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Get it while you still can: The Luxemburg-Gorky effect
by 13dka
The Radio Luxembourg longwave transmitter Junglinster in the 1930s [RTL Group]
“In radiophysics, the Luxemburg-Gorky effect (named after Radio Luxemburg and the city of Gorky (Nizhny Novgorod)) is a phenomenon of cross modulation between two radio waves, one of which is strong, passing through the same part of a medium, especially a conductive region of atmosphere or a plasma.” (Wikipedia)
That sounds pretty abstract, right? In my own words, imagine your radio is tuned to a station on let’s say 162 kHz, 500 miles away. Somewhere in the middle between your receiver and the 162 kHz transmitter is a station transmitting on a different frequency, let’s say 234 kHz. The Luxemburg effect is that you can hear the modulation of the 234 kHz transmitter in the middle, on the 162kHz station you are receiving. The effect is not depending that much on the frequency/wavelength though, the longwave station could affect medium wave stations and it has been created using shortwave frequencies far apart.
It was observed first in 1932, when listeners of the Swiss Beromünster 60kW medium wave station built just one year prior also heard a bit of Radio Luxemburg’s longwave transmitter (250kHz) on the Beromünster frequency (653kHz until 1934). Of course this was assumed to be some kind of crosstalk within the receivers and probably drove radio engineers insane until 1933, when Bernhard D.H. Tellegen, a Dutch electrical engineer and inventor suggested the true origin of the effect: The new (1932) 150kW Radio Luxemburg longwave transmitter in Junglinster was directly modifying the ionosphere hundreds of kilometers above, it “heated” the ionosphere in a way that it made the plasma’s charge and reflectivity follow the amplitude modulation of Radio Luxemburg, thus modulating waves of other wavelengths crossing this part of the ionosphere.
Practical demonstration
Even if you’re living in Europe, you may never have witnessed that effect and according to this article by Paul Litwinovich, chances to observe this in the US are rather slim, due to the relatively low power of the stations. I’m in Europe but never noticed it either – until recently: Continue reading →
Many thanks to SWLing Post contributor, Dan Robinson, who shares the following video which shows how connecting an external antenna to the HDR-747 extends reception range down to longwave:
Many thanks to SWLing Post contributor, Uli (DB1ULI), who writes:
Hello Thomas,
I started to enjoy BCL and SWL some week ago (again). I have a HAM license for many years, but was QRT for the past few years. Now, the HAM bug bit somehow again and I’ve been listening to the bands via a Tecsun H-501 but changed this one to a Reuter Pocket already.
The Reuter Pocket (Source: Reuter)
The Pocket is a really great receiver including also the FM Bands and the popular (in Europe) Digital Broadcasting DAB.
Still, it is just a receiver. So for now I am searching for a new rig, too. The current offerings are all tempting, FT-DX 10, FT-991A, IC-7300, IC-705 and so on. I really like the new models due to their features, and most due to their displays. My former rig was a Yaesu FT-897.
I already read your and the other reviews of the IC-705 (especially the BC receiving parts) and it could replace the Reuter in many ways. I am just a little bit reluctant because I like the longwave band a lot (we still have stations here) and there is no info to find anywhere how it works below 500kHz. MW seems to be on par with most other receivers.
Do you have an idea about a source of information concerning the capabilities of the IC-705 below 500kHz?
All the best and 73,
Uli
Great question, Uli. I’m hoping that some of our European IC-705 owners may be able to help you here. Although I’ve spent a lot of time on mediumwave with the IC-705, I’ve done little exploring of longwave.
Please comment if you have thoughts on the IC-705’s longwave performance!
Experimental Station will Recreate 1906 Fessenden Transmissions
Experimental station WI2XLQ will be on the air on 486 kHz AM for the Reginald Fessenden commemorative transmission. Brian Justin, WA1ZMS, is the licensee. He will transmit for 24 hours starting at 2000 UTC on December 24, with a repeat transmission starting at 2000 UTC on December 31. Justin will use a homebrew 1921-era MOPA exciter with Heising modulation, followed by a modern 500-W linear. The transmission will be the same as in past years — two violin pieces that Fessenden claims to have played as one of the very first voice transmissions from his Brant Rock, Massachusetts, radio lab site. “While doubt remains that such a transmission ever took place, Fessenden did perform some crude voice transmissions over a few miles distance in early December near Washington, DC, as a demonstration for the US Navy,” Justin said. “So, perhaps some credit is due Fessenden for his efforts to transmit the human voice in an era of spark transmissions.”
Radio Waves: Stories Making Waves in the World of Radio
Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers. To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!
Radio facsimile technology never fully caught on, but what if it had?
In the beginning, there were newspapers.
And then radio arrived, challenging the newspapers’ journalistic monopoly.
At first, many newspapers fought the new competitor, refusing to print radio news or program schedules. But some went in the opposite direction, deciding to operate their own radio stations to augment their businesses. And finally, a few brave pioneering publications went even farther: They tried to deliver their newspapers via radio facsimile.
In the early 1930s, radio facsimile looked like the dream application for newspapers. They could use their own local radio stations to deliver newspapers directly to consumers during overnight hours. It would eliminate the cost of printing and distribution and shift those costs onto consumers, who would provide their own printers and paper.
This led several radio stations and newspapers to experiment with facsimile transmission during the late 1930s.
THE FINCH SYSTEM
The person most responsible for this technology was William G. H. Finch. He worked for the International News Service and set up their first teletype circuits between New York, Chicago and Havana. He became interested in facsimile machines and eventually amassed hundreds of patents. [Continue reading the full article…]
Why Chicago Public Media and the Chicago Sun-Times are exploring a merger
The Chicago Sun-Times needs help. After being bought and sold several times over the last decade, the 73-year-old paper is looking for a more stable home to continue its award-winning reporting — and it may have finally found it in an unexpected place: a radio station.
Chicago Public Media, which owns the radio station WBEZ, is currently in talks with the Sun-Times to merge. A final deal would combine their newsrooms and audiences in hopes of creating a financially stable enterprise for both teams. Similar mergers and acquisitions have become a common way to bolster the struggling print industry, but if radio were to take on a major newspaper, that would be a first.
“Audio is a growth business,” says Jim Friedlich, chief executive of The Lenfest Institute for Journalism, who advised CPM on the potential merger. “Now Chicago Public Media and other media with audio roots have both the wherewithal and the self-confidence to take a bold step like this.”
Since 2004, US newspapers have shut down at a rate of 100 per year, a pace that’s only accelerated since the start of the pandemic. To stay afloat, some smaller newsrooms have given up independence, being bought by news conglomerates or becoming joint entities with other local outlets — and public radio and TV stations have increasingly offered themselves up as partners. New York Public Radio acquiring the website Gothamist was one of nine similar deals in recent years, triggering researchers to document the trend by creating the Public Media Mergers Project. Public radio has been a particularly strong force, holding its ground amid digitization and the podcasting craze (partially because it’s participated in it), and it might be strong enough to help print do the same thing. [Continue reading…]
In the 125 years since Marconi made his first radio transmissions, the spectrum has been divvied up into ranges and bands, most of which are reserved for governments and large telecom companies. Amidst all of the corporate greed, the ‘little guys managed to carve out their own small corner of the spectrum, with the help of organizations like the American Radio Relay League (ARRL).
Since 1914, the ARRL has represented the interests of us amateur radio enthusiasts and helped to protect the bands set aside for amateur use. To actually take advantage of the wonderful opportunity to transmit on these bands, you need a license, issued by the FCC. The licenses really aren’t hard to get, and you should get one, but what if you don’t feel like taking a test? Or if you’re just too impatient?
Well, fear not because there’s some space on the radio spectrum for you, too.
Welcome to the wonderful world of (legal!) unlicensed radio experimentation, where anything goes. Okay, not anything but the possibilities are wide open. There are a few experimental radio bands, known as LowFER, MedFER, and HiFER where anyone is welcome to play around. And of the three, LowFER seems the most promising.
LowFER, as the name would suggest, contains the lowest frequency range of the three, falling between 160 kHz and 190 kHz, with a whopping wavelength of around one mile. Also known as the 1750-meter band, this frequency range is well-suited for long transmission paths through ground wave propagation, a mode in which the radio signals move across the surface of the earth. This can easily carry even low-power signals hundreds of miles, and occasionally through some atmospheric black magic, signals have been known to travel thousands of miles. These ground wave signals also travel well across bodies of water, especially salt water.
We regret to inform our listeners that our colleague Juan Antonio “Tony” Middleton passed away in Buenos Aires due to health complications, at the age of 82. His distinctive British accent is part of the history of RAE, where he hosted the English-language program for almost three decades. English-speaking listeners around the world remember his warmth and clarity on the air, not to mention his classic opening line: “This is the international service of the Argentine Radio”.
Born in Argentina and son of British immigrants, he ventured into acting in the English language with the group “Suburban Players”, while he was engaged in various commercial activities with his family. In 1981 he had the opportunity to join RAE as a substitute, thanks to his impeccable English and his pleasant voice. In 1983 he joined as a regular and went on to become head of the English-language department at the station, until his retirement in 2008. [Continue reading…]
Mlburn Garland “Gil” Butler was born December 1, 1935 in Bradenton, Florida. He attended local schools, where his mother was a teacher. He grew up in a community where electrification was still being developed, where the Saturday morning movies were an all-day entertainment for kids, and where families would gather in the town square on Sundays for band music and ice cream. After a brief stint in the Army (serving as a quartermaster at a base near Washington, D.C.), Gil Butler went to college in Colorado, returning to Florida where he graduated from the University of Florida with a degree in radio engineering. Along the way, he met and after a whirlwind courtship married Judith Bunten, who would become his lifelong companion. Gil Butler began working as a DJ at a small radio station in Bradenton, Florida in the early 1950s, spinning disks from the very beginning of Rock and Roll. His love of music of all sorts, from Jazz to Rock to Classical, his collection evolved through several formats (LP, cassette, CD, and MPs), and his special chair was always surrounded by the music he would enjoy while reading in the evening. Professionally, Gil moved up to larger stations and more challenging positions in radio and television; working for radio stations around the Tampa Bay area. His first TV gig was as a general reporter for WTVT in Tampa. From there, he moved to WXYZ in Detroit, Michigan, before moving to Silver Spring in the Washington D.C. where he worked as a White House Correspondent for local CBS affiliate, WTOP, covering Washington politics under presidents Nixon and Ford. During this period, Gil appears briefly in Timothy Crouse’s The Boys on the Bus (a recounting of the White House Press Corps during the Nixon Era). He was one of the six “Knights of the Green Ottoman,” named for an item of furniture in the 1972 White House press complex, where the newsmen would gather and share notes. In one passage, he is described: “Gil Butler… the reporter for TV station WTOP, who was chuckling over a volume of Mencken…” This description will surprise no one who knew him, as Gil was a voracious reader. He was always in the middle of a massive nonfiction volume about politics, military history or the Space Race. After WTOP, in 1978, Gil began his ultimate career at the Voice of America, the United States Information Agency’s international radio network. Over a nearly three decade career with Voice of America, he covered 68 countries, working abroad in Cairo, Egypt, Beiruit Lebanon, Beijing, China, London, England, as well as covering the State Department and Pentagon during his time at home between foreign assignments. At the Voice of America’s 40th Anniversary Celebration, Gil received the Meritorious Honor Award for his work in Cairo covering the assassination and funeral of Egyptian President Sadat and its aftermath. Twenty-seven years later, Voice of America News ran a story looking back at that work and the restraint and integrity he exercised in waiting for confirmation before reporting that Sadat had been killed. [Continue reading…]
Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:
Gone fishing…for DX: Reception enhancement at the seaside
by 13dka
In each of my few reviews I referred to “the dike” or “my happy place”, which is a tiny stretch of the 380 miles of dike protecting Germany’s North Sea coast. This is the place where I like to go for maximum listening pleasure and of course for testing radios. Everyone knows that close proximity to an ocean is good for radio reception…but why is that? Is there a way to quantify “good”?
Of course there is, this has been documented before, there is probably lots of literature about it and old papers like this one (click here to download PDF). A complete answer to the question has at least two parts:
1. Less QRM
It may be obvious, but civilization and therefore QRM sources at such a place extend to one hemisphere only, because the other one is covered with ocean for 100s, if not 1000s of miles. There are few places on the planet that offer such a lack of civilization in such a big area, while still being accessible, habitable and in range for pizza delivery. Unless you’re in the midst of a noisy tourist trap town, QRM will be low. Still, you may have to find a good spot away from all tourist attractions and industry for absolutely minimal QRM.
My dike listening post is far enough from the next small tourist trap town (in which I live) and also sufficiently far away from the few houses of the next tiny village and it’s located in an area that doesn’t have HV power lines (important for MW and LW reception!) or industrial areas, other small villages are miles away and miles apart, the next town is 20 km/12 miles away from there. In other words, man-made noise is just not an issue there.
That alone would be making shortwave reception as good as it gets and it gives me an opportunity to check out radios on my own terms: The only way to assess a radio’s properties and qualities without or beyond test equipment is under ideal conditions, particularly for everything that has to do with sensitivity. It’s already difficult without QRM (because natural noise (QRN) can easily be higher than the receiver’s sensitivity threshold too, depending on a number of factors), and even small amounts of QRM on top make that assessment increasingly impossible. This is particularly true for portables, which often can’t be fully isolated from local noise sources for a couple of reasons.
Yes, most modern radios are all very sensitive and equal to the degree that it doesn’t make a difference in 98% of all regular reception scenarios but my experience at the dike is that there are still differences, and the difference between my least sensitive and my most sensitive portable is not at all negligible, even more because they are not only receivers but the entire receiving system including the antenna. You won’t notice that difference in the middle of a city, but you may notice it in the woods.
When the radio gets boring, I can still have fun with the swing and the slide!
2. More signal
I always had a feeling that signals actually increase at the dike and that made me curious enough to actually test this by having a receiver tuned to some station in the car, then driving away from the dike and back. Until recently it didn’t come to me to document or even quantify this difference though. When I was once again googling for simple answers to the question what the reason might be, I stumbled upon this video: Callum (M0MCX) demonstrating the true reason for this in MMANA (an antenna modeling software) on his “DX Commander” channel:
To summarize this, Callum explains how a pretty dramatic difference in ground conductivity near the sea (click here to download PDF) leads to an increase in antenna gain, or more precisely a decrease in ground return losses equaling more antenna gain. Of course I assumed that the salt water has something to do with but I had no idea how much: For example, average ground has a conductivity of 0.005 Siemens per meter, salt water is averaging at 5.0 S/m, that’s a factor of 1,000 (!) and that leads to roughly 10dB of gain. That’s right, whatever antenna you use at home in the backcountry would get a free 10dB gain increase by the sea, antennas with actual dBd or dBi gain have even more gain there.
That this has a nice impact on your transmitting signal should be obvious if you’re a ham, if not just imagine that you’d need a 10x more powerful amplifier or an array of wires or verticals or a full-size Yagi to get that kind of gain by directionality. But this is also great for reception: You may argue that 10dB is “only” little more than 1.5 S-units but 1.5 S-units at the bottom of the meter scale spans the entire range between “can’t hear a thing” and “fully copy”!
A practical test
It’s not that I don’t believe DX Commander’s assessment there but I just had to see it myself and find a way to share that with you. A difficulty was finding a station that has A) a stable signal but is B) not really local, C) on shortwave, D) always on air and E) propagation must be across water or at least along the coastline.
The army (or navy) to the rescue! After several days of observing STANAG stations for their variation in signal on different times of the day, I picked one on 4083 kHz (thanks to whoever pays taxes to keep that thing blasting the band day and night!). I don’t know where exactly (my KiwiSDR-assisted guess is the English channel region) that station is, but it’s always in the same narrow range of levels around S9 here at home, there’s usually the same little QSB on the signal, and the signals are the same day or night.
On top of that, I had a look at geological maps of my part of the country to find out how far I should drive into the backcountry to find conditions that are really different from the coast. Where I live, former sea ground and marsh land is forming a pretty wide strip of moist, fertile soil with above average conductivity, but approximately 20km/12mi to the east the ground changes to a composition typical for the terminal moraine inland formed in the ice age. So I picked a quiet place 25km east of my QTH to measure the level of that STANAG station and also to record the BBC on 198 kHz. Some source stated that the coastal enhancement effect can be observed within 10 lambda distance to the shoreline, that would be 730m for the 4 MHz STANAG station and 15km for the BBC, so 25km should suffice to rule out any residue enhancement from the seaside.
My car stereo has no S-meter (or a proper antenna, so reception is needlessly bad but this is good in this case) so all you get is the difference in audio. The car had the same orientation (nose pointing to the east) at both places. For the 4 MHz signal though (coincidence or not), the meter shows ~10dBm (or dBµV/EMF) more signal at the dike.
3. Effect on SNR
Remember, more signal alone does not equal better reception, what we’re looking for is a better signal-to-noise ratio (SNR). Now that we’ve established that the man-made noise should be as low as possible at “my” dike, the remaining question is: Does this signal enhancement have an effect on SNR as well? I mean, even if there is virtually no local QRM at my “happy place” – there is still natural noise (QRN) and wouldn’t that likely gain 10dB too?
Here are some hypotheses that may be subject of debate and some calculations way over my head (physics/math fans, please comment and help someone out who always got an F in math!). Sorry for all the gross oversimplifications:
Extremely lossy antennas
We know that pure reception antennas are often a bit different in that the general reciprocity rule has comparatively little meaning, many antennas designed for optimizing reception in specific situations would be terrible transmitting antennas. One quite extreme example, not meant to optimize anything but portability is the telescopic whip on shortwaves >10m. At the dike, those gain more signal too. When the QRN drops after sunset on higher frequencies, the extremely lossy whip might be an exception because the signal coming out of it is so small that it’s much closer to the receiver noise, so this friendly signal boost could lift very faint signals above the receiver noise more than the QRN, which in turn could mean a little increase in SNR, and as we know even a little increase in SNR can go a long way.
The BBC Radio 4 longwave recording is likely another example for this – the unusually weak signal is coming from a small and badly matched rubber antenna with abysmal performance on all frequency ranges including LW. The SNR is obviously increasing at the dike because the signal gets lifted more above the base noise of the receiving system, while the atmospheric noise component is likely still far below that threshold. Many deliberately lossy antenna design, such as flag/tennant, passive small aperture loops (like e.g. the YouLoop) or loop-on-ground antennas may benefit most from losses decreasing by 10dB.
Not so lossy antennas, polarization and elevation patterns
However, there is still more than a signal strength difference between “big” antennas and the whips at the dike: Not only at the sea, directionality will have an impact on QRN levels, a bidirectional antenna may already decrease QRN and hence increase SNR further, an unidirectional antenna even more, that’s one reason why proper Beverage antennas for example work wonders particularly on noisy low frequencies at night (but this is actually a bad example because Beverage antennas are said to work best on lossy ground).
Also, directional or not, the “ideal” ground will likely change the radiation pattern, namely the elevation angles, putting the “focus” of the antenna from near to far – or vice versa: As far as my research went, antennas with horizontal polarization are not ideal in this regard as they benefit much less from the “mirror effect” and a relatively low antenna height may be more disadvantageous for DX (but maybe good for NVIS/local ragchewing) than usual. Well, that explains why I never got particularly good results with horizontal dipoles at the dike!
Using a loop-on-ground antenna at a place without QRM may sound ridiculously out of place at first, but they are bidirectional and vertically polarized antennas, so the high ground conductivity theoretically flattens the take-off angle of the lobes, on top of that they are ~10dB less lossy at the dike, making even a LoG act more like something you’d string up as high as possible elsewhere. They are incredibly convenient, particularly on beaches where natural antenna supports may be non-existent and I found them working extremely well at the dike, now I think I know why. In particular the preamplified version I tried proved to be good enough to receive 4 continents on 20m and a 5th one on 40m – over the course of 4 hours on an evening when conditions were at best slightly above average. Though the really important point is that it increased the SNR further, despite the QRN still showing up on the little Belka’s meter when I connected the whip for comparison (alas not shown in the video).
The 5th continent is missing in this video because the signals from South Africa were not great anymore that late in the evening, but a recording exists.
Here’s a video I shot last year, comparing the same LoG with the whip on my Tecsun S-8800 on 25m (Radio Marti 11930 kHz):
At the same time, I recorded the station with the next decent (but more inland) KiwiSDR in my area:
Of course, these directionality vs noise mechanisms are basically the same on any soil. But compensating ground losses and getting flat elevation patterns may require great efforts, like extensive radial systems, buried meshes etc. and it’s pretty hard to cover enough area around the antenna (minimum 1/2 wavelength, ideally more!) to get optimum results on disadvantaged soils, while still never reaching the beach conditions. You may have to invest a lot of labor and/or money to overcome such geological hardships, while the beach gives you all that for free.
But there may be yet another contributing factor: The gain pattern is likely not symmetrical – signals (and QRN) coming from the land side will likely not benefit the same way from the enhancement, which tapers off quickly (10 wavelengths) on the land side of the dike and regular “cross-country” conditions take place in that direction, while salt water stretching far beyond the horizon is enhancing reception to the other side.
So my preliminary answer to that question would be: “Yes, under circumstances the shoreline signal increase and ground properties can improve SNR further, that improvement can be harvested easily with vertically polarized antennas”.
Would it be worthwhile driving 1000 miles to the next ocean beach… for SWLing?
Maybe not every week–? Seriously, it depends.
Sure, an ocean shoreline will generally help turning up the very best your radios and antennas can deliver, I think the only way to top this would be adding a sensible amount of elevation, a.k.a. cliff coasts.
If you’re interested in extreme DX or just in the technical performance aspect, if you want to experience what your stuff is capable of or if you don’t want to put a lot of effort into setting up antennas, you should definitely find a quiet place at the ocean, particularly if your options to get maximum performance are rather limited (space constraints, QRM, HOA restrictions, you name it) at home.
If you’re a BCL/program listener and more interested in the “content” than the way it came to you, if you’re generally happy with reception of your favorite programs or if you simply have some very well working setup at home, there’s likely not much the beach could offer you in terms of radio. But the seaside has much more to offer than fatter shortwaves of course.
From left to right: Starry sky capture with cellphone cam, nocticlucent clouds behind the dike, car with hot coffee inside and a shortwave portable suction-cupped to the side window – nights at the dike are usually cold but sometimes just beautiful. (Click to enlarge.)
However, getting away from the QRM means everything for a better SNR and best reception. In other words, if the next ocean is really a hassle to reach, it may be a better idea to just find a very quiet place nearby and maybe putting up some more substantial antenna than driving 1000 miles. But if you happen to plan on some seaside vacation, make absolutely sure you bring two radios (because it may break your heart if your only radio fails)!
A little update (2023):
Like I said, the +10dB signal boost works both ways and here’s a nice example that I thought should be here. This is W4SWV, literally standing with both feet in the Atlantic ocean at the South Carolina coastline, carrying a 25W backpack radio with a whip and talking to F6ARC in France on 17m – received at my side of the pond using my simple vertical 33’/10m monopole antenna at the dike:
This was recorded on July 4th, 2021 and does not provide a reference to demonstrate how good or bad this is of course, all you have is my word that getting such a solid and loud signal from a 25W station on the US East Coast was just outstanding (compared to a fair number of coastal QRP stations I copied at the dike over the years, or the average 100W inland stations).
Meanwhile I found out that I’m luckily not the only (or the first) person who tried to make some practical experiments to reassess the theories in recent times: Greg Lane (N4KGL) made measurements by transmitting a WSPR signal simultaneously off 2 locations, one near the shoreline and one more inland. Measuring the signals created in distant WSPR receivers, he got similar results. He made a presentation about it in 2020:
Many thanks to SWLing Post reader, Ian Harling (G7HFS), who writes:
I have been a SWL for about 50 yrs and also hold an amateur radio license, but here is where I need some advice.
Can you recommend a portable radio that performs well longwave and also NDB reception? I do have a Datong VLF converter that I can use but I’m looking for a dedicated portable set that works well on frequencies between 100 and 500 kHz. Any suggestions?
Good question, Ian. While I always do a basic check of longwave performance on shortwave portables–checking regional NDBs–I have never done a proper comparison test or used them for longwave listening or DXing sessions.
I know there are some dedicated LW DXers and listeners in the SWLing Post community, so my hope is someone can chime in with their radio suggestion in the comments section. Thank you in advance!
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