) takes over.
Listen to the above spectrogram in stereo. Soon you will hear that 90.8 MHz lags a bit in time. And that in the first seconds both channels are not in parallel.

The Radio Data System RDS provides an identifcation and often some additional information. First, you see the “Programm Identification Code – RDS-PI”. This is used to support an automatically scan of the receiver to tune always the best channel of this programme. Hence, it designates a programme which is used throughout a chaine of programmes. The “Programme Service Code – PDS-PS” needs a bit longer and gives, if programmed, additional information. As the RDS signal sits on edge of the channel and is quite slow, it is a bit delicate to receive from weak stations under interference. The first example below gives a full-blown RDS signal from a local broadcaster, followed by some RDS signals from DX stations.

Here you see all elements of an FM multplexed (local) stereo signal. The double-peak on the righ is the DSB-modulated RDS signal.
A selection of received RDS signals, in reading direction: 92AA Top Albania (1356 km), 505F Radio Sound/Italy, 5264 RDS/Italy (1304 km), 11DE Radio Epirus/Greece (1648 km), 5201 RAI Radio 1 /Italy (1635 km), Radio Soummam/Algeria (1810 km), E2ED Europa FM/Spain (1364 km), 2202 Chaine 2/Algeria (1802 km)

Fading can be nerve-wrecking. Stations come and go. And they reliably go at top of the hour when the listener expects a station identification … Below I compared the signal from a still near-regional transmitter at a distance of 83 km with that of Radio Constatine/Algeria, 1802 km away. The grey block marks the limit, whre Radio Constanine can be demodulated.

Sporadic-E: Some Examples FM-Band/Broadcast

Three in a row: Reception from three stations from Algeria at the same time over a distance of about 1’800 km on 31May2020, 12:00 UTC

Again, Sporadic-E reception. Now some examples from the FM Broadcast Band (87.5 to 108.0 MHz), as received in spring 2020 at my location in Northern Germany. See my former post for examples from the OIRT FM Band.

87,9 MHz: Radio France Culture, Porto Vecchio (1208 km), ID, 31May2020, 12:00 UTC.

88,8 MHz: Radio Annaba, Souk Aras/Algeria (1791 km). ID in Arabic, 31May2020, 15:00 UTC

90,4 MHz: Radio Setif FM, Setif/Algeria (1829 km). ID in Arabic, 29MAY2020, 18:28 UTC

91,9 MHz: Rádio Comercial, Serra de Bornes/Portugal (1772 km). ID-jingle in Portuguese. 29May2020, 17:50 UTC.

95,1 MHz: BBC Radio 4 FM from Eitshal/Isle of Lewis (1224 km). BBC-ID, 31May2020, 15:00 UTC.

94,1 MHz: Top Albania Radio/Shkoder (1356 km). ID in Albanian. 29May2020, 17:00 UTC

100.7 MHz: Radio Coran-Algerie from Kef El Akhal [1802 km]. ID in Arabic. 31May2020, 12:00 UTC.

102,3 MHz: Nevis Radio/Mallaig, UK (1139 km). 29May2020, 11:00 UTC.

92,8 MHz: Radio Energy, Kiew (1428 km), ID in Ukrainian, 31May2020, 15:53 UTC.

97,8 MHz: Radio Azzura, Marsala/Sicily (1640 km). ID in Italian, 31May2020, 15:02 UTC

Clandestine: Under false Flags

Clandestines on shortwave: Transmitter’s locations. For an interactive version of this map click here.

Non-official radio stations always attracted shortwave listeners who call them “clandestines”, follwing a mixture of mis-understanding and romanticism. The range of this class of stations is remarkably wide. Nowadays, the majority of them is renting time from major transmission centres like Nauen/Germany, Issoudun/France or Toshkent/Uzbekistan.

As all media, they are put into service to influence people and to sell something by propaganda. The difference between an official broadcaster, like Voice of America, and a “clandestine” like North Korea Reform Radio is not palpable – both are financed by the U.S. Congress.

With most broadcasters transmitting on a scale between facts (“white” – nearly only the BBC) and sheer disinformation (“black”), clandestines are placed on the darker third of this range. The separation between “clandestine” and “official” is rather artificial. There simply is no difference between e.g. the official World Harvest Radio and the clandestine Voice of Wilderness, both religious brodcasters, funded by Cornerstone Ministries International/USA – to take just two religious stations.

Today’s activity of clandestines is concentrated on Africa and Asia with especially taking countries like North Korea, China, Eritrea and Sudan into focus.

Some clandestines are jammed, mostly by official broadcasters of the target countries with more or less their usual broadcast; rarely by transmitters just carrying noise.

All known clandestines are official in the sense that the government of the transmitting country knows about their activity and, tacitly at least, is endorsing it. More often than not, clandestines are simply the grey/black arm of their governmental propaganda, like the South Korean “Echo of Hope”, presumably maintained by a (however, non-existing) “General Union of Overseas Compatriots” which in fact turned out to be the South Korean National Intelligence Service NIS.

If you want to look behind the veil, just “follow the money”. In most cases you will land at the U.S. Congress (see illustration below) or some other governmental entities of a third country. Yes, also take care of NGOs, as some (not all) of these “Non-governmental Organizations” are funded by – nothing more but governments of a third country; a system much reminding to money laundering or the game “three shells and a pea”.

“Free press”, western style: How the USA mislead listeners by feigning broadcasts via independent journalists and NGOs.

The overwhelming number of clandestines orignates from “the West”. You can play bullshit bingo with their names or the names of their funding organizations containing: “freedom”, “democracy” and “independence” at the least. That they are running under false flags, gives the right impression of how some kind of journalism works in “the West”.

The authoritative World Radio TV Handbook has an own section of “Clandestine and other target broadcasts”. Please find below some examples out of their 2020’s edition (pp. 509) plus some examples following my a bit wider definition of a clandestine station: each station, which intentionally disguises their source. So you will find Azadradio, but not “Voice of America/VoA Deewa Radio”, although both are financed by the U.S. government.

All stations had been received between December 2019 and April 2020 in Northern Germany. Their reception quality, of course, is very different; for some of them you should put your headphones over.

The following 27 audio clips, appearing in their target countries’ order (or, the country to/against which people/government their transmissions are targeted), were made from wide-band HF recordings with Winradio’s Über-SDR Excalibur Sigma, connected to MD300DX antenna, an active dipole, hung vertical, with 2 x 5m legs; software: SDRC V3.

P.S.: I know, you must not scroll. But please allow me for an expcetion in this case.

Azadradio with their headquarters in Kabul is a branch of RFE/RL, a mouthpiece of the U.S. government. Transmitting towards Afghanistan in Pashtu and Dari.

Azadradio: 17’880 kHz [Udon Thani/Thailand, 250kW], ID in Dari at 00:19; 13:30 UTC, 02APR2020

Voice of Free Talyshistan is transmitted by the Modus Vivendi Center, based in Yerevan/Armenia. Chairman of this non-governmental organization is Armenian lawyer, historian and diplomat Ara Papian. In an interview with TERT [an Armenian media] he supports Armenia’s president that “[land-locked] Armenia must divide [oil-rich] Azerbaijan [at Caspian Sea] as a political unit, cooperating with stateless nations”. One of this “stateless nation” are the Taliysh people, representing 1,4% of the people of Azerbaijan. Hence, Voice of Free Talyshtan is an instrument to separate a future and Armenia-friendly “Talyshistan” from Azerbaijan.

Voice of Free Talyshistan: 1395 kHz [Gavra/Armenia 500 kW?], ID in Talysh, 17:15 UTC, 16DEC2019

Radio Ndarason Internationale is based in N’djamena, the Chad’s capital. It is aimed to the people in the Northern Nigeria and Chad region and is directed against the islamic Boko Haram network. The programme is produced by Johannesburg-based Okapi Consulting, a “media consulting agency”, maintaining no less than five radio stations. Radio Ndarason is aired by BBC transmitters from Wofferton/UK and Ascension.

Radio Ndarason: 12’050kHz [Woofferton/UK, 100kW], IDs in Kanuri, 19:00 UTC, 16DEC2019

CHINA [1] [among others]
Radio Free Asia was founded by the US Congress and is financed by the USA as part of their foreign policy. Part of its task is to encourage separating movements – e.g. in China with transmissions in Tibetian and Uyghur; the common pattern of this kind of stations, see also the Azerbaijan entry above.

Radio Free Asia: 9355kHz [Dushanbe-Yangi Yul/Tajikistan, 200kW], start of transmission in Tibetian with ID “RFA, channel 3” {00:30], marking their virtual “Channel 3” via Eutelsat-70B and Intelsat-19. From 00:41, a transmission from China in Mandarin is also occupying the channel.

China [2]

Sound of Hope with headquarters in San Francisco/USA, is the broadcasting arm of Falun Gong. This organization covers a wide spectrum of religious, economical and political fields. It is controversly debated over in the West as in the East. In China, it is forbidden. SoH uses a couple of more or less low-power and frequency-agile transmitters from said locations in Taiwan; also Thailand is rumored. By errors in switching the audio onto a transmitter, I heard also the sound of Radio Free Asia’s Mandarin channel on some of their 100+ frequencies. China performs cat-and-mouse games to place one of their much more powerful transmitters on some of SoH’s active and ever-changing channels. Sound of Hope usually transmits some ±100Hz off nominal channels and also often outside the brodcasting bands to evade jamming. Funding is done by Falun Gong plus, presumably, also by the U.S. government via their USAGM.

Sound of Hope: 15’939.8kHz [“somewhere in Taiwan, a few kW”], IDs [“Xi wang zhi sheng guoji guangbo diantai”] at 00:12 [female] and 00:40 [male]; 08:00 UTC, 16DEC2019]

Voice of Tibet is producing from Dharamsala/India and promotes Tenzin Gyatso (Dalai Lama), living in exile in just this city. He himself considers the radiostation, as it “… allows us Tibetans to comment on events of Tibetan interest from our own perspective”. Voice of Tibet is funded by a Norwegian charitable foundation (Stiftelsen Tibetprojekt). It is mostly transmitting ±1 kHz off an designated channel.

Voice of Tibet: 9899kHz [Toshkent/Uzbekistan, 100kW], ID [“Di nor we bod kyi rlung ‘phrin kang yin”] at start of their transmission; 12:30UTC, 16DEC2019

CUBA [1]
Radio República is produced by Florida-based Directorio Democrático Cubano and transmitted via Issoudun/France.

Radio República: 9490kHz [Issoudun/France, 150kW], start of transmission in Spanish with ID, 02:00UTC, 16DEC2019

CUBA [2]

Radio Televisión Martí is produced by the Miami-based Office of Cuba Broadcasting, a branch of the U.S. Agency for Global Media, USAGM. This, in turn, is part of the U.S. federal entity “Broadcasting Board of Governors” – the usual matryoshka concept of a puppet in a puppet in a puppet, all firmly hanging on the strings of their government. They mention “democracy”, “independant”? Bingo!

Radio Televisión Martí: 7335kHz [Greenville/USA, 250kW], ID in Spanish; 03:00 UTC, 02APR2020

Radio Erena is produced by Eritrean journalists in Paris and is supported by by Reporters without Borders.

Radio Erena: 9720kHz [Sofia-Kostinbrod/Bulgaria, 200kW], ID in Tigrinya; 17:20 UTC, 18APR2020

Voice of Oromo Liberation is maintained by the Oromo Liberation Front, with the programme presumably produced in Berlin/Germany.

Voice of Oromo Liberation: 15’420kHz [Nauen/Germany, 125kW], ID in Oromo [“Kun Sagalee Bilisummaa Oromoo”], the slight echo comes from from the difference of short path and long path propagation; 17:00UTC, 23APR2020


Radio Farda with their headquarters in Prague/Czechoslovakia is a branch of RFE/RL, a mouthpiece of the U.S. government. Transmitting towards Iran in Farsi.

Radio Farda: 12’005kHz [Woofferton/UK, 300kW], rest of “Born in the USA”, followed by ID in Farsi; 13:30 UTC, 02APR2020

KOREA [North] [1]
Furusato no Kaze/Ilbon-ui Baram is officially brodcasted by the Japanese Government “to Japanese people who have abducted by North Korea and are still trapped in North Korea”. They are the same stations with Furusato no Kaze (Wind from the Homeland) is broadcasting in Japanese, whereas Ilbon-ui Baram (Wind from Japan) transmits in Korean. Both IDs are presented by each an audio clip.

Furusato no Kaze: 9705kHz [Baujong/Taiwan, 300kW], ID in Japanese; 14:30 UTC, 16DEC2019
Ilbon-ui Baram: 9705kHz [Baujong/Taiwan, 300kW], ID in Japanese; 13:00 UTC, 16DEC2019

Korea [North] [2]
Voice of Wilderness is produced in Seoul/Korea by the religious organisation Voice of Wilderness Ministries, based in “Tamil Nadu/South India”. As far as I understood their sermon, they believe in “a second coming of Jesus” – excactly the problem, that mankind and especially the targeted people in North Korea are interested in most. They seem to be affiliated to Cornerstone Ministries/USA and Korean Reconciliation Initiatice and Network, wanting to “restore the church” in North Korea.

Voice of Wilderness: 7615kHz [Toshkent/Uzbekistan, 100kW], ID in Korean; 14:00, 16DEC2019

Korea [North] [3]

National Unity Radio is produced by Unification Media Group, based in Seoul. Telling the public they are a non-governmental organization (NGO), this group in fact in funded by U.S. Congress.

National Unity Radio: 9445kHz [Toshkent/Uzbekistan, 100kW], ID in Korean; 13:00, 16DEC2019

Korea [North] [4]
Shiokaze is maintained by the Investigation Commission on Missing Japanese Probably Related to North Korea/COMJAN – a self-explaining name. On their website is also a banner of an otherwise silent “Strategic Intelligence Institute”.

Shiokaze: 6145kHz [Tokyo-Yamata, 300kW], ID in Japanese, Qinghai PBS on same channel, 13:00 UTC, 16DEC2019

Korea [North] [5]
Echo of Hope claims to be produced by the otherwise non-existing “General Union of Oversea’s Compatriots” which is an echo of South Korea’s National Intelligence Service NIS, in turn being an echo of the South Korean Government.

Echo of Hope: 6250kHz [Taereung/Seoul, 10kW], ID in Korean, 15:00 UTC, 16DEC2019

Korea [North] [6]
North Korea Reform Radio maintained by the so-called NGO North Korea Development Institute which in financed by the U.S. foundation “National Endwonment for Democracy”, funded by grants from the U.S. Congress.

North Korea Reform Radio: 7590kHz [Toshkent/Uzbekistan], start of transmission in Korean, 14:30 UTC, 16DEC2019

Korea [North] [7]
Voice of the People, operated by the South Korean National Intelligence Service by another yet unknown organization, dubbed “Korean Workers Union”.

Voice of the People: 3915kHz [Goyan/Seoul, 50kW], ID in Korean, 15:00UTC, 16DEC2019

Dandal Kura Radio International, funded by USAID, an organization under the US Department of State. It is aimed to the people in the Northern Nigeria and Chad region and is directed against the islamic Boko Haram network.

Dandal Kuraa Radio International: 13’590kHz [Nauen/Germany, 125kW], ID in Kanuri at 01:08; 07:00 UTC, 16DEC2019

Mashaalradio with their headquarters in Prague/Czechoslovakia is a branch of RFE/RL, a mouthpiece of the U.S. government. Transmitting towards Pakistan in Urdu.

Mashaalradio: 15’360kHz [Udon Thani/Thailand, 250kW]; ID at 00:35 in Urdu, 12:00 UTC, 02APR2020

RUSSIA [among others]
Radio Free Europe/Radio Liberty, now only a shadow of itself, was in nearly all aspects a role model of this kind of propaganda radio. Founded in 1949/1953 by an organization fully funded by the CIA (until 1972), it played a major role in Cold War’s “War with Waves”. It remains an United States Government-funded media agency until today with still a few outlets on medium wave and HF, covering East Europe as well as Russia, Iran, Central Asia, Caucasus, Southeast Asia and the Balkans.

Radio Free Europe [Radio Svoboda]: 1386kHz [Viešintos/Lithuania, 75kW], start of transmission in Russian with ID and news; 18:00 UTC, 02APR2020

Eye Radio is operated by Eye Media Ltd. and was/is supported by USAID, an organization under the US Department of State.

Eye Radio: 7340kHz [Santa Maria Galeria/Vatican, 250kW], ID in an Arabic-like dialect; 04:00 UTC, 16DEC2019


Radio Tamazuj is produced by the organization “Free Press Unlimited”, which is largely (89%) funded by the government of the Netherlands. Additional 8% of the budget comes from the Dutch Postcode Lottery. Targetting the people on both sides of the border between South Sudan and Sudan.

Radio Tamazuj: 11’705kHz [Talata Volonondry/Malagasy, 250kW], ID in Arabic-like dialect; ID at 00:38, 15:00 UTC, 16DEC2019

Radio Dabanga is produced by the organization “Free Press Unlimited”, which is largely (89%) funded by the government of the Netherlands. Additional 8% of the budget comes from the Dutch Postcode Lottery. Targetting the people on both sides of the border between South Sudan and Sudan.

Radio Dabanga: 7315kHz [Santa Maria Galeria/Vatican, 250kW], ID in an Arabic-like dialect; 04:30 UTC, 16DEC2019

TURKEY [among others]
Radio Dengê Welat is the third metamorphosis of what started in 2012 as Radio Dengê Mezopotamya, to be changed fived years later into Radio Dengê Kurdistanê. It transmits in four Kurdish dialects to Kurdish people. Their headquarters are said to be in Belgium in Denderleeuw near Brussels. It is backed by Uppsala-based Stiftelsen Kurdisk Media.

Radio Dengê Welat: 11’530kHz [Kishinev-Grigoriopol/Moldova, 300kW], ID in a Kurdish dialect at 00:41; 09:00UTC, 02APR2020

YEMEN [and others]
Radio Al-Azm is a branch of the Saudi Arab Broadcasting Authority with their programme aimed to Saudi military personnel in southern Saudi Arabia and Yemen

Radio Al-Azm [presumed]: 11’745kHz [Jeddah/Saudi Arabia, 250kW], in Arabic

Nĭ hăo, Xinjiang Broadcasting Station!

Still going strong since 1949: Radio Xinjiang, here their banner in Chinese and Mongolian; from their Mongolian website.

Okay, the birthday flowers are already letting hang their heads – but better late than never: Happy birthday, Radio Xinjiang, XJBS!

It was founded in the same year as the People’s Republic of China itself. Only the 1957 edition of the authorative World Radio Handbook took a first notice of their shortwave transmitters at Ürümqi. One of these frequencies, namely 4500 kHz, is still active today.

Among DXers, Radio Xinjiang is a welcomed signal from their transmitters at Ürümqi-Hutubi and at Ürümqi-Changii, some ten kilometeres northwest of Xinjiang’s capital Ürümqi, all in the north-west corner of China.

XJBS’ shortwave transmits in Uighur, Kazakh, Mongolian and Mandarin (“Chinese”) to serve the majority of listeners in each their mother tongue. Please find below their station’s announcement in each of those language. I especially like the “Nĭ hăo, Xinjiang” of the Mandarin recording at second 20. The announcer must have seen Good Morning, Vietnam, undoubtedly echoing Adrian Cronauer [the late Robin Williams].
Just for conaisseurs: in the YouTube clip, Adrian mentioned “Hanoi Hannah”, or Trịnh Thị Ngọ, a popular radio announcer at Radio Hanoi from 1965 airing three shows per day in English, directed towards US GIs. She left microphone only in 1973, after the USA fled from her country.

The following audio clips from my 25MHz/24h recording of December 16, 2019, received with Winradio’s Über-SDR Excalibur Sigma, connected to MD300DX antenna, an active dipole, hung vertical, with 2 x 5m legs.

Mandarin: “Gooood moorning, Xinjiiaaaaang!” 5960kHz, 02:00 UTC
Uighur: 6120kHz, 00:00UTC
Mongolian: 6190kHz, 02:00UTC
Kazakh: 6015kHz, 03:00UTC

I will come back to this interesting station with an analysis of their alltogether 24 HF frequencies between 3950kHz and 13670kHz here in Northern Germany in December 2019, as well as in early April 2020.

P.S. Below a QSL of this station, from 1984 on 4735kHz.

HF Broadcast still in fine health!

Screenshot of interactive Tableau.Map of HF broadcasters; see text

The news about the death of HF Broadcast are greatly exaggerated. The map on the top presents 574 active stations, scattered all over the world. This interactive map has been made with free Tableau Public software: simply click onto the map, an in another tab of your browser it pops up. Now you can point your mouse to a mark and see some data.

There even is more: as some transmitting sites are used by several broadcasters, this fact is shown by different colors. Your mouse will tell.

The best thing of this map is the fact that it is strictly geo-referenced. If you zoom into a station, you should directly see the transmitting site form above – depending, of course, from the resolution of the underlying OSM satellite map.

After having scrutinzed all sources (HFCC, WRTH …) available, I finally decided for ILGRadio. Only these data are concise, complete and precise – a great achievement of Bernd Friedewald since decades! [To keep things simple, only one transmitter’s power is noted for each site]

This map, together with ILGRadio (see below), works as a promising starting point of future work, e.g. band scans in the light of the 21st century …

Just a very small part of Bernd’s excellent ILGRadio list, opened in DBF Manager software, but matching perfectly to be tracked when tuning your receiver; with a choice of SDR software like SDRC V3 and CSVUB.

Winter and Spring: Comparing Signal Strengths

IRAN INTERNATIONAL’s relay station south of Tashkent/Uzbekistan, received on December 16, 2019 (blue line) and April 2, 2020 (yellow line). Day/night below, top pair for Tashkent, lower pair for DK8OK, on the two dates, respectively.

IRAN INTERNATIONAL is transmitting in Farsi via their relay station just at the outskrits of Uzbekistan’s capital, Toshkent, with 100kW on 6270kHz from 12:00 to 04:00 UTC, directed towards Iran.

I received this station in winter as in spring. In winter (namely 16DEC2019), the whole transmission from sign-on to sign-off can be received, wheras in spring (namely 02DEC2020) a considerable part of the transmission after sign-on has been lost in the noise, plus the time towards sign-off in the morning largely coinciding with fade-out; though still celarly visible.

You see also a clear greyline enhancement at least on the fade-in. Sunrise and sunsetset for both locations can be seen from the bar chart below in the diagram..

Path Tashkent-DK8OK of Apbil2, 2020 at 16:00 UTC, path length 4550km.

The graphs are based on 2 x 86’400 points each, providing a time resolution of one second. To make things more clearly, the bold blue and yellow lines represent a smoothed version (moving average: 601).

This is just one example of how the actual signal strength of a station differs from season to season. With 24 hours’s recordings of the whole HF on both dates, it is easy to compare also other stations and frequency ranges. If I have time, I will add some more examples in the future.

BTW: I passed the big transmission center southwest of Toshkent left-hand, riding M39 on the way to Samarkand; it was not encouraged to take any photos …

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot and DX Atlas

Fade-in: Voice of Broad Masses, Asmara/Eritrea

Figure 1: Signal strength of VoBM on 7140kHz from s/on around 14:06 UTC to s/off around 18:30 UTC.

The evening transmission of the Voice of Broad Masses from Asmara-Selae Daro in Eritrea signs on around 14:06 UTC and signing off around 18:30 UTC. Figure 1 shows the signal levels with a resolution of one second, marked by red points, and the smoothed level, yellow line, with a moving average of 601 points, or 10 ten minutes. Smoothed levels span a range from -106 dBm/Hz to -80 dBm/Hz.

There occur considerable peaks around 14:30 UTC, 16:15 UTC and 17:30 UTC. Raytracing the signal, transmitted by a Quadrant antenna HQ1/.25, will help to reveal some mechanics behind the curve.

Figure 2: At s/on, we have a four-hop propagation via the F1 layer, carrying the main signal.

Figure 2 shows a four-hop propagation via F1 layer at 140-160km with a relative steep elevation of about 22°. The much shorter hops, reflected at the E-layer at a height of about 100km, are of less to no importance. The signal gets through, but very weak. The path itself still is in full sunshine, see Figure 3.

Figure 3: At s/on just after 14:00 UTC, the path between Asmara and DK8OK still is in full daylight.

There is a very short, but distinctive peak at 14:30 UTC. This coincides with a similar short time of three-hop propagation (Figure 4) from a very low azimuth of 3°. Of course, the full path still is in daylight.

Figure 4: Around 14:30 UTC, signal improved a bit as a three-hop propagation (still via F1) comes into play.

Just after 16:30 UTC and near sunset at the transmitter (16:37 UTC), there is reached the bottom of kind of a “Hillary Step” before the last run to the peak. The way to a (quite short) plateau starts around 17:00 UTC. There we have a textbook-like two-hop propagation (Figure 5) with the greyline covering just more than half of the great circle path (Figure 6). There, an elevation of under 5° is needed.

Figure 5: From around 17:00 UTC, a time of good reception starts. Reason is the textbook-like two-hop propagation.
Figure 6: With more than half of the great circle path in darkness, VoBM puts a fine signal into Germany.

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot, PropLab

Propagation Day by Day: CRI Kashi, 15.260 kHz

Signal strengths of CRI/Kashi, day by day, from 08:58 UTC to 09:58 UTC on the nine consecutive days March 15 to March 23, 2020; see text.

Propagation on HF differs from day to day. The nine diagrams at the top show the signal strengths of China Radio International’s Kashi transmitter, 500 kW, beaming to Romania; 08:58 UTC to 09:58 UTC from March 15 to March 23. The basic resolution (black grey points in the background) is 100 milliseconds, whereas the blue line marks the moving average with 601 points. The “moving average” can be best understood as a lowpass filter, revealing possible trends on a coarser scale. In this case, you cannot see such a trend.

If you compare a part of each transmission on a much finer scale, you even see sheer chaos, as the Figure below is showing:

All nine signal levels drawn together into one diagram (top), and a small part of it zoomed (bottom) reveals sheer chaos.

There seems to be no visible correlation on any scale in this case. There are other cases where, however, some correlation can be found – to which I will come back in some future entries.

The last diagram at the bottom of this pages shows a much more forgiving picture of the signal: the average level changes not more than ±4 dB between best and worst days. This so-called box diagram illustrates best the actual receiving quality of the broadcast, demodulated with an synchronous detector to largely avoid severe distortion by selective fading. The difference of deciles 90% and 10% marks the fading range, a key figure in describing the quality of reception – see “Ionospheric Radio” by Kenneth Davies [London, 1990/96, pp. 232].

The box plot shows very similar signal strengths, day by day. You should concentrate on their each center of gravity. You will also see that the distribution of the signals strengths relative to the center is not symmetrically, with a clearly visible advantage to the percentalge below the average strengths. THis will be covered in some future entry.

Analyzing signal strenghts, is an interesting tool to get to know more about propagation. I will continue this topic – stay tuned!

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot

Greyline enhancement

Signal level on 4750 kHz, observed over some hours: After s/off of Bangladesh Betar, People’s Broadcasting Station at Hulun Buir emerged, showing a peak just after their local sunrise

Today’s SDRs plus able software allow for some new insights into propagation. The figure at the top shows but one example: greyline enhancement. It follows the signal levels on 4750 kHz with a resolution of one second. Smoothing this cloud of points, reveals the more general course of signal level. Here we see, after sign off of Bangladesh Betar, the 10 kW transmitter of People’s Broadcasting Station at Hulun Buir coming up. Most interesting is its short-living enhancement just after sunrise at Hailar in China’s Inner Mongolia, squeezed at their borders to Russia and Mongolia.

This greyline enhancement can be observed regularily on frequencies under, say, 10 MHz: at sunrise at the transmitter’s site, first the F2 layer of the ionosphere is building up, being responsible of the signal of, here, about 5 dB. The lower and attenuating D-layer needs a bit more time to build up, leaving a short-living window for an enhanced signal.

This is to encourage also other HF aficionados to to use this technique.

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot and DX Atlas

1993: "Die Grenzen des Amateurfunks"

Ein freundlicher Leser stöberte in alten Heften der längst von zwei DARC-Leuten absichtsvoll zerstörten Fachzeitschrift “funk”. Er stieß dabei auf ein Editorial, das ich im Juli 1993 dort über “Die Grenzen des Amateurfunks” veröffentlichte. Ihr könnt es ihr hier nachlesen.

Diese Grenzen verortete ich schon damals hauptsächlich in der Betriebstechnik der Funkamateure sowie in falschen Schwerpunkten bei der Auswahl von Gerätschaften und Modulationsarten. An diesem Befund hat sich leider auch eine Generation später wenig geändert. Nur die Störungen, die uns damals schon das Leben etwas schwerer also notwendig machten, die sind nochmals stark angestiegen.

Bedauern kann man überdies, dass es heute keine Funk-Fachpresse mehr gibt, die in gleicher Weise wie die “funk” begeisternd und anregend über technische Innovationen berichtete, sie durchaus kritisch prüfte, Hintergründen – auch bei Besuchen der Hersteller bis hin in Tokio und Osaka – nachspürte, darüber professionell informierte und Monat für Monat lebhaft Werbung für unser Hobby auch unter jenen machte, die zunächst nur lose am Thema “Funk” interessiert waren. Viele von ihnen legten daraufhin ihre Prüfung erfolgreich ab, während nach erfolgreicher Zerstörung der “funk” die “Teilnehmerzahlen am Amateurfunkdienst”, wie der Begriff in aller offizieller Umständlichkeit lautet, kräftig gesunken ist. Unbedingt ein weiterer Erfolg, den sich der DARC ans Revers heften kann – gleich neben die Goldene Deppenraute mit Antenne und Brillanten 😉

« Older Entries