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<\/a>The Radio Luxembourg longwave transmitter Junglinster in the 1930s [RTL Group<\/a>]<\/p><\/div> 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.\u00a0 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.<\/p>\n It was observed first in 1932, when listeners of the Swiss Berom\u00fcnster 60kW medium wave station built just one year prior also heard a bit of Radio Luxemburg’s longwave transmitter (250kHz) on the Berom\u00fcnster frequency (653kHz until 1934).\u00a0 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>, 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.<\/p>\n Even if you’re living in Europe, you may never have witnessed that effect and according to this article<\/a> by Paul Litwinovich, chances to observe this in the US are rather slim, due to the relatively low power of the stations.\u00a0 I’m in Europe but never noticed it either – until recently:<\/p>\n By the turn of the year 2017, “France Inter” was no longer broadcasting via the longwave transmitter in Allouis, France, formerly transmitting the French time signal “TDF” simultaneously with the radio program on 162 kHz. Since then the station was renamed “ALS162” and carries only a phase-modulated digital time signal with no discernible amplitude modulation anymore, making it appear to the listener as an unmodulated carrier. This in turn made it possible to observe the effect without disturbing modulation from the to-be-modulated station itself.<\/p>\n The longwave transmitter in Allouis [WikiMedia Commons<\/a>]<\/p><\/div>Of course you don’t need Radio Luxemburg to observe the effect: Clint of the Oxford Shortwave blog<\/a> recorded the Luxemburg effect using ALS162 in 2018, reporting that he had a UK station weakly modulating the signal, possibly the Orfordness 200kW transmitter carrying the BBC World Service program.<\/p>\n
\n“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.”<\/em> (Wikipedia)<\/p>\n<\/a><\/p>\nPractical demonstration<\/h2>\n
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