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.
The BBC’s new Korean-language service is being “aggressively targeted” by North Korean jamming of its broadcasts.
The service was launched on Monday and delivers a mixture of global news, sport and radio features to the whole of the Korean Peninsula for a three-hour window that starts at midnight local time.
Broadcasts are going out on two shortwave frequencies, from Taiwan and Tashkent, while the hour-long segment from 1am is relayed on medium wave from Mongolia, according to a report on the 38 North web site, operated by the US-Korea Institute at Johns Hopkins University.
“As listening to foreign radio is illegal, the government makes a great effort to prevent people from doing so”, the report states. “At the most basic level, it modifies radios so they cannot be tuned to anything but state-run channels, although that can be later reverse engineered.
[…]The BBC broadcasts are going out after midnight, which will make it easier for listeners with access to short wave to tune in secretly.
Ambulances in Stockholm are testing a system that interrupts in-car audio systems to warn drivers that they need to get through.
The solution was developed by students at the KTH Royal Institute of Technology in the city.
It broadcasts a voice warning, while a text message also appears in the radio display.
It uses an FM radio signal to jam drivers’ speakers and stop music playing.
It will only be able to alert cars that have their radios turned on. It can also interrupt CDs and music connected via Bluetooth.
The radio transmission is sent from the emergency vehicle to nearby FM tuners that are equipped with RDS, a communications protocol for embedding small amounts of digital information in FM radio broadcasts. It is most commonly used to display the station or song title.
[…]The city will begin testing the system in a limited number of ambulances and fire engines, with plans to expand across the country later this year.
The warning system can work out how far in advance messages need to be heard depending on the speed of traffic.
Many thanks to SWLing Post contributor, Vlado (N3CZ), for sharing the following story from the South African Radio League newsletter:
Broadcasters, jammers wreak havoc on amateur radio frequencies
The ARRL reports the battle in the amateur radio 7 MHz band continues between Radio Eritrea and Radio Ethiopia, which is said to be jamming the Eritrean broadcaster with broadband white noise
The problem for radio amateurs is that the battle is taking place in the 40 meter phone band 7,145 and 7,175 MHz with the jamming signal reported by the IARU Region 1 Monitoring System (IARUMS) to be 20 kHz wide on each channel.
The on-air conflict has been going on for years; Ethiopia constructed new transmitting sites in 2008 and is said to use two or three of them for jamming purposes. The interfering signals can be heard in North America after dark.
According to IARUMS Region 1 Coordinator Wolf Hadel, DK2OM, Radio Eritrea is airing separate programs on each frequency. He said in the IARUMS September newsletter that telecommunications regulators in Germany, Austria and Switzerland have been informed, so they could file official complaints.
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.