Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:
Massive jamming on 40m (possibly from Cuba) is bugging the radio community
Apparently this is going on for a week now on 40m:
Spent last night at my beach listening post on the German North Sea coast and found this fairly strong signal and a 40m band mostly cleared of any other signals. As soon as I found out that it wasn’t something local, I was wondering who’s responsible for this mess again. It looks like Josh (“Ham Radio Crash Course” YouTube channel) may have found a possible origin of that signal:
Here’s what it sounds like on each of the apparently manually controlled jamming channels:
Cuba would’ve probably been my last guess here on the other side of the big pond. 🙂 In other words, they – whoever they are – jam the band for at least half of the world. Luckily 40m isn’t exactly a pleasure in most of the summer anyway but after having to suffer OTH radars, FHSS blips and politically motivated broadcasting with associated jamming on 40m for a long time, this is a new low. I don’t want to get all political here but trying to erect some electromagnetic fence around a country has never really worked out, it’s just a futile, at most temporarily effective and symbolic act, perceived as pointless and aggressive vandalism out of blank despair by the rest of the world.
North Korea has been from the beginning of March continually signal jamming radio broadcasts on the shortwave frequency used by the South Korean non-profit broadcaster Unification Media Group (UMG). Given the present situation, in which North Korean residents might be influenced by outside information condemning the regime and explaining the purpose of the sanctions imposed by the United Nations, the regime has showed the will to block sources of outside information that might cause unrest.
The shortwave frequency […] in question, 7515 [kHz], has been actively jammed starting on March 1st making it extremely difficult for North Korean listeners to tune in. On the 15, UMG organization began using three receivers to test out reception at that and adjacent frequencies on a daily basis and was able to confirm that the exact signal is being jammed.
The blocking effort is being concentrated on the time period from 10pm- midnight. Specifically, from 10-11pm the jamming is very strong. The signal jamming is undetectable from midnight to 1am. The signal blocking became weaker at midnight on March 15, from which point onward the entire three hour broadcast was audible. Starting on the 17, UMG moved the frequency, but the jamming operators seemed not to notice because the interference continued on the old wavelength.
In the latest episode of Over To You, host Rajan Datar discusses how the BBC World Service’s shortwave transmissions are being affected by jamming in parts of Asia. It’s a short but informative episode.
Over To You explores the way that the World Service’s shortwave transmissions are being affected by jamming in parts of Asia, following up from an email from a listener in West Bengal who was having problems listening to the service. With the help of the World Service’s head of business development, we find out how jamming of the World Service shortwave transmissions inside China is spilling over into neighbouring countries, and explore what the BBC can do to redress the situation through international organisations.