We have a interfering signal on our amateurradio digimode 5357 KHz channel since a few weeks now. It is audible in Europe but also in the USA. I've seen very strong reports from stations, sometimes it is completely wiping away all the digimode FT8 signals from 5357. Annoying it is, and I've even seen some spots on the DXcluster calling it "PUTINRADAR" referring of course to Russian OHTR. But it is not a radar signal this time. It seems it is transmitted by a Israeli Naval station 4XZ from Haifa in Israel. The mode is called Israeli Navy Hybrid Modem (188-100 MOD) and was easily found using the sigidwiki signal identification guide. It is used as a broadcast transmitter to ships. Here is a recording from early this evening made just below the "FT8 channel":
Now, we know that we are 5MHz secondary users. The primary users are government and militairy stations around the world. The question is if we should continue transmitting on 60m with a naval station using almost the same frequency? Officialy we should stop all communication if a primary station is using the frequency. Although I'm not shure if they suffer any QRM from amateurradio FT8 signals? What do you think?
4 comments:
Hi Bas, in Germany, the Federal Network Agency explicitly points out that interference should be avoided. The maximum power should only be used if it is absolutely necessary to maintain the qso. The text of the law is clear: No interference may be caused to radio stations of another radio service and there is no protection against interference from radio stations of other radio services.
So this is the answer to your question:In Germany, we have to stop transmitting immediately if the primary users are using the frequency.
Since this is not done, it can happen very quickly that the 60m band is taken away from us again - as happened in New Zealand.
73 Ham, DB6LL
The strange thing is that I didn't see the signal anymore after this recording. But probabely the same is counting everywere in the world. We are not the primary users so we should be silent if the frequency is in use. Unfortunately, we as licensed radioamateurs, all think we are king of the bands. Well, let's hope we can keep 60m....73, Bas
Hallo Bas, Het kan zomaar zijn, dat jij het signaal veel sterker ontvangt, dan het station waarvoor de uitzending bedoeld is. Bijvoorbeeld, omdat jij één mooie hop verderop zit. Radio amateurs luisteren ook voor ze gaan zenden. Dat hoeft niet te gelden voor de Radio operator, die aan de lopende band telegrammen of andere boodschappen verstuurt. Het lijkt mij raadzaam om botsingen te voorkomen. 73, Bert
Hallo Bert, radio amateurs luisteren niet meer met FT8....ze kijken alleen maar naar een vrije plek in de waterval. Het kan inderdaad zijn dat het ontvangende station zelfs niet eens de boodschappen ontvangt omdat radioamateurs het storen met hun FT8 signalen. Als zo een station als 4XZ een klacht deponeert bij de ITU dan zou het inderdaad einde 60m toegang kunnen zijn! 73, Bas
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