Many thanks to SWLing Post contributor, David Iurescia, who shares the following news from The Japan News:
Shortwave Radio for Japanese Abductees Faces Crisis
Tokyo, Dec. 31 (Jiji Press)—The Shiokaze shortwave radio service for Japanese nationals abducted to North Korea faces a crisis because it will be unable to counter jamming by Pyongyang during facility renewal work in fiscal 2024.
The situation “contradicts the government’s policy of giving top priority to the abduction issue,” said the group playing the leading role in the radio broadcasts.
Shiokaze, which means sea breeze, began broadcasting in 2005, operated mainly by the Investigation Commission on Missing Japanese Probably Related to North Korea. It conveys messages from family members of abductees and news from Japan and abroad.
The radio is constantly hit by jamming signals from North Korea. Since 2019, Shiokaze has been conducting double broadcasting using two frequencies as a countermeasure.
Shiokaze’s transmission base is within KDDI Corp.’s Yamata transmitting station in Koga, Ibaraki Prefecture, eastern Japan.
The number of transmitters at the station will be reduced by two from the current seven partly due to the aging facility. There will be a period when double broadcasting is not possible during the work.
Japanese public broadcaster NHK, which uses the KDDI station as a base for its overseas radio services, said that work related to the transmitters will last up to 10 months from the second half of fiscal 2024.
“For a while during the work, Shiokaze is expected to broadcast on one frequency,” said an official of NHK, formally called Japan Broadcasting Corp.
“We recognize that the work is necessary in order to continue the two frequency system although (Shiokaze) will be a single frequency service temporarily,” then Chief Cabinet Secretary Hirokazu Matsuno told a meeting of a parliamentary special panel on the abduction issue Dec. 4, 2023.
Meanwhile, a Cabinet Secretariat official expressed concern, saying that “the risk of obstruction will increase more than ever,” albeit temporarily. [Continue reading…]
North Korea already transmits DRM in the same band
https://swling.com/blog/2022/10/mark-explores-north-korean-drm-broadcasts-over-shortwave/
https://www.redtech.pro/north-korea-doubles-digital-radio-output/
https://www.northkoreatech.org/2020/12/16/korean-central-radio-testing-digital-broadcasting/
DRM location 40° 14′ N 125° 49′ power 100 kW
Who and how many have DRM capable receivers is unknown
Joe,
I like your comment about the use of an SDR because they are able to filter out interference from an adjacent channel much better than the older receivers using either ceramic filters or even worse intermediate frequency coil & capacitor filters.
An even more reliable option would be Digital Radio Mondiale. All that is required that at the receiving site the DRM signal data is stronger than the AM sidebands then error correction will make the jamming inaudible. Remember that DRM data is virtually all the transmitted power where as AM the maximum volume the sound is only 33 % of the total transmitted power.
mangosman
The only issue is I imagine DRM receivers are pretty much non-existent among Japanese nationals trapped in North Korea. This is one of those instances where a more universal and accessible mode like AM has distinct advantages.
Calling the failed DRM system a “reliable” way of delivering information to North Korea is another level of delusion. DRM receivers are $300+ and average wages in NK are around $2. Leaving prices aside, we already know from the reports by the defectors that some of them used primitive homemade radios to get information from shortwave and mediumwave stations. DRM receiver cannot be assembled at home. Not to mention the fact that DRM signals are extremely easy to jam (as opposite to AM, where something will always get through, a DRM decoder will always fail when anything other than the desired signal appears on the frequency), which could be kind of beneficial for a country which is… hm, not really renowned for allowing free flow of information, to say the least. It would be a godsend for such tyrannical dictatorships like DPRK if the free world switched to a broadcasting system which could not be received by their citizens – like DRM.
Qwertyamdz.
Please update your information on DRM receiver prices. Firstly you quote dollars so it would appear to be a US dollar price imported into the USA from China and charging what the market will pay in an area of the world where there are no DRM broadcasts or any directed at North America.
Last year a receiver module which takes an antenna input and produces a speaker signal output priced at $US10 to manufacturers was released. It is in the latest Chinese Gospell receivers.
What you say about jamming has been proven untrue. AM jamming makes both signals audible simultaneously to make the jamee’s signal unintelligible. DRM the jamming signal is inaudible even if in DRM..This has been demonstrated in the past. Only if the jamming audio signal is stronger will the error rate exceed the ability of the receivers’ error correction and cause the receiver to mute. It was proven in South Africa that muting in MF DRM occurs when the MF AM signal from the same transmitter was unintelligible. The signal strength was measured in each case but the tests were sequential.
So please provide us with an update on the prices of receivers, not modules which are of no use for anyone other than the manufacturer. It’s a manipulation – I could use this argument to try to persuade you that an iPhone doesn’t really cost hundreds of dollars because the wholesale CPU prices are different. It’s absurd. For the customer, the only thing that matters is the price paid at the counter, not the price of individual components used to assemble a device.
The prices I’m quoting are from Aliexpress store which IIRC was linked in some of the other threads by someone else. If there’s any other business which sells these receivers on any of the domestic markets, please provide the info. But I think these markets are now limited to India, China (to some extent) and possibly the DPRK – so there’s not much of a space for competition anyway?
As for jamming, it is not true that “AM jamming makes both signals audible simultaneously to make the jamee’s signal unintelligible” – it depends on multiple factors including the propagation conditions. The proven historical fact is that VoA, Radio Free Europe et al. were able to get through the jamming conducted by USSR & its allies. Now the broadcasters who are targeting DPRK are doing the same and it has also been proved that the signals are getting through.
In case of DRM, the jamming station doesn’t even have to transmit on the same frequency, because DRM is not even resistant to co-channel interference. There are multiple topics on drmrx.org forum which confirm that, like “5970 kHz BBC WS Rampisham” and “KRTPC 6050 kHZ”, “DW on 9495 kHz” – quote: “The first 55 minutes or so were quite OK. Then a carrier on the same frequency popped up and made decoding almost impossible”, “DW Sines 11640 kHz 18.00-19.55” – another quote: “Rather bad with on-channel interference so that I got annoyed by the large number of dropouts and switched off” etc. For a DRM signal to be properly decoded, the selected frequency and its surroundings have to be almost crystal clean.
DRM was designed in a completely different geopolitical reality and resistance to jamming attempts conducted by authoritarian regimes was not considered. Something unthinkable today: at that time (before 2010), Deutsche Welle was even transmitting in DRM via Russian site located in Taldom near Moscow. Now the site is gone and DW, similar to the absolute majority of broadcasters, have abandoned DRM completely.
Does anyone know if they have ever confirmed reception of Japanese nationals actually hearing these broadcasts while in NK?
NHK should try and broadcast quite close to NK’s domestic frequencies. This might be helpful as the NKs would then obstruct their own programmes. But I am sure they will have thought about that, too.
I was able to listen to them and contact them last year via the Twente SDR.